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