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Using software render (Maya), an expression like blinn1.colorR = file1.uCoord renders a gradient. How to do similar in Arnold?
I am trying to connect a file texture node and getting information from pixels using uCoord, vCoord. But in Arnold it seems some pre-calculation discards outcolor affected by expressions.
(Below can draw a circle on the middle of a plane for software render)
$u = place2dTexture1.uCoord - .5; $v = place2dTexture1.vCoord - .5; $uv = <<$u,$v, 0>>; $d = mag($uv); $r = 0.3; $c = smoothstep($r, $r+.02, $d); $col =<<$c, $c, $c>>; blinn1.colorR = $col.x; blinn1.colorG = $col.y; blinn1.colorB = $col.z;
Expressions are not going to be evaluated at render time. At best, they'll be evaluated when MtoA translates the scene, and some constant values will be exported.