Help With Depth Testing

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#1

Good Afternoon,

I am trying to write a shader using the refract pass that compares the depth at a given screen position with the depth at the same screen position from the previous passes. The goal being that I find the difference in depth between the object I am rendering and all others in the scene. Currently, this is what I am trying to do.

//this retrieves the previous depth at location
texture2D(sDepthBuffer, vScreenPos.xy).r;
//this retrieves the depth at the current fragment (this is done in the vertex and interpolated to the fragment)
GetDepth(gl_Position);

Perhaps this is not the correct way to achieve this. Could someone point me in the right direction? Thanks!

#2

Just bumping this thread.

#3

The goal being that I find the difference in depth between the object I am rendering and all others in the scene.

You need to have two depth textures. One is input as texture, the second is destination buffer for rendering,

#4

That would make sense, given that OpenGL does not allow buffers to written to and read in the same pass. Could you show me how I would structure a render path or technique to accomplish this? I still don’t quite understand how shaders/materials/render paths/techniques work together.

#5

Hello,

cadaver explained depth rendering in more detail: How xml rendering framework works to get depth?

Until more specific info comes to the thread, there are a number of depth texture threads that may be informative.

(other than, of course, the docs on Rendering that links to the subjects you mention)

HTH