RenderDoc. a small value in Mesh Output is an approximation?

Question

Terminology

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In this post, I refer to this window as Mesh Output.

And I refer to this window as Debug vert().

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Problem

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I found that values of TEXCOORD3 and TEXCOORD4 in Mesh Output is not equal to values in Debug vert().

Values in MeshOutput

TEXCOORD1

-0.89371    0.01009     -0.44853    

TEXCOORD2

0.29143    -0.74704     -0.59749    

TEXCOORD3

-1.68456E-08    -1.68456E-08    -1.68456E-08    -1.68456E-08    

TEXCOORD4

-7.43176E-09    -7.43176E-09    -7.43176E-09    -7.43176E-09

Values in Debug vert()

TEXCOORD1

-0.89371    0.01009     -0.44853    

TEXCOORD2

0.29143    -0.74704     -0.59749    

TEXCOORD3

 -2.98023e-08    -2.98023e-08   -2.98023e-08   -2.98023e-08

TEXCOORD4

0   0   0   0

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Question

I wonder why the values in Mesh output is not equal to the values in Debug Vert().

I guess the reason that is values in small Mesh Output are an approximation.

This guess is right?

Answer 1

the vertex debugging (Debug vert()) is emulated (on the CPU), so it might have tiny differences to mesh output (from the GPU).

ref https://twitter.com/baldurk/status/919935224066334720