I spent the last three days trying to create a small application using SDL + OpenGL. The application itself works fine - except that it never displays any graphics; just a black screen.
I have reduced it to a minimal C file, and I hope someone can give me some tips. I'm running out of ideas.
I use Windows Vista, MinGW and MSYS. Thank you in advance for any advice!
#include <SDL/SDL.h> #include <SDL_opengl.h> size_t sx=600, sy=600, bpp=32; void render(void) { glEnable(GL_DEPTH_TEST); // enable depth testing glClearColor(0.0f, 0.0f, 0.0f, 0.0f); // clear to black glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // clear color/depth buffer glLoadIdentity(); // reset modelview matrix glColor3b(255, 0, 0); // red glLineWidth(3.0); // line width=3 glRecti(10, 10, sx-10, sy-10); // draw rectangle glFlush(); SDL_GL_SwapBuffers(); } int input(void) { SDL_Event event; while (SDL_PollEvent(&event)) if (event.type == SDL_QUIT || (event.type == SDL_KEYUP && event.key.keysym.sym == SDLK_ESCAPE)) return 0; return 1; } int main(int argc, char *argv[]) { SDL_Surface* surf; if (SDL_Init(SDL_INIT_EVERYTHING) != 0) return 0; if (!(surf = SDL_SetVideoMode(sx, sy, bpp, SDL_HWSURFACE|SDL_DOUBLEBUF))) return 0; glViewport(0, 0, sx, sy); // reset the viewport to new dimensions glMatrixMode(GL_PROJECTION); // set projection matrix to be current glLoadIdentity(); // reset projection matrix glOrtho(0, sx, sy, 0, -1.0, 1.0); // create ortho view glMatrixMode(GL_MODELVIEW); // set modelview matrix glLoadIdentity(); // reset modelview matrix for (;;) { if (!input()) break; render(); SDL_Delay(10); } SDL_FreeSurface(surf); SDL_Quit(); exit(0); }
UPDATE: I have a version that works, but it changes the spelling perspective. I'm not sure why this works, and the other is not, but for future reference, the version is used here:
#include <SDL/SDL.h> #include <SDL_opengl.h> size_t sx=600, sy=600, bpp=32; void render(void) { glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glLoadIdentity(); // set location in front of camera glTranslated(0, 0, -10); glBegin(GL_QUADS); // draw a square glColor3d(1, 0, 0); glVertex3d(-2, 2, 0); glVertex3d( 2, 2, 0); glVertex3d( 2, -2, 0); glVertex3d(-2, -2, 0); glEnd(); glFlush(); SDL_GL_SwapBuffers(); } int input(void) { SDL_Event event; while (SDL_PollEvent(&event)) if (event.type == SDL_QUIT || (event.type == SDL_KEYUP && event.key.keysym.sym == SDLK_ESCAPE)) return 0; return 1; } int main(int argc, char *argv[]) { SDL_Surface *surf; if (SDL_Init(SDL_INIT_EVERYTHING) != 0) return 0; if (!(surf = SDL_SetVideoMode(sx, sy, bpp, SDL_OPENGL))) return 0; glViewport(0, 0, sx, sy); glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(45.0, (float)sx / (float)sy, 1.0, 100.0); glMatrixMode(GL_MODELVIEW); glClearColor(0, 0, 0, 1); glClearDepth(1.0); glEnable(GL_DEPTH_TEST); for (;;) { if (!input()) break; render(); SDL_Delay(10); } SDL_FreeSurface(surf); SDL_Quit(); return 0; }