Surface Shader screenPos

Unity Engine
1

Can someone let me know what the members are and if it is in pixels or normalized (and if so what range). I can’t find anything detail in the documentation and can’t really glean anything from the few postings I found searching.

I assume the components are x,y, z &w with x y corresponding to the X and Y positions, z width and w height.

Reason I ask is that I would like to write a shader that approximates a scanline effect so want to clip every other line of the texture I am writing, or possibly increase its alpha (so it will become more transparent).

2

BUMP - Anyone?

3

If I understand :

The screenPos register contains the 3D coord of a vertex after MVP tranformation (in homogenous values) so if you would like to get the screenPos in normalized screen coord you’ve to compute :

screenUV_01 = screenPos.xy / screenPos.w;

Or in viewport dim :

screenUV = ScreenWidthHeight * screenUV_01;

Nope ?