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Replace perturbNormal implementation with a more robust version #21299

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Merged
merged 2 commits into from
Feb 18, 2021
Merged

Replace perturbNormal implementation with a more robust version #21299

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6437c5c
Replace perturbNormal implementation with a more robust version
zeux Feb 18, 2021
ab7458e
Fix code style in the shader
zeux Feb 18, 2021
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19 changes: 10 additions & 9 deletions src/renderers/shaders/ShaderChunk/normalmap_pars_fragment.glsl.js
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Original file line number Diff line number Diff line change
Expand Up @@ -14,8 +14,8 @@ export default /* glsl */`

#if ! defined ( USE_TANGENT ) && ( defined ( TANGENTSPACE_NORMALMAP ) || defined ( USE_CLEARCOAT_NORMALMAP ) )

// Per-Pixel Tangent Space Normal Mapping
// http://hacksoflife.blogspot.ch/2009/11/per-pixel-tangent-space-normal-mapping.html
// Normal Mapping Without Precomputed Tangents
// http://www.thetenthplanet.de/archives/1180

vec3 perturbNormal2Arb( vec3 eye_pos, vec3 surf_norm, vec3 mapN, float faceDirection ) {

Expand All @@ -26,17 +26,18 @@ export default /* glsl */`
vec2 st0 = dFdx( vUv.st );
vec2 st1 = dFdy( vUv.st );

float scale = sign( st1.t * st0.s - st0.t * st1.s ); // we do not care about the magnitude
vec3 N = surf_norm; // normalized

vec3 S = normalize( ( q0 * st1.t - q1 * st0.t ) * scale );
vec3 T = normalize( ( - q0 * st1.s + q1 * st0.s ) * scale );
vec3 N = normalize( surf_norm );
vec3 q1perp = cross( q1, N );
vec3 q0perp = cross( N, q0 );

mat3 tsn = mat3( S, T, N );
vec3 T = q1perp * st0.x + q0perp * st1.x;
vec3 B = q1perp * st0.y + q0perp * st1.y;

mapN.xy *= faceDirection;
float det = max( dot( T, T ), dot( B, B ) );
float scale = ( det == 0.0 ) ? 0.0 : faceDirection * inversesqrt( det );

return normalize( tsn * mapN );
return normalize( T * ( mapN.x * scale ) + B * ( mapN.y * scale ) + N * mapN.z );

}

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