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PhysicalLightingModel: Cleanup evalIridescence #29702

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Merged
merged 1 commit into from
Oct 20, 2024
+14 −12
Merged

PhysicalLightingModel: Cleanup evalIridescence #29702

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26 changes: 14 additions & 12 deletions src/nodes/functions/PhysicalLightingModel.js
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Original file line number Diff line number Diff line change
@@ -74,7 +74,7 @@ const getTransmissionSample = /*@__PURE__*/ Fn( ( [ fragCoord, roughness, ior ]
const transmissionSample = singleViewportMipTexture.uv( fragCoord );
//const transmissionSample = viewportMipTexture( fragCoord );

const lod = log2( float( screenSize.x ) ).mul( applyIorToRoughness( roughness, ior ) );
const lod = log2( screenSize.x ).mul( applyIorToRoughness( roughness, ior ) );

return textureBicubic( transmissionSample, lod );

@@ -233,15 +233,16 @@ const evalIridescence = /*@__PURE__*/ Fn( ( { outsideIOR, eta2, cosTheta1, thinF
// Force iridescenceIOR -> outsideIOR when thinFilmThickness -> 0.0
const iridescenceIOR = mix( outsideIOR, eta2, smoothstep( 0.0, 0.03, thinFilmThickness ) );
// Evaluate the cosTheta on the base layer (Snell law)
const sinTheta2Sq = outsideIOR.div( iridescenceIOR ).pow2().mul( float( 1 ).sub( cosTheta1.pow2() ) );
const sinTheta2Sq = outsideIOR.div( iridescenceIOR ).pow2().mul( cosTheta1.pow2().oneMinus() );

// Handle TIR:
const cosTheta2Sq = float( 1 ).sub( sinTheta2Sq );
/*if ( cosTheta2Sq < 0.0 ) {
const cosTheta2Sq = sinTheta2Sq.oneMinus();

return vec3( 1.0 );
If( cosTheta2Sq.lessThan( 0 ), () => {

}*/
return vec3( 1.0 );

} );

const cosTheta2 = cosTheta2Sq.sqrt();

@@ -274,17 +275,18 @@ const evalIridescence = /*@__PURE__*/ Fn( ( { outsideIOR, eta2, cosTheta1, thinF

// Reflectance term for m = 0 (DC term amplitude)
const C0 = R12.add( Rs );
let I = C0;
const I = C0.toVar();

// Reflectance term for m > 0 (pairs of diracs)
let Cm = Rs.sub( T121 );
for ( let m = 1; m <= 2; ++ m ) {
const Cm = Rs.sub( T121 ).toVar();

Loop( { start: 1, end: 2, condition: '<=', name: 'm' }, ( { m } ) => {

Cm = Cm.mul( r123 );
Cm.mulAssign( r123 );
const Sm = evalSensitivity( float( m ).mul( OPD ), float( m ).mul( phi ) ).mul( 2.0 );
I = I.add( Cm.mul( Sm ) );
I.addAssign( Cm.mul( Sm ) );

}
} );

// Since out of gamut colors might be produced, negative color values are clamped to 0.
return I.max( vec3( 0.0 ) );