Addons: Add SSRNode.

examples/files.json

@@ -398,6 +398,7 @@
 		"webgpu_postprocessing_smaa",
 		"webgpu_postprocessing_sobel",
 		"webgpu_postprocessing_ssaa",
+		"webgpu_postprocessing_ssr",
 		"webgpu_postprocessing_transition",
 		"webgpu_postprocessing",
 		"webgpu_procedural_texture",

examples/jsm/tsl/display/SSRNode.js

@@ -0,0 +1,349 @@
+import { NearestFilter, RenderTarget, Vector2, PostProcessingUtils } from 'three';
+import { getViewPosition, sqrt, mul, div, cross, float, Continue, Break, Loop, int, max, abs, sub, If, dot, reflect, normalize, screenCoordinate, QuadMesh, TempNode, nodeObject, Fn, NodeUpdateType, passTexture, NodeMaterial, uv, uniform, perspectiveDepthToViewZ, orthographicDepthToViewZ, vec2, vec3, vec4 } from 'three/tsl';
+
+const _quadMesh = /*@__PURE__*/ new QuadMesh();
+const _size = /*@__PURE__*/ new Vector2();
+let _rendererState;
+
+/**
+ * References:
+ * https://lettier.github.io/3d-game-shaders-for-beginners/screen-space-reflection.html
+ */
+class SSRNode extends TempNode {
+
+	static get type() {
+
+		return 'SSRNode';
+
+	}
+
+	constructor( colorNode, depthNode, normalNode, metalnessNode, camera ) {
+
+		super();
+
+		this.colorNode = colorNode;
+		this.depthNode = depthNode;
+		this.normalNode = normalNode;
+		this.metalnessNode = metalnessNode;
+		this.camera = camera;
+
+		this.resolutionScale = 0.5;
+
+		this.updateBeforeType = NodeUpdateType.FRAME;
+
+		// render targets
+
+		this._ssrRenderTarget = new RenderTarget( 1, 1, { depthBuffer: false, minFilter: NearestFilter, magFilter: NearestFilter } );
+		this._ssrRenderTarget.texture.name = 'SSRNode.SSR';
+
+		// uniforms
+
+		this.maxDistance = uniform( 1 ); // controls how far a fragment can reflect
+		this.thickness = uniform( 0.1 ); // controls the cutoff between what counts as a possible reflection hit and what does not
+		this.opacity = uniform( 1 ); // controls the transparency of the reflected colors
+
+		this._cameraNear = uniform( camera.near );
+		this._cameraFar = uniform( camera.far );
+		this._cameraProjectionMatrix = uniform( camera.projectionMatrix );
+		this._cameraProjectionMatrixInverse = uniform( camera.projectionMatrixInverse );
+		this._isPerspectiveCamera = uniform( camera.isPerspectiveCamera ? 1 : 0 );
+		this._resolution = uniform( new Vector2() );
+		this._maxStep = uniform( 0 );
+
+		// materials
+
+		this._material = new NodeMaterial();
+		this._material.name = 'SSRNode.SSR';
+
+		//
+
+		this._textureNode = passTexture( this, this._ssrRenderTarget.texture );
+
+	}
+
+	getTextureNode() {
+
+		return this._textureNode;
+
+	}
+
+	setSize( width, height ) {
+
+		width = Math.round( this.resolutionScale * width );
+		height = Math.round( this.resolutionScale * height );
+
+		this._resolution.value.set( width, height );
+		this._maxStep.value = Math.round( Math.sqrt( width * width + height * height ) );
+
+		this._ssrRenderTarget.setSize( width, height );
+
+	}
+
+	updateBefore( frame ) {
+
+		const { renderer } = frame;
+
+		_rendererState = PostProcessingUtils.resetRendererState( renderer, _rendererState );
+
+		const size = renderer.getDrawingBufferSize( _size );
+
+		_quadMesh.material = this._material;
+
+		this.setSize( size.width, size.height );
+
+		// clear
+
+		renderer.setMRT( null );
+		renderer.setClearColor( 0x000000, 0 );
+
+		// ssr
+
+		renderer.setRenderTarget( this._ssrRenderTarget );
+		_quadMesh.render( renderer );
+
+		// restore
+
+		PostProcessingUtils.setRendererState( renderer, _rendererState );
+
+	}
+
+	setup( builder ) {
+
+		const uvNode = uv();
+
+		const pointToLineDistance = Fn( ( [ point, linePointA, linePointB ] )=> {
+
+			// https://mathworld.wolfram.com/Point-LineDistance3-Dimensional.html
+
+			return cross( point.sub( linePointA ), point.sub( linePointB ) ).length().div( linePointB.sub( linePointA ).length() );
+
+		} );
+
+		const pointPlaneDistance = Fn( ( [ point, planePoint, planeNormal ] )=> {
+
+			// https://mathworld.wolfram.com/Point-PlaneDistance.html
+			// https://en.wikipedia.org/wiki/Plane_(geometry)
+			// http://paulbourke.net/geometry/pointlineplane/
+
+			const d = mul( planeNormal.x, planePoint.x ).add( mul( planeNormal.y, planePoint.y ) ).add( mul( planeNormal.z, planePoint.z ) ).negate().toVar();
+
+			const denominator = sqrt( mul( planeNormal.x, planeNormal.x, ).add( mul( planeNormal.y, planeNormal.y ) ).add( mul( planeNormal.z, planeNormal.z ) ) ).toVar();
+			const distance = div( mul( planeNormal.x, point.x ).add( mul( planeNormal.y, point.y ) ).add( mul( planeNormal.z, point.z ) ).add( d ), denominator );
+			return distance;
+
+		} );
+
+		const getViewZ = Fn( ( [ depth ] ) => {
+
+			let viewZNode;
+
+			if ( this.camera.isPerspectiveCamera ) {
+
+				viewZNode = perspectiveDepthToViewZ( depth, this._cameraNear, this._cameraFar );
+
+			} else {
+
+				viewZNode = orthographicDepthToViewZ( depth, this._cameraNear, this._cameraFar );
+
+			}
+
+			return viewZNode;
+
+		} );
+
+		const viewPositionToSceneUv = Fn( ( [ sampleViewPos ] )=> {
+
+			const sampleClipPos = this._cameraProjectionMatrix.mul( vec4( sampleViewPos, 1.0 ) );
+			const sampleUv = sampleClipPos.xy.div( sampleClipPos.w ).mul( 0.5 ).add( 0.5 ).toVar();
+			return vec2( sampleUv.x, sampleUv.y.oneMinus() );
+
+		} );
+
+		const ssr = Fn( () => {
+
+			const metalness = this.metalnessNode.uv( uvNode ).r;
+
+			 // fragments with no metalness do not reflect their environment
+			metalness.equal( 0.0 ).discard();
+
+			// compute some standard FX entities
+			const depth = this.depthNode.uv( uvNode ).r.toVar();
+			const viewPosition = getViewPosition( uvNode, depth, this._cameraProjectionMatrixInverse ).toVar();
+			const viewNormal = this.normalNode.rgb.normalize().toVar();
+
+			// compute the direction from the position in view space to the camera
+			const viewIncidentDir = ( ( this.camera.isPerspectiveCamera ) ? normalize( viewPosition ) : vec3( 0, 0, - 1 ) ).toVar();
+
+			// compute the direction in which the light is reflected on the surface
+			const viewReflectDir = reflect( viewIncidentDir, viewNormal ).toVar();
+
+			// adapt maximum distance to the local geometry (see https://www.mathsisfun.com/algebra/vectors-dot-product.html)
+			const maxReflectRayLen = this.maxDistance.div( dot( viewIncidentDir.negate(), viewNormal ) ).toVar();
+
+			// compute the maximum point of the reflection ray in view space
+			const d1viewPosition = viewPosition.add( viewReflectDir.mul( maxReflectRayLen ) ).toVar();
+
+			// check if d1viewPosition lies behind the camera near plane
+			If( this._isPerspectiveCamera.equal( float( 1 ) ).and( d1viewPosition.z.greaterThan( this._cameraNear.negate() ) ), () => {
+
+				// if so, ensure d1viewPosition is clamped on the near plane.
+				// this prevents artifacts during the ray marching process
+				const t = sub( this._cameraNear.negate(), viewPosition.z ).div( viewReflectDir.z );
+				d1viewPosition.assign( viewPosition.add( viewReflectDir.mul( t ) ) );
+
+			} );
+
+			// d0 and d1 are the start and maximum points of the reflection ray in screen space
+			const d0 = screenCoordinate.xy.toVar();
+			const d1 = viewPositionToSceneUv( d1viewPosition ).mul( this._resolution ).toVar();
+
+			// below variables are used to control the raymarching process
+
+			// total length of the ray
+			const totalLen = d1.sub( d0 ).length().toVar();
+
+			// offset in x and y direction
+			const xLen = d1.x.sub( d0.x ).toVar();
+			const yLen = d1.y.sub( d0.y ).toVar();
+
+			// determine the larger delta
+			// The larger difference will help to determine how much to travel in the X and Y direction each iteration and
+			// how many iterations are needed to travel the entire ray
+			const totalStep = max( abs( xLen ), abs( yLen ) ).toVar();
+
+			// step sizes in the x and y directions
+			const xSpan = xLen.div( totalStep ).toVar();
+			const ySpan = yLen.div( totalStep ).toVar();
+
+			const output = vec4( 0 ).toVar();
+
+			// the actual ray marching loop
+			// starting from d0, the code gradually travels along the ray and looks for an intersection with the geometry.
+			// it does not exceed d1 (the maximum ray extend)
+			Loop( { start: int( 0 ), end: int( this._maxStep ), type: 'int', condition: '<' }, ( { i } ) => {
+
+				// stop if the maximum number of steps is reached for this specific ray
+				If( float( i ).greaterThanEqual( totalStep ), () => {
+
+					Break();
+
+				} );
+
+				// advance on the ray by computing a new position in screen space
+				const xy = vec2( d0.x.add( xSpan.mul( float( i ) ) ), d0.y.add( ySpan.mul( float( i ) ) ) ).toVar();
+
+				// stop processing if the new position lies outside of the screen
+				If( xy.x.lessThan( 0 ).or( xy.x.greaterThan( this._resolution.x ) ).or( xy.y.lessThan( 0 ) ).or( xy.y.greaterThan( this._resolution.y ) ), () => {
+
+					Break();
+
+				} );
+
+				// compute new uv, depth, viewZ and viewPosition for the new location on the ray
+				const uvNode = xy.div( this._resolution );
+				const d = this.depthNode.uv( uvNode ).r.toVar();
+				const vZ = getViewZ( d ).toVar();
+				const vP = getViewPosition( uvNode, d, this._cameraProjectionMatrixInverse ).toVar();
+
+				const viewReflectRayZ = float( 0 ).toVar();
+
+				// normalized distance between the current position xy and the starting point d0
+				const s = xy.sub( d0 ).length().div( totalLen );
+
+				// depending on the camera type, we now compute the z-coordinate of the reflected ray at the current step in view space
+				If( this._isPerspectiveCamera.equal( float( 1 ) ), () => {
+
+					const recipVPZ = float( 1 ).div( viewPosition.z ).toVar();
+					viewReflectRayZ.assign( float( 1 ).div( recipVPZ.add( s.mul( float( 1 ).div( d1viewPosition.z ).sub( recipVPZ ) ) ) ) );
+
+				} ).Else( () => {
+
+					viewReflectRayZ.assign( viewPosition.z.add( s.mul( d1viewPosition.z.sub( viewPosition.z ) ) ) );
+
+				} );
+
+				// if viewReflectRayZ is less or equal than the real z-coordinate at this place, it potentially intersects the geometry
+				If( viewReflectRayZ.lessThanEqual( vZ ), () => {
+
+					// compute the distance of the new location to the ray in view space
+					// to clarify vP is the fragment's view position which is not an exact point on the ray
+					const away = pointToLineDistance( vP, viewPosition, d1viewPosition ).toVar();
+
+					// compute the minimum thickness between the current fragment and its neighbor in the x-direction.
+					const xyNeighbor = vec2( xy.x.add( 1 ), xy.y ).toVar(); // move one pixel
+					const uvNeighbor = xyNeighbor.div( this._resolution );
+					const vPNeighbor = getViewPosition( uvNeighbor, d, this._cameraProjectionMatrixInverse ).toVar();
+					const minThickness = vPNeighbor.x.sub( vP.x ).toVar();
+					minThickness.mulAssign( 3 ); // expand a bit to avoid errors
+
+					const tk = max( minThickness, this.thickness ).toVar();
+
+					If( away.lessThanEqual( tk ), () => { // hit
+
+						const vN = this.normalNode.uv( uvNode ).rgb.normalize().toVar();
+
+						If( dot( viewReflectDir, vN ).greaterThanEqual( 0 ), () => {
+
+							// the reflected ray is pointing towards the same side as the fragment's normal (current ray position),
+							// which means it wouldn't reflect off the surface. The loop continues to the next step for the next ray sample.
+							Continue();
+
+						} );
+
+						// this distance represents the depth of the intersection point between the reflected ray and the scene.
+						const distance = pointPlaneDistance( vP, viewPosition, viewNormal ).toVar();
+
+						If( distance.greaterThan( this.maxDistance ), () => {
+
+							// Distance exceeding limit: The reflection is potentially too far away and
+							// might not contribute significantly to the final color
+							Break();
+
+						} );
+
+						// distance attenuation (the reflection should fade out the farther it is away from the surface)
+						const ratio = float( 1 ).sub( distance.div( this.maxDistance ) ).toVar();
+						const attenuation = ratio.mul( ratio );
+						const op = this.opacity.mul( attenuation ).toVar();
+
+						// fresnel (reflect more light on surfaces that are viewed at grazing angles)
+						const fresnelCoe = div( dot( viewIncidentDir, viewReflectDir ).add( 1 ), 2 );
+						op.mulAssign( fresnelCoe );
+
+						// output
+						const reflectColor = this.colorNode.uv( uvNode );
+						output.assign( vec4( reflectColor.rgb, op ) );
+						Break();
+
+					} );
+
+				} );
+
+			} );
+
+			return output;
+
+		} );
+
+		this._material.fragmentNode = ssr().context( builder.getSharedContext() );
+		this._material.needsUpdate = true;
+
+		//
+
+		return this._textureNode;
+
+	}
+
+	dispose() {
+
+		this._ssrRenderTarget.dispose();
+
+		this._material.dispose();
+
+	}
+
+}
+
+export default SSRNode;
+
+export const ssr = ( colorNode, depthNode, normalNode, metalnessNode, camera ) => nodeObject( new SSRNode( nodeObject( colorNode ), nodeObject( depthNode ), nodeObject( normalNode ), nodeObject( metalnessNode ), camera ) );