I'm trying to load a screenshot into an OpenGLES Texture, but when i display it, it is just black.
Here is how I get the screenshot:
UIGraphicsBeginImageContext(self.bounds.size);
[self.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage* image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
and here is how I'm trying to load the image into the Texture:
GLuint setupTextureFromImage(UIImage* image) {
CGImageRef spriteImage = image.CGImage;
if (!spriteImage) {
NSLog(#"Failed to load image");
exit(1);
}
size_t width = CGImageGetWidth(spriteImage);
size_t height = CGImageGetHeight(spriteImage);
GLubyte * spriteData = (GLubyte *) calloc(width*height*4, sizeof(GLubyte));
CGContextRef spriteContext = CGBitmapContextCreate(spriteData, width, height, 8, width*4, CGImageGetColorSpace(spriteImage), kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Host);
CGContextDrawImage(spriteContext, CGRectMake(0, 0, width, height), spriteImage);
CGContextRelease(spriteContext);
GLuint texName;
glGenTextures(1, &texName);
glBindTexture(GL_TEXTURE_2D, texName);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, (int) width, (int) height, 0, GL_RGBA, GL_UNSIGNED_BYTE, spriteData);
free(spriteData);
return texName;
}
if I load an image from the resources with [UIImage imageNamed: #"FileName.png"] it works and if I'm setting the screenshot as the background color it also works, so both parts work separately
Related
I am using OpenGL to do my drawing on screen and want to draw a portion of the screen to a UIImage. This is code I've cobbled together looking at examples, which works, but produces a memory leak every time it's called. I've tested this on device and the leak still persists and eventually causes a crash. The returned UIImage is saved to an instance variable and is later definitely set to nil again. What is causing the memory leak here?
- (UIImage *)renderToImageWithContentFrame:(CGRect)contentFrame
exportFrame:(CGRect)exportFrame
scale:(float)scale {
float screenWidth = contentFrame.size.width * scale;
float screenHeight = contentFrame.size.height * scale;
GLuint framebuffer;
glGenFramebuffers(1, &framebuffer);
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
GLuint renderTex;
glGenTextures(1, &renderTex);
glBindTexture(GL_TEXTURE_2D, renderTex);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, screenWidth, screenHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, renderTex, 0);
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
glViewport(0, 0, screenWidth, screenHeight);
[self _renderImageGL];
// grabbing image from FBO
NSInteger dataLength = screenWidth * screenHeight * 4;
GLubyte *data = (GLubyte*)malloc(dataLength * sizeof(GLubyte));
glPixelStorei(GL_PACK_ALIGNMENT, 4);
glReadPixels(0, 0, screenWidth, screenHeight, GL_RGBA, GL_UNSIGNED_BYTE, data);
glDeleteFramebuffers(1, &framebuffer);
CGDataProviderRef ref = CGDataProviderCreateWithData(NULL, data, dataLength, NULL);
CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
CGImageRef iref = CGImageCreate(screenWidth, screenHeight, 8, 32, screenWidth * 4, colorspace,
kCGBitmapByteOrder32Big | kCGImageAlphaPremultipliedLast,
ref, NULL, true, kCGRenderingIntentDefault);
float x = (exportFrame.origin.x - contentFrame.origin.x) * scale;
float y = (exportFrame.origin.y - contentFrame.origin.y) * scale;
float width = exportFrame.size.width * scale;
float height = exportFrame.size.height * scale;
CGImageRef cropped = CGImageCreateWithImageInRect(iref, (CGRect){x, y, width, height});
UIGraphicsBeginImageContext((CGSize){width, height});
CGContextRef cgcontext = UIGraphicsGetCurrentContext();
CGContextSetBlendMode(cgcontext, kCGBlendModeCopy);
CGContextDrawImage(cgcontext, (CGRect){0, 0, width, height}, cropped);
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
free(data);
CFRelease(ref);
CFRelease(colorspace);
CGImageRelease(iref);
CGImageRelease(cropped);
return image;
}
The variable renderTex is not being freed (via a call to glDeleteTextures(1, &renderTex);). My guess is that Instruments may not know about OpenGL-allocated memory because that memory may reside on a graphics card and may be harder (or impossible) to track. (Though that's mainly a guess.)
In my opengl project I need to convert an UIImage in texture; what's the way to do it?
Can you help me?
I haven't test the following but i will decompose the conversion in 3 steps:
Extract info for your image:
UIImage* image = [UIImage imageNamed:#"imageToApplyAsATexture.png"];
CGImageRef imageRef = [image CGImage];
int width = CGImageGetWidth(imageRef);
int height = CGImageGetHeight(imageRef);
Allocate a textureData with the above properties:
GLubyte* textureData = (GLubyte *)malloc(width * height * 4); // if 4 components per pixel (RGBA)
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
NSUInteger bytesPerPixel = 4;
NSUInteger bytesPerRow = bytesPerPixel * width;
NSUInteger bitsPerComponent = 8;
CGContextRef context = CGBitmapContextCreate(textureData, width, height,
bitsPerComponent, bytesPerRow, colorSpace,
kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
CGColorSpaceRelease(colorSpace);
CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef);
CGContextRelease(context);
Set-up your texture:
GLuint textureID;
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glGenTextures(1, &textureID);
glBindTexture(GL_TEXTURE_2D, textureID);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, textureData);
EDIT:
Read this tut; everything is explained from the conversion of one image to a texture and applying a texture in an iOS environment.
Here is swift version of getting texture out of an UIImage
func setupTexture(sourceImage: UIImage) -> GLuint {
guard let textureImage = sourceImage.cgImage else {
print("Failed to load image")
return 0
}
let width = textureImage.width
let height = textureImage.height
/*
it will write one byte each for red, green, blue, and alpha – so 4 bytes in total.
*/
let textureData = calloc(width * height * 4, MemoryLayout<GLubyte>.size) //4 components per pixel (RGBA)
let spriteContext = CGContext(data: textureData,
width: width,
height: height,
bitsPerComponent: 8,
bytesPerRow: width * 4,
space: textureImage.colorSpace!,
bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue)
spriteContext?.draw(textureImage, in: CGRect(x: 0, y: 0, width: width, height: height))
var textName = GLuint()
glGenTextures(1, &textName)
glBindTexture(GLenum(GL_TEXTURE_2D), textName)
glTexParameteri(GLenum(GL_TEXTURE_2D), GLenum(GL_TEXTURE_MIN_FILTER), GL_NEAREST)
glTexImage2D(GLenum(GL_TEXTURE_2D), 0, GL_RGBA, GLsizei(width),
GLsizei(height), 0, GLenum(GL_RGBA), GLenum(GL_UNSIGNED_BYTE), textureData)
return textName
}
Note: Need to keep in mind that Core Graphics flips images when we load them in.
Another way of doing this using the GLKit framework:
//Path to image
NSString *path = [[NSBundle mainBundle] pathForResource:#"textureImage" ofType:#"png"];
//Set eaglContext
[EAGLContext setCurrentContext:[[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2]];
//Create texture
NSError *theError;
GLKTextureInfo *texture = [GLKTextureLoader textureWithContentsOfFile:filePath options:nil error:&theError];
glBindTexture(texture.target, texture.name);
texture.name is The OpenGL context’s name for the texture.
I have 6 squares made up of 2 trangles, each of which is supposed to have a different texture mapped onto it. Instead, each texture is having the last binded texture on it instead of its own. Heres my drawView and setView:
- (void)drawView:(GLView*)view
{
glBindTexture(GL_TEXTURE_2D, texture[0]);
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
static const Vertex3D vertices[] = {
{0,0, 1}, //TL
{ 1024,0, 1}, //TR
{0,-1024, 1}, //BL
{ 1024.0f, -1024.0f, 1} //BR
};
static const GLfloat texCoords[] = {
0.0, 1.0,
1.0, 1.0,
0.0, 0.0,
1.0, 0.0
};
glVertexPointer(3, GL_FLOAT, 0, vertices);
glTexCoordPointer(2, GL_FLOAT, 0, texCoords);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_TEXTURE_COORD_ARRAY);
}
- (void)setupView:(GLView*)view {
// Bind the number of textures we need.
glGenTextures(1, &texture[0]);
glBindTexture(GL_TEXTURE_2D, texture[0]);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_NEAREST);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_GENERATE_MIPMAP,GL_TRUE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glLoadIdentity();
NSString *path = [[NSBundle mainBundle] pathForResource:filename ofType:#"jpg"];
NSData *texData = [[NSData alloc] initWithContentsOfFile:path];
UIImage *image = [[UIImage alloc] initWithData:texData];
if (image == nil)
NSLog(#"Do real error checking here");
GLuint width = CGImageGetWidth(image.CGImage);
GLuint height = CGImageGetHeight(image.CGImage);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
void *imageData = malloc( height * width * 4 );
CGContextRef context = CGBitmapContextCreate( imageData, width, height, 8, 4 * width, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big );
// Flip the Y-axis
CGContextTranslateCTM (context, 0, height);
CGContextScaleCTM (context, 1.0, -1.0);
CGColorSpaceRelease( colorSpace );
CGContextClearRect( context, CGRectMake( 0, 0, width, height ) );
CGContextDrawImage( context, CGRectMake( 0, 0, width, height ), image.CGImage );
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageData);
CGContextRelease(context);
free(imageData);
}
You're always using texture[0], so you will indeed get the same texture every time. You need to pass the id of the texture you want to glBindTexture ().
I think the problem is related to the texture binding and in particular to this line:
glBindTexture(GL_TEXTURE_2D, texture[0]);
Double check that you use the right value of the gluint required for the texture binding.
Are you using shaders? In case double check it as well though it is most probably not the case.
I suggest to use texture atlas in order to not kill the overall engine's performances by binding every time a different texture in the GPU.
I am trying to read UIImage into the texture on iOS platform. I found the code snippet on StackOverflow that does the trick, but the problem is when I display the texture it is displayed Mirrored upside down.
int numComponents = 4;
UIImage* image = [UIImage imageNamed:#"Test.png"];
CGImageRef imageRef = [image CGImage];
int width = CGImageGetWidth(imageRef);
int height = CGImageGetHeight(imageRef);
//Allocate texture data
GLubyte* textureData = (GLubyte *)malloc(width * height * numComponents);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
NSUInteger bytesPerPixel = 4;
NSUInteger bytesPerRow = bytesPerPixel * width;
NSUInteger bitsPerComponent = 8;
CGContextRef context = CGBitmapContextCreate(textureData, width, height,
bitsPerComponent, bytesPerRow, colorSpace,
kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
CGColorSpaceRelease(colorSpace);
CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef);
CGContextRelease(context);
//texture setup
GLuint textureID;
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glGenTextures(1, &textureID);
glBindTexture(GL_TEXTURE_2D, textureID);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, textureDataMirrored);
I also tried to mirror the UIImage using following line (before reading the data) but its not working either. In fact no effect whatsoever.
image = [UIImage imageWithCGImage:image.CGImage scale:image.scale orientation:UIImageOrientationUpMirrored];
Please let me know what am I doing wrong here. Thank you.
This two lines fixed the problem
CGAffineTransform flipVertical = CGAffineTransformMake(1, 0, 0, -1, 0,height);
CGContextConcatCTM(context, flipVertical);
Simple question, is it possible to load texture asynchronously with iOS and OpenGL ES ?
Here is my loading method, called on a separate thread:
//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);
If I don't dispatch OpenGL calls on the main thread, my textures wont be displayed...
Same question for the glDeleteTextures call...
Any idea ?
You need to use the same context on your background thread that you're using on the main one. For this use setCurrentContext:.
So on main thread create new thread (as an example the simplest way) and pass main context
[self performSelectorInBackground: #selector(loadTextureWithContext:) withObject: [EAGLContext currentContext]];
And the creation code:
-(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];
}
As an option you can also create the new context and share the same EAGLSharegroup with the main one.