I’m having trouble getting double buffering working still. The program
executes and the drawling loop keeps repeating, but nothing is drawn to
the screen. I’m posting below the functions that load the bitmaps,
initialize display, and the animation loop. Hope it isn’t too much, I
just don’t know what I’m doing wrong.
void hover::loadImages(void)// loads images
{
/* cone = load_pcx(“cone.pcx”,pal);
background = load_pcx(“road.pcx”,pal);
playerCar[0] = load_pcx(“hovercar1.pcx”,pal); Old functions
playerCar[1] = load_pcx(“blank.pcx”,pal2); from allegro
library
enemyCar[0] = load_pcx(“modifiedstock.pcx”,pal);
set_palette(pal);
image = create_bitmap(640,480);
playerCar[3] = create_bitmap(400,400);
/
/ Load a BMP image into a surface */
background = SDL_LoadBMP(“road.bmp”);
if ( background == NULL ) {
ComplainAndExit();
}
/* Load a BMP image into a surface */
playerCar[0] = SDL_LoadBMP("road.bmp");
if ( playerCar[0] == NULL ) {
ComplainAndExit();
}
/* Load a BMP image into a surface */
AICar[0] = SDL_LoadBMP("road.bmp");
if ( AICar[0] == NULL ) {
ComplainAndExit();
}
}
void hover::initVideoDisplay(void) / initializes video display
{
/* Set the video mode (640x480 at native depth) /
screen = SDL_AllocSurface(0,640, 480, 8, 0, 0, 0, 0);
if ( screen == NULL ) {
ComplainAndExit();
}
images = SDL_SetVideoMode(640, 480, 0, SDL_HWSURFACE|SDL_FULLSCREEN);
/ Set the video colormap /
if ( background->format->palette != NULL ) {
SDL_SetColors(screen,
background->format->palette->colors, 0,
background->format->palette->ncolors);
}
/ Draw bands of color on the raw surface /
if ( SDL_MUSTLOCK(screen) ) {
if ( SDL_LockSurface(screen) < 0 )
ComplainAndExit();
}
buffer=(Uint8 )screen->pixels;
for ( i=0; ih; ++i ) {
memset(buffer,(i255)/screen->h,
screen->wscreen->format->BytesPerPixel);
buffer += screen->pitch;
}
if ( SDL_MUSTLOCK(screen) ) {
SDL_UnlockSurface(screen);
}
}
void hover::anim(void) // animation Loop
{
int GameOver;
cerr << “in anim Loop” << endl;
/* Convert the image to the video format (maps colors) */
cerr << “Die here? 1” << endl;
surface[sectorDisplay + 10] =
SDL_DisplayFormat(surface[sectorDisplay]);
cerr << “Die here? 2” << endl;
obstacles[sectorDisplay + 10] =
SDL_DisplayFormat(obstacles[sectorDisplay]);
cerr << “Die here? 3” << endl;
barrier[sectorDisplay + 10] =
SDL_DisplayFormat(barrier[sectorDisplay]);
cerr << “Die here? 4” << endl;
playerCar[1] = SDL_DisplayFormat(playerCar[0]);
cerr << “Die here? 5” << endl;
AICar[1] = SDL_DisplayFormat(AICar[0]);
cerr << “alive” << endl;
// Code to blit the background to the screen
// Blits Surface of terrain
surfrect.x = 0;
surfrect.y = 0;
surfrect.w = surface[sectorDisplay + 10]->w;
surfrect.h = surface[sectorDisplay + 10]->h;
cerr << “dead 0” << endl;
if ( SDL_BlitSurface(surface[sectorDisplay + 10], NULL, screen,
&surfrect) < 0 )
{
freeVidMem();
ComplainAndExit();
}
cerr << “dead .5” << endl;
SDL_FreeSurface(surface[sectorDisplay + 10]);
SDL_UpdateRects(screen, 1, &surfrect);
cerr << “dead one” << endl;
// Blits the barrier(s)
barrect.x = barrierX[sectorDisplay];
barrect.y = barrierY[sectorDisplay];
barrect.w = barrier[sectorDisplay + 10]->w;
barrect.h = barrier[sectorDisplay + 10]->h;
if ( SDL_BlitSurface(barrier[sectorDisplay + 10], NULL, screen,
&barrect) < 0 )
{
freeVidMem();
ComplainAndExit();
}
SDL_FreeSurface(barrier[sectorDisplay + 10]);
SDL_UpdateRects(screen, 1, &barrect);
// Blits obstacle(s) to the screen
obsrect.x = obstacleX[sectorDisplay];
obsrect.y = obstacleY[sectorDisplay];
obsrect.w = obstacles[sectorDisplay + 10]->w;
obsrect.h = obstacles[sectorDisplay + 10]->h;
if ( SDL_BlitSurface(obstacles[sectorDisplay + 10], NULL, screen,
&obsrect) < 0 )
{
freeVidMem();
ComplainAndExit();
}
SDL_FreeSurface(obstacles[sectorDisplay + 10]);
SDL_UpdateRects(screen, 1, &obsrect);
// Code to blit the Player Car(s) to the screen
plyrect.x = playerX;
plyrect.y = playerY;
plyrect.w = playerCar[1]->w;
plyrect.h = playerCar[1]->h;
if ( SDL_BlitSurface(playerCar[1], NULL, screen, &plyrect) < 0 )
{
ComplainAndExit();
}
// Update the screen
SDL_FreeSurface(playerCar[1]);
SDL_UpdateRects(screen, 1, &plyrect);
// Code to blit the AI Car(s) to the screen.
AIrect.x = AIX;
AIrect.y = AIY;
AIrect.w = AICar[1]->w;
AIrect.h = AICar[1]->h;
if ( SDL_BlitSurface(AICar[1], NULL, screen, &AIrect) < 0 )
{
ComplainAndExit();
}
// Update the screen
SDL_FreeSurface(AICar[1]);
SDL_UpdateRects(screen, 1, &AIrect);
cerr << “at image display” << endl;
img.x = 0;
img.y = 0;
img.w = screen->w;
img.h = screen->h;
cerr << “blitting!” << endl;
if ( SDL_BlitSurface(screen, NULL, images, &img) < 0 )
{
ComplainAndExit();
}
cerr << “not dead” << endl;
// SDL_FreeSurface(screen);
cerr << “still not dead” << endl;
SDL_UpdateRects(images,1,&img);
anim();
//exit(0);
}
Man I feel dumb not being able to figure this out 
Mike.
