[英]OpenGL ES Async texture loading
简单的问题是,是否可以与iOS和OpenGL ES异步加载纹理?
这是我的加载方法,在一个单独的线程上调用:
//Image size
GLuint width = CGImageGetWidth(image.CGImage);
GLuint height = CGImageGetHeight(image.CGImage);
//Create context
void *imageData = malloc(height * width * 4);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(imageData, width, height, 8, 4 * width, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
CGColorSpaceRelease(colorSpace);
//Prepare image
CGContextClearRect(context, CGRectMake(0, 0, width, height));
CGContextDrawImage(context, CGRectMake(0, 0, width, height), image.CGImage);
//Dispatch OpenGL stuff on main thread
dispatch_sync(dispatch_get_main_queue(), ^{
//Bind texture
glBindTexture(GL_TEXTURE_2D, name);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageData);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
});
//Release
CGContextRelease(context);
free(imageData);
如果我不在主线程上调度OpenGL调用,我的纹理将不会显示...
glDeleteTextures调用的同样问题......
任何想法 ?
您需要在主要背景线程上使用相同的上下文。 为此使用setCurrentContext : . 所以在主线程上创建新线程(作为一个例子,最简单的方法)并传递主上下文
[self performSelectorInBackground: @selector(loadTextureWithContext:) withObject: [EAGLContext currentContext]];
而创作代码:
-(void) loadTextureWithContext:(EAGLContext*) main_context {
[EAGLContext setCurrentContext: main_context];
//Image size
GLuint width = CGImageGetWidth(image.CGImage);
GLuint height = CGImageGetHeight(image.CGImage);
//Create context
void *imageData = malloc(height * width * 4);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(imageData, width, height, 8, 4 * width, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
CGColorSpaceRelease(colorSpace);
//Prepare image
CGContextClearRect(context, CGRectMake(0, 0, width, height));
CGContextDrawImage(context, CGRectMake(0, 0, width, height), image.CGImage);
//Bind texture
glBindTexture(GL_TEXTURE_2D, name);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageData);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
//Release
CGContextRelease(context);
free(imageData);
[EAGLContext setCurrentContext: nil];
}
作为选项,您还可以创建新上下文并与主要上下文共享相同的EAGLSharegroup 。
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