Ok let's start to change some things...
Remember that to have this code work on the fly you must use my template, but you can take the base function to do what you need.
template.cpp
In the Loop change the simple agk:Sync() with those lines:
agk::Update();
agk::Render();
if(Opzioni[0].screenshot == 0){
agk::Swap();
} else if(Opzioni[0].screenshot == 1){
UIImage *_im = GLScreenShot();
//[g_View FBPostScreenShot:_im];
Opzioni[0].screenshot = 0;
}
Now the real OpenGL get pixel function
The Function
//*****************************************
// SCREENSHOTS
//*****************************************
UIImage* GLScreenShot(){
Opzioni[0].screenshot = 1;
GLint backingWidth, backingHeight;
// Get the size of the backing CAEAGLLayer
glGetRenderbufferParameterivOES(GL_RENDERBUFFER_OES, GL_RENDERBUFFER_WIDTH_OES, &backingWidth);
glGetRenderbufferParameterivOES(GL_RENDERBUFFER_OES, GL_RENDERBUFFER_HEIGHT_OES, &backingHeight);
NSInteger x = 0, y = 0, width = backingWidth, height = backingHeight;
NSInteger dataLength = width * height * 4;
GLubyte *data = (GLubyte*)malloc(dataLength * sizeof(GLubyte));
// Read pixel data from the framebuffer
glPixelStorei(GL_PACK_ALIGNMENT, 4);
glReadPixels(x, y, width, height, GL_RGBA, GL_UNSIGNED_BYTE, data);
// Create a CGImage with the pixel data
// If your OpenGL ES content is opaque, use kCGImageAlphaNoneSkipLast to ignore the alpha channel
// otherwise, use kCGImageAlphaPremultipliedLast
CGDataProviderRef ref = CGDataProviderCreateWithData(NULL, data, dataLength, NULL);
CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
CGImageRef iref = CGImageCreate (width, height, 8, 32, width * 4, colorspace,
// Fix from Apple implementation
// (was: kCGBitmapByteOrder32Big | kCGImageAlphaPremultipliedLast).
kCGBitmapByteOrderDefault,
//kCGImageAlphaNoneSkipLast,
ref, NULL, true, kCGRenderingIntentDefault);
// OpenGL ES measures data in PIXELS
// Create a graphics context with the target size measured in POINTS
NSInteger widthInPoints, heightInPoints;
CGFloat scale = g_View.view.contentScaleFactor;
widthInPoints = width / scale;
heightInPoints = height / scale;
UIGraphicsBeginImageContextWithOptions(CGSizeMake(widthInPoints, heightInPoints), NO, scale);
CGContextRef cgcontext = UIGraphicsGetCurrentContext();
// UIKit coordinate system is upside down to GL/Quartz coordinate system
// Flip the CGImage by rendering it to the flipped bitmap context
// The size of the destination area is measured in POINTS
CGContextSetBlendMode(cgcontext, kCGBlendModeCopy);
CGContextDrawImage(cgcontext, CGRectMake(0.0, 0.0, widthInPoints, heightInPoints), iref);
// Retrieve the UIImage from the current context
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
// Clean up
free(data);
CFRelease(ref);
CFRelease(colorspace);
CGImageRelease(iref);
Opzioni[0].screenshot = 0;
return image;
}
Now you have an UIImage to use where you want.
Remember : don't call it from a thread that is not the AppGameKit thread or you will lose the Swap and the image will be white or black!!
Enjoy!!!
Long life to Steve!
