Refactored interface to OpenGL with a minimum requirement of version 1.4

* If the implementation reports a lower than required version; display a critical message and gracefully abort startup.
* Reworked GL_state with a more practical distinction between high-level "features" (abstract) and the implementation/vendor specific extensions used to implement them. Availability of features considered static post initialization.
* Multitexture functionaliy assumed present.
* Cleaned up GL initialization centralising all default state configuration in Sys_GLConfigureDefaultState.
* Pruned dead code for unused extensions.

Todo: I've left the texture combiner stuff alone for now as I've no way to test any potential changes on anything other than my main dev system presently (which effectively means the NVIDIA paths only).

doomsday/engine/portable/include/gl_main.h

@@ -81,13 +81,6 @@ const char*     GL_ChooseFixedFont(void);
 const char*     GL_ChooseVariableFont(glfontstyle_t style, int resX, int resY);
 void            GL_LowRes(void);
 
-/**
- * Set the currently active GL texture unit by ident.
- *
- * @param texture  GL texture unit ident to make active.
- */
-void GL_ActiveTexture(const DGLenum texture);
-
 void            GL_ModulateTexture(int mode);
 void            GL_SelectTexUnits(int count);
 void            GL_SetTextureCompression(boolean on);

doomsday/engine/portable/include/sys_opengl.h

@@ -60,49 +60,52 @@
  * Configure available features
  * \todo Move out of this header.
  */
-#define USE_MULTITEXTURE                1
 #define USE_TEXTURE_COMPRESSION_S3      1
 
 /**
  * High-level GL state information.
  */
 typedef struct gl_state_s {
+    /// Global config:
+    boolean forceFinishBeforeSwap;
     int maxTexFilterAniso;
-    int maxTexSize;
-#ifdef USE_MULTITEXTURE
+    int maxTexSize; // Logical pixels.
     int maxTexUnits;
-#endif
-#if WIN32
     int multisampleFormat;
-#endif
-    boolean allowTexCompression;
-    boolean forceFinishBeforeSwap;
-    boolean haveCubeMap;
-    boolean useArrays;
-    boolean useFog;
-    boolean useMultiTex;
-    boolean useTexCompression;
-    boolean useTexFilterAniso;
-    boolean useVSync;
-    float currentLineWidth, currentPointSize;
+
+    /// Current state:
+    boolean currentUseFog;
+    boolean currentUseTexCompression;
     float currentGrayMipmapFactor;
-    // Extension availability bits:
+    float currentLineWidth;
+    float currentPointSize;
+
+    /// Feature (abstract) availability bits:
+    /// Vendor and implementation agnostic.
+    struct {
+        uint blendSubtract : 1;
+        uint elementArrays : 1;
+        uint genMipmap : 1;
+        uint multisample : 1;
+        uint texCompression : 1;
+        uint texFilterAniso : 1;
+        uint texNonPowTwo : 1;
+        uint vsync : 1;
+    } features;
+
+    /// Extension availability bits:
     struct {
         uint blendSub : 1;
-        uint framebufferObject : 1;
         uint genMipmapSGIS : 1;
         uint lockArray : 1;
-#ifdef USE_MULTITEXTURE
-        uint multiTex : 1;
-#endif
 #ifdef USE_TEXTURE_COMPRESSION_S3
         uint texCompressionS3 : 1;
 #endif
         uint texEnvComb : 1;
         uint texEnvCombNV : 1;
         uint texEnvCombATI : 1;
         uint texFilterAniso : 1;
-        uint texNonPow2 : 1;
+        uint texNonPowTwo : 1;
 #if WIN32
         uint wglMultisampleARB : 1;
         uint wglSwapIntervalEXT : 1;
@@ -123,31 +126,19 @@ typedef enum arraytype_e {
     AR_TEXCOORD7
 } arraytype_t;
 
-#ifdef USE_MULTITEXTURE
-#  define DGL_MAX_TEXTURE_UNITS  (GL_state.useMultiTex? GL_state.maxTexUnits : 1)
-#  ifdef WIN32
-extern PFNGLCLIENTACTIVETEXTUREARBPROC glClientActiveTextureARB;
-extern PFNGLACTIVETEXTUREARBPROC glActiveTextureARB;
-extern PFNGLMULTITEXCOORD2FARBPROC glMultiTexCoord2fARB;
-extern PFNGLMULTITEXCOORD2FVARBPROC glMultiTexCoord2fvARB;
-#  endif
-#else
-#  define DGL_MAX_TEXTURE_UNITS  (1)
-#endif
-
 extern gl_state_t GL_state;
 
 #ifdef WIN32
-# ifdef GL_EXT_framebuffer_object
-extern PFNGLGENERATEMIPMAPEXTPROC glGenerateMipmapEXT;
-# endif
-
 extern PFNWGLSWAPINTERVALEXTPROC wglSwapIntervalEXT;
 extern PFNWGLCHOOSEPIXELFORMATARBPROC wglChoosePixelFormatARB;
 
 extern PFNGLBLENDEQUATIONEXTPROC glBlendEquationEXT;
 extern PFNGLLOCKARRAYSEXTPROC glLockArraysEXT;
 extern PFNGLUNLOCKARRAYSEXTPROC glUnlockArraysEXT;
+extern PFNGLCLIENTACTIVETEXTUREARBPROC glClientActiveTexture;
+extern PFNGLACTIVETEXTUREARBPROC glActiveTexture;
+extern PFNGLMULTITEXCOORD2FARBPROC glMultiTexCoord2f;
+extern PFNGLMULTITEXCOORD2FVARBPROC glMultiTexCoord2fv;
 #endif
 
 #ifndef GL_ATI_texture_env_combine3
@@ -186,4 +177,4 @@ boolean Sys_GLQueryExtension(const char* name, const GLubyte* extensions);
 
 boolean Sys_GLCheckError(void);
 
-#endif /* LIBDENG_SYSTEM_OPENGL_H */
+#endif /* LIBDENG_SYSTEM_OPENGL_H */

doomsday/engine/portable/include/sys_system.h

@@ -1,10 +1,10 @@
-/**\file
+/**\file sys_system.h
  *\section License
  * License: GPL
  * Online License Link: http://www.gnu.org/licenses/gpl.html
  *
- *\author Copyright © 2003-2010 Jaakko Keränen <jaakko.keranen@iki.fi>
- *\author Copyright © 2006-2010 Daniel Swanson <danij@dengine.net>
+ *\author Copyright © 2003-2011 Jaakko Keränen <jaakko.keranen@iki.fi>
+ *\author Copyright © 2006-2011 Daniel Swanson <danij@dengine.net>
  *\author Copyright © 2006 Jamie Jones <jamie_jones_au@yahoo.com.au>
  *
  * This program is free software; you can redistribute it and/or modify
@@ -24,7 +24,7 @@
  */
 
 /**
- * sys_system.h: OS Specific Services Subsystem
+ * OS Specific Services Subsystem.
  */
 
 #ifndef LIBDENG_FILESYS_SYSTEM_H
@@ -43,7 +43,9 @@ void Sys_Init(void);
 void Sys_Shutdown(void);
 void Sys_Quit(void);
 
-int Sys_CriticalMessage(char* msg);
+int Sys_CriticalMessage(const char* msg);
+int Sys_CriticalMessagef(const char* format, ...) PRINTF_F(1,2);
+
 void Sys_Sleep(int millisecs);
 void Sys_ShowCursor(boolean show);
 void Sys_HideMouse(void);