How to write values to depth buffer in godot fragment shader?

Question

How do you specify the depth value in the fragment shader, if you would like to for example render a texture of a sphere that also affect depht buffer in the cameras z-direction?

In OpenGL you can use gl_FragDepth. Is there a similar builtin variable in godot?

Edit: I found that there is a variable DEPTH after posting the question that seems to be merged.. I have not had time to try it yet. If you have any experience from using successfully, I would accept that answer.

Answer 1

Yes, you can write to DEPTH from the fragment buffer of the shader of an spatial material.

Godot will, of course, also draw depth by default. You can control that with the render modes depth_draw_*, see Depth Draw Mode.

And if you want to read depth, you can use DEPTH_TEXTURE. The article Screen Reading Shaders has an example.

Refer to Spatial Shader for the list available variables and options in spatial shaders.