InstancedMeshBVH: optional get box from boundingSphere (#10)

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@three.ez/instanced-mesh",
-  "version": "0.2.1",
+  "version": "0.2.2",
   "description": "Simplified and enhanced InstancedMesh with frustum culling, fast raycasting (using BVH), sorting, visibility management and more.",
   "author": "Andrea Gargaro <[email protected]>",
   "license": "MIT",
@@ -21,7 +21,8 @@
     "performance",
     "BVH",
     "acceleration",
-    "raycasting"
+    "raycasting",
+    "LOD"
   ],
   "scripts": {
     "start": "vite",
@@ -36,7 +37,7 @@
   "devDependencies": {
     "@eslint/js": "^9.10.0",
     "@three.ez/main": "^0.5.7",
-    "@types/three": "^0.168.0",
+    "@types/three": "^0.169.0",
     "eslint": "^9.9.0",
     "typescript": "^5.1.3",
     "typescript-eslint": "^8.1.0",

src/objects/InstancedMesh2.ts

@@ -38,7 +38,7 @@ export class InstancedMesh2<
 > extends Mesh<TGeometry, TMaterial, TEventMap> {
 
   public override type = 'InstancedMesh2';
-  public isInstancedMesh2 = true;
+  public readonly isInstancedMesh2 = true;
   public instances: Entity<TCustomData>[];
   public instanceIndex: GLInstancedBufferAttribute;
   public matricesTexture: DataTexture;
@@ -65,9 +65,9 @@ export class InstancedMesh2<
   public override customDistanceMaterial = new MeshDistanceMaterial();
 
   // HACK TO MAKE IT WORK WITHOUT UPDATE CORE
-  private isInstancedMesh = true; // must be set to use instancing rendering
-  private instanceMatrix = new InstancedBufferAttribute(new Float32Array(0), 16); // must be init to avoid exception
-  private instanceColor = null; // must be null to avoid exception
+  private readonly isInstancedMesh = true; // must be set to use instancing rendering
+  private readonly instanceMatrix = new InstancedBufferAttribute(new Float32Array(0), 16); // must be init to avoid exception
+  private readonly instanceColor = null; // must be null to avoid exception
 
   public get count() { return this._count }
   public get maxCount() { return this._maxCount }
@@ -160,7 +160,7 @@ export class InstancedMesh2<
 
     material.onBeforeCompile = (shader: WebGLProgramParametersWithUniforms, renderer) => {
       if (onBeforeCompile) onBeforeCompile(shader, renderer);
-      
+
       if (!shader.instancing) return;
 
       shader.instancing = false;
@@ -521,7 +521,7 @@ export class InstancedMesh2<
     for (let i = 0; i < instancesCount; i++) {
       if (!this.getVisibilityAt(i)) continue;
 
-      const matrix = this.getMatrixAt(i);
+      const matrix = this.getMatrixAt(i); // we can optimize this a little avoiding copy? what about using instances if available?
       if (geometryCentered) _sphere.center.copy(_position.setFromMatrixPosition(matrix));
       else _sphere.center.copy(center).applyMatrix4(matrix);
       _sphere.radius = radius * matrix.getMaxScaleOnAxis();

src/objects/InstancedMeshBVH.ts

@@ -1,7 +1,8 @@
 import { box3ToArray, BVH, BVHNode, FloatArray, HybridBuilder, onFrustumIntersectionCallback, onFrustumIntersectionLODCallback, onIntersectionCallback, onIntersectionRayCallback, vec3ToArray, WebGLCoordinateSystem } from 'bvh.js';
-import { Box3, Matrix4, Raycaster, Vector3 } from 'three';
+import { Box3, Matrix4, Raycaster, Sphere, Vector3 } from 'three';
 import { InstancedMesh2 } from './InstancedMesh2.js';
 import { InstancedMeshLOD, LODLevel } from './InstancedMeshLOD.js';
+import { getSphereFromMatrix, SphereTarget } from '../utils/matrixUtils.js';
 
 export class InstancedMeshBVH {
     public target: InstancedMesh2 | InstancedMeshLOD;
@@ -15,23 +16,33 @@ export class InstancedMeshBVH {
     protected _boxArray: FloatArray;
     protected _cameraPos: FloatArray;
     protected _levels: FloatArray; // TODO improve this
+    protected _getBoxFromSphere: boolean; // works only if geometry is centered for now
+    protected _geoBoundingSphere: Sphere = null;
+    protected _sphereTarget: SphereTarget = null;
 
-    constructor(target: InstancedMesh2 | InstancedMeshLOD, margin = 0, highPrecision = false) {
+    constructor(target: InstancedMesh2 | InstancedMeshLOD, margin = 0, highPrecision = false, getBoxFromSphere = false) {
         this._margin = margin;
         this.target = target;
 
         const geometry = (target as InstancedMesh2).isInstancedMesh2 ?
             (target as InstancedMesh2).geometry :
             (target as InstancedMeshLOD).levels[(target as InstancedMeshLOD).levels.length - 1].object.geometry; // TODO improve this
-        
-            if (!geometry.boundingBox) geometry.computeBoundingBox();
+
+        if (!geometry.boundingBox) geometry.computeBoundingBox();
         this.geoBoundingBox = geometry.boundingBox;
 
+        if (getBoxFromSphere) {
+            if (!geometry.boundingSphere) geometry.computeBoundingSphere();
+            this._geoBoundingSphere = geometry.boundingSphere;
+            this._sphereTarget = { centerX: 0, centerY: 0, centerZ: 0, maxScale: 0 };
+        }
+
         this._arrayType = highPrecision ? Float64Array : Float32Array;
         this.bvh = new BVH(new HybridBuilder(highPrecision), WebGLCoordinateSystem);
         this._origin = new this._arrayType(3);
         this._dir = new this._arrayType(3);
         this._cameraPos = new this._arrayType(3);
+        this._getBoxFromSphere = getBoxFromSphere;
     }
 
     public create(): void {
@@ -108,7 +119,7 @@ export class InstancedMeshBVH {
         if (this._levels?.length !== levels.length) { // TODO improve
             this._levels = new this._arrayType(levels.length);
         }
-        
+
         const levelsArray = this._levels;
         for (let i = 0; i < levels.length; i++) {
             levelsArray[i] = levels[i].distance;
@@ -153,8 +164,21 @@ export class InstancedMeshBVH {
     }
 
     protected getBox(id: number, array: FloatArray): FloatArray {
-        _box3.copy(this.geoBoundingBox).applyMatrix4(this.target.getMatrixAt(id));
-        box3ToArray(_box3, array);
+        // TODO add check if geometry is centered. adjust ref using this._matrixArray insteaad of this.target._matrixArray
+        if (this._getBoxFromSphere) {
+            const { centerX, centerY, centerZ, maxScale } = getSphereFromMatrix(id, this.target._matrixArray, this._sphereTarget);
+            const radius = this._geoBoundingSphere.radius * maxScale;
+            array[0] = centerX - radius;
+            array[1] = centerX + radius;
+            array[2] = centerY - radius;
+            array[3] = centerY + radius;
+            array[4] = centerZ - radius;
+            array[5] = centerZ + radius;
+        } else {
+            _box3.copy(this.geoBoundingBox).applyMatrix4(this.target.getMatrixAt(id));
+            box3ToArray(_box3, array);
+        }
+
         return array;
     }
 }

src/utils/createTexture.ts

@@ -1,4 +1,4 @@
-import { DataTexture, FloatType, RedFormat, RGBAFormat, RGFormat } from "three";
+import { DataTexture, FloatType, RedFormat, RedIntegerFormat, RGBAFormat, RGFormat, UnsignedIntType } from "three";
 
 export function createTexture_float(count: number): DataTexture {
     const size = Math.ceil(Math.sqrt(count));
@@ -8,6 +8,14 @@ export function createTexture_float(count: number): DataTexture {
     return texture;
 }
 
+export function createTexture_uint(count: number): DataTexture {
+    const size = Math.ceil(Math.sqrt(count));
+    const array = new Uint32Array(size * size);
+    const texture = new DataTexture(array, size, size, RedIntegerFormat, UnsignedIntType);
+    texture.needsUpdate = true;
+    return texture;
+}
+
 export function createTexture_vec2(count: number): DataTexture {
     const size = Math.ceil(Math.sqrt(count));
     const array = new Float32Array(size * size * 2);

src/utils/matrixUtils.ts

@@ -0,0 +1,37 @@
+import { FloatArray } from "bvh.js";
+
+export interface SphereTarget {
+    centerX: number;
+    centerY: number;
+    centerZ: number;
+    maxScale: number;
+}
+
+// this method works if geometry is centered
+export function getSphereFromMatrix(id: number, array: FloatArray, target: SphereTarget): SphereTarget {
+    const offset = id * 16;
+
+    // get max scale from matrix
+    const m0 = array[offset + 0];
+    const m1 = array[offset + 1];
+    const m2 = array[offset + 2];
+    const m4 = array[offset + 4];
+    const m5 = array[offset + 5];
+    const m6 = array[offset + 6];
+    const m8 = array[offset + 8];
+    const m9 = array[offset + 9];
+    const m10 = array[offset + 10];
+
+    const scaleXSq = m0 * m0 + m1 * m1 + m2 * m2;
+    const scaleYSq = m4 * m4 + m5 * m5 + m6 * m6;
+    const scaleZSq = m8 * m8 + m9 * m9 + m10 * m10;
+
+    target.maxScale = Math.sqrt(Math.max(scaleXSq, scaleYSq, scaleZSq));
+
+    // get position from matrix
+    target.centerX = array[offset + 12];
+    target.centerY = array[offset + 13];
+    target.centerZ = array[offset + 14];
+
+    return target;
+}