I have a sdl/opengl game I am working on for fun. I get a decent fps on average, but movement is really choppy because SDL_GL_SwapBuffers() will randomly take a crazy long amount of time to process. With textures loaded and written to the buffer sometimes it will take over 100ms! I cut out a lot of my code to try and figure out if it was something I did wrong but I haven't had much luck. When I run this bare bones program it will still block for up to 70ms at times.
Main:
// Don't forget to link to opengl32, glu32, SDL_image.lib // includes #include <stdio.h> // SDL #include <cstdlib> #include <SDL/SDL.h> // Video #include "videoengine.h" int main(int argc, char *argv[]) { // begin SDL if ( SDL_Init(SDL_INIT_VIDEO) != 0 ) { printf("Unable to initialize SDL: %s\n", SDL_GetError()); } // begin video class VideoEngine videoEngine; // BEGIN MAIN LOOP bool done = false; while (!done) { int loopStart = SDL_GetTicks(); printf("STARTING SWAP BUFFER : %d\n", SDL_GetTicks() - loopStart); SDL_GL_SwapBuffers(); int total = SDL_GetTicks() - loopStart; if (total > 6) printf("END LOOP : %d ------------------------------------------------------------>\n", total); else printf("END LOOP : %d\n", total); } // END MAIN LOOP return 0; } My "VideoEngine" constructor:
VideoEngine::VideoEngine() { UNIT = 16; SCREEN_X = 320; SCREEN_Y = 240; SCALE = 1; // Begin Initalization SDL_Surface *screen; SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER, 1 ); // [!] SDL_GL_SetAttributes must be done BEFORE SDL_SetVideoMode screen = SDL_SetVideoMode( SCALE*SCREEN_X, SCALE*SCREEN_Y, 16, SDL_OPENGL ); // Set screen to the window with opengl if ( !screen ) // make sure the window was created { printf("Unable to set video mode: %s\n", SDL_GetError()); } // set opengl state opengl_init(); // End Initalization } void VideoEngine::opengl_init() { // Set the OpenGL state after creating the context with SDL_SetVideoMode //glClearColor( 0, 0, 0, 0 ); // sets screen buffer to black //glClearDepth(1.0f); // Tells OpenGL what value to reset the depth buffer when it is cleared glViewport( 0, 0, SCALE*SCREEN_X, SCALE*SCREEN_Y ); // sets the viewport to the default resolution (SCREEN_X x SCREEN_Y) multiplied by SCALE. (x,y,w,h) glMatrixMode( GL_PROJECTION ); // Applies subsequent matrix operations to the projection matrix stack. glLoadIdentity(); // Replaces the current matrix with the identity matrix glOrtho( 0, SCALE*SCREEN_X, SCALE*SCREEN_Y, 0, -1, 1 ); //describes a transformation that produces a parallel projection glMatrixMode( GL_MODELVIEW ); // Applies subsequent matrix operations to the projection matrix stack. glEnable(GL_TEXTURE_2D); // Need this to display a texture glLoadIdentity(); // Replaces the current matrix with the identity matrix glEnable(GL_BLEND); // Enable blending for transparency glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); // Specifies pixel arithmetic //glDisable( GL_LIGHTING ); // Disable lighting //glDisable( GL_DITHER ); // Disable dithering //glDisable( GL_DEPTH_TEST ); // Disable depth testing //Check for error GLenum error = glGetError(); if( error != GL_NO_ERROR ) { printf( "Error initializing OpenGL! %s\n", gluErrorString( error ) ); } return; } I'm starting to think possibly I have a hardware issue? I have never had this problem with a game though.