Ios 使用openGL绘制UIGL图像

我使用以下代码使用openGL渲染UIImage。Texture2D类来自Apple，因此我认为它是正确的。图像无法显示。我只是得到glClearColor生成的背景色。我的应用程序基于苹果的GLpaint示例代码，因此设置正确，我能够使用openGL很好地绘制线条

下面的渲染代码是否缺少某些内容

- (void) render:(UIImage *)image
{
[EAGLContext setCurrentContext:context];
glViewport(0, 0, backingWidth, backingHeight);

glMatrixMode(GL_PROJECTION);
glLoadIdentity();

// texturing will need these
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
glEnableClientState(GL_VERTEX_ARRAY);
glEnable(GL_TEXTURE_2D);

glOrthof(0, backingWidth, 0, backingHeight, -1, 1);

glMatrixMode(GL_MODELVIEW);

glClearColor(0.2f, 0.2f, 0.2f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glLoadIdentity();

Texture2D *texture = [[Texture2D alloc] initWithImage:image];

[texture drawInRect: self.frame];


// This application only creates a single color renderbuffer which is already bound at this point.
// This call is redundant, but needed if dealing with multiple renderbuffers.
glBindRenderbuffer(GL_RENDERBUFFER, viewRenderbuffer);
[context presentRenderbuffer:GL_RENDERBUFFER];
}

---

更新：用实际代码替换原始答案中的断开链接

以下是对我有用的代码：

-(void) mergeWithImage:(UIImage*) image
{
if(image==nil)
{
    return;
}
glPushMatrix();
glColor4f(256,
          256,
          256,
          1.0);
GLuint stampTexture; // = texture.id;

glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
glGenTextures(1, &stampTexture);
glBindTexture(GL_TEXTURE_2D, stampTexture);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);

GLuint imgwidth = CGImageGetWidth(image.CGImage);
GLuint imgheight = CGImageGetHeight(image.CGImage);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
void *imageData = malloc( imgheight * imgwidth * 4 );
CGContextRef context2 = CGBitmapContextCreate( imageData, imgwidth, imgheight, 8, 4 * imgwidth, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big );
CGContextTranslateCTM (context2, 0, imgheight);
CGContextScaleCTM (context2, 1.0, -1.0);
CGColorSpaceRelease( colorSpace );
CGContextClearRect( context2, CGRectMake( 0, 0, imgwidth, imgheight ) );
CGContextTranslateCTM( context2, 0, imgheight - imgheight );
CGContextDrawImage( context2, CGRectMake( 0, 0, imgwidth, imgheight ), image.CGImage );

glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, imgwidth, imgheight, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageData);

CGContextRelease(context2);

free(imageData);

static const GLfloat texCoords[] = {
    0.0, 1.0,
    1.0, 1.0,
    0.0, 0.0,
    1.0, 0.0
};

glEnableClientState(GL_TEXTURE_COORD_ARRAY);
glTexCoordPointer(2, GL_FLOAT, 0, texCoords);

glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_NORMAL_ARRAY);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);

/*
 These arrays would need to be changed if the size of the paintview changes. You must make sure that all image imput is 64x64, 256x256, 512x512 or 1024x1024.  Here we are using 512, but you can use 1024 as follows:

 use the numbers:
 {
 0.0, height, 0.0,
 1024, height, 0.0,
 0.0, height-1024, 0.0,
 1024, height-1024, 0.0
 }
 */

NSLog(@"height of me: %f", self.bounds.size.height);

static const GLfloat vertices[] = {
    0.0,  643, 0.0,
    1024,  643, 0.0,
    0.0, -381, 0.0,
    1024, -381, 0.0
};

static const GLfloat normals[] = {
    0.0, 0.0, 1024,
    0.0, 0.0, 1024,
    0.0, 0.0, 1024,
    0.0, 0.0, 1024
};


glBindTexture(GL_TEXTURE_2D, stampTexture);
glVertexPointer(3, GL_FLOAT, 0, vertices);
glNormalPointer(GL_FLOAT, 0, normals);
glTexCoordPointer(2, GL_FLOAT, 0, texCoords);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);

glPopMatrix();

glDeleteTextures( 1, &stampTexture );

// Display the buffer
glBindRenderbufferOES(GL_RENDERBUFFER_OES, viewRenderbuffer);
[context presentRenderbuffer:GL_RENDERBUFFER_OES];

}



-(void) addImageToView{
UIImage* imageToAdd= [UIImage imageNamed:@"IMAGE_TO_ADD_TO_GL_VIEW.png"];


//     all images added to the paining view MUST be 512x512.
//     You can also add smaller images (even transformed ones) using this method - just add it to a UIView and then get it's graphics context

UIView* imageView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 512, 512)];



UIImageView* subView   = [[UIImageView alloc] initWithImage:imageToAdd];


[imageView addSubview:subView];
UIImage* blendedImage =nil;

UIGraphicsBeginImageContext(imageView.frame.size);

[imageView.layer renderInContext:UIGraphicsGetCurrentContext()];

blendedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

[self mergeWithImage: blendedImage ];

---

这不是您问题的答案，但请注意，在每一帧调用

[[Texture2D alloc]initWithImage:image]

而不释放它，会导致大量内存泄漏。@hanno ARC可能已启用，在这种情况下不会泄漏。尽管如此，如果每帧都使用它，可能有更好的方法来缓存返回值，而不是在每次调用时创建一个新的值。链接无效。请提供一个解决方案，而不仅仅是一个链接死链接。无用的anwserI用代码替换了断开的链接。请考虑取消投票，以免人们使用代码。