update extension usage..

nearly all of the previous required extensions are CORE in OpenGL 2.0
the remaining ones need to have fallback checks for ARB vs EXT vs APPLE 
variants..

src/bitmap.cpp

@@ -873,7 +873,7 @@ void Bitmap::drawText(const IntRect &rect, const char *str, int align)
 				}
 
 				TEX::bind(p->gl.tex);
-				TEX::uploadSubImage(posRect.x, posRect.y, posRect.w, posRect.h, txtSurf->pixels, GL_BGRA_EXT);
+				TEX::uploadSubImage(posRect.x, posRect.y, posRect.w, posRect.h, txtSurf->pixels, GL_BGRA);
 
 				PixelStore::reset();
 			}
@@ -884,7 +884,7 @@ void Bitmap::drawText(const IntRect &rect, const char *str, int align)
 			TEXFBO &gpTF = shState->gpTexFBO(txtSurf->w, txtSurf->h);
 
 			TEX::bind(gpTF.tex);
-			TEX::uploadSubImage(0, 0, txtSurf->w, txtSurf->h, txtSurf->pixels, GL_BGRA_EXT);
+			TEX::uploadSubImage(0, 0, txtSurf->w, txtSurf->h, txtSurf->pixels, GL_BGRA);
 
 			FBO::bind(gpTF.fbo, FBO::Read);
 			p->bindFBO();
@@ -917,7 +917,7 @@ void Bitmap::drawText(const IntRect &rect, const char *str, int align)
 		shader.setOpacity(txtAlpha);
 
 		shState->bindTex();
-		TEX::uploadSubImage(0, 0, txtSurf->w, txtSurf->h, txtSurf->pixels, GL_BGRA_EXT);
+		TEX::uploadSubImage(0, 0, txtSurf->w, txtSurf->h, txtSurf->pixels, GL_BGRA);
 		TEX::setSmooth(true);
 
 		Quad &quad = shState->gpQuad();

src/gl-util.h

@@ -109,19 +109,19 @@ namespace RBO
 	inline ID gen()
 	{
 		ID id;
-		glGenRenderbuffersEXT(1, &id.gl);
+		glGenRenderbuffers(1, &id.gl);
 
 		return id;
 	}
 
 	inline void del(ID id)
 	{
-		glDeleteRenderbuffersEXT(1, &id.gl);
+		glDeleteRenderbuffers(1, &id.gl);
 	}
 
 	inline void bind(ID id)
 	{
-		glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, id.gl);
+		glBindRenderbuffer(GL_RENDERBUFFER, id.gl);
 	}
 
 	inline void unbind()
@@ -131,7 +131,7 @@ namespace RBO
 
 	inline void allocEmpty(GLsizei width, GLsizei height)
 	{
-		glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_RGBA8, width, height);
+		glRenderbufferStorage(GL_RENDERBUFFER, GL_RGBA8, width, height);
 	}
 }
 
@@ -155,25 +155,25 @@ namespace FBO
 	inline ID gen()
 	{
 		ID id;
-		glGenFramebuffersEXT(1, &id.gl);
+		glGenFramebuffers(1, &id.gl);
 
 		return id;
 	}
 
 	inline void del(ID id)
 	{
-		glDeleteFramebuffersEXT(1, &id.gl);
+		glDeleteFramebuffers(1, &id.gl);
 	}
 
 	inline void bind(ID id, Mode mode)
 	{
 		static const GLenum modes[] =
 		{
-			GL_DRAW_FRAMEBUFFER_EXT,
+			GL_DRAW_FRAMEBUFFER,
-			GL_READ_FRAMEBUFFER_EXT
+			GL_READ_FRAMEBUFFER
 		};
 
-		glBindFramebufferEXT(modes[mode], id.gl);
+		glBindFramebuffer(modes[mode], id.gl);
 	}
 
 	inline void unbind(Mode mode)
@@ -183,12 +183,12 @@ namespace FBO
 
 	inline void setTarget(TEX::ID target, unsigned colorAttach = 0)
 	{
-		glFramebufferTexture2DEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0 + colorAttach, GL_TEXTURE_2D, target.gl, 0);
+		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0 + colorAttach, GL_TEXTURE_2D, target.gl, 0);
 	}
 
 	inline void setTarget(RBO::ID target, unsigned colorAttach = 0)
 	{
-		glFramebufferRenderbufferEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0 + colorAttach, GL_RENDERBUFFER, target.gl);
+		glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0 + colorAttach, GL_RENDERBUFFER, target.gl);
 	}
 
 	inline void blit(int srcX, int srcY,
@@ -203,7 +203,7 @@ namespace FBO
 			GL_LINEAR
 		};
 
-		glBlitFramebufferEXT(srcX, srcY, srcX+srcW, srcY+srcH,
+		glBlitFramebuffer(srcX, srcY, srcX+srcW, srcY+srcH,
 						  dstX, dstY, dstX+dstW, dstY+dstH,
 						  GL_COLOR_BUFFER_BIT, modes[mode]);
 	}

src/glstate.cpp

@@ -71,20 +71,20 @@ void GLBlendMode::apply(const BlendType &value)
 
 	case BlendNormal :
 		glBlendEquation(GL_FUNC_ADD);
-		glBlendFuncSeparateEXT(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA,
+		glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA,
 		                    GL_ONE,       GL_ONE_MINUS_SRC_ALPHA);
 		break;
 
 	case BlendAddition :
 		glBlendEquation(GL_FUNC_ADD);
-		glBlendFuncSeparateEXT(GL_SRC_ALPHA, GL_ONE,
+		glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE,
 		                    GL_ONE,       GL_ONE);
 		break;
 
 	case BlendSubstraction :
 		// FIXME Alpha calculation is untested
-		glBlendEquation(GL_FUNC_REVERSE_SUBTRACT_EXT);
+		glBlendEquation(GL_FUNC_REVERSE_SUBTRACT);
-		glBlendFuncSeparateEXT(GL_SRC_ALPHA, GL_ONE,
+		glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE,
 		                    GL_ONE,       GL_ONE);
 		break;
 	}

src/main.cpp

@@ -39,21 +39,11 @@
 
 static const char *reqExt[] =
 {
-	"GL_ARB_fragment_shader",
+	// Everything we are using is CORE in OpenGL 2.0 except FBOs and VAOs which we'll handle in a special function
-	"GL_ARB_shader_objects",
-	"GL_ARB_vertex_shader",
-	"GL_ARB_shading_language_100",
-	"GL_ARB_texture_non_power_of_two",
-	"GL_ARB_vertex_array_object",
-	"GL_ARB_vertex_buffer_object",
-	"GL_EXT_bgra",
-	"GL_EXT_blend_func_separate",
-	"GL_EXT_blend_subtract",
-	"GL_EXT_framebuffer_object",
-	"GL_EXT_framebuffer_blit",
 	0
 };
 
+
 static void
 rgssThreadError(RGSSThreadData *rtData, const std::string &msg)
 {
@@ -77,6 +67,50 @@ printGLInfo()
 	Debug() << "GLSL Version :" << glGetStringInt(GL_SHADING_LANGUAGE_VERSION);
 }
 
+static bool
+setupOptionalGLExtensions(RGSSThreadData* threadData)
+{
+	if (!GLEW_ARB_framebuffer_object) {
+		if (!GLEW_EXT_framebuffer_object && !GLEW_EXT_framebuffer_blit) {
+			rgssThreadError(threadData, "GL extensions \"GL_ARB_framebuffer_object\" or compatible extensiosns GL_EXT_framebuffer_object and GL_EXT_framebuffer_blit are not present");
+			return false;
+		} else {
+			// setup compat
+			// From EXT_framebuffer_object
+			glGenRenderbuffers      = glGenRenderbuffersEXT;
+			glDeleteRenderbuffers   = glDeleteRenderbuffersEXT;
+			glBindRenderbuffer      = glBindRenderbufferEXT;
+			glRenderbufferStorage   = glRenderbufferStorageEXT;
+
+			glGenFramebuffers       = glGenFramebuffersEXT;
+			glDeleteFramebuffers    = glDeleteFramebuffersEXT;
+			glBindFramebuffer       = glBindFramebufferEXT;
+			glFramebufferTexture2D  = glFramebufferTexture2DEXT;
+			glFramebufferRenderbuffer = glFramebufferRenderbufferEXT;
+
+			// From EXT_framebuffer_blit
+			glBlitFramebuffer       = glBlitFramebufferEXT;
+		}
+	}
+	if (!GLEW_ARB_timer_query && GLEW_EXT_timer_query) {
+		glGetQueryObjecti64v = glGetQueryObjecti64vEXT;
+		glGetQueryObjectui64v = glGetQueryObjectui64vEXT;
+	}
+	if (!GLEW_ARB_vertex_array_object ) {
+		if (!GLEW_APPLE_vertex_array_object) {
+			rgssThreadError(threadData, "GL extensions \"GL_ARB_vertex_array_object\" or compatible extensiosn GL_APPLE_vertex_array_object are not present");
+			return false;
+		} else {
+			// setup compat
+			glBindVertexArray = glBindVertexArrayAPPLE;
+			// the cast is because apple's uses const GLuint* and ARB doesn't
+			glGenVertexArrays = (PFNGLGENVERTEXARRAYSPROC)glGenVertexArraysAPPLE;
+			glDeleteVertexArrays = glDeleteVertexArraysAPPLE;
+		}
+	}
+	return true;
+}
+
 int rgssThreadFun(void *userdata)
 {
 	RGSSThreadData *threadData = static_cast<RGSSThreadData*>(userdata);
@@ -132,6 +166,11 @@ int rgssThreadFun(void *userdata)
 			return 0;
 		}
 	}
+	/* Setup optional GL extensions */
+	if (!setupOptionalGLExtensions(threadData)) {
+		SDL_GL_DeleteContext(glCtx);
+		return 0;
+	}
 
 	SDL_GL_SetSwapInterval(threadData->config.vsync ? 1 : 0);
 

src/perftimer.cpp

@@ -193,7 +193,7 @@ PerfTimer *createCPUTimer(int iter)
 
 PerfTimer *createGPUTimer(int iter)
 {
-	if (GLEW_EXT_timer_query)
+	if (GLEW_ARB_timer_query || GLEW_EXT_timer_query)
 	{
 		return new GPUTimerGLQuery(iter);
 	}