Added OSMesa based GLContext.

- Renders 3D using Mesa offscreen software renderer.
- Will be used to run 3D tests on bots that do not support native OpenGL.
- Extended glew library to use the osmesa shared library instead of the regular OpenGL one if it is in the search path.
- Only works on Windows with this changelist, though other platforms will continue to use native OpenGL.
- Added a stub GLContext implementation for use in unit tests.

Review URL: http://codereview.chromium.org/1629029

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@45093 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 88 insertions, 2 deletions

diff --git a/third_party/glew/include/GL/glew.h b/third_party/glew/include/GL/glew.h
index 90438a7..34183a9 100644
--- a/third_party/glew/include/GL/glew.h
+++ b/third_party/glew/include/GL/glew.h
@@ -12863,6 +12863,8 @@ GLEW_VAR_EXPORT GLboolean __GLEW_WIN_swap_hint;
 }; /* GLEWContextStruct */
 #endif /* GLEW_MX */
 
+typedef void* (GLAPIENTRY * PFNOSMESAGETPROCADDRESSPROC) (const GLubyte* name);
+
 /* ------------------------------------------------------------------------- */
 
 /* error codes */
@@ -12898,6 +12900,7 @@ GLEWAPI GLboolean glewContextIsSupported (GLEWContext* ctx, const char* name);
 
 #else /* GLEW_MX */
 
+void osmewContextInit ();
 GLEWAPI GLenum glewInit ();
 GLEWAPI GLenum glewInitGL2Hack ();
 GLEWAPI GLboolean glewIsSupported (const char* name);
diff --git a/third_party/glew/include/GL/osmew.h b/third_party/glew/include/GL/osmew.h
new file mode 100644
index 0000000..4816694
--- /dev/null
+++ b/third_party/glew/include/GL/osmew.h
@@ -0,0 +1,51 @@
+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef __osmew_h__
+#define __osmew_h__
+#define __OSMEW_H__
+
+#include <GL/glew.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#if !defined(GLAPIENTRY)
+#if defined(_WIN32)
+#define GLAPIENTRY __stdcall
+#else
+#define GLAPIENTRY
+#endif
+#endif
+
+#define OSMEW_GET_FUN(x) x
+
+// Subset of OSMesa functions.
+
+typedef struct osmesa_context *OSMesaContext;
+typedef OSMesaContext (GLAPIENTRY * PFNOSMESACREATECONTEXTPROC) (GLenum format, OSMesaContext sharelist);
+typedef void (GLAPIENTRY * PFNOSMESADESTROYCONTEXTPROC) (OSMesaContext ctx);
+typedef GLboolean (GLAPIENTRY * PFNOSMESAMAKECURRENTPROC) (OSMesaContext ctx, void* buffer, GLenum type, GLsizei width, GLsizei height);
+typedef OSMesaContext (GLAPIENTRY * PFNOSMESAGETCURRENTCONTEXTPROC) (void);
+
+#define OSMesaCreateContext OSMEW_GET_FUN(__osmesaCreateContext)
+#define OSMesaDestroyContext OSMEW_GET_FUN(__osmesaDestroyContext)
+#define OSMesaMakeCurrent OSMEW_GET_FUN(__osmesaMakeCurrent)
+#define OSMesaGetCurrentContext OSMEW_GET_FUN(__osmesaGetCurrentContext)
+
+extern PFNOSMESACREATECONTEXTPROC __osmesaCreateContext;
+extern PFNOSMESADESTROYCONTEXTPROC __osmesaDestroyContext;
+extern PFNOSMESAMAKECURRENTPROC __osmesaMakeCurrent;
+extern PFNOSMESAGETCURRENTCONTEXTPROC __osmesaGetCurrentContext;
+
+void osmewInit ();
+
+#undef GLAPIENTRY
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __osmew_h__ */
diff --git a/third_party/glew/src/glew.c b/third_party/glew/src/glew.c
index d987695..a9fe3a5 100644
--- a/third_party/glew/src/glew.c
+++ b/third_party/glew/src/glew.c
@@ -36,6 +36,8 @@
 #  include <GL/glxew.h>
 #endif
 
+#include <GL/osmew.h>
+
 /*
  * Define glewGetContext and related helper macros.
  */
@@ -75,16 +77,28 @@ void* WinGetProcAddress(const GLubyte* name)
   /* Need to use GetProcAddress to bootstrap things now that we are
      dynamically looking up OpenGL 1.1 entry points as well. */
   static HMODULE oglImage = NULL;
+  static PFNOSMESAGETPROCADDRESSPROC osmesaGetProcAddress = NULL;
   void* proc = NULL;
 
   if (NULL == oglImage) {
-    oglImage = LoadLibraryA("opengl32.dll");
+    oglImage = LoadLibraryA("osmesa.dll");
+    if (NULL == oglImage) {
+      oglImage = LoadLibraryA("opengl32.dll");
+    }
+    else {
+      osmesaGetProcAddress = (PFNOSMESAGETPROCADDRESSPROC) GetProcAddress(oglImage, "_OSMesaGetProcAddress@4");
+    }
   }
   if (NULL != oglImage) {
     proc = (void*) GetProcAddress(oglImage, (LPCSTR) name);
   }
   if (NULL == proc) {
-    proc = wglGetProcAddress((LPCSTR) name);
+    if (osmesaGetProcAddress) {
+      proc = osmesaGetProcAddress(name);
+    }
+    else {
+      proc = wglGetProcAddress((LPCSTR) name);
+    }
   }
   return proc;
 }
@@ -9887,6 +9901,22 @@ const GLubyte* glewGetString (GLenum name)
 GLboolean glewExperimental = GL_FALSE;
 
 #if !defined(GLEW_MX)
+

+// Subset of OSMesa functions.

+PFNOSMESACREATECONTEXTPROC __osmesaCreateContext = NULL;

+PFNOSMESADESTROYCONTEXTPROC __osmesaDestroyContext = NULL;

+PFNOSMESAMAKECURRENTPROC __osmesaMakeCurrent = NULL;

+PFNOSMESAGETCURRENTCONTEXTPROC __osmesaGetCurrentContext = NULL;

+
+void osmewInit (void)
+{
+  // Attempt to get OSMesa entry points on all platforms. Must get OSMesaGetProcAddress first so future calls to
+  // glewGetProcAddress use it.
+  __osmesaCreateContext = (PFNOSMESACREATECONTEXTPROC)glewGetProcAddress((const GLubyte*)"OSMesaCreateContext");
+  __osmesaDestroyContext = (PFNOSMESADESTROYCONTEXTPROC)glewGetProcAddress((const GLubyte*)"OSMesaDestroyContext");
+  __osmesaMakeCurrent = (PFNOSMESAMAKECURRENTPROC)glewGetProcAddress((const GLubyte*)"OSMesaMakeCurrent");
+  __osmesaGetCurrentContext = (PFNOSMESAGETCURRENTCONTEXTPROC)glewGetProcAddress((const GLubyte*)"OSMesaGetCurrentContext");
+}
 
 #if defined(_WIN32)
 extern GLenum wglewContextInit (void);
@@ -9899,6 +9929,8 @@ GLenum glewInit ()
   GLenum r;
   if ( (r = glewContextInit()) ) return r;
 #if defined(_WIN32)
+  // TODO(apatrick): Do this on other platforms.
+  osmewInit();
   return wglewContextInit();
 #elif !defined(__APPLE__) || defined(GLEW_APPLE_GLX) /* _UNIX */
   return glxewContextInit();