45 lines
1.3 KiB
Plaintext
45 lines
1.3 KiB
Plaintext
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#ifdef USE_BUMPMAP
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uniform sampler2D bumpMap;
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uniform float bumpScale;
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// Bump Mapping Unparametrized Surfaces on the GPU by Morten S. Mikkelsen
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// http://api.unrealengine.com/attachments/Engine/Rendering/LightingAndShadows/BumpMappingWithoutTangentSpace/mm_sfgrad_bump.pdf
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// Evaluate the derivative of the height w.r.t. screen-space using forward differencing (listing 2)
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vec2 dHdxy_fwd() {
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vec2 dSTdx = dFdx( vUv );
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vec2 dSTdy = dFdy( vUv );
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float Hll = bumpScale * texture2D( bumpMap, vUv ).x;
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float dBx = bumpScale * texture2D( bumpMap, vUv + dSTdx ).x - Hll;
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float dBy = bumpScale * texture2D( bumpMap, vUv + dSTdy ).x - Hll;
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return vec2( dBx, dBy );
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}
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vec3 perturbNormalArb( vec3 surf_pos, vec3 surf_norm, vec2 dHdxy ) {
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// Workaround for Adreno 3XX dFd*( vec3 ) bug. See #9988
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vec3 vSigmaX = vec3( dFdx( surf_pos.x ), dFdx( surf_pos.y ), dFdx( surf_pos.z ) );
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vec3 vSigmaY = vec3( dFdy( surf_pos.x ), dFdy( surf_pos.y ), dFdy( surf_pos.z ) );
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vec3 vN = surf_norm; // normalized
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vec3 R1 = cross( vSigmaY, vN );
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vec3 R2 = cross( vN, vSigmaX );
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float fDet = dot( vSigmaX, R1 );
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fDet *= ( float( gl_FrontFacing ) * 2.0 - 1.0 );
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vec3 vGrad = sign( fDet ) * ( dHdxy.x * R1 + dHdxy.y * R2 );
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return normalize( abs( fDet ) * surf_norm - vGrad );
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}
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#endif
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