Im using the newest version of SDL, in software mode. My screen size is 800x600x32. My images are 32Bit PNGs (I use SDL_Image). The thing is that I get very different FPS on computer that have similar stats. I get ~200 FPS in windowed on my machine and 19 FPS on fullscreen. There is not that much Blitting involved. I use a mixture of images, ones that use the alpha channel in the PNG file and ones that use a color key for transparency. Here is some of my code:
Init:
SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO);
// Bite Order
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
rmask = 0x00000000;
gmask = 0x000000ff;
bmask = 0x0000ff00;
amask = 0x00ff0000;
#else
rmask = 0x00ff0000;
gmask = 0x0000ff00;
bmask = 0x000000ff;
amask = 0x00000000;
#endif
newScr = SDL_SetVideoMode(800, 600, 32, SDL_SWSURFACE | SDL_DOUBLEBUF | SDL_FULLSCREEN);
Here is How I load my Images.
SDL_Surface *LoadImage(const char *file, SDL_Surface *screen, bool AlphaFlag)
- file is the File Name
- screen is the main SDL Surface
- AlphaFlag tells the function to use PNG alpha channel or not. [T/F]
SDL_Surface *LoadImage(const char *file, SDL_Surface *screen, bool AlphaFlag)
{
Uint32 color_key;
SDL_Surface *tempImg;
SDL_Surface *newImg;
SDL_RWops *rwop;
// Opens the file and reads it into a temp image
rwop = SDL_RWFromFile(file, "rb");
tempImg = IMG_LoadPNG_RW(rwop);
// If the Image is Alpha Enabled
if (AlphaFlag)
{
// Creates a new Surface With Alpha Channel
newImg = SDL_CreateRGBSurface(SDL_SWSURFACE, tempImg->w, tempImg->h, 32, rmask, gmask, bmask, amask);
newImg = SDL_DisplayFormatAlpha(tempImg);
}else{
// Creates a new Surface without an Alpha Channel
newImg = SDL_CreateRGBSurface(SDL_SWSURFACE, tempImg->w, tempImg->h, 32, rmask, gmask, bmask, amask);
newImg = SDL_DisplayFormat(tempImg);
}
if (tempImg)
{
// Kills the temp Image
SDL_FreeSurface(tempImg);
}
// Sets the transparency
if (AlphaFlag)
{
color_key = SDL_MapRGBA(screen->format, 0, 0, 0, 255);
}else{
// Resort to Pure Green as Transparency
color_key = SDL_MapRGB(screen->format, 0, 255, 0);
}
// Set Color Key
SDL_SetColorKey(newImg, SDL_SRCCOLORKEY | SDL_RLEACCEL, color_key);
return newImg;
}
Is SDL_RLEACCEL a bad thing in this case?
Is it slow because of the SDL_BYTEORDER?
Could the speed be better if it was run on Hardware Instead?
In some cases there are over 50 images being blitted onto the screen, all are preloaded into memory before they are rendered in a loop (for a menu system). Is there a way i can boost this code??
Could the slow down be because im running it in Visual Studio with Debug mode, and not release mode?
