为什么在iOS 6.0中glReadPixels()在这段代码中失败?
以下是我用于从OpenGL ES场景读取图像的代码:为什么在iOS 6.0中glReadPixels()在这段代码中失败?,ios,opengl-es,ios6,Ios,Opengl Es,Ios6,以下是我用于从OpenGL ES场景读取图像的代码: -(UIImage *)getImage{ GLint width; GLint height; glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_WIDTH, &width); glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_HEIGHT, &a
-(UIImage *)getImage{
GLint width;
GLint height;
glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_WIDTH, &width);
glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_HEIGHT, &height);
NSLog(@"%d %d",width,height);
NSInteger myDataLength = width * height * 4;
// allocate array and read pixels into it.
GLubyte *buffer = (GLubyte *) malloc(myDataLength);
glReadPixels(0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, buffer);
// gl renders "upside down" so swap top to bottom into new array.
// there's gotta be a better way, but this works.
GLubyte *buffer2 = (GLubyte *) malloc(myDataLength);
for(int y = 0; y < height; y++)
{
for(int x = 0; x < width * 4; x++)
{
buffer2[((height - 1) - y) * width * 4 + x] = buffer[y * 4 * width + x];
}
}
// make data provider with data.
CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, buffer2, myDataLength, NULL);
// prep the ingredients
int bitsPerComponent = 8;
int bitsPerPixel = 32;
int bytesPerRow = 4 * width;
CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();
CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault;
CGColorRenderingIntent renderingIntent = kCGRenderingIntentDefault;
// make the cgimage
CGImageRef imageRef = CGImageCreate(width, height, bitsPerComponent, bitsPerPixel, bytesPerRow, colorSpaceRef, bitmapInfo, provider, NULL, NO, renderingIntent);
// then make the uiimage from that
UIImage *myImage = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
CGDataProviderRelease(provider);
CGColorSpaceRelease(colorSpaceRef);
free(buffer);
free(buffer2);
return myImage;
}
-(UIImage*)获取图像{
闪烁宽度;
闪烁高度;
glGetRenderBuffer参数(GL_RENDERBUFFER、GL_RENDERBUFFER_WIDTH和WIDTH);
GLGetRenderBuffer参数(GL_RENDERBUFFER、GL_RENDERBUFFER_高度和高度);
NSLog(@“%d%d”,宽度,高度);
NSInteger myDataLength=宽度*高度*4;
//分配数组并将像素读入其中。
GLubyte*buffer=(GLubyte*)malloc(myDataLength);
glReadPixels(0,0,宽度,高度,GL_RGBA,GL_无符号字节,缓冲区);
//gl呈现“倒置”,以便从上到下交换到新阵列中。
//肯定有更好的办法,但这是可行的。
GLubyte*buffer2=(GLubyte*)malloc(myDataLength);
对于(int y=0;y
这在iOS 5.x及更低版本中可以正常工作,但在iOS 6.0上,它现在返回黑色图像。为什么在iOS 6.0上,
glReadPixels()
失败了?bro请尝试使用此方法获取屏幕截图图像。输出图像是MailImage
- (UIImage*)screenshot
{
// Create a graphics context with the target size
// On iOS 4 and later, use UIGraphicsBeginImageContextWithOptions to take the scale into consideration
// On iOS prior to 4, fall back to use UIGraphicsBeginImageContext
CGSize imageSize = [[UIScreen mainScreen] bounds].size;
if (NULL != UIGraphicsBeginImageContextWithOptions)
UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0);
else
UIGraphicsBeginImageContext(imageSize);
CGContextRef context = UIGraphicsGetCurrentContext();
// Iterate over every window from back to front
for (UIWindow *window in [[UIApplication sharedApplication] windows])
{
if (![window respondsToSelector:@selector(screen)] || [window screen] == [UIScreen mainScreen])
{
// -renderInContext: renders in the coordinate space of the layer,
// so we must first apply the layer's geometry to the graphics context
CGContextSaveGState(context);
// Center the context around the window's anchor point
CGContextTranslateCTM(context, [window center].x, [window center].y);
// Apply the window's transform about the anchor point
CGContextConcatCTM(context, [window transform]);
// Offset by the portion of the bounds left of and above the anchor point
CGContextTranslateCTM(context,
-[window bounds].size.width * [[window layer] anchorPoint].x,
-[window bounds].size.height * [[window layer] anchorPoint].y);
// Render the layer hierarchy to the current context
[[window layer] renderInContext:context];
// Restore the context
CGContextRestoreGState(context);
}
}
// Retrieve the screenshot image
Mailimage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return Mailimage;
}
设置
(我不知道为什么这个技巧进展顺利..//)hm,除了
glink viewport[4],我的外观和效果都一样;glGetIntegerv(GL_视口,视口);int width=视口[2];int height=视口[3]代码>是,@SAKrisT这在iOS 6.0中不起作用在我的项目工作中,检查opengl错误glGetError();请不要回滚我的编辑。他们使问题更具描述性,也更容易搜索。此外,这与GPUImage无关,因此我删除了该标记。它为我提供了整个屏幕图像,不包括缓冲区中的图像。原因可能是您试图在使用[context presentRenderbuffer:GL_RENDERBUFFER]呈现内容后从屏幕读取代码>。除非像上面所做的那样,将图层设置为使用保留背衬,否则不能保证在呈现内容后仍保留该内容。iOS 6.0似乎更积极地删除不再需要的内容。上述操作将导致性能下降,因此最好执行glFinish()
操作,然后捕获屏幕,然后显示渲染缓冲区;在我的代码中,我删除了eaglLayer.opaque=TRUE,这也阻止了截图代码的工作;并设置KeaglDrawablePropertyRetaineBacking=YES。现在它工作了。您如何设置KeaglDrawablePropertyRetaineBacking=YES?在哪里?嗨,我已经设置了KeaglDrawablePropertyRetaineBacking=是,但仍然不工作
CAEAGLLayer *eaglLayer = (CAEAGLLayer *) self.layer;
eaglLayer.drawableProperties = @{
kEAGLDrawablePropertyRetainedBacking: [NSNumber numberWithBool:YES],
kEAGLDrawablePropertyColorFormat: kEAGLColorFormatRGBA8
};
kEAGLDrawablePropertyRetainedBacking = YES