Questions for hacking OpenGL ES2 template project from Xcode 4 - ios

Question

Create new project from opengl template via xcode4, you will see one color square moving.
I want to put two more small views to show the same thing. What I did is to add two
EAGLView *glView1;
EAGLView *glView2;
Then set up with property/systhesize etc, and same coding with self.view like these
[(EAGLView *)self.view setContext:context];
[(EAGLView *)self.view setFramebuffer];
if (!glView2) {
glView2 = [[EAGLView alloc] init];
}
[self.glView2 setContext:context2];
[self.glView2 setFramebuffer];
if (!glView1) {
glView1 = [[EAGLView alloc] init];
}
[self.glView1 setContext:context];
[self.glView1 setFramebuffer];
Do same thing for other place which self.view did. Also do the right thing to link within interface builder. (xcode4)
But the result show
I found that the last draw order in drawFrame will decide which window will show
[self.glView1 setFramebuffer];
[self.glView2 setFramebuffer]; // these will not show , but if put last, it will show
[(EAGLView *)self.view setFramebuffer]; // this will work
Does that make sense to explain my purpose and issues ?
Thanks very much for point out the root cause and help me go through this.

Answer 1

You need to read about OpenGL ES 2.0 ("OGLES2.0") . You shouldn't be using multiple EAGLView instances. You need only one, and you use OGLES2.0 commands to draw on it.
OpenGL is not easy to learn, and you will have to invest many hours of your time before you can achieve even simple renders with it. You should seek an external library like cocos2D to help you achieve what you want. Read the tutorials and documentation there carefully, and experiment. It will still take you a lot of time to achieve pleasing results, but far less than if you were using OGLES directly yourselfe