@polygonjs/polygonjs
Version:
node-based WebGL 3D engine https://polygonjs.com
113 lines (112 loc) • 4.38 kB
JavaScript
"use strict";
import { Triangle } from "three";
const _face = new Triangle();
export class MeshSurfaceSampler {
constructor(mesh, additionalAttributeNames) {
this.additionalAttributeNames = additionalAttributeNames;
this.randomFunction = Math.random;
this.additionalAttributes = /* @__PURE__ */ new Map();
this.weightAttribute = null;
this.distribution = null;
let geometry = mesh.geometry;
if (!geometry.isBufferGeometry || geometry.attributes.position.itemSize !== 3) {
throw new Error("THREE.MeshSurfaceSampler: Requires BufferGeometry triangle mesh.");
}
if (geometry.index) {
console.warn("THREE.MeshSurfaceSampler: Converting geometry to non-indexed BufferGeometry.");
geometry = geometry.toNonIndexed();
}
this.geometry = geometry;
this.positionAttribute = this.geometry.getAttribute("position");
for (let attribName of additionalAttributeNames) {
const attribute = this.geometry.getAttribute(attribName);
if (attribute) {
this.additionalAttributes.set(attribName, attribute);
}
}
}
setWeightAttribute(name) {
this.weightAttribute = name ? this.geometry.getAttribute(name) : null;
return this;
}
build() {
const positionAttribute = this.positionAttribute;
const weightAttribute = this.weightAttribute;
const faceWeights = new Float32Array(positionAttribute.count / 3);
for (let i = 0; i < positionAttribute.count; i += 3) {
let faceWeight = 1;
if (weightAttribute) {
faceWeight = weightAttribute.getX(i) + weightAttribute.getX(i + 1) + weightAttribute.getX(i + 2);
}
_face.a.fromBufferAttribute(positionAttribute, i);
_face.b.fromBufferAttribute(positionAttribute, i + 1);
_face.c.fromBufferAttribute(positionAttribute, i + 2);
faceWeight *= _face.getArea();
faceWeights[i / 3] = faceWeight;
}
this.distribution = new Float32Array(positionAttribute.count / 3);
let cumulativeTotal = 0;
for (let i = 0; i < faceWeights.length; i++) {
cumulativeTotal += faceWeights[i];
this.distribution[i] = cumulativeTotal;
}
return this;
}
setRandomGenerator(randomFunction) {
this.randomFunction = randomFunction;
return this;
}
sample(index, targetPosition, targetNormal, targetAdditionalVectors) {
const cumulativeTotal = this.distribution[this.distribution.length - 1];
const faceIndex = this.binarySearch(this.randomFunction(index) * cumulativeTotal);
return this.sampleFace(index, faceIndex, targetPosition, targetNormal, targetAdditionalVectors);
}
binarySearch(x) {
const dist = this.distribution;
let start = 0;
let end = dist.length - 1;
let index = -1;
while (start <= end) {
const mid = Math.ceil((start + end) / 2);
if (mid === 0 || dist[mid - 1] <= x && dist[mid] > x) {
index = mid;
break;
} else if (x < dist[mid]) {
end = mid - 1;
} else {
start = mid + 1;
}
}
return index;
}
sampleFace(i, faceIndex, targetPosition, targetNormal, targetAdditionalVectors) {
let u = this.randomFunction(i * (faceIndex + 1456));
let v = this.randomFunction((i + 9851) * (faceIndex + 7646));
if (u + v > 1) {
u = 1 - u;
v = 1 - v;
}
_face.a.fromBufferAttribute(this.positionAttribute, faceIndex * 3);
_face.b.fromBufferAttribute(this.positionAttribute, faceIndex * 3 + 1);
_face.c.fromBufferAttribute(this.positionAttribute, faceIndex * 3 + 2);
targetPosition.set(0, 0, 0).addScaledVector(_face.a, u).addScaledVector(_face.b, v).addScaledVector(_face.c, 1 - (u + v));
if (targetNormal !== void 0) {
_face.getNormal(targetNormal);
}
if (targetAdditionalVectors) {
let i2 = 0;
for (let attribName of this.additionalAttributeNames) {
const attrib = this.additionalAttributes.get(attribName);
if (attrib) {
_face.a.fromBufferAttribute(attrib, faceIndex * 3);
_face.b.fromBufferAttribute(attrib, faceIndex * 3 + 1);
_face.c.fromBufferAttribute(attrib, faceIndex * 3 + 2);
const targetVector = targetAdditionalVectors[i2];
targetVector.set(0, 0, 0).addScaledVector(_face.a, u).addScaledVector(_face.b, v).addScaledVector(_face.c, 1 - (u + v));
}
i2++;
}
}
return this;
}
}