Open GL ES z buffer setup help needed

[Davespice]

Hey folks;

I am playing around with reverse engineering the hello_triangle (link) example program that comes with the Pi and I want to add a proper depth buffer. I think I need to modify something in the init_ogl function but I am not exactly sure what to do. I have added calls to the following EGL methods in my set up view function;

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glEnable(GL_DEPTH_TEST);
glDepthMask(GL_TRUE);
glDepthFunc(GL_LEQUAL);
glDepthRange(0.0f, 1.0f);

In my draw view method I am calling the methods below just before I set up my vertex and colour pointers and call into glDrawElements, but despite this the depth buffering in my scene doesn't actually work. So this is why I think it's something in the init_ogl function.

Here is a short video of the problem (link), ignore the mad colours - they're just for testing purposes.

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glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
glClearDepth(1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 

So this is why I think it's something in the init_ogl function. If anyone could point me in the right direction I would be really grateful.

Cheers!
Dave

[Paeryn]

Have you asked for a depth buffer? In the config attributes for EGL you want something like this:

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static const EGLint attribute_list[] =
   {
      EGL_RED_SIZE, 8,
      EGL_GREEN_SIZE, 8,
      EGL_BLUE_SIZE, 8,
      EGL_ALPHA_SIZE, 8,
      EGL_DEPTH_SIZE, 16,   // You need this line for depth buffering to work
      EGL_SURFACE_TYPE, EGL_WINDOW_BIT,
      EGL_NONE
   };

[Davespice]

Ahh, that is different to what I have... this is what my code has, which is straight out of the demo code;

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static const EGLint attribute_list[] =
	{
		EGL_RED_SIZE, 8,
		EGL_GREEN_SIZE, 8,
		EGL_BLUE_SIZE, 8,
		EGL_ALPHA_SIZE, 8,
		EGL_SURFACE_TYPE, EGL_WINDOW_BIT,
		EGL_NONE
	};

I'll give it a try this evening and report back, thanks for the help!

[Davespice]

Have you asked for a depth buffer? In the config attributes for EGL you want something like this:

This did the trick, thank you so much.

[avatar1337]

Yes! Helped me aswell =)