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authormarha <marha@users.sourceforge.net>2011-08-29 08:51:20 +0200
committermarha <marha@users.sourceforge.net>2011-08-29 08:51:20 +0200
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xwininfo libX11 libXmu libxcb mesa xserver xkeyboard-config git update 29
aug 2011
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+++ b/mesalib/docs/libGL.txt
@@ -1,197 +1,197 @@
-
-
-
-Introduction
-------------
-
-This document describes the implementation of the XFree86 4.0 libGL.so
-library defined by the Linux/OpenGL Base specification found at
-http://reality.sgi.com/opengl/linux/linuxbase.html.
-
-The documentation is divided into two sections:
- User's Guide
- Driver Developer's Guide
-
-Author: Brian Paul (brian@precisioninsight.com)
-Date: February 2000
-
-
-
-User's Guide
-------------
-
-Using libGL.so
-
-The libGL.so library defines the gl- and glX-prefixed functions needed to
-run OpenGL programs. OpenGL client applications should link with the
--lGL option to use it.
-
-libGL.so serves two primary functions: GLX protocol generation for indirect
-rendering and loading/management of hardware drivers for direct rendering.
-
-When libGL.so initializes itself it uses the DRI to determine the
-appropriate hardware driver for each screen on the local X display.
-The hardware drivers are expected to be in the /usr/X11R6/lib/modules/dri/
-directory. Drivers are named with the convention <name>_dri.so where
-<name> is a driver such as "tdfx", "i810", "gamma", etc.
-
-The LIBGL_DRIVERS_DIR environment variable may be used to specify a
-different DRI modules directory, overriding /usr/X11R6/lib/modules/dri/.
-This environment variable is ignored in setuid programs for security
-reasons.
-
-When libGL.so is unable to locate appropriate hardware drivers it will
-fall back to using indirect GLX rendering.
-
-To aid in solving problems, libGL.so will print diagnostic messages to
-stderr if the LIBGL_DEBUG environment variable is defined.
-
-libGL.so is thread safe. The overhead of thread safety for common,
-single-thread clients is negligible. However, the overhead of thread
-safety for multi-threaded clients is significant. Each GL API call
-requires two calls to pthread_get_specific() which can noticably
-impact performance. Warning: libGL.so is thread safe but individual
-DRI drivers may not be. Please consult the documentation for a driver
-to learn if it is thread safe.
-
-
-
-Indirect Rendering
-
-You can force indirect rendering mode by setting the LIBGL_ALWAYS_INDIRECT
-environment variable. Hardware acceleration will not be used.
-
-
-
-libGL.so Extensibility
-
-libGL.so is designed to be extended without upgrading. That is,
-drivers may install new OpenGL extension functions into libGL.so
-without requiring libGL.so to be replaced. Clients of libGL.so should
-use the glXGetProcAddressEXT() function to obtain the address of
-functions by name. For more details of GLX_ARB_get_proc_address see
-http://oss.sgi.com/projects/ogl-sample/registry/ARB/get_proc_address.spec
-
-libGL.so is also designed with flexibility such that it may be used
-with many generations of hardware drivers to come.
-
-
-
-
-Driver Developer's Guide
-------------------------
-
-This section describes the requirements to make an XFree86 4.0
-libGL.so-compatible hardware driver. It is not intended for end
-users of libGL.so.
-
-
-XFree86 source files
-
-libGL.so is built inside XFree86 with sources found in xc/lib/GL/.
-Specifically, libGL.so is built from:
-
- xc/lib/GL/glx/*.c
- xc/lib/dri/XF86dri.c
- xc/lib/dri/dri_glx.c
- xc/lib/GL/mesa/src/glapi.c
- xc/lib/GL/mesa/src/glapitemp.h
- xc/lib/GL/mesa/src/glapitable.h
- xc/lib/GL/mesa/src/glapioffsets.h
- xc/lib/GL/mesa/src/glapinoop.c
- xc/lib/GL/mesa/src/glheader.h
- xc/lib/GL/mesa/src/glthread.c
- xc/lib/GL/mesa/src/glthread.h
- xc/lib/GL/mesa/src/X86/glapi_x86.S
- xc/lib/GL/mesa/src/X86/assyntax.h
-
-Understand that the mesa/src/gl*.[ch] files are not tied to Mesa. They
-have no dependencies on the rest of Mesa and are designed to be reusable
-in a number of projects.
-
-The glapi_x86.X and assyntax.h files implement x86-optimized dispatch
-of GL functions. They are not required; C-based dispatch can be used
-instead, with a slight performance penalty.
-
-
-
-Driver loading and binding
-
-When libGL.so initializes itself (via the __glXInitialize function) a
-call is made to driCreateDisplay(). This function uses DRI facilities
-to determine the driver file appropriate for each screen on the local
-display. Each screen's driver is then opened with dlopen() and asked
-for its __driCreateScreen() function. The pointers to the __driCreateScreen()
-functions are kept in an array, indexed by screen number, in the
-__DRIdisplayRec struct.
-
-When a driver's __driCreateScreen() function is called, it must initialize
-a __DRIscreenRec struct. This struct acts as the root of a tree of
-function pointers which are called to create and destroy contexts and
-drawables and perform all the operations needed by the GLX interface.
-See the xc/lib/GL/glx/glxclient.h file for details.
-
-
-
-Dynamic Extension Function Registration
-
-In order to provide forward compatibility with future drivers, libGL.so
-allows drivers to register new OpenGL extension functions which weren't
-known when libGL.so was built.
-
-The register_extensions() function in xc/lib/GL/dri/dri_glx.c is called
-as soon as libGL.so is loaded. This is done with gcc's constructor
-attribute. This mechanism will likely have to be changed for other compilers.
-
-register_extensions() loops over all local displays and screens, determines
-the DRI driver for each, and calls the driver's __driRegisterExtensions()
-function, if present.
-
-The __driRegisterExtensions() function can add new entrypoints to libGL
-by calling:
-
- GLboolean _glapi_add_entrypoint(const char *funcName, GLuint offset)
-
-The parameters are the name of the function (such as "glFoobarEXT") and the
-offset of the dispatch slot in the API dispatch table. The return value
-indicates success (GL_TRUE) or failure (GL_FALSE).
-
-_glapi_add_entrypoint() will synthesize entrypoint code in assembly
-language. Assembly languages is required since parameter passing
-can't be handled correctly using a C-based solution.
-
-The address of the new entrypoint is obtained by calling the
-glXGetProcAddressARB() function.
-
-The dispatch offset number MUST be a number allocated by SGI in the same
-manner in which new GL_* constants are allocated. Using an arbitrary
-offset number will result in many problems.
-
-
-
-Dispatch Management
-
-When a GL context is made current, the driver must install its dispatch
-table as the current dispatch table. This is done by calling
-
- void _glapi_set_dispatch(struct _glapi_table *dispatch);
-
-This will install the named dispatch table for the calling thread.
-The current dispatch table for a thread can be obtained by calling
-
- struct _glapi_table *_glapi_get_dispatch(void);
-
-For higher performance in the common single-thread case, the global
-variable _glapi_Dispatch will point to the current dispatch table.
-This variable will be NULL when in multi-thread mode.
-
-
-
-Context Management
-
-libGL.so uses the XFree86 xthreads package to manage a thread-specific
-current context pointer. See __glXGet/SetCurrentContext() in glext.c
-
-Drivers may use the _glapi_set/get_context() functions to maintain
-a private thread-specific context pointer.
-
+
+
+
+Introduction
+------------
+
+This document describes the implementation of the XFree86 4.0 libGL.so
+library defined by the Linux/OpenGL Base specification found at
+http://reality.sgi.com/opengl/linux/linuxbase.html.
+
+The documentation is divided into two sections:
+ User's Guide
+ Driver Developer's Guide
+
+Author: Brian Paul (brian@precisioninsight.com)
+Date: February 2000
+
+
+
+User's Guide
+------------
+
+Using libGL.so
+
+The libGL.so library defines the gl- and glX-prefixed functions needed to
+run OpenGL programs. OpenGL client applications should link with the
+-lGL option to use it.
+
+libGL.so serves two primary functions: GLX protocol generation for indirect
+rendering and loading/management of hardware drivers for direct rendering.
+
+When libGL.so initializes itself it uses the DRI to determine the
+appropriate hardware driver for each screen on the local X display.
+The hardware drivers are expected to be in the /usr/X11R6/lib/modules/dri/
+directory. Drivers are named with the convention <name>_dri.so where
+<name> is a driver such as "radeon", "i965", "nouveau", etc.
+
+The LIBGL_DRIVERS_DIR environment variable may be used to specify a
+different DRI modules directory, overriding /usr/X11R6/lib/modules/dri/.
+This environment variable is ignored in setuid programs for security
+reasons.
+
+When libGL.so is unable to locate appropriate hardware drivers it will
+fall back to using indirect GLX rendering.
+
+To aid in solving problems, libGL.so will print diagnostic messages to
+stderr if the LIBGL_DEBUG environment variable is defined.
+
+libGL.so is thread safe. The overhead of thread safety for common,
+single-thread clients is negligible. However, the overhead of thread
+safety for multi-threaded clients is significant. Each GL API call
+requires two calls to pthread_get_specific() which can noticably
+impact performance. Warning: libGL.so is thread safe but individual
+DRI drivers may not be. Please consult the documentation for a driver
+to learn if it is thread safe.
+
+
+
+Indirect Rendering
+
+You can force indirect rendering mode by setting the LIBGL_ALWAYS_INDIRECT
+environment variable. Hardware acceleration will not be used.
+
+
+
+libGL.so Extensibility
+
+libGL.so is designed to be extended without upgrading. That is,
+drivers may install new OpenGL extension functions into libGL.so
+without requiring libGL.so to be replaced. Clients of libGL.so should
+use the glXGetProcAddressEXT() function to obtain the address of
+functions by name. For more details of GLX_ARB_get_proc_address see
+http://oss.sgi.com/projects/ogl-sample/registry/ARB/get_proc_address.spec
+
+libGL.so is also designed with flexibility such that it may be used
+with many generations of hardware drivers to come.
+
+
+
+
+Driver Developer's Guide
+------------------------
+
+This section describes the requirements to make an XFree86 4.0
+libGL.so-compatible hardware driver. It is not intended for end
+users of libGL.so.
+
+
+XFree86 source files
+
+libGL.so is built inside XFree86 with sources found in xc/lib/GL/.
+Specifically, libGL.so is built from:
+
+ xc/lib/GL/glx/*.c
+ xc/lib/dri/XF86dri.c
+ xc/lib/dri/dri_glx.c
+ xc/lib/GL/mesa/src/glapi.c
+ xc/lib/GL/mesa/src/glapitemp.h
+ xc/lib/GL/mesa/src/glapitable.h
+ xc/lib/GL/mesa/src/glapioffsets.h
+ xc/lib/GL/mesa/src/glapinoop.c
+ xc/lib/GL/mesa/src/glheader.h
+ xc/lib/GL/mesa/src/glthread.c
+ xc/lib/GL/mesa/src/glthread.h
+ xc/lib/GL/mesa/src/X86/glapi_x86.S
+ xc/lib/GL/mesa/src/X86/assyntax.h
+
+Understand that the mesa/src/gl*.[ch] files are not tied to Mesa. They
+have no dependencies on the rest of Mesa and are designed to be reusable
+in a number of projects.
+
+The glapi_x86.X and assyntax.h files implement x86-optimized dispatch
+of GL functions. They are not required; C-based dispatch can be used
+instead, with a slight performance penalty.
+
+
+
+Driver loading and binding
+
+When libGL.so initializes itself (via the __glXInitialize function) a
+call is made to driCreateDisplay(). This function uses DRI facilities
+to determine the driver file appropriate for each screen on the local
+display. Each screen's driver is then opened with dlopen() and asked
+for its __driCreateScreen() function. The pointers to the __driCreateScreen()
+functions are kept in an array, indexed by screen number, in the
+__DRIdisplayRec struct.
+
+When a driver's __driCreateScreen() function is called, it must initialize
+a __DRIscreenRec struct. This struct acts as the root of a tree of
+function pointers which are called to create and destroy contexts and
+drawables and perform all the operations needed by the GLX interface.
+See the xc/lib/GL/glx/glxclient.h file for details.
+
+
+
+Dynamic Extension Function Registration
+
+In order to provide forward compatibility with future drivers, libGL.so
+allows drivers to register new OpenGL extension functions which weren't
+known when libGL.so was built.
+
+The register_extensions() function in xc/lib/GL/dri/dri_glx.c is called
+as soon as libGL.so is loaded. This is done with gcc's constructor
+attribute. This mechanism will likely have to be changed for other compilers.
+
+register_extensions() loops over all local displays and screens, determines
+the DRI driver for each, and calls the driver's __driRegisterExtensions()
+function, if present.
+
+The __driRegisterExtensions() function can add new entrypoints to libGL
+by calling:
+
+ GLboolean _glapi_add_entrypoint(const char *funcName, GLuint offset)
+
+The parameters are the name of the function (such as "glFoobarEXT") and the
+offset of the dispatch slot in the API dispatch table. The return value
+indicates success (GL_TRUE) or failure (GL_FALSE).
+
+_glapi_add_entrypoint() will synthesize entrypoint code in assembly
+language. Assembly languages is required since parameter passing
+can't be handled correctly using a C-based solution.
+
+The address of the new entrypoint is obtained by calling the
+glXGetProcAddressARB() function.
+
+The dispatch offset number MUST be a number allocated by SGI in the same
+manner in which new GL_* constants are allocated. Using an arbitrary
+offset number will result in many problems.
+
+
+
+Dispatch Management
+
+When a GL context is made current, the driver must install its dispatch
+table as the current dispatch table. This is done by calling
+
+ void _glapi_set_dispatch(struct _glapi_table *dispatch);
+
+This will install the named dispatch table for the calling thread.
+The current dispatch table for a thread can be obtained by calling
+
+ struct _glapi_table *_glapi_get_dispatch(void);
+
+For higher performance in the common single-thread case, the global
+variable _glapi_Dispatch will point to the current dispatch table.
+This variable will be NULL when in multi-thread mode.
+
+
+
+Context Management
+
+libGL.so uses the XFree86 xthreads package to manage a thread-specific
+current context pointer. See __glXGet/SetCurrentContext() in glext.c
+
+Drivers may use the _glapi_set/get_context() functions to maintain
+a private thread-specific context pointer.
+