81 lines
2.3 KiB
JavaScript
81 lines
2.3 KiB
JavaScript
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import TempNode from '../core/TempNode.js';
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import { addNodeClass } from '../core/Node.js';
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import { uv } from '../accessors/UVNode.js';
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import { normalView } from '../accessors/NormalNode.js';
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import { positionView } from '../accessors/PositionNode.js';
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import { faceDirection } from './FrontFacingNode.js';
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import { addNodeElement, tslFn, nodeProxy, float, vec2 } from '../shadernode/ShaderNode.js';
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// Bump Mapping Unparametrized Surfaces on the GPU by Morten S. Mikkelsen
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// https://mmikk.github.io/papers3d/mm_sfgrad_bump.pdf
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const dHdxy_fwd = tslFn( ( { textureNode, bumpScale } ) => {
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// It's used to preserve the same TextureNode instance
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const sampleTexture = ( callback ) => textureNode.cache().context( { getUV: ( texNode ) => callback( texNode.uvNode || uv() ), forceUVContext: true } );
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const Hll = float( sampleTexture( ( uvNode ) => uvNode ) );
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return vec2(
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float( sampleTexture( ( uvNode ) => uvNode.add( uvNode.dFdx() ) ) ).sub( Hll ),
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float( sampleTexture( ( uvNode ) => uvNode.add( uvNode.dFdy() ) ) ).sub( Hll )
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).mul( bumpScale );
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} );
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// Evaluate the derivative of the height w.r.t. screen-space using forward differencing (listing 2)
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const perturbNormalArb = tslFn( ( inputs ) => {
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const { surf_pos, surf_norm, dHdxy } = inputs;
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// normalize is done to ensure that the bump map looks the same regardless of the texture's scale
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const vSigmaX = surf_pos.dFdx().normalize();
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const vSigmaY = surf_pos.dFdy().normalize();
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const vN = surf_norm; // normalized
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const R1 = vSigmaY.cross( vN );
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const R2 = vN.cross( vSigmaX );
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const fDet = vSigmaX.dot( R1 ).mul( faceDirection );
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const vGrad = fDet.sign().mul( dHdxy.x.mul( R1 ).add( dHdxy.y.mul( R2 ) ) );
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return fDet.abs().mul( surf_norm ).sub( vGrad ).normalize();
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} );
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class BumpMapNode extends TempNode {
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constructor( textureNode, scaleNode = null ) {
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super( 'vec3' );
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this.textureNode = textureNode;
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this.scaleNode = scaleNode;
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}
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setup() {
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const bumpScale = this.scaleNode !== null ? this.scaleNode : 1;
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const dHdxy = dHdxy_fwd( { textureNode: this.textureNode, bumpScale } );
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return perturbNormalArb( {
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surf_pos: positionView,
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surf_norm: normalView,
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dHdxy
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} );
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}
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}
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export default BumpMapNode;
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export const bumpMap = nodeProxy( BumpMapNode );
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addNodeElement( 'bumpMap', bumpMap );
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addNodeClass( 'BumpMapNode', BumpMapNode );
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