InstanceNode: Support velocity. (#32586)

src/nodes/accessors/InstanceNode.js

@@ -2,7 +2,7 @@ import Node from '../core/Node.js';
 import { varyingProperty } from '../core/PropertyNode.js';
 import { instancedBufferAttribute, instancedDynamicBufferAttribute } from './BufferAttributeNode.js';
 import { normalLocal, transformNormal } from './Normal.js';
-import { positionLocal } from './Position.js';
+import { positionLocal, positionPrevious } from './Position.js';
 import { nodeProxy, vec3, mat4 } from '../tsl/TSLBase.js';
 import { NodeUpdateType } from '../core/constants.js';
 import { buffer } from '../accessors/BufferNode.js';
@@ -99,6 +99,14 @@ class InstanceNode extends Node {
 		 */
 		this.bufferColor = null;
 
+		/**
+		 * The previous instance matrices. Required for computing motion vectors.
+		 *
+		 * @type {?Node}
+		 * @default null
+		 */
+		this.previousInstanceMatrixNode = null;
+
 	}
 
 	/**
@@ -136,51 +144,22 @@ class InstanceNode extends Node {
 	 */
 	setup( builder ) {
 
-		const { instanceMatrix, instanceColor, isStorageMatrix, isStorageColor } = this;
-
-		const { count } = instanceMatrix;
-
 		let { instanceMatrixNode, instanceColorNode } = this;
 
-		if ( instanceMatrixNode === null ) {
-
-			if ( isStorageMatrix ) {
-
-				instanceMatrixNode = storage( instanceMatrix, 'mat4', Math.max( count, 1 ) ).element( instanceIndex );
-
-			} else {
-
-				// Both backends have ~64kb UBO limit; fallback to attributes above 1000 matrices.
-
-				if ( count <= 1000 ) {
-
-					instanceMatrixNode = buffer( instanceMatrix.array, 'mat4', Math.max( count, 1 ) ).element( instanceIndex );
-
-				} else {
-
-					const interleaved = new InstancedInterleavedBuffer( instanceMatrix.array, 16, 1 );
-
-					this.buffer = interleaved;
+		// instance matrix
 
-					const bufferFn = instanceMatrix.usage === DynamicDrawUsage ? instancedDynamicBufferAttribute : instancedBufferAttribute;
-
-					const instanceBuffers = [
-						bufferFn( interleaved, 'vec4', 16, 0 ),
-						bufferFn( interleaved, 'vec4', 16, 4 ),
-						bufferFn( interleaved, 'vec4', 16, 8 ),
-						bufferFn( interleaved, 'vec4', 16, 12 )
-					];
-
-					instanceMatrixNode = mat4( ...instanceBuffers );
-
-				}
+		if ( instanceMatrixNode === null ) {
 
-			}
+			instanceMatrixNode = this._createInstanceMatrixNode( true );
 
 			this.instanceMatrixNode = instanceMatrixNode;
 
 		}
 
+		// instance color
+
+		const { instanceColor, isStorageColor } = this;
+
 		if ( instanceColor && instanceColorNode === null ) {
 
 			if ( isStorageColor ) {
@@ -208,6 +187,12 @@ class InstanceNode extends Node {
 		const instancePosition = instanceMatrixNode.mul( positionLocal ).xyz;
 		positionLocal.assign( instancePosition );
 
+		if ( builder.needsPreviousData() ) {
+
+			positionPrevious.assign( this.getPreviousInstancedPosition( builder ) );
+
+		}
+
 		// NORMAL
 
 		if ( builder.hasGeometryAttribute( 'normal' ) ) {
@@ -235,7 +220,7 @@ class InstanceNode extends Node {
 	 *
 	 * @param {NodeFrame} frame - The current node frame.
 	 */
-	update( /*frame*/ ) {
+	update( frame ) {
 
 		if ( this.buffer !== null && this.isStorageMatrix !== true ) {
 
@@ -265,6 +250,85 @@ class InstanceNode extends Node {
 
 		}
 
+		if ( this.previousInstanceMatrixNode !== null ) {
+
+			frame.object.previousInstanceMatrix.array.set( this.instanceMatrix.array );
+
+		}
+
+	}
+
+	/**
+	 * Computes the transformed/instanced vertex position of the previous frame.
+	 *
+	 * @param {NodeBuilder} builder - The current node builder.
+	 * @return {Node<vec3>} The instanced position from the previous frame.
+	 */
+	getPreviousInstancedPosition( builder ) {
+
+		const instancedMesh = builder.object;
+
+		if ( this.previousInstanceMatrixNode === null ) {
+
+			instancedMesh.previousInstanceMatrix = this.instanceMatrix.clone();
+
+			this.previousInstanceMatrixNode = this._createInstanceMatrixNode( false );
+
+		}
+
+		return this.previousInstanceMatrixNode.mul( positionPrevious ).xyz;
+
+	}
+
+	/**
+	 * Creates a node representing the instance matrix data.
+	 *
+	 * @private
+	 * @param {boolean} assignBuffer - Whether the created interleaved buffer should be assigned to the `buffer` member or not.
+	 * @return {Node} The instance matrix node.
+	 */
+	_createInstanceMatrixNode( assignBuffer ) {
+
+		let instanceMatrixNode;
+
+		const { instanceMatrix } = this;
+		const { count } = instanceMatrix;
+
+		if ( this.isStorageMatrix ) {
+
+			instanceMatrixNode = storage( instanceMatrix, 'mat4', Math.max( count, 1 ) ).element( instanceIndex );
+
+		} else {
+
+			// Both backends have ~64kb UBO limit; fallback to attributes above 1000 matrices.
+
+			if ( count <= 1000 ) {
+
+				instanceMatrixNode = buffer( instanceMatrix.array, 'mat4', Math.max( count, 1 ) ).element( instanceIndex );
+
+			} else {
+
+				const interleaved = new InstancedInterleavedBuffer( instanceMatrix.array, 16, 1 );
+
+				if ( assignBuffer === true ) this.buffer = interleaved;
+
+				const bufferFn = instanceMatrix.usage === DynamicDrawUsage ? instancedDynamicBufferAttribute : instancedBufferAttribute;
+
+				const instanceBuffers = [
+					bufferFn( interleaved, 'vec4', 16, 0 ),
+					bufferFn( interleaved, 'vec4', 16, 4 ),
+					bufferFn( interleaved, 'vec4', 16, 8 ),
+					bufferFn( interleaved, 'vec4', 16, 12 )
+				];
+
+				instanceMatrixNode = mat4( ...instanceBuffers );
+
+			}
+
+		}
+
+		return instanceMatrixNode;
+
 	}
 
 }

src/nodes/accessors/SkinningNode.js

@@ -9,7 +9,6 @@ import { positionLocal, positionPrevious } from './Position.js';
 import { tangentLocal } from './Tangent.js';
 import { uniform } from '../core/UniformNode.js';
 import { buffer } from './BufferNode.js';
-import { getDataFromObject } from '../core/NodeUtils.js';
 import { storage } from './StorageBufferNode.js';
 import { InstancedBufferAttribute } from '../../core/InstancedBufferAttribute.js';
 import { instanceIndex } from '../core/IndexNode.js';
@@ -199,21 +198,6 @@ class SkinningNode extends Node {
 
 	}
 
-	/**
-	 * Returns `true` if bone matrices from the previous frame are required. Relevant
-	 * when computing motion vectors with {@link VelocityNode}.
-	 *
-	 * @param {NodeBuilder} builder - The current node builder.
-	 * @return {boolean} Whether bone matrices from the previous frame are required or not.
-	 */
-	needsPreviousBoneMatrices( builder ) {
-
-		const mrt = builder.renderer.getMRT();
-
-		return ( mrt && mrt.has( 'velocity' ) ) || getDataFromObject( builder.object ).useVelocity === true;
-
-	}
-
 	/**
 	 * Setups the skinning node by assigning the transformed vertex data to predefined node variables.
 	 *
@@ -222,7 +206,7 @@ class SkinningNode extends Node {
 	 */
 	setup( builder ) {
 
-		if ( this.needsPreviousBoneMatrices( builder ) ) {
+		if ( builder.needsPreviousData() ) {
 
 			positionPrevious.assign( this.getPreviousSkinnedPosition( builder ) );
 

src/nodes/core/NodeBuilder.js

@@ -8,7 +8,7 @@ import ParameterNode from './ParameterNode.js';
 import StructType from './StructType.js';
 import FunctionNode from '../code/FunctionNode.js';
 import NodeMaterial from '../../materials/nodes/NodeMaterial.js';
-import { getTypeFromLength } from './NodeUtils.js';
+import { getDataFromObject, getTypeFromLength } from './NodeUtils.js';
 import { NodeUpdateType, defaultBuildStages, shaderStages } from './constants.js';
 
 import {
@@ -3118,6 +3118,20 @@ class NodeBuilder {
 
 	}
 
+	/**
+	 * Returns `true` if data from the previous frame are required. Relevant
+	 * when computing motion vectors with {@link VelocityNode}.
+	 *
+	 * @return {boolean} Whether data from the previous frame are required or not.
+	 */
+	needsPreviousData() {
+
+		const mrt = this.renderer.getMRT();
+
+		return ( mrt && mrt.has( 'velocity' ) ) || getDataFromObject( this.object ).useVelocity === true;
+
+	}
+
 }
 
 export default NodeBuilder;

src/objects/InstancedMesh.js

@@ -56,6 +56,15 @@ class InstancedMesh extends Mesh {
 		 */
 		this.instanceMatrix = new InstancedBufferAttribute( new Float32Array( count * 16 ), 16 );
 
+		/**
+		 * Represents the local transformation of all instances of the previous frame.
+		 * Required for computing velocity. Maintained in {@link InstanceNode}.
+		 *
+		 * @type {?InstancedBufferAttribute}
+		 * @default null
+		 */
+		this.previousInstanceMatrix = null;
+
 		/**
 		 * Represents the color of all instances. You have to set its
 		 * {@link BufferAttribute#needsUpdate} flag to true if you modify instanced data
@@ -185,6 +194,8 @@ class InstancedMesh extends Mesh {
 
 		this.instanceMatrix.copy( source.instanceMatrix );
 
+		if ( source.previousInstanceMatrix !== null ) this.previousInstanceMatrix = source.previousInstanceMatrix.clone();
+
 		if ( source.morphTexture !== null ) this.morphTexture = source.morphTexture.clone();
 		if ( source.instanceColor !== null ) this.instanceColor = source.instanceColor.clone();