11-05-2019, 04:46 AM
Whoooo, don't I feel like a fool. After typing up my previous entry, something occurred to me that I probably should have realized earlier. If you use the SDL_CreateRGBSurfaceWithFormat function in SDL2 to construct your "target" Surface for Tilengine rendering, and you set its format to SDL_PIXELFORMAT_BGRA32, you don't actually need the second surface. Your target surface may not be the exact same format as what the GPU shader wants, but it's close enough that conversion can be handled successfully by the glTexImage2D function. So having a second Surface is unnecessary, and can be safely skipped.
This is why it is useful to review your code. I went back and removed the second surface, and just do the pixel writing and converting with a single SDL_Surface that Tilengine targets directly. It's likely not quite as efficient as accessing a minimal array directly, but it's much closer than having a second extraneous surface lying around or trying to copy the contents of one array to another. Good stuff.
This is why it is useful to review your code. I went back and removed the second surface, and just do the pixel writing and converting with a single SDL_Surface that Tilengine targets directly. It's likely not quite as efficient as accessing a minimal array directly, but it's much closer than having a second extraneous surface lying around or trying to copy the contents of one array to another. Good stuff.