src/osmesa_context.c - third_party/glfw - Git at Google

 //========================================================================
 // GLFW 3.5 OSMesa - www.glfw.org
 //------------------------------------------------------------------------
 // Copyright (c) 2016 Google Inc.
 // Copyright (c) 2016-2017 Camilla Löwy <elmindreda@glfw.org>
 //
 // This software is provided 'as-is', without any express or implied
 // warranty. In no event will the authors be held liable for any damages
 // arising from the use of this software.
 //
 // Permission is granted to anyone to use this software for any purpose,
 // including commercial applications, and to alter it and redistribute it
 // freely, subject to the following restrictions:
 //
 // 1. The origin of this software must not be misrepresented; you must not
 //    claim that you wrote the original software. If you use this software
 //    in a product, an acknowledgment in the product documentation would
 //    be appreciated but is not required.
 //
 // 2. Altered source versions must be plainly marked as such, and must not
 //    be misrepresented as being the original software.
 //
 // 3. This notice may not be removed or altered from any source
 //    distribution.
 //
 //========================================================================

 #include "internal.h"

 #include <stdlib.h>
 #include <string.h>
 #include <assert.h>

 static void makeContextCurrentOSMesa(_GLFWwindow* window)
 {
     if (window)
     {
         int width, height;
         _glfw.platform.getFramebufferSize(window, &width, &height);

         // Check to see if we need to allocate a new buffer
         if ((window->context.osmesa.buffer == NULL) ||
             (width != window->context.osmesa.width) ||
             (height != window->context.osmesa.height))
         {
             _glfw_free(window->context.osmesa.buffer);

             // Allocate the new buffer (width * height * 8-bit RGBA)
             window->context.osmesa.buffer = _glfw_calloc(4, (size_t) width * height);
             window->context.osmesa.width  = width;
             window->context.osmesa.height = height;
         }

         if (!OSMesaMakeCurrent(window->context.osmesa.handle,
                                window->context.osmesa.buffer,
                                GL_UNSIGNED_BYTE,
                                width, height))
         {
             _glfwInputError(GLFW_PLATFORM_ERROR,
                             "OSMesa: Failed to make context current");
             return;
         }
     }

     _glfwPlatformSetTls(&_glfw.contextSlot, window);
 }

 static GLFWglproc getProcAddressOSMesa(const char* procname)
 {
     return (GLFWglproc) OSMesaGetProcAddress(procname);
 }

 static void destroyContextOSMesa(_GLFWwindow* window)
 {
     if (window->context.osmesa.handle)
     {
         OSMesaDestroyContext(window->context.osmesa.handle);
         window->context.osmesa.handle = NULL;
     }

     if (window->context.osmesa.buffer)
     {
         _glfw_free(window->context.osmesa.buffer);
         window->context.osmesa.width = 0;
         window->context.osmesa.height = 0;
     }
 }

 static void swapBuffersOSMesa(_GLFWwindow* window)
 {
     // No double buffering on OSMesa
 }

 static void swapIntervalOSMesa(int interval)
 {
     // No swap interval on OSMesa
 }

 static int extensionSupportedOSMesa(const char* extension)
 {
     // OSMesa does not have extensions
     return GLFW_FALSE;
 }


 //////////////////////////////////////////////////////////////////////////
 //////                       GLFW internal API                      //////
 //////////////////////////////////////////////////////////////////////////

 GLFWbool _glfwInitOSMesa(void)
 {
     int i;
     const char* sonames[] =
     {
 #if defined(_GLFW_OSMESA_LIBRARY)
         _GLFW_OSMESA_LIBRARY,
 #elif defined(_WIN32)
         "libOSMesa.dll",
         "OSMesa.dll",
 #elif defined(__APPLE__)
         "libOSMesa.8.dylib",
 #elif defined(__CYGWIN__)
         "libOSMesa-8.so",
 #elif defined(__OpenBSD__) || defined(__NetBSD__)
         "libOSMesa.so",
 #else
         "libOSMesa.so.8",
         "libOSMesa.so.6",
 #endif
         NULL
     };

     if (_glfw.osmesa.handle)
         return GLFW_TRUE;

     for (i = 0;  sonames[i];  i++)
     {
         _glfw.osmesa.handle = _glfwPlatformLoadModule(sonames[i]);
         if (_glfw.osmesa.handle)
             break;
     }

     if (!_glfw.osmesa.handle)
     {
         _glfwInputError(GLFW_API_UNAVAILABLE, "OSMesa: Library not found");
         return GLFW_FALSE;
     }

     _glfw.osmesa.CreateContextExt = (PFN_OSMesaCreateContextExt)
         _glfwPlatformGetModuleSymbol(_glfw.osmesa.handle, "OSMesaCreateContextExt");
     _glfw.osmesa.CreateContextAttribs = (PFN_OSMesaCreateContextAttribs)
         _glfwPlatformGetModuleSymbol(_glfw.osmesa.handle, "OSMesaCreateContextAttribs");
     _glfw.osmesa.DestroyContext = (PFN_OSMesaDestroyContext)
         _glfwPlatformGetModuleSymbol(_glfw.osmesa.handle, "OSMesaDestroyContext");
     _glfw.osmesa.MakeCurrent = (PFN_OSMesaMakeCurrent)
         _glfwPlatformGetModuleSymbol(_glfw.osmesa.handle, "OSMesaMakeCurrent");
     _glfw.osmesa.GetColorBuffer = (PFN_OSMesaGetColorBuffer)
         _glfwPlatformGetModuleSymbol(_glfw.osmesa.handle, "OSMesaGetColorBuffer");
     _glfw.osmesa.GetDepthBuffer = (PFN_OSMesaGetDepthBuffer)
         _glfwPlatformGetModuleSymbol(_glfw.osmesa.handle, "OSMesaGetDepthBuffer");
     _glfw.osmesa.GetProcAddress = (PFN_OSMesaGetProcAddress)
         _glfwPlatformGetModuleSymbol(_glfw.osmesa.handle, "OSMesaGetProcAddress");

     if (!_glfw.osmesa.CreateContextExt ||
         !_glfw.osmesa.DestroyContext ||
         !_glfw.osmesa.MakeCurrent ||
         !_glfw.osmesa.GetColorBuffer ||
         !_glfw.osmesa.GetDepthBuffer ||
         !_glfw.osmesa.GetProcAddress)
     {
         _glfwInputError(GLFW_PLATFORM_ERROR,
                         "OSMesa: Failed to load required entry points");

         _glfwTerminateOSMesa();
         return GLFW_FALSE;
     }

     return GLFW_TRUE;
 }

 void _glfwTerminateOSMesa(void)
 {
     if (_glfw.osmesa.handle)
     {
         _glfwPlatformFreeModule(_glfw.osmesa.handle);
         _glfw.osmesa.handle = NULL;
     }
 }

 #define SET_ATTRIB(a, v) \
 { \
     assert(((size_t) index + 1) < sizeof(attribs) / sizeof(attribs[0])); \
     attribs[index++] = a; \
     attribs[index++] = v; \
 }

 GLFWbool _glfwCreateContextOSMesa(_GLFWwindow* window,
                                   const _GLFWctxconfig* ctxconfig,
                                   const _GLFWfbconfig* fbconfig)
 {
     OSMesaContext share = NULL;
     const int accumBits = fbconfig->accumRedBits +
                           fbconfig->accumGreenBits +
                           fbconfig->accumBlueBits +
                           fbconfig->accumAlphaBits;

     if (ctxconfig->client == GLFW_OPENGL_ES_API)
     {
         _glfwInputError(GLFW_API_UNAVAILABLE,
                         "OSMesa: OpenGL ES is not available on OSMesa");
         return GLFW_FALSE;
     }

     if (ctxconfig->share)
         share = ctxconfig->share->context.osmesa.handle;

     if (OSMesaCreateContextAttribs)
     {
         int index = 0, attribs[40];

         SET_ATTRIB(OSMESA_FORMAT, OSMESA_RGBA);
         SET_ATTRIB(OSMESA_DEPTH_BITS, fbconfig->depthBits);
         SET_ATTRIB(OSMESA_STENCIL_BITS, fbconfig->stencilBits);
         SET_ATTRIB(OSMESA_ACCUM_BITS, accumBits);

         if (ctxconfig->profile == GLFW_OPENGL_CORE_PROFILE)
         {
             SET_ATTRIB(OSMESA_PROFILE, OSMESA_CORE_PROFILE);
         }
         else if (ctxconfig->profile == GLFW_OPENGL_COMPAT_PROFILE)
         {
             SET_ATTRIB(OSMESA_PROFILE, OSMESA_COMPAT_PROFILE);
         }

         if (ctxconfig->major != 1 || ctxconfig->minor != 0)
         {
             SET_ATTRIB(OSMESA_CONTEXT_MAJOR_VERSION, ctxconfig->major);
             SET_ATTRIB(OSMESA_CONTEXT_MINOR_VERSION, ctxconfig->minor);
         }

         if (ctxconfig->forward)
         {
             _glfwInputError(GLFW_VERSION_UNAVAILABLE,
                             "OSMesa: Forward-compatible contexts not supported");
             return GLFW_FALSE;
         }

         SET_ATTRIB(0, 0);

         window->context.osmesa.handle =
             OSMesaCreateContextAttribs(attribs, share);
     }
     else
     {
         if (ctxconfig->profile)
         {
             _glfwInputError(GLFW_VERSION_UNAVAILABLE,
                             "OSMesa: OpenGL profiles unavailable");
             return GLFW_FALSE;
         }

         window->context.osmesa.handle =
             OSMesaCreateContextExt(OSMESA_RGBA,
                                    fbconfig->depthBits,
                                    fbconfig->stencilBits,
                                    accumBits,
                                    share);
     }

     if (window->context.osmesa.handle == NULL)
     {
         _glfwInputError(GLFW_VERSION_UNAVAILABLE,
                         "OSMesa: Failed to create context");
         return GLFW_FALSE;
     }

     window->context.makeCurrent = makeContextCurrentOSMesa;
     window->context.swapBuffers = swapBuffersOSMesa;
     window->context.swapInterval = swapIntervalOSMesa;
     window->context.extensionSupported = extensionSupportedOSMesa;
     window->context.getProcAddress = getProcAddressOSMesa;
     window->context.destroy = destroyContextOSMesa;

     return GLFW_TRUE;
 }

 #undef SET_ATTRIB


 //////////////////////////////////////////////////////////////////////////
 //////                        GLFW native API                       //////
 //////////////////////////////////////////////////////////////////////////

 GLFWAPI int glfwGetOSMesaColorBuffer(GLFWwindow* handle, int* width,
                                      int* height, int* format, void** buffer)
 {
     void* mesaBuffer;
     GLint mesaWidth, mesaHeight, mesaFormat;

     _GLFW_REQUIRE_INIT_OR_RETURN(GLFW_FALSE);

     _GLFWwindow* window = (_GLFWwindow*) handle;
     assert(window != NULL);

     if (window->context.source != GLFW_OSMESA_CONTEXT_API)
     {
         _glfwInputError(GLFW_NO_WINDOW_CONTEXT, NULL);
         return GLFW_FALSE;
     }

     if (!OSMesaGetColorBuffer(window->context.osmesa.handle,
                               &mesaWidth, &mesaHeight,
                               &mesaFormat, &mesaBuffer))
     {
         _glfwInputError(GLFW_PLATFORM_ERROR,
                         "OSMesa: Failed to retrieve color buffer");
         return GLFW_FALSE;
     }

     if (width)
         *width = mesaWidth;
     if (height)
         *height = mesaHeight;
     if (format)
         *format = mesaFormat;
     if (buffer)
         *buffer = mesaBuffer;

     return GLFW_TRUE;
 }

 GLFWAPI int glfwGetOSMesaDepthBuffer(GLFWwindow* handle,
                                      int* width, int* height,
                                      int* bytesPerValue,
                                      void** buffer)
 {
     void* mesaBuffer;
     GLint mesaWidth, mesaHeight, mesaBytes;

     _GLFW_REQUIRE_INIT_OR_RETURN(GLFW_FALSE);

     _GLFWwindow* window = (_GLFWwindow*) handle;
     assert(window != NULL);

     if (window->context.source != GLFW_OSMESA_CONTEXT_API)
     {
         _glfwInputError(GLFW_NO_WINDOW_CONTEXT, NULL);
         return GLFW_FALSE;
     }

     if (!OSMesaGetDepthBuffer(window->context.osmesa.handle,
                               &mesaWidth, &mesaHeight,
                               &mesaBytes, &mesaBuffer))
     {
         _glfwInputError(GLFW_PLATFORM_ERROR,
                         "OSMesa: Failed to retrieve depth buffer");
         return GLFW_FALSE;
     }

     if (width)
         *width = mesaWidth;
     if (height)
         *height = mesaHeight;
     if (bytesPerValue)
         *bytesPerValue = mesaBytes;
     if (buffer)
         *buffer = mesaBuffer;

     return GLFW_TRUE;
 }

 GLFWAPI OSMesaContext glfwGetOSMesaContext(GLFWwindow* handle)
 {
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);

     _GLFWwindow* window = (_GLFWwindow*) handle;
     assert(window != NULL);

     if (window->context.source != GLFW_OSMESA_CONTEXT_API)
     {
         _glfwInputError(GLFW_NO_WINDOW_CONTEXT, NULL);
         return NULL;
     }

     return window->context.osmesa.handle;
 }
	//========================================================================
	// GLFW 3.5 OSMesa - www.glfw.org
	//------------------------------------------------------------------------
	// Copyright (c) 2016 Google Inc.
	// Copyright (c) 2016-2017 Camilla Löwy <elmindreda@glfw.org>
	//
	// This software is provided 'as-is', without any express or implied
	// warranty. In no event will the authors be held liable for any damages
	// arising from the use of this software.
	//
	// Permission is granted to anyone to use this software for any purpose,
	// including commercial applications, and to alter it and redistribute it
	// freely, subject to the following restrictions:
	//
	// 1. The origin of this software must not be misrepresented; you must not
	// claim that you wrote the original software. If you use this software
	// in a product, an acknowledgment in the product documentation would
	// be appreciated but is not required.
	//
	// 2. Altered source versions must be plainly marked as such, and must not
	// be misrepresented as being the original software.
	//
	// 3. This notice may not be removed or altered from any source
	// distribution.
	//
	//========================================================================

	#include "internal.h"

	#include <stdlib.h>
	#include <string.h>
	#include <assert.h>

	static void makeContextCurrentOSMesa(_GLFWwindow* window)
	{
	if (window)
	{
	int width, height;
	_glfw.platform.getFramebufferSize(window, &width, &height);

	// Check to see if we need to allocate a new buffer
	if ((window->context.osmesa.buffer == NULL) \|\|
	(width != window->context.osmesa.width) \|\|
	(height != window->context.osmesa.height))
	{
	_glfw_free(window->context.osmesa.buffer);

	// Allocate the new buffer (width * height * 8-bit RGBA)
	window->context.osmesa.buffer = _glfw_calloc(4, (size_t) width * height);
	window->context.osmesa.width = width;
	window->context.osmesa.height = height;
	}

	if (!OSMesaMakeCurrent(window->context.osmesa.handle,
	window->context.osmesa.buffer,
	GL_UNSIGNED_BYTE,
	width, height))
	{
	_glfwInputError(GLFW_PLATFORM_ERROR,
	"OSMesa: Failed to make context current");
	return;
	}
	}

	_glfwPlatformSetTls(&_glfw.contextSlot, window);
	}

	static GLFWglproc getProcAddressOSMesa(const char* procname)
	{
	return (GLFWglproc) OSMesaGetProcAddress(procname);
	}

	static void destroyContextOSMesa(_GLFWwindow* window)
	{
	if (window->context.osmesa.handle)
	{
	OSMesaDestroyContext(window->context.osmesa.handle);
	window->context.osmesa.handle = NULL;
	}

	if (window->context.osmesa.buffer)
	{
	_glfw_free(window->context.osmesa.buffer);
	window->context.osmesa.width = 0;
	window->context.osmesa.height = 0;
	}
	}

	static void swapBuffersOSMesa(_GLFWwindow* window)
	{
	// No double buffering on OSMesa
	}

	static void swapIntervalOSMesa(int interval)
	{
	// No swap interval on OSMesa
	}

	static int extensionSupportedOSMesa(const char* extension)
	{
	// OSMesa does not have extensions
	return GLFW_FALSE;
	}


	//////////////////////////////////////////////////////////////////////////
	////// GLFW internal API //////
	//////////////////////////////////////////////////////////////////////////

	GLFWbool _glfwInitOSMesa(void)
	{
	int i;
	const char* sonames[] =
	{
	#if defined(_GLFW_OSMESA_LIBRARY)
	_GLFW_OSMESA_LIBRARY,
	#elif defined(_WIN32)
	"libOSMesa.dll",
	"OSMesa.dll",
	#elif defined(__APPLE__)
	"libOSMesa.8.dylib",
	#elif defined(__CYGWIN__)
	"libOSMesa-8.so",
	#elif defined(__OpenBSD__) \|\| defined(__NetBSD__)
	"libOSMesa.so",
	#else
	"libOSMesa.so.8",
	"libOSMesa.so.6",
	#endif
	NULL
	};

	if (_glfw.osmesa.handle)
	return GLFW_TRUE;

	for (i = 0; sonames[i]; i++)
	{
	_glfw.osmesa.handle = _glfwPlatformLoadModule(sonames[i]);
	if (_glfw.osmesa.handle)
	break;
	}

	if (!_glfw.osmesa.handle)
	{
	_glfwInputError(GLFW_API_UNAVAILABLE, "OSMesa: Library not found");
	return GLFW_FALSE;
	}

	_glfw.osmesa.CreateContextExt = (PFN_OSMesaCreateContextExt)
	_glfwPlatformGetModuleSymbol(_glfw.osmesa.handle, "OSMesaCreateContextExt");
	_glfw.osmesa.CreateContextAttribs = (PFN_OSMesaCreateContextAttribs)
	_glfwPlatformGetModuleSymbol(_glfw.osmesa.handle, "OSMesaCreateContextAttribs");
	_glfw.osmesa.DestroyContext = (PFN_OSMesaDestroyContext)
	_glfwPlatformGetModuleSymbol(_glfw.osmesa.handle, "OSMesaDestroyContext");
	_glfw.osmesa.MakeCurrent = (PFN_OSMesaMakeCurrent)
	_glfwPlatformGetModuleSymbol(_glfw.osmesa.handle, "OSMesaMakeCurrent");
	_glfw.osmesa.GetColorBuffer = (PFN_OSMesaGetColorBuffer)
	_glfwPlatformGetModuleSymbol(_glfw.osmesa.handle, "OSMesaGetColorBuffer");
	_glfw.osmesa.GetDepthBuffer = (PFN_OSMesaGetDepthBuffer)
	_glfwPlatformGetModuleSymbol(_glfw.osmesa.handle, "OSMesaGetDepthBuffer");
	_glfw.osmesa.GetProcAddress = (PFN_OSMesaGetProcAddress)
	_glfwPlatformGetModuleSymbol(_glfw.osmesa.handle, "OSMesaGetProcAddress");

	if (!_glfw.osmesa.CreateContextExt \|\|
	!_glfw.osmesa.DestroyContext \|\|
	!_glfw.osmesa.MakeCurrent \|\|
	!_glfw.osmesa.GetColorBuffer \|\|
	!_glfw.osmesa.GetDepthBuffer \|\|
	!_glfw.osmesa.GetProcAddress)
	{
	_glfwInputError(GLFW_PLATFORM_ERROR,
	"OSMesa: Failed to load required entry points");

	_glfwTerminateOSMesa();
	return GLFW_FALSE;
	}

	return GLFW_TRUE;
	}

	void _glfwTerminateOSMesa(void)
	{
	if (_glfw.osmesa.handle)
	{
	_glfwPlatformFreeModule(_glfw.osmesa.handle);
	_glfw.osmesa.handle = NULL;
	}
	}

	#define SET_ATTRIB(a, v) \
	{ \
	assert(((size_t) index + 1) < sizeof(attribs) / sizeof(attribs[0])); \
	attribs[index++] = a; \
	attribs[index++] = v; \
	}

	GLFWbool _glfwCreateContextOSMesa(_GLFWwindow* window,
	const _GLFWctxconfig* ctxconfig,
	const _GLFWfbconfig* fbconfig)
	{
	OSMesaContext share = NULL;
	const int accumBits = fbconfig->accumRedBits +
	fbconfig->accumGreenBits +
	fbconfig->accumBlueBits +
	fbconfig->accumAlphaBits;

	if (ctxconfig->client == GLFW_OPENGL_ES_API)
	{
	_glfwInputError(GLFW_API_UNAVAILABLE,
	"OSMesa: OpenGL ES is not available on OSMesa");
	return GLFW_FALSE;
	}

	if (ctxconfig->share)
	share = ctxconfig->share->context.osmesa.handle;

	if (OSMesaCreateContextAttribs)
	{
	int index = 0, attribs[40];

	SET_ATTRIB(OSMESA_FORMAT, OSMESA_RGBA);
	SET_ATTRIB(OSMESA_DEPTH_BITS, fbconfig->depthBits);
	SET_ATTRIB(OSMESA_STENCIL_BITS, fbconfig->stencilBits);
	SET_ATTRIB(OSMESA_ACCUM_BITS, accumBits);

	if (ctxconfig->profile == GLFW_OPENGL_CORE_PROFILE)
	{
	SET_ATTRIB(OSMESA_PROFILE, OSMESA_CORE_PROFILE);
	}
	else if (ctxconfig->profile == GLFW_OPENGL_COMPAT_PROFILE)
	{
	SET_ATTRIB(OSMESA_PROFILE, OSMESA_COMPAT_PROFILE);
	}

	if (ctxconfig->major != 1 \|\| ctxconfig->minor != 0)
	{
	SET_ATTRIB(OSMESA_CONTEXT_MAJOR_VERSION, ctxconfig->major);
	SET_ATTRIB(OSMESA_CONTEXT_MINOR_VERSION, ctxconfig->minor);
	}

	if (ctxconfig->forward)
	{
	_glfwInputError(GLFW_VERSION_UNAVAILABLE,
	"OSMesa: Forward-compatible contexts not supported");
	return GLFW_FALSE;
	}

	SET_ATTRIB(0, 0);

	window->context.osmesa.handle =
	OSMesaCreateContextAttribs(attribs, share);
	}
	else
	{
	if (ctxconfig->profile)
	{
	_glfwInputError(GLFW_VERSION_UNAVAILABLE,
	"OSMesa: OpenGL profiles unavailable");
	return GLFW_FALSE;
	}

	window->context.osmesa.handle =
	OSMesaCreateContextExt(OSMESA_RGBA,
	fbconfig->depthBits,
	fbconfig->stencilBits,
	accumBits,
	share);
	}

	if (window->context.osmesa.handle == NULL)
	{
	_glfwInputError(GLFW_VERSION_UNAVAILABLE,
	"OSMesa: Failed to create context");
	return GLFW_FALSE;
	}

	window->context.makeCurrent = makeContextCurrentOSMesa;
	window->context.swapBuffers = swapBuffersOSMesa;
	window->context.swapInterval = swapIntervalOSMesa;
	window->context.extensionSupported = extensionSupportedOSMesa;
	window->context.getProcAddress = getProcAddressOSMesa;
	window->context.destroy = destroyContextOSMesa;

	return GLFW_TRUE;
	}

	#undef SET_ATTRIB


	//////////////////////////////////////////////////////////////////////////
	////// GLFW native API //////
	//////////////////////////////////////////////////////////////////////////

	GLFWAPI int glfwGetOSMesaColorBuffer(GLFWwindow* handle, int* width,
	int* height, int* format, void** buffer)
	{
	void* mesaBuffer;
	GLint mesaWidth, mesaHeight, mesaFormat;

	_GLFW_REQUIRE_INIT_OR_RETURN(GLFW_FALSE);

	_GLFWwindow* window = (_GLFWwindow*) handle;
	assert(window != NULL);

	if (window->context.source != GLFW_OSMESA_CONTEXT_API)
	{
	_glfwInputError(GLFW_NO_WINDOW_CONTEXT, NULL);
	return GLFW_FALSE;
	}

	if (!OSMesaGetColorBuffer(window->context.osmesa.handle,
	&mesaWidth, &mesaHeight,
	&mesaFormat, &mesaBuffer))
	{
	_glfwInputError(GLFW_PLATFORM_ERROR,
	"OSMesa: Failed to retrieve color buffer");
	return GLFW_FALSE;
	}

	if (width)
	*width = mesaWidth;
	if (height)
	*height = mesaHeight;
	if (format)
	*format = mesaFormat;
	if (buffer)
	*buffer = mesaBuffer;

	return GLFW_TRUE;
	}

	GLFWAPI int glfwGetOSMesaDepthBuffer(GLFWwindow* handle,
	int* width, int* height,
	int* bytesPerValue,
	void** buffer)
	{
	void* mesaBuffer;
	GLint mesaWidth, mesaHeight, mesaBytes;

	_GLFW_REQUIRE_INIT_OR_RETURN(GLFW_FALSE);

	_GLFWwindow* window = (_GLFWwindow*) handle;
	assert(window != NULL);

	if (window->context.source != GLFW_OSMESA_CONTEXT_API)
	{
	_glfwInputError(GLFW_NO_WINDOW_CONTEXT, NULL);
	return GLFW_FALSE;
	}

	if (!OSMesaGetDepthBuffer(window->context.osmesa.handle,
	&mesaWidth, &mesaHeight,
	&mesaBytes, &mesaBuffer))
	{
	_glfwInputError(GLFW_PLATFORM_ERROR,
	"OSMesa: Failed to retrieve depth buffer");
	return GLFW_FALSE;
	}

	if (width)
	*width = mesaWidth;
	if (height)
	*height = mesaHeight;
	if (bytesPerValue)
	*bytesPerValue = mesaBytes;
	if (buffer)
	*buffer = mesaBuffer;

	return GLFW_TRUE;
	}

	GLFWAPI OSMesaContext glfwGetOSMesaContext(GLFWwindow* handle)
	{
	_GLFW_REQUIRE_INIT_OR_RETURN(NULL);

	_GLFWwindow* window = (_GLFWwindow*) handle;
	assert(window != NULL);

	if (window->context.source != GLFW_OSMESA_CONTEXT_API)
	{
	_glfwInputError(GLFW_NO_WINDOW_CONTEXT, NULL);
	return NULL;
	}

	return window->context.osmesa.handle;
	}