Guile-OpenGL: Low-Level GLX

5.3 Low-Level GLX

The functions from this section may be had by loading the module:

(use-modules (glx low-level)

This section of the manual was derived from the upstream OpenGL documentation. Each function’s documentation has its own copyright statement; for full details, see the upstream documentation. The copyright notices and licenses present in this section are as follows.

Function: GLXFBConfig-* glXChooseFBConfig dpy screen attrib_list nelements

Return a list of GLX frame buffer configurations that match the specified attributes.

dpy: Specifies the connection to the X server.
screen: Specifies the screen number.
attrib_list: Specifies a list of attribute/value pairs. The last attribute must be None.
nelements: Returns the number of elements in the list returned by glXChooseFBConfig.

glXChooseFBConfig returns GLX frame buffer configurations that match the attributes specified in attrib_list, or NULL if no matches are found. If attrib_list is NULL, then glXChooseFBConfig returns an array of GLX frame buffer configurations that are available on the specified screen. If an error occurs, no frame buffer configurations exist on the specified screen, or if no frame buffer configurations match the specified attributes, then NULL is returned. Use XFree to free the memory returned by glXChooseFBConfig.

All attributes in attrib_list, including boolean attributes, are immediately followed by the corresponding desired value. The list is terminated with None. If an attribute is not specified in attrib_list, then the default value (see below) is used (and the attribute is said to be specified implicitly). For example, if GLX_STEREO is not specified, then it is assumed to be False. For some attributes, the default is GLX_DONT_CARE, meaning that any value is OK for this attribute, so the attribute will not be checked.

Attributes are matched in an attribute-specific manner. Some of the attributes, such as GLX_LEVEL, must match the specified value exactly; others, such as, GLX_RED_SIZE must meet or exceed the specified minimum values. If more than one GLX frame buffer configuration is found, then a list of configurations, sorted according to the “best” match criteria, is returned. The match criteria for each attribute and the exact sorting order is defined below.

The interpretations of the various GLX visual attributes are as follows:

GLX_FBCONFIG_ID: Must be followed by a valid XID that indicates the desired GLX frame buffer configuration. When a GLX_FBCONFIG_ID is specified, all attributes are ignored. The default value is GLX_DONT_CARE.
GLX_BUFFER_SIZE: Must be followed by a nonnegative integer that indicates the desired color index buffer size. The smallest index buffer of at least the specified size is preferred. This attribute is ignored if GLX_COLOR_INDEX_BIT is not set in GLX_RENDER_TYPE. The default value is 0.
GLX_LEVEL: Must be followed by an integer buffer-level specification. This specification is honored exactly. Buffer level 0 corresponds to the default frame buffer of the display. Buffer level 1 is the first overlay frame buffer, level two the second overlay frame buffer, and so on. Negative buffer levels correspond to underlay frame buffers. The default value is 0.
GLX_DOUBLEBUFFER: Must be followed by True or False. If True is specified, then only double-buffered frame buffer configurations are considered; if False is specified, then only single-buffered frame buffer configurations are considered. The default value is GLX_DONT_CARE.
GLX_STEREO: Must be followed by True or False. If True is specified, then only stereo frame buffer configurations are considered; if False is specified, then only monoscopic frame buffer configurations are considered. The default value is False.
GLX_AUX_BUFFERS: Must be followed by a nonnegative integer that indicates the desired number of auxiliary buffers. Configurations with the smallest number of auxiliary buffers that meet or exceed the specified number are preferred. The default value is 0.
GLX_RED_SIZE, GLX_GREEN_SIZE, GLX_BLUE_SIZE, GLX_ALPHA_SIZE: Each attribute, if present, must be followed by a nonnegative minimum size specification or GLX_DONT_CARE. The largest available total RGBA color buffer size (sum of GLX_RED_SIZE, GLX_GREEN_SIZE, GLX_BLUE_SIZE, and GLX_ALPHA_SIZE) of at least the minimum size specified for each color component is preferred. If the requested number of bits for a color component is 0 or GLX_DONT_CARE, it is not considered. The default value for each color component is 0.
GLX_DEPTH_SIZE: Must be followed by a nonnegative minimum size specification. If this value is zero, frame buffer configurations with no depth buffer are preferred. Otherwise, the largest available depth buffer of at least the minimum size is preferred. The default value is 0.
GLX_STENCIL_SIZE: Must be followed by a nonnegative integer that indicates the desired number of stencil bitplanes. The smallest stencil buffer of at least the specified size is preferred. If the desired value is zero, frame buffer configurations with no stencil buffer are preferred. The default value is 0.
GLX_ACCUM_RED_SIZE: Must be followed by a nonnegative minimum size specification. If this value is zero, frame buffer configurations with no red accumulation buffer are preferred. Otherwise, the largest possible red accumulation buffer of at least the minimum size is preferred. The default value is 0.
GLX_ACCUM_GREEN_SIZE: Must be followed by a nonnegative minimum size specification. If this value is zero, frame buffer configurations with no green accumulation buffer are preferred. Otherwise, the largest possible green accumulation buffer of at least the minimum size is preferred. The default value is 0.
GLX_ACCUM_BLUE_SIZE: Must be followed by a nonnegative minimum size specification. If this value is zero, frame buffer configurations with no blue accumulation buffer are preferred. Otherwise, the largest possible blue accumulation buffer of at least the minimum size is preferred. The default value is 0.
GLX_ACCUM_ALPHA_SIZE: Must be followed by a nonnegative minimum size specification. If this value is zero, frame buffer configurations with no alpha accumulation buffer are preferred. Otherwise, the largest possible alpha accumulation buffer of at least the minimum size is preferred. The default value is 0.
GLX_RENDER_TYPE: Must be followed by a mask indicating which OpenGL rendering modes the frame buffer configuration must support. Valid bits are GLX_RGBA_BIT and GLX_COLOR_INDEX_BIT. If the mask is set to GLX_RGBA_BIT | GLX_COLOR_INDEX_BIT, then only frame buffer configurations that can be bound to both RGBA contexts and color index contexts will be considered. The default value is GLX_RGBA_BIT.
GLX_DRAWABLE_TYPE: Must be followed by a mask indicating which GLX drawable types the frame buffer configuration must support. Valid bits are GLX_WINDOW_BIT, GLX_PIXMAP_BIT, and GLX_PBUFFER_BIT. For example, if mask is set to GLX_WINDOW_BIT | GLX_PIXMAP_BIT, only frame buffer configurations that support both windows and GLX pixmaps will be considered. The default value is GLX_WINDOW_BIT.
GLX_X_RENDERABLE: Must be followed by True or False. If True is specified, then only frame buffer configurations that have associated X visuals (and can be used to render to Windows and/or GLX pixmaps) will be considered. The default value is GLX_DONT_CARE.
GLX_X_VISUAL_TYPE: Must be followed by one of GLX_TRUE_COLOR, GLX_DIRECT_COLOR, GLX_PSEUDO_COLOR, GLX_STATIC_COLOR, GLX_GRAY_SCALE, or GLX_STATIC_GRAY, indicating the desired X visual type. Not all frame buffer configurations have an associated X visual. If GLX_DRAWABLE_TYPE is specified in attrib_list and the mask that follows does not have GLX_WINDOW_BIT set, then this value is ignored. It is also ignored if GLX_X_RENDERABLE is specified as False. RGBA rendering may be supported for visuals of type GLX_TRUE_COLOR, GLX_DIRECT_COLOR, GLX_PSEUDO_COLOR, or GLX_STATIC_COLOR, but color index rendering is only supported for visuals of type GLX_PSEUDO_COLOR or GLX_STATIC_COLOR (i.e., single-channel visuals). The tokens GLX_GRAY_SCALE and GLX_STATIC_GRAY will not match current OpenGL enabled visuals, but are included for future use. The default value for GLX_X_VISUAL_TYPE is GLX_DONT_CARE.
GLX_CONFIG_CAVEAT: Must be followed by one of GLX_NONE, GLX_SLOW_CONFIG, GLX_NON_CONFORMANT_CONFIG. If GLX_NONE is specified, then only frame buffer configurations with no caveats will be considered; if GLX_SLOW_CONFIG is specified, then only slow frame buffer configurations will be considered; if GLX_NON_CONFORMANT_CONFIG is specified, then only nonconformant frame buffer configurations will be considered. The default value is GLX_DONT_CARE.
GLX_TRANSPARENT_TYPE: Must be followed by one of GLX_NONE, GLX_TRANSPARENT_RGB, GLX_TRANSPARENT_INDEX. If GLX_NONE is specified, then only opaque frame buffer configurations will be considered; if GLX_TRANSPARENT_RGB is specified, then only transparent frame buffer configurations that support RGBA rendering will be considered; if GLX_TRANSPARENT_INDEX is specified, then only transparent frame buffer configurations that support color index rendering will be considered. The default value is GLX_NONE.
GLX_TRANSPARENT_INDEX_VALUE: Must be followed by an integer value indicating the transparent index value; the value must be between 0 and the maximum frame buffer value for indices. Only frame buffer configurations that use the specified transparent index value will be considered. The default value is GLX_DONT_CARE. This attribute is ignored unless GLX_TRANSPARENT_TYPE is included in attrib_list and specified as GLX_TRANSPARENT_INDEX.
GLX_TRANSPARENT_RED_VALUE: Must be followed by an integer value indicating the transparent red value; the value must be between 0 and the maximum frame buffer value for red. Only frame buffer configurations that use the specified transparent red value will be considered. The default value is GLX_DONT_CARE. This attribute is ignored unless GLX_TRANSPARENT_TYPE is included in attrib_list and specified as GLX_TRANSPARENT_RGB.
GLX_TRANSPARENT_GREEN_VALUE: Must be followed by an integer value indicating the transparent green value; the value must be between 0 and the maximum frame buffer value for green. Only frame buffer configurations that use the specified transparent green value will be considered. The default value is GLX_DONT_CARE. This attribute is ignored unless GLX_TRANSPARENT_TYPE is included in attrib_list and specified as GLX_TRANSPARENT_RGB.
GLX_TRANSPARENT_BLUE_VALUE: Must be followed by an integer value indicating the transparent blue value; the value must be between 0 and the maximum frame buffer value for blue. Only frame buffer configurations that use the specified transparent blue value will be considered. The default value is GLX_DONT_CARE. This attribute is ignored unless GLX_TRANSPARENT_TYPE is included in attrib_list and specified as GLX_TRANSPARENT_RGB.
GLX_TRANSPARENT_ALPHA_VALUE: Must be followed by an integer value indicating the transparent alpha value; the value must be between 0 and the maximum frame buffer value for alpha. Only frame buffer configurations that use the specified transparent alpha value will be considered. The default value is GLX_DONT_CARE.

When more than one GLX frame buffer configuration matches the specified attributes, a list of matching configurations is returned. The list is sorted according to the following precedence rules, which are applied in ascending order (i.e., configurations that are considered equal by a lower numbered rule are sorted by the higher numbered rule):

1.: By GLX_CONFIG_CAVEAT where the precedence is GLX_NONE, GLX_SLOW_CONFIG, and GLX_NON_CONFORMANT_CONFIG.
2.: Larger total number of RGBA color components (GLX_RED_SIZE, GLX_GREEN_SIZE, GLX_BLUE_SIZE, plus GLX_ALPHA_SIZE) that have higher number of bits. If the requested number of bits in attrib_list is zero or GLX_DONT_CARE for a particular color component, then the number of bits for that component is not considered.
3.: Smaller GLX_BUFFER_SIZE.
4.: Single buffered configuration (GLX_DOUBLEBUFFER being False precedes a double buffered one.
5.: Smaller GLX_AUX_BUFFERS.
6.: Larger GLX_DEPTH_SIZE.
7.: Smaller GLX_STENCIL_SIZE.
8.: Larger total number of accumulation buffer color components (GLX_ACCUM_RED_SIZE, GLX_ACCUM_GREEN_SIZE, GLX_ACCUM_BLUE_SIZE, plus GLX_ACCUM_ALPHA_SIZE) that have higher number of bits. If the requested number of bits in attrib_list is zero or GLX_DONT_CARE for a particular color component, then the number of bits for that component is not considered.
9.: By GLX_X_VISUAL_TYPE where the precedence order is GLX_TRUE_COLOR, GLX_DIRECT_COLOR, GLX_PSEUDO_COLOR, GLX_STATIC_COLOR, GLX_GRAY_SCALE, GLX_STATIC_GRAY.

NULL is returned if an undefined GLX attribute is encountered in attrib_list, if screen is invalid, or if dpy does not support the GLX extension.

Function: XVisualInfo* glXChooseVisual dpy screen attribList

Return a visual that matches specified attributes.

dpy: Specifies the connection to the X server.
screen: Specifies the screen number.
attribList: Specifies a list of boolean attributes and integer attribute/value pairs. The last attribute must be None.

glXChooseVisual returns a pointer to an XVisualInfo structure describing the visual that best meets a minimum specification. The boolean GLX attributes of the visual that is returned will match the specified values, and the integer GLX attributes will meet or exceed the specified minimum values. If all other attributes are equivalent, then TrueColor and PseudoColor visuals have priority over DirectColor and StaticColor visuals, respectively. If no conforming visual exists, NULL is returned. To free the data returned by this function, use XFree.

All boolean GLX attributes default to False except GLX_USE_GL, which defaults to True. All integer GLX attributes default to zero. Default specifications are superseded by attributes included in attribList. Boolean attributes included in attribList are understood to be True. Integer attributes and enumerated type attributes are followed immediately by the corresponding desired or minimum value. The list must be terminated with None.

The interpretations of the various GLX visual attributes are as follows:

GLX_USE_GL: Ignored. Only visuals that can be rendered with GLX are considered.
GLX_BUFFER_SIZE: Must be followed by a nonnegative integer that indicates the desired color index buffer size. The smallest index buffer of at least the specified size is preferred. Ignored if GLX_RGBA is asserted.
GLX_LEVEL: Must be followed by an integer buffer-level specification. This specification is honored exactly. Buffer level zero corresponds to the main frame buffer of the display. Buffer level one is the first overlay frame buffer, level two the second overlay frame buffer, and so on. Negative buffer levels correspond to underlay frame buffers.
GLX_RGBA: If present, only TrueColor and DirectColor visuals are considered. Otherwise, only PseudoColor and StaticColor visuals are considered.
GLX_DOUBLEBUFFER: If present, only double-buffered visuals are considered. Otherwise, only single-buffered visuals are considered.
GLX_STEREO: If present, only stereo visuals are considered. Otherwise, only monoscopic visuals are considered.
GLX_AUX_BUFFERS: Must be followed by a nonnegative integer that indicates the desired number of auxiliary buffers. Visuals with the smallest number of auxiliary buffers that meets or exceeds the specified number are preferred.
GLX_RED_SIZE: Must be followed by a nonnegative minimum size specification. If this value is zero, the smallest available red buffer is preferred. Otherwise, the largest available red buffer of at least the minimum size is preferred.
GLX_GREEN_SIZE: Must be followed by a nonnegative minimum size specification. If this value is zero, the smallest available green buffer is preferred. Otherwise, the largest available green buffer of at least the minimum size is preferred.
GLX_BLUE_SIZE: Must be followed by a nonnegative minimum size specification. If this value is zero, the smallest available blue buffer is preferred. Otherwise, the largest available blue buffer of at least the minimum size is preferred.
GLX_ALPHA_SIZE: Must be followed by a nonnegative minimum size specification. If this value is zero, the smallest available alpha buffer is preferred. Otherwise, the largest available alpha buffer of at least the minimum size is preferred.
GLX_DEPTH_SIZE: Must be followed by a nonnegative minimum size specification. If this value is zero, visuals with no depth buffer are preferred. Otherwise, the largest available depth buffer of at least the minimum size is preferred.
GLX_STENCIL_SIZE: Must be followed by a nonnegative integer that indicates the desired number of stencil bitplanes. The smallest stencil buffer of at least the specified size is preferred. If the desired value is zero, visuals with no stencil buffer are preferred.
GLX_ACCUM_RED_SIZE: Must be followed by a nonnegative minimum size specification. If this value is zero, visuals with no red accumulation buffer are preferred. Otherwise, the largest possible red accumulation buffer of at least the minimum size is preferred.
GLX_ACCUM_GREEN_SIZE: Must be followed by a nonnegative minimum size specification. If this value is zero, visuals with no green accumulation buffer are preferred. Otherwise, the largest possible green accumulation buffer of at least the minimum size is preferred.
GLX_ACCUM_BLUE_SIZE: Must be followed by a nonnegative minimum size specification. If this value is zero, visuals with no blue accumulation buffer are preferred. Otherwise, the largest possible blue accumulation buffer of at least the minimum size is preferred.
GLX_ACCUM_ALPHA_SIZE: Must be followed by a nonnegative minimum size specification. If this value is zero, visuals with no alpha accumulation buffer are preferred. Otherwise, the largest possible alpha accumulation buffer of at least the minimum size is preferred.

NULL is returned if an undefined GLX attribute is encountered in attribList.

Function: void glXCopyContext dpy src dst mask

Copy state from one rendering context to another.

dpy: Specifies the connection to the X server.
src: Specifies the source context.
dst: Specifies the destination context.
mask: Specifies which portions of src state are to be copied to dst.

glXCopyContext copies selected groups of state variables from src to dst. mask indicates which groups of state variables are to be copied. mask contains the bitwise OR of the same symbolic names that are passed to the GL command glPushAttrib. The single symbolic constant GLX_ALL_ATTRIB_BITS can be used to copy the maximum possible portion of rendering state.

The copy can be done only if the renderers named by src and dst share an address space. Two rendering contexts share an address space if both are nondirect using the same server, or if both are direct and owned by a single process. Note that in the nondirect case it is not necessary for the calling threads to share an address space, only for their related rendering contexts to share an address space.

Not all values for GL state can be copied. For example, pixel pack and unpack state, render mode state, and select and feedback state are not copied. The state that can be copied is exactly the state that is manipulated by the GL command glPushAttrib.

An implicit glFlush is done by glXCopyContext if src is the current context for the calling thread.

BadMatch is generated if rendering contexts src and dst do not share an address space or were not created with respect to the same screen.

BadAccess is generated if dst is current to any thread (including the calling thread) at the time glXCopyContext is called.

GLXBadCurrentWindow is generated if src is the current context and the current drawable is a window that is no longer valid.

GLXBadContext is generated if either src or dst is not a valid GLX context.

Function: GLXContext glXCreateContext dpy vis shareList direct

Create a new GLX rendering context.

dpy: Specifies the connection to the X server.
vis: Specifies the visual that defines the frame buffer resources available to the rendering context. It is a pointer to an XVisualInfo structure, not a visual ID or a pointer to a Visual.
shareList: Specifies the context with which to share display lists. NULL indicates that no sharing is to take place.
direct: Specifies whether rendering is to be done with a direct connection to the graphics system if possible (True) or through the X server (False).

glXCreateContext creates a GLX rendering context and returns its handle. This context can be used to render into both windows and GLX pixmaps. If glXCreateContext fails to create a rendering context, NULL is returned.

If direct is True, then a direct rendering context is created if the implementation supports direct rendering, if the connection is to an X server that is local, and if a direct rendering context is available. (An implementation may return an indirect context when direct is True.) If direct is False, then a rendering context that renders through the X server is always created. Direct rendering provides a performance advantage in some implementations. However, direct rendering contexts cannot be shared outside a single process, and they may be unable to render to GLX pixmaps.

If shareList is not NULL, then all display-list indexes and definitions are shared by context shareList and by the newly created context. An arbitrary number of contexts can share a single display-list space. However, all rendering contexts that share a single display-list space must themselves exist in the same address space. Two rendering contexts share an address space if both are nondirect using the same server, or if both are direct and owned by a single process. Note that in the nondirect case, it is not necessary for the calling threads to share an address space, only for their related rendering contexts to share an address space.

If the GL version is 1.1 or greater, then all texture objects except object 0 are shared by any contexts that share display lists.

NULL is returned if execution fails on the client side.

BadMatch is generated if the context to be created would not share the address space or the screen of the context specified by shareList.

BadValue is generated if vis is not a valid visual (for example, if a particular GLX implementation does not support it).

GLXBadContext is generated if shareList is not a GLX context and is not NULL.

BadAlloc is generated if the server does not have enough resources to allocate the new context.

Function: GLXPixmap glXCreateGLXPixmap dpy vis pixmap

Create an off-screen GLX rendering area.

dpy: Specifies the connection to the X server.
vis: Specifies the visual that defines the structure of the rendering area. It is a pointer to an XVisualInfo structure, not a visual ID or a pointer to a Visual.
pixmap: Specifies the X pixmap that will be used as the front left color buffer of the off-screen rendering area.

glXCreateGLXPixmap creates an off-screen rendering area and returns its XID. Any GLX rendering context that was created with respect to vis can be used to render into this off-screen area. Use glXMakeCurrent to associate the rendering area with a GLX rendering context.

The X pixmap identified by pixmap is used as the front left buffer of the resulting off-screen rendering area. All other buffers specified by vis, including color buffers other than the front left buffer, are created without externally visible names. GLX pixmaps with double-buffering are supported. However, glXSwapBuffers is ignored by these pixmaps.

Some implementations may not support GLX pixmaps with direct rendering contexts.

BadMatch is generated if the depth of pixmap does not match the depth value reported by core X11 for vis, or if pixmap was not created with respect to the same screen as vis.

BadValue is generated if vis is not a valid XVisualInfo pointer (for example, if a particular GLX implementation does not support this visual).

BadPixmap is generated if pixmap is not a valid pixmap.

BadAlloc is generated if the server cannot allocate the GLX pixmap.

Function: GLXContext glXCreateNewContext dpy config render_type share_list direct

Create a new GLX rendering context.

dpy: Specifies the connection to the X server.
config: Specifies the GLXFBConfig structure with the desired attributes for the context.
render_type: Specifies the type of the context to be created. Must be one of GLX_RGBA_TYPE or GLX_COLOR_INDEX_TYPE.
share_list: Specifies the context with which to share display lists. NULL indicates that no sharing is to take place.
share_list: Specifies whether rendering is to be done with a direct connection to the graphics system if possible (True) or through the X server (False).

glXCreateNewContext creates a GLX rendering context and returns its handle. This context can be used to render into GLX windows, pixmaps, or pixel buffers. If glXCreateNewContext fails to create a rendering context, NULL is returned.

If render_type is GLX_RGBA_TYPE, then a context that supports RGBA rendering is created. If config is GLX_COLOR_INDEX_TYPE, then context supporting color-index rendering is created.

If render_type is not NULL, then all display-list indexes and definitions are shared by context render_type and by the newly created context. An arbitrary number of contexts can share a single display-list space. However, all rendering contexts that share a single display-list space must themselves exist in the same address space. Two rendering contexts share an address space if both are nondirect using the same server, or if both are direct and owned by a single process. Note that in the nondirect case, it is not necessary for the calling threads to share an address space, only for their related rendering contexts to share an address space.

If share_list is True, then a direct-rendering context is created if the implementation supports direct rendering, if the connection is to an X server that is local, and if a direct-rendering context is available. (An implementation may return an indirect context when share_list is True.) If share_list is False, then a rendering context that renders through the X server is always created. Direct rendering provides a performance advantage in some implementations. However, direct-rendering contexts cannot be shared outside a single process, and they may be unable to render to GLX pixmaps.

NULL is returned if execution fails on the client side.

GLXBadContext is generated if render_type is not a GLX context and is not NULL.

GLXBadFBConfig is generated if config is not a valid GLXFBConfig.

BadMatch is generated if the context to be created would not share the address space or the screen of the context specified by render_type.

BadAlloc is generated if the server does not have enough resources to allocate the new context.

BadValue is generated if config is not a valid visual (for example, if a particular GLX implementation does not support it).

Function: GLXPbuffer glXCreatePbuffer dpy config attrib_list

Create an off-screen rendering area.

dpy: Specifies the connection to the X server.
config: Specifies a GLXFBConfig structure with the desired attributes for the window.
attrib_list: Specifies a list of attribute value pairs, which must be terminated with None or NULL. Accepted attributes are GLX_PBUFFER_WIDTH, GLX_PBUFFER_HEIGHT, GLX_PRESERVED_CONTENTS, and GLX_LARGEST_PBUFFER.

glXCreatePbuffer creates an off-screen rendering area and returns its XID. Any GLX rendering context that was created with respect to config can be used to render into this window. Use glXMakeContextCurrent to associate the rendering area with a GLX rendering context.

The accepted attributes for a GLXPbuffer are:

GLX_PBUFFER_WIDTH: Specify the pixel width of the requested GLXPbuffer. The default value is 0.
GLX_PBUFFER_HEIGHT: Specify the pixel height of the requested GLXPbuffer. The default value is 0.
GLX_LARGEST_PBUFFER: Specify to obtain the largest available pixel buffer, if the requested allocation would have failed. The width and height of the allocated pixel buffer will never exceed the specified GLX_PBUFFER_WIDTH or GLX_PBUFFER_HEIGHT, respectively. Use glXQueryDrawable to retrieve the dimensions of the allocated pixel buffer. The default value is False.
GLX_PRESERVED_CONTENTS: Specify if the contents of the pixel buffer should be preserved when a resource conflict occurs. If set to False, the contents of the pixel buffer may be lost at any time. If set to True, or not specified in attrib_list, then the contents of the pixel buffer will be preserved (most likely by copying the contents into main system memory from the frame buffer). In either case, the client can register (using glXSelectEvent, to receive pixel buffer clobber events that are generated when the pbuffer contents have been preserved or damaged.

GLXPbuffers contain the color and ancillary buffers specified by config. It is possible to create a pixel buffer with back buffers and to swap those buffers using glXSwapBuffers.

BadAlloc is generated if there are insufficient resources to allocate the requested GLXPbuffer.

GLXBadFBConfig is generated if config is not a valid GLXFBConfig.

BadMatch is generated if config does not support rendering to pixel buffers (e.g., GLX_DRAWABLE_TYPE does not contain GLX_PBUFFER_BIT).

Function: GLXPixmap glXCreatePixmap dpy config pixmap attrib_list

Create an off-screen rendering area.

dpy: Specifies the connection to the X server.
config: Specifies a GLXFBConfig structure with the desired attributes for the window.
pixmap: Specifies the X pixmap to be used as the rendering area.
attrib_list: Currently unused. This must be set to NULL or be an empty list (i.e., one in which the first element is None).

glXCreatePixmap creates an off-screen rendering area and returns its XID. Any GLX rendering context that was created with respect to config can be used to render into this window. Use glXMakeCurrent to associate the rendering area with a GLX rendering context.

BadMatch is generated if pixmap was not created with a visual that corresponds to config.

BadMatch is generated if config does not support rendering to windows (e.g., GLX_DRAWABLE_TYPE does not contain GLX_WINDOW_BIT).

BadWindow is generated if pixmap is not a valid window XID. BadAlloc is generated if there is already a GLXFBConfig associated with pixmap.

BadAlloc is generated if the X server cannot allocate a new GLX window.

GLXBadFBConfig is generated if config is not a valid GLXFBConfig.

Function: GLXWindow glXCreateWindow dpy config win attrib_list

Create an on-screen rendering area.

dpy: Specifies the connection to the X server.
config: Specifies a GLXFBConfig structure with the desired attributes for the window.
win: Specifies the X window to be used as the rendering area.
attrib_list: Currently unused. This must be set to NULL or be an empty list (i.e., one in which the first element is None).

glXCreateWindow creates an on-screen rendering area from an existing X window that was created with a visual matching config. The XID of the GLXWindow is returned. Any GLX rendering context that was created with respect to config can be used to render into this window. Use glXMakeContextCurrent to associate the rendering area with a GLX rendering context.

BadMatch is generated if win was not created with a visual that corresponds to config.

BadMatch is generated if config does not support rendering to windows (i.e., GLX_DRAWABLE_TYPE does not contain GLX_WINDOW_BIT).

BadWindow is generated if win is not a valid pixmap XID.

BadAlloc is generated if there is already a GLXFBConfig associated with win.

BadAlloc is generated if the X server cannot allocate a new GLX window.

GLXBadFBConfig is generated if config is not a valid GLXFBConfig.

Function: void glXDestroyContext dpy ctx

Destroy a GLX context.

dpy: Specifies the connection to the X server.
ctx: Specifies the GLX context to be destroyed.

If the GLX rendering context ctx is not current to any thread, glXDestroyContext destroys it immediately. Otherwise, ctx is destroyed when it becomes not current to any thread. In either case, the resource ID referenced by ctx is freed immediately.

GLXBadContext is generated if ctx is not a valid GLX context.

Function: void glXDestroyGLXPixmap dpy pix

Destroy a GLX pixmap.

dpy: Specifies the connection to the X server.
pix: Specifies the GLX pixmap to be destroyed.

If the GLX pixmap pix is not current to any client, glXDestroyGLXPixmap destroys it immediately. Otherwise, pix is destroyed when it becomes not current to any client. In either case, the resource ID is freed immediately.

GLXBadPixmap is generated if pix is not a valid GLX pixmap.

Function: void glXDestroyPbuffer dpy pbuf

Destroy an off-screen rendering area.

dpy: Specifies the connection to the X server.
pbuf: Specifies the GLXPbuffer to be destroyed.

glXDestroyPbuffer destroys a GLXPbuffer created by glXCreatePbuffer.

GLXBadPbuffer is generated if pbuf is not a valid GLXPbuffer.

Function: void glXDestroyPixmap dpy pixmap

Destroy an off-screen rendering area.

dpy: Specifies the connection to the X server.
pixmap: Specifies the GLXPixmap to be destroyed.

glXDestroyPixmap destroys a GLXPixmap created by glXCreatePixmap.

GLXBadPixmap is generated if pixmap is not a valid GLXPixmap.

Function: void glXDestroyWindow dpy win

Destroy an on-screen rendering area.

dpy: Specifies the connection to the X server.
win: Specifies the GLXWindow to be destroyed.

glXDestroyWindow destroys a GLXWindow created by glXCreateWindow.

GLXBadWindow is generated if win is not a valid GLXPixmap.

Function: void glXFreeContextEXT dpy ctx

Free client-side memory for imported context.

dpy: Specifies the connection to the X server.
ctx: Specifies a GLX rendering context.

glXFreeContextEXT frees the client-side part of a GLXContext that was created with glXImportContextEXT. glXFreeContextEXT does not free the server-side context information or the XID associated with the server-side context.

glXFreeContextEXT is part of the EXT_import_context extension, not part of the core GLX command set. If _glxextstring(EXT_import_context) is included in the string returned by glXQueryExtensionsString, when called with argument GLX_EXTENSIONS, extension EXT_vertex_array is supported.

GLXBadContext is generated if ctx does not refer to a valid context.

Function: const-char-* glXGetClientString dpy name

Return a string describing the client.

dpy: Specifies the connection to the X server.
name: Specifies which string is returned. The symbolic constants GLX_VENDOR, GLX_VERSION, and GLX_EXTENSIONS are accepted.

glXGetClientString returns a string describing some aspect of the client library. The possible values for name are GLX_VENDOR, GLX_VERSION, and GLX_EXTENSIONS. If name is not set to one of these values, glXGetClientString returns NULL. The format and contents of the vendor string is implementation dependent.

The extensions string is null-terminated and contains a space-separated list of extension names. (The extension names never contain spaces.) If there are no extensions to GLX, then the empty string is returned.

The version string is laid out as follows:

<major_version.minor_version><space><vendor-specific info>

Both the major and minor portions of the version number are of arbitrary length. The vendor-specific information is optional. However, if it is present, the format and contents are implementation specific.

Function: int glXGetConfig dpy vis attrib value

Return information about GLX visuals.

dpy: Specifies the connection to the X server.
vis: Specifies the visual to be queried. It is a pointer to an XVisualInfo structure, not a visual ID or a pointer to a Visual.
attrib: Specifies the visual attribute to be returned.
value: Returns the requested value.

glXGetConfig sets value to the attrib value of windows or GLX pixmaps created with respect to vis. glXGetConfig returns an error code if it fails for any reason. Otherwise, zero is returned.

attrib is one of the following:

GLX_USE_GL: True if OpenGL rendering is supported by this visual, False otherwise.
GLX_BUFFER_SIZE: Number of bits per color buffer. For RGBA visuals, GLX_BUFFER_SIZE is the sum of GLX_RED_SIZE, GLX_GREEN_SIZE, GLX_BLUE_SIZE, and GLX_ALPHA_SIZE. For color index visuals, GLX_BUFFER_SIZE is the size of the color indexes.
GLX_LEVEL: Frame buffer level of the visual. Level zero is the default frame buffer. Positive levels correspond to frame buffers that overlay the default buffer, and negative levels correspond to frame buffers that underlay the default buffer.
GLX_RGBA: True if color buffers store red, green, blue, and alpha values. False if they store color indexes.
GLX_DOUBLEBUFFER: True if color buffers exist in front/back pairs that can be swapped, False otherwise.
GLX_STEREO: True if color buffers exist in left/right pairs, False otherwise.
GLX_AUX_BUFFERS: Number of auxiliary color buffers that are available. Zero indicates that no auxiliary color buffers exist.
GLX_RED_SIZE: Number of bits of red stored in each color buffer. Undefined if GLX_RGBA is False.
GLX_GREEN_SIZE: Number of bits of green stored in each color buffer. Undefined if GLX_RGBA is False.
GLX_BLUE_SIZE: Number of bits of blue stored in each color buffer. Undefined if GLX_RGBA is False.
GLX_ALPHA_SIZE: Number of bits of alpha stored in each color buffer. Undefined if GLX_RGBA is False.
GLX_DEPTH_SIZE: Number of bits in the depth buffer.
GLX_STENCIL_SIZE: Number of bits in the stencil buffer.
GLX_ACCUM_RED_SIZE: Number of bits of red stored in the accumulation buffer.
GLX_ACCUM_GREEN_SIZE: Number of bits of green stored in the accumulation buffer.
GLX_ACCUM_BLUE_SIZE: Number of bits of blue stored in the accumulation buffer.
GLX_ACCUM_ALPHA_SIZE: Number of bits of alpha stored in the accumulation buffer.

The X protocol allows a single visual ID to be instantiated with different numbers of bits per pixel. Windows or GLX pixmaps that will be rendered with OpenGL, however, must be instantiated with a color buffer depth of GLX_BUFFER_SIZE.

Although a GLX implementation can export many visuals that support GL rendering, it must support at least one RGBA visual. This visual must have at least one color buffer, a stencil buffer of at least 1 bit, a depth buffer of at least 12 bits, and an accumulation buffer. Alpha bitplanes are optional in this visual. However, its color buffer size must be as great as that of the deepest TrueColor, DirectColor, PseudoColor, or StaticColor visual supported on level zero, and it must itself be made available on level zero.

In addition, if the X server exports a PseudoColor or StaticColor visual on framebuffer level 0, a color index visual is also required on that level. It must have at least one color buffer, a stencil buffer of at least 1 bit, and a depth buffer of at least 12 bits. This visual must have as many color bitplanes as the deepest PseudoColor or StaticColor visual supported on level 0.

Applications are best written to select the visual that most closely meets their requirements. Creating windows or GLX pixmaps with unnecessary buffers can result in reduced rendering performance as well as poor resource allocation.

GLX_NO_EXTENSION is returned if dpy does not support the GLX extension.

GLX_BAD_SCREEN is returned if the screen of vis does not correspond to a screen.

GLX_BAD_ATTRIBUTE is returned if attrib is not a valid GLX attribute.

GLX_BAD_VISUAL is returned if vis doesn’t support GLX and an attribute other than GLX_USE_GL is requested.

Function: GLXContextID glXGetContextIDEXT ctx

Get the XID for a context..

ctx: Specifies a GLX rendering context.

glXGetContextIDEXT returns the XID associated with a GLXContext.

No round trip is forced to the server; unlike most X calls that return a value, glXGetContextIDEXT does not flush any pending events.

glXGetContextIDEXT is part of the EXT_import_context extension, not part of the core GLX command set. If _glxextstring(EXT_import_context) is included in the string returned by glXQueryExtensionsString, when called with argument GLX_EXTENSIONS, extension EXT_import_context is supported.

GLXBadContext is generated if ctx does not refer to a valid context.

Function: GLXContext glXGetCurrentContext

Return the current context.

glXGetCurrentContext returns the current context, as specified by glXMakeCurrent. If there is no current context, NULL is returned.

glXGetCurrentContext returns client-side information. It does not make a round trip to the server.

Function: Display-* glXGetCurrentDisplay

Get display for current context.

glXGetCurrentDisplay returns the display for the current context. If no context is current, NULL is returned.

glXGetCurrentDisplay returns client-side information. It does not make a round-trip to the server, and therefore does not flush any pending events.

Function: GLXDrawable glXGetCurrentDrawable

Return the current drawable.

glXGetCurrentDrawable returns the current drawable, as specified by glXMakeCurrent. If there is no current drawable, None is returned.

glXGetCurrentDrawable returns client-side information. It does not make a round trip to the server.

Function: GLXDrawable glXGetCurrentReadDrawable

Return the current drawable.

glXGetCurrentReadDrawable returns the current read drawable, as specified by read parameter of glXMakeContextCurrent. If there is no current drawable, None is returned.

glXGetCurrentReadDrawable returns client-side information. It does not make a round-trip to the server.

Function: int glXGetFBConfigAttrib dpy config attribute value

Return information about a GLX frame buffer configuration.

dpy: Specifies the connection to the X server.
config: Specifies the GLX frame buffer configuration to be queried.
attribute: Specifies the attribute to be returned.
value: Returns the requested value.

glXGetFBConfigAttrib sets value to the attribute value of GLX drawables created with respect to config. glXGetFBConfigAttrib returns an error code if it fails for any reason. Otherwise, Success is returned.

attribute is one of the following:

GLX_FBCONFIG_ID: XID of the given GLXFBConfig.
GLX_BUFFER_SIZE: Number of bits per color buffer. If the frame buffer configuration supports RGBA contexts, then GLX_BUFFER_SIZE is the sum of GLX_RED_SIZE, GLX_GREEN_SIZE, GLX_BLUE_SIZE, and GLX_ALPHA_SIZE. If the frame buffer configuration supports only color index contexts, GLX_BUFFER_SIZE is the size of the color indexes.
GLX_LEVEL: Frame buffer level of the configuration. Level zero is the default frame buffer. Positive levels correspond to frame buffers that overlay the default buffer, and negative levels correspond to frame buffers that underlie the default buffer.
GLX_DOUBLEBUFFER: True if color buffers exist in front/back pairs that can be swapped, False otherwise.
GLX_STEREO: True if color buffers exist in left/right pairs, False otherwise.
GLX_AUX_BUFFERS: Number of auxiliary color buffers that are available. Zero indicates that no auxiliary color buffers exist.
GLX_RED_SIZE: Number of bits of red stored in each color buffer. Undefined if RGBA contexts are not supported by the frame buffer configuration.
GLX_GREEN_SIZE: Number of bits of green stored in each color buffer. Undefined if RGBA contexts are not supported by the frame buffer configuration.
GLX_BLUE_SIZE: Number of bits of blue stored in each color buffer. Undefined if RGBA contexts are not supported by the frame buffer configuration.
GLX_ALPHA_SIZE: Number of bits of alpha stored in each color buffer. Undefined if RGBA contexts are not supported by the frame buffer configuration.
GLX_DEPTH_SIZE: Number of bits in the depth buffer.
GLX_STENCIL_SIZE: Number of bits in the stencil buffer.
GLX_ACCUM_RED_SIZE: Number of bits of red stored in the accumulation buffer.
GLX_ACCUM_GREEN_SIZE: Number of bits of green stored in the accumulation buffer.
GLX_ACCUM_BLUE_SIZE: Number of bits of blue stored in the accumulation buffer.
GLX_ACCUM_ALPHA_SIZE: Number of bits of alpha stored in the accumulation buffer.
GLX_RENDER_TYPE: Mask indicating what type of GLX contexts can be made current to the frame buffer configuration. Valid bits are GLX_RGBA_BIT and GLX_COLOR_INDEX_BIT.
GLX_DRAWABLE_TYPE: Mask indicating what drawable types the frame buffer configuration supports. Valid bits are GLX_WINDOW_BIT, GLX_PIXMAP_BIT, and GLX_PBUFFER_BIT.
GLX_X_RENDERABLE: True if drawables created with the frame buffer configuration can be rendered to by X.
GLX_VISUAL_ID: XID of the corresponding visual, or zero if there is no associated visual (i.e., if GLX_X_RENDERABLE is False or GLX_DRAWABLE_TYPE does not have the GLX_WINDOW_BIT bit set).
GLX_X_VISUAL_TYPE: Visual type of associated visual. The returned value will be one of: GLX_TRUE_COLOR, GLX_DIRECT_COLOR, GLX_PSEUDO_COLOR, GLX_STATIC_COLOR, GLX_GRAY_SCALE, GLX_STATIC_GRAY, or GLX_NONE, if there is no associated visual (i.e., if GLX_X_RENDERABLE is False or GLX_DRAWABLE_TYPE does not have the GLX_WINDOW_BIT bit set).
GLX_CONFIG_CAVEAT: One of GLX_NONE, GLX_SLOW_CONFIG, or GLX_NON_CONFORMANT_CONFIG, indicating that the frame buffer configuration has no caveats, some aspect of the frame buffer configuration runs slower than other frame buffer configurations, or some aspect of the frame buffer configuration is nonconformant, respectively.
GLX_TRANSPARENT_TYPE: One of GLX_NONE, GLX_TRANSPARENT_RGB, GLX_TRANSPARENT_INDEX, indicating that the frame buffer configuration is opaque, is transparent for particular values of red, green, and blue, or is transparent for particular index values, respectively.
GLX_TRANSPARENT_INDEX_VALUE: Integer value between 0 and the maximum frame buffer value for indices, indicating the transparent index value for the frame buffer configuration. Undefined if GLX_TRANSPARENT_TYPE is not GLX_TRANSPARENT_INDEX.
GLX_TRANSPARENT_RED_VALUE: Integer value between 0 and the maximum frame buffer value for red, indicating the transparent red value for the frame buffer configuration. Undefined if GLX_TRANSPARENT_TYPE is not GLX_TRANSPARENT_RGB.
GLX_TRANSPARENT_GREEN_VALUE: Integer value between 0 and the maximum frame buffer value for green, indicating the transparent green value for the frame buffer configuration. Undefined if GLX_TRANSPARENT_TYPE is not GLX_TRANSPARENT_RGB.
GLX_TRANSPARENT_BLUE_VALUE: Integer value between 0 and the maximum frame buffer value for blue, indicating the transparent blue value for the frame buffer configuration. Undefined if GLX_TRANSPARENT_TYPE is not GLX_TRANSPARENT_RGB.
GLX_TRANSPARENT_ALPHA_VALUE: Integer value between 0 and the maximum frame buffer value for alpha, indicating the transparent blue value for the frame buffer configuration. Undefined if GLX_TRANSPARENT_TYPE is not GLX_TRANSPARENT_RGB.
GLX_MAX_PBUFFER_WIDTH: The maximum width that can be specified to glXCreatePbuffer.
GLX_MAX_PBUFFER_HEIGHT: The maximum height that can be specified to glXCreatePbuffer.
GLX_MAX_PBUFFER_PIXELS: The maximum number of pixels (width times height) for a pixel buffer. Note that this value may be less than GLX_MAX_PBUFFER_WIDTH times GLX_MAX_PBUFFER_HEIGHT. Also, this value is static and assumes that no other pixel buffers or X resources are contending for the frame buffer memory. As a result, it may not be possible to allocate a pixel buffer of the size given by GLX_MAX_PBUFFER_PIXELS.

Applications should choose the frame buffer configuration that most closely meets their requirements. Creating windows, GLX pixmaps, or GLX pixel buffers with unnecessary buffers can result in reduced rendering performance as well as poor resource allocation.

GLX_NO_EXTENSION is returned if dpy does not support the GLX extension. GLX_BAD_ATTRIBUTE is returned if attribute is not a valid GLX attribute.

Function: GLXFBConfig-* glXGetFBConfigs dpy screen nelements

List all GLX frame buffer configurations for a given screen.

dpy: Specifies the connection to the X server.
screen: Specifies the screen number.
nelements: Returns the number of GLXFBConfigs returned.

glXGetFBConfigs returns a list of all GLXFBConfigs available on the screen specified by screen. Use glXGetFBConfigAttrib to obtain attribute values from a specific GLXFBConfig.

Function: void(*)() glXGetProcAddress procName

Obtain a pointer to an OpenGL or GLX function.

procName: Specifies the name of the OpenGL or GLX function whose address is to be returned.

glXGetProcAddress returns the address of the function specified in procName. This is necessary in environments where the OpenGL link library exports a different set of functions than the runtime library.

Function: void glXGetSelectedEvent dpy draw event_mask

Returns GLX events that are selected for a window or a GLX pixel buffer.

dpy: Specifies the connection to the X server.
draw: Specifies a GLX drawable. Must be a GLX pixel buffer or a window.
event_mask: Returns the events that are selected for draw.

glXGetSelectedEvent returns in event_mask the events selected for draw.

GLXBadDrawable is generated if draw is not a valid window or a valid GLX pixel buffer.

Function: XVisualInfo-* glXGetVisualFromFBConfig dpy config

Return visual that is associated with the frame buffer configuration.

dpy: Specifies the connection to the X server.
config: Specifies the GLX frame buffer configuration.

If config is a valid GLX frame buffer configuration and it has an associated X Visual, then information describing that visual is returned; otherwise NULL is returned. Use XFree to free the data returned.

Returns NULL if config is not a valid GLXFBConfig.

Function: GLXContext glXImportContextEXT dpy contextID

Import another process’s indirect rendering context..

dpy: Specifies the connection to the X server.
contextID: Specifies a GLX rendering context.

glXImportContextEXT creates a GLXContext given the XID of an existing GLXContext. It may be used in place of glXCreateContext, to share another process’s indirect rendering context.

Only the server-side context information can be shared between X clients; client-side state, such as pixel storage modes, cannot be shared. Thus, glXImportContextEXT must allocate memory to store client-side information. This memory is freed by calling glXFreeContextEXT.

This call does not create a new XID. It merely makes an existing object available to the importing client (Display *). Like any XID, it goes away when the creating client drops its connection or the ID is explicitly deleted. Note that this is when the XID goes away. The object goes away when the XID goes away AND the context is not current to any thread.

If contextID refers to a direct rendering context then no error is generated but glXImportContextEXT returns NULL.

glXImportContextEXT is part of the EXT_import_context extension, not part of the core GLX command set. If _glxextstring(EXT_import_context) is included in the string returned by glXQueryExtensionsString, when called with argument GLX_EXTENSIONS, extension EXT_import_context is supported.

GLXBadContext is generated if contextID does not refer to a valid context.

Function: Bool glXIsDirect dpy ctx

Indicate whether direct rendering is enabled.

dpy: Specifies the connection to the X server.
ctx: Specifies the GLX context that is being queried.

glXIsDirect returns True if ctx is a direct rendering context, False otherwise. Direct rendering contexts pass rendering commands directly from the calling process’s address space to the rendering system, bypassing the X server. Nondirect rendering contexts pass all rendering commands to the X server.

GLXBadContext is generated if ctx is not a valid GLX context.

Function: Bool glXMakeContextCurrent display draw read ctx

Attach a GLX context to a GLX drawable.

display: Specifies the connection to the X server.
draw: Specifies a GLX drawable to render into. Must be an XID representing a GLXWindow, GLXPixmap, or GLXPbuffer.
read: Specifies a GLX drawable to read from. Must be an XID representing a GLXWindow, GLXPixmap, or GLXPbuffer.
ctx: Specifies the GLX context to be bound to read and ctx.

glXMakeContextCurrent binds ctx to the current rendering thread and to the draw and read GLX drawables. draw and read may be the same.

draw is used for all OpenGL operations except:

Any pixel data that are read based on the value of GLX_READ_BUFFER. Note that accumulation operations use the value of GLX_READ_BUFFER, but are not allowed unless draw is identical to read.

Any depth values that are retrieved by glReadPixels or glCopyPixels.

Any stencil values that are retrieved by glReadPixels or glCopyPixels.

Frame buffer values are taken from draw.

If the current rendering thread has a current rendering context, that context is flushed and replaced by ctx.

The first time that ctx is made current, the viewport and scissor dimensions are set to the size of the draw drawable. The viewport and scissor are not modified when ctx is subsequently made current.

To release the current context without assigning a new one, call glXMakeContextCurrent with draw and read set to None and ctx set to NULL.

glXMakeContextCurrent returns True if it is successful, False otherwise. If False is returned, the previously current rendering context and drawable (if any) remain unchanged.

BadMatch is generated if draw and read are not compatible.

BadAccess is generated if ctx is current to some other thread.

GLXContextState is generated if there is a current rendering context and its render mode is either GLX_FEEDBACK or GLX_SELECT.

GLXBadContext is generated if ctx is not a valid GLX rendering context.

GLXBadDrawable is generated if draw or read is not a valid GLX drawable.

GLXBadWindow is generated if the underlying X window for either draw or read is no longer valid.

GLXBadCurrentDrawable is generated if the previous context of the calling thread has unflushed commands and the previous drawable is no longer valid.

BadAlloc is generated if the X server does not have enough resources to allocate the buffers.

BadMatch is generated if:

draw and read cannot fit into frame buffer memory simultaneously.

draw or read is a GLXPixmap and ctx is a direct-rendering context.

draw or read is a GLXPixmap and ctx was previously bound to a GLXWindow or GLXPbuffer.

draw or read is a GLXWindow or GLXPbuffer and ctx was previously bound to a GLXPixmap.

Function: Bool glXMakeCurrent dpy drawable ctx

Attach a GLX context to a window or a GLX pixmap.

dpy: Specifies the connection to the X server.
drawable: Specifies a GLX drawable. Must be either an X window ID or a GLX pixmap ID.
ctx: Specifies a GLX rendering context that is to be attached to drawable.

glXMakeCurrent does two things: It makes ctx the current GLX rendering context of the calling thread, replacing the previously current context if there was one, and it attaches ctx to a GLX drawable, either a window or a GLX pixmap. As a result of these two actions, subsequent GL rendering calls use rendering context ctx to modify GLX drawable drawable (for reading and writing). Because glXMakeCurrent always replaces the current rendering context with ctx, there can be only one current context per thread.

Pending commands to the previous context, if any, are flushed before it is released.

The first time ctx is made current to any thread, its viewport is set to the full size of drawable. Subsequent calls by any thread to glXMakeCurrent with ctx have no effect on its viewport.

To release the current context without assigning a new one, call glXMakeCurrent with drawable set to None and ctx set to NULL.

glXMakeCurrent returns True if it is successful, False otherwise. If False is returned, the previously current rendering context and drawable (if any) remain unchanged.

BadMatch is generated if drawable was not created with the same X screen and visual as ctx. It is also generated if drawable is None and ctx is not NULL.

BadAccess is generated if ctx was current to another thread at the time glXMakeCurrent was called.

GLXBadDrawable is generated if drawable is not a valid GLX drawable.

GLXBadContext is generated if ctx is not a valid GLX context.

GLXBadContextState is generated if glXMakeCurrent is executed between the execution of glBegin and the corresponding execution of glEnd.

GLXBadContextState is also generated if the rendering context current to the calling thread has GL renderer state GLX_FEEDBACK or GLX_SELECT.

GLXBadCurrentWindow is generated if there are pending GL commands for the previous context and the current drawable is a window that is no longer valid.

BadAlloc may be generated if the server has delayed allocation of ancillary buffers until glXMakeCurrent is called, only to find that it has insufficient resources to complete the allocation.

Function: int glXQueryContextInfoEXT dpy ctx attribute value

Query context information.

dpy: Specifies the connection to the X server.
ctx: Specifies a GLX rendering context.
attribute: Specifies that a context parameter should be retrieved. Must be one of GLX_SHARED_CONTEXT_EXT, GLX_VISUAL_ID_EXT, or GLX_SCREEN_EXT.
value: Contains the return value for attribute.

glXQueryContextInfoEXT sets value to the value of attribute with respect to ctx. glXQueryContextInfoEXT returns an error code if it fails for any reason. Otherwise, Success is returned.

attribute may be one of the following:

GLX_SHARED_CONTEXT_EXT: Returns the XID of the share list context associated with ctx at its creation.
GLX_VISUAL_ID_EXT: Returns the XID of the GLX Visual associated with ctx.
GLX_SCREEN_EXT: Returns the screen number associated with ctx.

This call may cause a round-trip to the server.

glXQueryContextInfoEXT is part of the EXT_import_context extension, not part of the core GLX command set. If _glxextstring(EXT_import_context) is included in the string returned by glXQueryExtensionsString, when called with argument GLX_EXTENSIONS, extension EXT_import_context is supported.

GLXBadContext is generated if ctx does not refer to a valid context.

GLX_BAD_ATTRIBUTE is returned if attribute is not a valid GLX context attribute.

fred GLX_BAD_CONTEXT is returned if attribute is not a valid context.

Function: int glXQueryContext dpy ctx attribute value

Query context information.

dpy: Specifies the connection to the X server.
ctx: Specifies a GLX rendering context.
attribute: Specifies that a context parameter should be retrieved. Must be one of GLX_FBCONFIG_ID, GLX_RENDER_TYPE, or GLX_SCREEN.
value: Contains the return value for attribute.

glXQueryContext sets value to the value of attribute with respect to ctx. attribute may be one of the following:

GLX_FBCONFIG_ID: Returns the XID of the GLXFBConfig associated with ctx.
GLX_RENDER_TYPE: Returns the rendering type supported by ctx.
GLX_SCREEN: Returns the screen number associated with ctx.

Success is returned unless attribute is not a valid GLX context attribute, in which case GLX_BAD_ATTRIBUTE is returned.

This call may cause a round-trip to the server.

GLXBadContext is generated if ctx does not refer to a valid context.

Function: int glXQueryDrawable dpy draw attribute value

Returns an attribute assoicated with a GLX drawable.

dpy: Specifies the connection to the X server.
draw: Specifies the GLX drawable to be queried.
attribute: Specifies the attribute to be returned. Must be one of GLX_WIDTH, GLX_HEIGHT, GLX_PRESERVED_CONTENTS, GLX_LARGEST_PBUFFER, or GLX_FBCONFIG_ID.
value: Contains the return value for attribute.

glXQueryDrawable sets value to the value of attribute with respect to the GLXDrawable draw.

attribute may be one of the following:

GLX_WIDTH: Returns the width of ctx.
GLX_HEIGHT: Returns the height of ctx.
GLX_PRESERVED_CONTENTS: Returns True if the contents of a GLXPbuffer are preserved when a resource conflict occurs; False otherwise.
GLX_LARGEST_PBUFFER: Returns the value set when glXCreatePbuffer was called to create the GLXPbuffer. If False is returned, then the call to glXCreatePbuffer will fail to create a GLXPbuffer if the requested size is larger than the implementation maximum or available resources. If True is returned, a GLXPbuffer of the maximum availble size (if less than the requested width and height) is created.
GLX_FBCONFIG_ID: Returns the XID for draw.

If draw is a GLXWindow or GLXPixmap and attribute is set to GLX_PRESERVED_CONTENTS or GLX_LARGETST_PBUFFER, the contents of value are undefined. If attribute is not one of the attributes listed above, the contents of value are unedfined.

A GLXBadDrawable is generated if draw is not a valid GLXDrawable.

Function: const-char-* glXQueryExtensionsString dpy screen

Return list of supported extensions.

dpy: Specifies the connection to the X server.
screen: Specifies the screen number.

glXQueryExtensionsString returns a pointer to a string describing which GLX extensions are supported on the connection. The string is null-terminated and contains a space-separated list of extension names. (The extension names themselves never contain spaces.) If there are no extensions to GLX, then the empty string is returned.

Function: Bool glXQueryExtension dpy errorBase eventBase

Indicate whether the GLX extension is supported.

dpy: Specifies the connection to the X server.
errorBase: Returns the base error code of the GLX server extension.
eventBase: Returns the base event code of the GLX server extension.

glXQueryExtension returns True if the X server of connection dpy supports the GLX extension, False otherwise. If True is returned, then errorBase and eventBase return the error base and event base of the GLX extension. These values should be added to the constant error and event values to determine the actual event or error values. Otherwise, errorBase and eventBase are unchanged.

errorBase and eventBase do not return values if they are specified as NULL.

Function: const-char-* glXQueryServerString dpy screen name

Return string describing the server.

dpy: Specifies the connection to the X server.
screen: Specifies the screen number.
name: Specifies which string is returned: one of GLX_VENDOR, GLX_VERSION, or GLX_EXTENSIONS.

glXQueryServerString returns a pointer to a static, null-terminated string describing some aspect of the server’s GLX extension. The possible values for name and the format of the strings is the same as for glXGetClientString. If name is not set to a recognized value, NULL is returned.

Function: Bool glXQueryVersion dpy major minor

Return the version numbers of the GLX extension.

dpy: Specifies the connection to the X server.
major: Returns the major version number of the GLX server extension.
minor: Returns the minor version number of the GLX server extension.

glXQueryVersion returns the major and minor version numbers of the GLX extension implemented by the server associated with connection dpy. Implementations with the same major version number are upward compatible, meaning that the implementation with the higher minor number is a superset of the version with the lower minor number.

major and minor do not return values if they are specified as NULL.

glXQueryVersion returns False if it fails, True otherwise.

major and minor are not updated when False is returned.

Function: void glXSelectEvent dpy draw event_mask

Select GLX events for a window or a GLX pixel buffer.

dpy: Specifies the connection to the X server.
draw: Specifies a GLX drawable. Must be a GLX pixel buffer or a window.
event_mask: Specifies the events to be returned for draw.

glXSelectEvent sets the GLX event mask for a GLX pixel buffer or a window. Calling glXSelectEvent overrides any previous event mask that was set by the client for draw. Note that it does not affect the event masks that other clients may have specified for draw since each client rendering to draw has a separate event mask for it.

Currently, only one GLX event, GLX_PBUFFER_CLOBBER_MASK, can be selected. The following data is returned to the client when a GLX_PBUFFER_CLOBBER_MASK event occurs:

typedef struct {

int event_type;: /* GLX_DAMAGED or GLX_SAVED */
int draw_type;: /* GLX_WINDOW or GLX_PBUFFER */
unsigned long serial;: /* # of last request processed by server */
Bool send_event;: /* true if this came for SendEvent request */
Display *display;: /* display the event was read from */
GLXDrawable drawable;: /* i.d. of Drawable */
unsigned int buffer_mask;: /* mask indicating affected buffers */
int x, y;
int width, height;
int count;: /* if nonzero, at least this many more */

} GLXPbufferClobberEvent; The valid bit masks used in buffer_mask are:

Bitmask: Corresponding Buffer
GLX_FRONT_LEFT_BUFFER_BIT: Front left color buffer
GLX_FRONT_RIGHT_BUFFER_BIT: Front right color buffer
GLX_BACK_LEFT_BUFFER_BIT: Back left color buffer
GLX_BACK_RIGHT_BUFFER_BIT: Back right color buffer
GLX_AUX_BUFFERS_BIT: Auxiliary buffer
GLX_DEPTH_BUFFER_BIT: Depth buffer
GLX_STENCIL_BUFFER_BIT: Stencil buffer
GLX_ACCUM_BUFFER_BIT: Accumulation buffer

A single X server operation can cause several buffer clobber events to be sent. (e.g., a single GLX pixel buffer may be damaged and cause multiple buffer clobber events to be generated). Each event specifies one region of the GLX drawable that was affected by the X Server operation. The buffer_mask field indicates which color buffers and ancillary buffers were affected. All the buffer clobber events generated by a single X server action are guaranteed to be contiguous in the event queue. The conditions under which this event is generated and the event_type varies, depending on the type of the GLX drawable.

When the GLX_AUX_BUFFERS_BIT is set in buffer_mask, then aux_buffer is set to indicate which buffer was affected. If more than one aux buffer was affected, then additional events are generated as part of the same contiguous event group. Each additional event will have only the GLX_AUX_BUFFERS_BIT set in buffer_mask, and the aux_buffer field will be set appropriately. For nonstereo drawables, GLX_FRONT_LEFT_BUFFER_BIT and GLX_BACK_LEFT_BUFFER_BIT are used to specify the front and back color buffers.

For preserved GLX pixel buffers, a buffer clobber event with type GLX_SAVED is generated whenever the contents of the GLX pixel buffer is moved out of offscreen memory. The event(s) describes which portions of the GLX pixel buffer were affected. Clients who receive many buffer clobber events, referring to different save actions, should consider freeing the GLX pixel buffer resource in order to prevent the system from thrashing due to insufficient resources.

For an unpreserved GLXPbuffer, a buffer clobber event, with type GLX_DAMAGED, is generated whenever a portion of the GLX pixel buffer becomes invalid. The client may wish to regenerate the invalid portions of the GLX pixel buffer.

For Windows, buffer clobber events, with type GLX_SAVED, occur whenever an ancillary buffer, associated with the window, gets clobbered or moved out of off-screen memory. The event contains information indicating which color buffers and ancillary buffers\(emand which portions of those buffers\(emwere affected.

GLXBadDrawable is generated if draw is not a valid window or a valid GLX pixel buffer.

Function: void glXSwapBuffers dpy drawable

Exchange front and back buffers.

dpy: Specifies the connection to the X server.
drawable: Specifies the drawable whose buffers are to be swapped.

glXSwapBuffers promotes the contents of the back buffer of drawable to become the contents of the front buffer of drawable. The contents of the back buffer then become undefined. The update typically takes place during the vertical retrace of the monitor, rather than immediately after glXSwapBuffers is called.

glXSwapBuffers performs an implicit glFlush before it returns. Subsequent OpenGL commands may be issued immediately after calling glXSwapBuffers, but are not executed until the buffer exchange is completed.

If drawable was not created with respect to a double-buffered visual, glXSwapBuffers has no effect, and no error is generated.

GLXBadDrawable is generated if drawable is not a valid GLX drawable.

GLXBadCurrentWindow is generated if dpy and drawable are respectively the display and drawable associated with the current context of the calling thread, and drawable identifies a window that is no longer valid.

Function: void glXUseXFont font first count listBase

Create bitmap display lists from an X font.

font: Specifies the font from which character glyphs are to be taken.
first: Specifies the index of the first glyph to be taken.
count: Specifies the number of glyphs to be taken.
listBase: Specifies the index of the first display list to be generated.

glXUseXFont generates count display lists, named listBase through listBase+count-1, each containing a single glBitmap command. The parameters of the glBitmap command of display list listBase+i are derived from glyph first+i. Bitmap parameters xorig, yorig, width, and height are computed from font metrics as descent-1, -lbearing, rbearing-lbearing, and ascent+descent, respectively. xmove is taken from the glyph’s width metric, and ymove is set to zero. Finally, the glyph’s image is converted to the appropriate format for glBitmap.

Using glXUseXFont may be more efficient than accessing the X font and generating the display lists explicitly, both because the display lists are created on the server without requiring a round trip of the glyph data, and because the server may choose to delay the creation of each bitmap until it is accessed.

Empty display lists are created for all glyphs that are requested and are not defined in font. glXUseXFont is ignored if there is no current GLX context.

BadFont is generated if font is not a valid font.

GLXBadContextState is generated if the current GLX context is in display-list construction mode.

GLXBadCurrentWindow is generated if the drawable associated with the current context of the calling thread is a window, and that window is no longer valid.

Function: void glXWaitGL

Complete GL execution prior to subsequent X calls.

GL rendering calls made prior to glXWaitGL are guaranteed to be executed before X rendering calls made after glXWaitGL. Although this same result can be achieved using glFinish, glXWaitGL does not require a round trip to the server, and it is therefore more efficient in cases where client and server are on separate machines.

glXWaitGL is ignored if there is no current GLX context.

GLXBadCurrentWindow is generated if the drawable associated with the current context of the calling thread is a window, and that window is no longer valid.

Function: void glXWaitX

Complete X execution prior to subsequent GL calls.

X rendering calls made prior to glXWaitX are guaranteed to be executed before GL rendering calls made after glXWaitX. Although the same result can be achieved using XSync, glXWaitX does not require a round trip to the server, and it is therefore more efficient in cases where client and server are on separate machines.

glXWaitX is ignored if there is no current GLX context.

GLXBadCurrentWindow is generated if the drawable associated with the current context of the calling thread is a window, and that window is no longer valid.