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const MASS = 0.1;
class Constraint {
constructor(p1, p2, distance) {
this.p1 = p1;
this.p2 = p2;
this.distance = distance;
}
}
class Particle {
constructor(x, y, z, mass) {
this.position = new THREE.Vector3(x, y, z);
this.previous = new THREE.Vector3(x, y, z);
this.acceleration = new THREE.Vector3(0, 0, 0);
this.mass = mass;
}
addForce(force) {
}
verlet(dt) {
}
}
class Cloth {
constructor(width, height, numPointsWidth, numPointsHeight) {
this.width = width;
this.height = height;
this.numPointsWidth = numPointsWidth;
this.numPointsHeight = numPointsHeight;
/**
* distance between two vertices horizontally/vertically
* divide by the number of points minus one
* because there are (n - 1) lines between n vertices
*/
let stepWidth = width / (numPointsWidth - 1);
let stepHeight = height / (numPointsHeight - 1);
/**
* iterate over the number of vertices in x/y axis
* and add a new Particle to "particles"
*/
this.particles = [];
for (let y = 0; y < numPointsHeight; y++) {
for (let x = 0; x < numPointsWidth; x++) {
this.particles.push(
new Particle(
(x - ((numPointsWidth-1)/2)) * stepWidth,
height - (y + ((numPointsHeight-1)/2)) * stepHeight,
0,
MASS)
);
}
}
const REST_DIST_X = width / (numPointsWidth-1);
const REST_DIST_Y = height / (numPointsHeight-1);
/**
* generate constraints (springs)
*/
this.constraints = [];
for (let y = 0; y < numPointsHeight; y++) {
for (let x = 0; x < numPointsWidth; x++) {
if (x < numPointsWidth-1) {
this.constraints.push(new Constraint(
this.particles[this.getVertexIndex(x, y)],
this.particles[this.getVertexIndex(x+1, y)],
REST_DIST_X
));
}
if (x < numPointsWidth-1) {
this.constraints.push(new Constraint(
this.particles[this.getVertexIndex(x, y)],
this.particles[this.getVertexIndex(x, y+1)],
REST_DIST_Y
));
}
}
}
}
generateGeometry() {
const geometry = new THREE.BufferGeometry();
const vertices = [];
const normals = [];
const indices = [];
for (let particle of this.particles) {
vertices.push(
particle.position.x,
particle.position.y,
particle.position.z);
}
const numPointsWidth = this.numPointsWidth;
const numPointsHeight = this.numPointsHeight;
/**
* generate faces based on 4 vertices
* and 6 springs each
*/
for (let y = 0; y < numPointsHeight - 1; y++) {
for (let x = 0; x < numPointsWidth - 1; x++) {
indices.push(
this.getVertexIndex(x, y),
this.getVertexIndex(x+1, y),
this.getVertexIndex(x+1, y+1)
);
indices.push(
this.getVertexIndex(x, y),
this.getVertexIndex(x+1, y+1),
this.getVertexIndex(x, y+1)
);
}
}
geometry.setIndex(indices);
geometry.setAttribute('position', new THREE.Float32BufferAttribute(vertices, 3));
//geometry.setAttribute('normal', new THREE.Float32BufferAttribute(normals, 3));
geometry.computeBoundingSphere();
geometry.computeVertexNormals();
return geometry;
}
updateGeometry(geometry) {
}
satisfyConstraints() {
}
simulate() {
}
/**
* helper function to calculate index of vertex
* in "vertices" array based on its x and y positions
* in the mesh
* @param {number} x - x index of vertex
* @param {number} y - y index of vertex
*/
getVertexIndex(x, y) {
return y * this.numPointsWidth + x;
}
}
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