Separated initialization of GL functions for basic functionality

vs. GLSL stuff.  This should allow users who don't have GLSL to still
use the OpenGL renderer.  Related to this, added a stub for GL FBO,
which I hope to add for a future release.


git-svn-id: svn://svn.code.sf.net/p/stella/code/trunk@1810 8b62c5a3-ac7e-4cc8-8f21-d9a121418aba

src/common/FrameBufferGL.cxx

@@ -126,7 +126,7 @@ bool FrameBufferGL::loadLibrary(const string& library)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool FrameBufferGL::loadFuncs()
+bool FrameBufferGL::loadFuncs(GLFunctionality functionality)
 {
 #define OGL_INIT(RET,FUNC,PARAMS) \
   p_ ## FUNC = (RET(APIENTRY*)PARAMS) SDL_GL_GetProcAddress(#FUNC); if(!p_ ## FUNC) return false
@@ -135,6 +135,9 @@ bool FrameBufferGL::loadFuncs()
   {
     // Fill the function pointers for GL functions
     // If anything fails, we'll know it immediately, and return false
+    switch(functionality)
+    {
+      case kGL_BASIC:
         OGL_INIT(void,glClear,(GLbitfield));
         OGL_INIT(void,glEnable,(GLenum));
         OGL_INIT(void,glDisable,(GLenum));
@@ -164,7 +167,9 @@ bool FrameBufferGL::loadFuncs()
         OGL_INIT(void,glTexImage2D,(GLenum, GLint, GLint, GLsizei, GLsizei, GLint, GLenum, GLenum, const GLvoid*));
         OGL_INIT(void,glTexSubImage2D,(GLenum, GLint, GLint, GLint, GLsizei, GLsizei, GLenum, GLenum, const GLvoid*));
         OGL_INIT(void,glTexParameteri,(GLenum, GLenum, GLint));
+        break; // kGLBasic
 
+      case kGL_SHADER:
         OGL_INIT(GLuint,glCreateShader,(GLenum));
         OGL_INIT(void,glDeleteShader,(GLuint));
         OGL_INIT(void,glShaderSource,(GLuint, int, const char**, int));
@@ -184,6 +189,13 @@ bool FrameBufferGL::loadFuncs()
         OGL_INIT(void,glTexEnvi,(GLenum, GLenum, GLint));
         OGL_INIT(void,glMultiTexCoord2f,(GLenum, GLfloat, GLfloat));
         OGL_INIT(GLenum,glGetError,(void));
+        break;  // kGLShader
+
+      case kGL_FBO:
+        // TODO - add support for frame buffer objects / render-to-texture
+        return false;
+        break;  // kGL_FBO
+    }
   }
   else
     return false;
@@ -336,15 +348,22 @@ bool FrameBufferGL::setVidMode(VideoMode& mode)
   // Make sure the flags represent the current screen state
   mySDLFlags = myScreen->flags;
 
-  // Reload OpenGL function pointers.  This only seems to be needed for Windows
+  // Load OpenGL function pointers
-  // Vista, but it shouldn't hurt on other systems.
+  // Basic functionaity is an absolute requirement
-  if(!loadFuncs())
+  // TV effects require GLSL, but not having them still allows basic GL support
-    return false;
+  myGLSLAvailable = myFBOAvailable = false;
-
+  if(loadFuncs(kGL_BASIC))
+  {
     // Grab OpenGL version number
     string version((const char *)p_glGetString(GL_VERSION));
     myGLVersion = atof(version.substr(0, 3).c_str());
 
+    // TV effects depend on the GLSL functions being available
+    myGLSLAvailable = loadFuncs(kGL_SHADER);
+  }
+  else
+    return false;
+
   // Check for some extensions that can potentially speed up operation
   // Don't use it if we've been instructed not to
   if(myOSystem->settings().getBool("gl_texrect"))
@@ -413,7 +432,7 @@ cerr << "dimensions: " << (fullScreen() ? "(full)" : "") << endl
     // Also note that TV filtering is only available with OpenGL 2.0+
     myTiaSurface = new FBSurfaceGL(*this, baseWidth>>1, baseHeight,
                                      mode.image_w, mode.image_h,
-                                     myGLVersion >= 2.0);
+                                     myGLSLAvailable);
     myTiaSurface->setPos(mode.image_x, mode.image_y);
     myTiaSurface->setFilter(myOSystem->settings().getString("gl_filter"));
   }
@@ -1641,10 +1660,16 @@ GLuint FBSurfaceGL::genShader(ShaderType type)
   return program;
 }
 
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+bool FrameBufferGL::myLibraryLoaded = false;
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 float FrameBufferGL::myGLVersion = 0.0;
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool FrameBufferGL::myLibraryLoaded = false;
+bool FrameBufferGL::myGLSLAvailable = false;
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+bool FrameBufferGL::myFBOAvailable = false;
 
 #endif  // DISPLAY_OPENGL

src/common/FrameBufferGL.hxx

@@ -69,6 +69,16 @@ class FrameBufferGL : public FrameBuffer
     */
     static float glVersion() { return myGLVersion; }
 
+    /**
+      Indicates whether GL shading language was detected and enabled.
+    */
+    static bool isGLSLAvailable() { return myGLSLAvailable; }
+
+    /**
+      Indicates whether GL FBO functionality was detected and enabled.
+    */
+    static bool isFBOAvailable() { return myFBOAvailable; }
+
     //////////////////////////////////////////////////////////////////////
     // The following are derived from public methods in FrameBuffer.hxx
     //////////////////////////////////////////////////////////////////////
@@ -162,7 +172,10 @@ class FrameBufferGL : public FrameBuffer
     void postFrameUpdate();
 
   private:
-    bool loadFuncs();
+    enum GLFunctionality {
+      kGL_BASIC, kGL_SHADER, kGL_FBO
+    };
+    bool loadFuncs(GLFunctionality functionality);
 
     /**
       Enable/disable texture effect.
@@ -213,11 +226,17 @@ class FrameBufferGL : public FrameBuffer
     // Indicates whether or not the phosphor filter is enabled
     bool myUseGLPhosphor;
 
+    // Indicates if the OpenGL library has been properly loaded
+    static bool myLibraryLoaded;
+
     // Indicates the OpenGL version found (0 indicates none)
     static float myGLVersion;
 
-    // Indicates if the OpenGL library has been properly loaded
+    // Indicates whether GLSL functions were properly loaded
-    static bool myLibraryLoaded;
+    static bool myGLSLAvailable;
+
+    // Indicates whether Frame Buffer Object functions were properly loaded
+    static bool myFBOAvailable;
 };
 
 /**

src/common/Version.hxx

@@ -19,7 +19,7 @@
 #ifndef VERSION_HXX
 #define VERSION_HXX
 
-#define STELLA_BASE_VERSION "2.8.1"
+#define STELLA_BASE_VERSION "2.8.2_svn"
 
 #ifdef NIGHTLY_BUILD
   #define STELLA_VERSION STELLA_BASE_VERSION "pre-" NIGHTLY_BUILD

src/gui/VideoDialog.cxx

@@ -416,9 +416,9 @@ void VideoDialog::loadConfig()
 
 #ifdef DISPLAY_OPENGL
   //////////////////////////////////////////////////////////////////////
-  // TV effects are only enabled in OpenGL mode, and only if OpenGL 2.0+
+  // TV effects are only enabled in OpenGL mode, and only if GLSL is
-  // is available; for now, 'gl_texrect' must also be disabled
+  // available; for now, 'gl_texrect' must also be disabled
-  bool tv = gl && FrameBufferGL::glVersion() >= 2.0 &&
+  bool tv = gl && FrameBufferGL::isGLSLAvailable() &&
             !instance().settings().getBool("gl_texrect");
   //////////////////////////////////////////////////////////////////////