方法1:
- (UIImage *)imageFromTextureWithwidth:(int)width height:(int)height { // glActiveTexture(GL_TEXTURE1); 先绑定某个纹理 int size = width * height * 4; GLubyte *buffer = malloc(size); glReadPixels(0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, buffer); CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, buffer, size, NULL); int bitsPerComponent = 8; int bitsPerPixel = 32; int bytesPerRow = 4 * width; CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB(); CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault; CGColorRenderingIntent renderingIntent = kCGRenderingIntentDefault; CGImageRef imageRef = CGImageCreate(width, height, bitsPerComponent, bitsPerPixel, bytesPerRow, colorSpaceRef, bitmapInfo, provider, NULL, NO, renderingIntent); UIImage *image = [UIImage imageWithCGImage:imageRef]; free(buffer); return image; }
方法2:
#if 1 - 读取framebuffer到CPU内存 //glFinish(); //glActiveTexture(GL_TEXTURE3); //先绑定某个纹理 GLint x = 0, y = 0, width = 512, height = 512; NSInteger dataLength = width * height * 4; GLubyte *data = (GLubyte*)malloc(dataLength * sizeof(GLubyte)); NSDate *startTime = [NSDate date]; // Read pixel data from the framebuffer glPixelStorei(GL_PACK_ALIGNMENT, 1); //glReadPixels(x, y, width, height, GL_RGBA, GL_UNSIGNED_BYTE, data); glReadPixels(x, y, width, height, GL_RGB, GL_BYTE, data); NSLog(@"code runing Time duration : %f", -[startTime timeIntervalSinceNow]); // 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 | kCGImageAlphaNone, 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 = [UIScreen mainScreen].scale; 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(); image = nil; UIGraphicsEndImageContext(); // Clean up free(data); #endif
方法1参考内容:https://www.jianshu.com/p/949b8b1075d8