I'm working in an openGL for iPhone , and although everything works great I have to wait about a second in certain sections of the game which use a ton of sprite sheets. It's there any way to create a loading screen for such sections ?, or any way to know if a certain texture has finished loading with openGL?
EDIT:
I load my textures with this function:
-(void)loadTexture:(NSString*)nombre {
CGImageRef textureImage = [UIImage imageNamed:nombre].CGImage;
if (textureImage == nil) {
NSLog(@"Failed to load texture image");
return;
}
textureWidth = NextPowerOfTwo(CGImageGetWidth(textureImage));
textureHeight = NextPowerOfTwo(CGImageGetHeight(textureImage));
imageSizeX= CGImageGetWidth(textureImage);
imageSizeY= CGImageGetHeight(textureImage);
GLubyte *textureData = (GLubyte *)calloc(1,textureWidth * textureHeight * 4); // Por 4 pues cada pixel necesita 4 bytes, RGBA
CGContextRef textureContext = CGBitmapContextCreate(textureData, textureWidth,textureHeight,8, textureWidth * 4,CGImageGetColorSpace(textureImage),kCGImageAlphaPremultipliedLast );
CGContextDrawImage(textureContext, CGRectMake(0.0, 0.0, (float)textureWidth, (float)textureHeight), textureImage);
CGContextRelease(textureContext);
glGenTextures(1, &textures[0]);
glBindTexture(GL_TEXTURE_2D, textures[0]);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, textureWidth, textureHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, textureData);
free(textureData);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
}
I usually load the textures i need deppending on the section of the game, for example, one or two 1024×1024 textures which serve me as sprite sheets are enough for most levels, but in certain levels, like boss battles for example, I load about 5 or 6 textures ( the boss is big and has a ton of different attacks) and the game takes about 2 or 3 secs to load all those textures at once.
Best Answer
As Till explained, since you are loading the texture synchronously, it will be loaded once "loadTexture" is done.
Rendering to the screen in another thread via OpenGL while loading via OpenGL can become really messy real quick.
A - quite often used - hack is to update the screen between texture loads:
With a little bit of extra work it's easy to generate a small table that has timing information about the loading, so the "x%" is close to the truth ;)
We usually automate this step and before shipping a new version do a "load through" run, in which we log when what resource is loaded and how long it takes.