Hack in crude OSMesa support

Mostly this is quick, "do nothing" ifdefs when built with
SYSTEM=linux-osmesa, to support the off-screen rendering mode of Mesa in
headless tests.  Support in glewinfo and visualinfo is enough to get
them compile, but insufficient for them to run successfully.

auto/Makefile

@@ -204,7 +204,8 @@ $(S.DEST)/glew.c: $(EXT)/.dummy
 	$(BIN)/make_list.pl $(GL_CORE_SPEC) | grep -v '\"GL_VERSION' >> $@
 	$(BIN)/make_list.pl $(GL_EXT_SPEC) >> $@
 	echo -e "\n  return GLEW_OK;\n}\n" >> $@
-	echo -e "\n#if defined(_WIN32)" >> $@
+	echo -e "\n#if defined(GLEW_OSMESA)" >> $@
+	echo -e "\n#elif defined(_WIN32)" >> $@
 	echo -e "\n#if !defined(GLEW_MX)" >> $@
 	$(BIN)/make_def_fun.pl WGL $(WGL_EXT_SPEC) >> $@
 	$(BIN)/make_def_var.pl WGL $(WGL_EXT_SPEC) >> $@

auto/src/glew_head.c

@@ -1,6 +1,9 @@
 #include <GL/glew.h>
 
-#if defined(_WIN32)
+#if defined(GLEW_OSMESA)
+#  define GLAPI extern
+#  include <GL/osmesa.h>
+#elif defined(_WIN32)
 #  include <GL/wglew.h>
 #elif !defined(__ANDROID__) && !defined(__native_client__) && !defined(__HAIKU__) && (!defined(__APPLE__) || defined(GLEW_APPLE_GLX))
 #  include <GL/glxew.h>
@@ -137,7 +140,9 @@ void* NSGLGetProcAddress (const GLubyte *name)
 /*
  * Define glewGetProcAddress.
  */
-#if defined(GLEW_REGAL)
+#if defined(GLEW_OSMESA)
+#  define glewGetProcAddress(name) OSMesaGetProcAddress((const char *)name)
+#elif defined(GLEW_REGAL)
 #  define glewGetProcAddress(name) regalGetProcAddress((const GLchar *) name)
 #elif defined(_WIN32)
 #  define glewGetProcAddress(name) wglGetProcAddress((LPCSTR)name)

auto/src/glew_init_tail.c

@@ -39,6 +39,8 @@ GLenum GLEWAPIENTRY glewInit (void)
   GLenum r;
   r = glewContextInit();
   if ( r != 0 ) return r;
+#if defined(GLEW_OSMESA)
+  return r;
 #if defined(_WIN32)
   return wglewInit();
 #elif !defined(__ANDROID__) && !defined(__native_client__) && !defined(__HAIKU__) && (!defined(__APPLE__) || defined(GLEW_APPLE_GLX)) /* _UNIX */

auto/src/glew_str_wgl.c

@@ -4,7 +4,8 @@
   return ret;
 }
 
-#if defined(_WIN32)
+#if defined(GLEW_OSMESA)
+#elif defined(_WIN32)
 
 #if defined(GLEW_MX)
 GLboolean GLEWAPIENTRY wglewContextIsSupported (const WGLEWContext* ctx, const char* name)

auto/src/glewinfo_head.c

@@ -2,7 +2,10 @@
 #include <stdlib.h>
 #include <string.h>
 #include <GL/glew.h>
-#if defined(_WIN32)
+#if defined(GLEW_OSMESA)
+#define GLAPI extern
+#include <GL/osmesa.h>
+#elif defined(_WIN32)
 #include <GL/wglew.h>
 #elif !defined(__APPLE__) && !defined(__HAIKU__) || defined(GLEW_APPLE_GLX)
 #include <GL/glxew.h>
@@ -21,7 +24,8 @@ static FILE* f;
 #ifdef GLEW_MX
 GLEWContext _glewctx;
 #define glewGetContext() (&_glewctx)
-#ifdef _WIN32
+#if defined(GLEW_OSMESA)
+#elif defined(_WIN32)
 WGLEWContext _wglewctx;
 #define wglewGetContext() (&_wglewctx)
 #elif !defined(__APPLE__) && !defined(__HAIKU__) || defined(GLEW_APPLE_GLX)
@@ -34,7 +38,8 @@ GLXEWContext _glxewctx;
 
 struct createParams
 {
-#if defined(_WIN32)
+#if defined(GLEW_OSMESA)
+#elif defined(_WIN32)
   int         pixelformat;
 #elif !defined(__APPLE__) && !defined(__HAIKU__) || defined(GLEW_APPLE_GLX)
   const char* display;

auto/src/glewinfo_tail.c

@@ -9,7 +9,8 @@ int main (int argc, char** argv)
   GLuint err;
   struct createParams params = 
   {
-#if defined(_WIN32)
+#if defined(GLEW_OSMESA)
+#elif defined(_WIN32)
     -1,  /* pixelformat */
 #elif !defined(__HAIKU__) && !defined(__APPLE__) || defined(GLEW_APPLE_GLX)
     "",  /* display */
@@ -24,7 +25,8 @@ int main (int argc, char** argv)
   if (glewParseArgs(argc-1, argv+1, &params))
   {
     fprintf(stderr, "Usage: glewinfo "
-#if defined(_WIN32)
+#if defined(GLEW_OSMESA)
+#elif defined(_WIN32)
 	    "[-pf <pixelformat>] "
 #elif !defined(__HAIKU__) && !defined(__APPLE__) || defined(GLEW_APPLE_GLX)
 	    "[-display <display>] "
@@ -46,7 +48,8 @@ int main (int argc, char** argv)
   glewExperimental = GL_TRUE;
 #ifdef GLEW_MX
   err = glewContextInit(glewGetContext());
-#ifdef _WIN32
+#if defined(GLEW_OSMESA)
+#elif defined(_WIN32)
   err = err || wglewContextInit(wglewGetContext());
 #elif !defined(__HAIKU__) && !defined(__APPLE__) || defined(GLEW_APPLE_GLX)
   err = err || glxewContextInit(glxewGetContext());
@@ -76,7 +79,8 @@ int main (int argc, char** argv)
   fprintf(f, "    GLEW Extension Info\n");
   fprintf(f, "---------------------------\n\n");
   fprintf(f, "GLEW version %s\n", glewGetString(GLEW_VERSION));
-#if defined(_WIN32)
+#if defined(GLEW_OSMESA)
+#elif defined(_WIN32)
   fprintf(f, "Reporting capabilities of pixelformat %d\n", params.pixelformat);
 #elif !defined(__APPLE__) || defined(GLEW_APPLE_GLX)
   fprintf(f, "Reporting capabilities of display %s, visual 0x%x\n", 
@@ -86,7 +90,8 @@ int main (int argc, char** argv)
 	  glGetString(GL_RENDERER), glGetString(GL_VENDOR));
   fprintf(f, "OpenGL version %s is supported\n", glGetString(GL_VERSION));
   glewInfo();
-#if defined(_WIN32)
+#if defined(GLEW_OSMESA)
+#elif defined(_WIN32)
   wglewInfo();
 #else
   glxewInfo();
@@ -150,7 +155,22 @@ GLboolean glewParseArgs (int argc, char** argv, struct createParams *params)
 
 /* ------------------------------------------------------------------------ */
 
-#if defined(_WIN32)
+#if defined(GLEW_OSMESA)
+OSMesaContext ctx;
+
+GLboolean glewCreateContext ()
+{
+  ctx = OSMesaCreateContext(OSMESA_RGBA, NULL);
+  if (NULL == ctx) return GL_TRUE;
+  return GL_FALSE;
+}
+
+void glewDestroyContext ()
+{
+  if (NULL != ctx) OSMesaDestroyContext(ctx);
+}
+
+#elif defined(_WIN32)
 
 HWND wnd = NULL;
 HDC dc = NULL;

auto/src/glewinfo_wgl.c

@@ -2,7 +2,8 @@
 
 /* ------------------------------------------------------------------------ */
 
-#ifdef _WIN32
+#if defined(GLEW_OSMESA)
+#elif defined(_WIN32)
 
 static void wglewInfo ()
 {

config/Makefile.linux-osmesa

@@ -0,0 +1,36 @@
+NAME = $(GLEW_NAME)
+CC = cc
+LD = cc
+M_ARCH ?= $(shell uname -m)
+ARCH64 = false
+ifeq (x86_64,${M_ARCH})
+  ARCH64 = true
+endif
+ifeq (ppc64,${M_ARCH})
+  ARCH64 = true
+endif
+ifeq (${ARCH64},true)
+  LDFLAGS.EXTRA = -L/usr/lib64
+  LIBDIR = $(GLEW_DEST)/lib64
+else
+  LDFLAGS.EXTRA = -L/usr/lib
+  LIBDIR = $(GLEW_DEST)/lib
+endif
+LDFLAGS.GL = -lOSMesa
+LDFLAGS.STATIC = -Wl,-Bstatic
+LDFLAGS.DYNAMIC = -Wl,-Bdynamic
+NAME = GLEW
+WARN = -Wall -W
+POPT = -O2
+CFLAGS.EXTRA += -fPIC -DGLEW_OSMESA
+BIN.SUFFIX =
+LIB.SONAME = lib$(NAME).so.$(SO_MAJOR)
+LIB.DEVLNK = lib$(NAME).so
+LIB.SHARED = lib$(NAME).so.$(SO_VERSION)
+LIB.STATIC = lib$(NAME).a
+LDFLAGS.SO = -shared -Wl,-soname=$(LIB.SONAME)
+LIB.SONAME.MX = lib$(NAME)mx.so.$(SO_MAJOR)
+LIB.DEVLNK.MX = lib$(NAME)mx.so
+LIB.SHARED.MX = lib$(NAME)mx.so.$(SO_VERSION)
+LIB.STATIC.MX = lib$(NAME)mx.a
+LDFLAGS.SO.MX = -shared -Wl,-soname=$(LIB.SONAME.MX)

src/visualinfo.c

@@ -34,7 +34,10 @@
 #include <stdlib.h>
 #include <string.h>
 #include <GL/glew.h>
-#if defined(_WIN32)
+#if defined(GLEW_OSMESA)
+#define GLAPI extern
+#include <GL/osmesa.h>
+#elif defined(_WIN32)
 #include <GL/wglew.h>
 #elif defined(__APPLE__) && !defined(GLEW_APPLE_GLX)
 #include <OpenGL/OpenGL.h>
@@ -57,7 +60,9 @@ GLXEWContext _glxewctx;
 
 typedef struct GLContextStruct
 {
-#ifdef _WIN32
+#if defined(GLEW_OSMESA)
+  OSMesaContext ctx;
+#elif defined(_WIN32)
   HWND wnd;
   HDC dc;
   HGLRC rc;
@@ -180,7 +185,8 @@ main (int argc, char** argv)
 
   /* ---------------------------------------------------------------------- */
   /* extensions string */
-#if defined(_WIN32)
+#if defined(GLEW_OSMESA)
+#elif defined(_WIN32)
   /* WGL extensions */
   if (WGLEW_ARB_extensions_string || WGLEW_EXT_extensions_string)
   {
@@ -1003,7 +1009,26 @@ VisualInfo (GLContext* ctx)
 
 /* ------------------------------------------------------------------------ */
 
-#if defined(_WIN32)
+#if defined(GLEW_OSMESA)
+void InitContext (GLContext* ctx)
+{
+  ctx->ctx = NULL;
+}
+
+GLboolean CreateContext (GLContext* ctx)
+{
+  if (NULL == ctx) return GL_TRUE;
+  ctx->ctx = OSMesaCreateContext(OSMESA_RGBA, NULL);
+  if (NULL == ctx->ctx) return GL_TRUE;
+  return GL_FALSE;
+}
+
+void DestroyContext (GLContext* ctx)
+{
+  if (NULL == ctx) return;
+  if (NULL != ctx->ctx) OSMesaDestroyContext(ctx->ctx);
+}
+#elif defined(_WIN32)
 
 void InitContext (GLContext* ctx)
 {