How to get depth from GPU

[copark86]

I know there is a function to download a rendered image from GPU

Image GetTextureData(Texture2D texture);

But is there a way to download depth from GPU? I am going to use it for image processing (not related to OpenGL).

[raysan5]

@copark86 I'm afraid this is out-of-scope for raylib, it's a specific use-case. Still, it can be accomplished rendering the depth buffer using a shader and getting it. Here there is an issue explaining the process: #1872

A brief summary:

1. Use a RenderTexture with a depth Texture instead of RenderBuffer (you need to change LoadRenderTexture() function or use rlgl directly for that)
2. Render your world
3. Render RenderTexture.depth using a Shader to linearize the depth values of that texture.
4. LoadImageFromScreen() should return the drawn depth texture linearized currently on the screen framebuffer

There is probably a simpler way to do that but not exposed by raylib, you should use OpenGL directly and call yourself glGetTexImage() requesting a GL_DEPTH_COMPONENT as GL_FLOAT but I think returned data won't be linear.

[copark86]

Thanks! That helped me a lot.

[TextBox75]

Question, how can I render RenderTexture.depth? I'm trying to render the depth buffer to do shadow mapping.

[chriscamacho]

I did a toon shader using the same technique using normals instead of depth, but the process is identical save for an simple tweak in the shader, take a look at bedroomcoders.co.uk