98 lines
2.4 KiB
JavaScript
98 lines
2.4 KiB
JavaScript
let vec = p5.Vector
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class IKJoint {
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constructor(numSegments, pointDist) {
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this.origin = new vec(0, 0);
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this.points = [];
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for (let i = 0; i < numSegments + 1; i++) {
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this.points.push(new ConstraintPoint(0, 0, pointDist, 1.3));
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}
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this.pointDist = pointDist;
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this.iterations = 20;
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}
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moveStart(targetX, targetY) {
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let numPts = this.points.length;
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this.points[0].size = 1;
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this.points[0].follow(targetX, targetY);
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for (let i = 1; i < numPts; i++) {
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let prevPoint = this.points[i - 1];
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this.points[i].follow(prevPoint.pos.x, prevPoint.pos.y, prevPoint.forward);
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}
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}
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moveEnd(targetX, targetY) {
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let numPts = this.points.length;
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this.points[numPts - 1].pos.x = targetX;
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this.points[numPts - 1].pos.y = targetY;
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for (let i = numPts - 2; i >= 0; i--) {
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let prevPoint = this.points[i + 1];
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this.points[i].follow(prevPoint.pos.x, prevPoint.pos.y, null);
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}
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}
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moveTo(origX, origY, targetX, targetY) {
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for (let i = 0; i < this.iterations; i++) {
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this.moveEnd(targetX, targetY);
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this.moveStart(origX, origY);
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}
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}
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}
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class ConstraintPoint {
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constructor(x, y, size, angleConstraint = 0.2) {
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this.size = size;
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this.pos = new vec(x, y);
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this.forward = new vec(0, 0);
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this.angleConstraint = angleConstraint;
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}
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getRel(angleOffset, dist) {
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let dir = vec.rotate(this.forward, angleOffset);
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dir.setMag(dist);
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return vec.add(this.pos, dir);
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}
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follow(targetX, targetY, parentForward = null) {
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let target = new vec(targetX, targetY);
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let targetForward = vec.sub(target, this.pos);
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let targetAngle = targetForward.heading();
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if (parentForward) {
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let parentAngle = parentForward.heading();
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let diff = targetAngle - parentAngle;
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while (diff < -PI) diff += TWO_PI;
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while (diff > PI) diff -= TWO_PI;
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let maxAngle = this.angleConstraint;
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diff = constrain(diff, -maxAngle, maxAngle);
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targetAngle = parentAngle + diff;
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}
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this.forward = p5.Vector.fromAngle(targetAngle);
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let dir = p5.Vector.mult(this.forward, -this.size);
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this.pos = vec.add(target, dir);
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}
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}
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let ik = new IKJoint(8, 20);
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function setup() {
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createCanvas(400, 400);
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}
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function draw() {
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background(220);
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ik.moveTo(200, 200, mouseX, mouseY);
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for (let i = 0;i < 8;i++) {
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let p = ik.points[i].pos
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noFill();
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circle(p.x, p.y, 20);
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}
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}
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