Graphics: AMD Radeon HD 7900 Series
Running: Windows 7(64 bit)
Program: CodeBlocks(32 bit)
OpenGL Library: GLee
This is where I setup the window. Its an SDL window using OpenGL rendering.
void Init(int w, int h, bool fullScr)
{
if ( SDL_Init(SDL_INIT_VIDEO) != 0 ) {
printf("Unable to initialize SDL: %s\n", SDL_GetError());
}
winW = w*scale;
winH = h*scale;
original_winW = w;
origianl_winH = h;
putenv("SDL_VIDEO_WINDOW_POS");
putenv("SDL_VIDEO_CENTERED=1");
getenv("SDL_VIDEO_WINDOW_POS");
getenv("SDL_VIDEO_CENTERED");
SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER, 1 ); // *new*
SDL_GL_SetAttribute( SDL_GL_SWAP_CONTROL, 0 ); // *new*
//Sets up the screen and displays the window
screen = SDL_SetVideoMode( winW, winH, 32, SDL_OPENGL | (fullScr*SDL_FULLSCREEN) ); // *changed*
screenRect.x = 0;
screenRect.y = 0;
screenRect.w = winW;
screenRect.h = winH;
SDL_ShowCursor(false);
SetGLState();
}
This is the SetGLState() mentioned above.
void SetGLState(){
glEnable( GL_TEXTURE_2D ); //Enable 2d texturing
glClearColor( 0.0f, 0.0f, 0.0f, 0.0f ); //Set clear color (rgba)
glViewport( 0, 0, winW, winH ); //Set the viewport
glClear( GL_COLOR_BUFFER_BIT ); //Clear back buffer?
glMatrixMode( GL_PROJECTION ); //Set to projection
glLoadIdentity();
glOrtho(0.0f, winW, winH, 0.0f, -1.0f, 1.0f); //Create orthogonal projection matrix
glMatrixMode( GL_MODELVIEW ); //Set back to model view
glLoadIdentity();
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
}
This is where the images are drawn to the screen
void DrawImage(GLSurface image, float x, float y)
{
// Bind the texture to which subsequent calls refer to
if(boundTexture != image.Surface){glBindTexture( GL_TEXTURE_2D, image.Surface ); boundTexture = image.Surface; }
glReadPixels(x,y,image.w*2,image.h*2,GL_UNSIGNED_BYTE,NULL,NULL);
glLoadIdentity();
glScalef(scale,scale,1);
glRotatef(image.rotation[0], 1.0f, 0.0f, 0.0f);
glRotatef(image.rotation[1], 0.0f, 1.0f, 0.0f);
glRotatef(image.rotation[2], 0.0f, 0.0f, 1.0f);
if(scale == 7.5)x += 48;
glBegin( GL_QUADS );
//Bottom-left vertex (corner)
glColor3b(127,127,127);
glTexCoord2i( 0, 0 ); //Position on texture to begin interpolation
glVertex3f( x, y, 0.f ); //Vertex Coords
//Bottom-right vertex (corner)
glTexCoord2i( 1, 0 );
glVertex3f( x+image.w, y, 0.f );
//Top-right vertex (corner)
glTexCoord2i( 1, 1 );
glVertex3f( x+image.w, y+image.h, 0.f );
//Top-left vertex (corner)
glTexCoord2i( 0, 1 );
glVertex3f( x, y+image.h, 0.f );
glEnd();
}
This window doesn't draw anything, and I can't figure out why. I haven't looked at this code in awhile, but I know that on a previous install of windows, I had it working. All of my other projects run, but this one doesn't. It just renders a blank screen. The weird thing is--I have a resize function for this window. When that function gets called, the screen displays a white screen instead of a black one.
Edit** This code is called at the end once everything has been drawn to the screen. It was already included in my code.
void Flip(){
SDL_GL_SwapBuffers();
glClear( GL_COLOR_BUFFER_BIT );
}
All the state set in SetGLState is drawing state. Call it from the DrawImage function. Most importantly, glClear must be put in the draw function, it doesn't make sense anywhere else.
That call to
glReadPixels
makes no sense.And you must swap the buffers when done
SDL_SwapBuffers
(IIRC, haven't used SDL in some time).