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- Capturing image of 3d object in Open GLES
- (UIImage*)snapshot:(UIView*)eaglview
- {
- GLint backingWidth, backingHeight;
- // Bind the color renderbuffer used to render the OpenGL ES view
- // If your application only creates a single color renderbuffer which is already bound at this point,
- // this call is redundant, but it is needed if you're dealing with multiple renderbuffers.
- // Note, replace "_colorRenderbuffer" with the actual name of the renderbuffer object defined in your class.
- glBindRenderbufferOES(GL_RENDERBUFFER_OES, _colorRenderbuffer);
- // 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, kCGBitmapByteOrder32Big | kCGImageAlphaPremultipliedLast,
- ref, NULL, true, kCGRenderingIntentDefault);
- // OpenGL ES measures data in PIXELS
- // Create a graphics context with the target size measured in POINTS
- NSInteger widthInPoints, heightInPoints;
- if (NULL != UIGraphicsBeginImageContextWithOptions) {
- // On iOS 4 and later, use UIGraphicsBeginImageContextWithOptions to take the scale into consideration
- // Set the scale parameter to your OpenGL ES view's contentScaleFactor
- // so that you get a high-resolution snapshot when its value is greater than 1.0
- CGFloat scale = eaglview.contentScaleFactor;
- widthInPoints = width / scale;
- heightInPoints = height / scale;
- UIGraphicsBeginImageContextWithOptions(CGSizeMake(widthInPoints, heightInPoints), NO, scale);
- }
- else {
- // On iOS prior to 4, fall back to use UIGraphicsBeginImageContext
- widthInPoints = width;
- heightInPoints = height;
- UIGraphicsBeginImageContext(CGSizeMake(widthInPoints, heightInPoints));
- }
- 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);
- return image;
- }
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