planck-js/example/ShapeCast.ts

2D JavaScript/TypeScript physics engine for cross-platform HTML5 game development

/*
 * Copyright (c) Erin Catto
 * Licensed under the MIT license
 */

import {
  Vec2,
  Transform,
  World,
  Settings,
  ShapeCastInput,
  ShapeCastOutput,
  ShapeCast,
  DistanceInput,
  DistanceOutput,
  Distance,
  SimplexCache,
  Testbed,
  Vec2Value,
} from "planck";

const world = new World();

const testbed = Testbed.mount();
testbed.width = 40;
testbed.height = 40;
testbed.start(world);

const vAs = new Array(3).fill(null).map(() => ({ x: 0, y: 0 }));
let countA: number;
let radiusA: number;

const vBs = new Array(Settings.maxPolygonVertices).fill(null).map(() => ({ x: 0, y: 0 }));
let countB: number;
let radiusB: number;

let transformA: Transform;
let transformB: Transform;
let translationB: Vec2Value;

if (true) {
  vAs[0].x = -0.5;
  vAs[0].y = 1.0;
  vAs[1].x = 0.5;
  vAs[1].y = 1.0;
  vAs[2].x = 0.0;
  vAs[2].y = 0.0;
  countA = 3;
  radiusA = Settings.polygonRadius;
  vBs[0].x = -0.5;
  vBs[0].y = -0.5;
  vBs[1].x = 0.5;
  vBs[1].y = -0.5;
  vBs[2].x = 0.5;
  vBs[2].y = 0.5;
  vBs[3].x = -0.5;
  vBs[3].y = 0.5;
  countB = 4;
  radiusB = Settings.polygonRadius;

  transformA = new Transform({ x: 4, y: 0.25 });
  transformB = new Transform({ x: -4, y: 0 });
  translationB = { x: 8.0, y: 0.0 };
} else if (true) {
  vAs[0].x = 0.0;
  vAs[0].y = 0.0;
  countA = 1;
  radiusA = 0.5;

  vBs[0].x = 0.0;
  vBs[0].y = 0.0;
  countB = 1;
  radiusB = 0.5;

  transformA = new Transform({ x: 0, y: 0.25 });
  transformB = new Transform({ x: -4, y: 0 });
  translationB = { x: 8.0, y: 0.0 };
} else {
  vAs[0].x = 0.0;
  vAs[0].y = 0.0;
  vAs[1].x = 2.0;
  vAs[1].y = 0.0;
  countA = 2;
  radiusA = Settings.polygonRadius;

  vBs[0].x = 0.0;
  vBs[0].y = 0.0;
  countB = 1;
  radiusB = 0.25;

  // Initial overlap
  transformA = new Transform({ x: 0, y: 0 });
  transformB = new Transform({ x: -0.244360745, y: 0.05999358 });
  transformB.q.setIdentity();
  translationB = { x: 0.0, y: 0.0399999991 };
}

testbed.step = function () {
  const transformB = Transform.identity();

  const input = new ShapeCastInput();
  input.proxyA.setVertices(vAs, countA, radiusA);
  input.proxyB.setVertices(vBs, countB, radiusB);
  input.transformA.set(transformA);
  input.transformB.set(transformB);
  input.translationB.set(translationB);

  const output = new ShapeCastOutput();

  const hit = ShapeCast(output, input);

  const transformB2 = new Transform(
    Vec2.combine(1, transformB.p, output.lambda, input.translationB),
    transformB.q.getAngle(),
  );

  const distanceInput = new DistanceInput();
  distanceInput.proxyA.setVertices(vAs, countA, radiusA);
  distanceInput.proxyB.setVertices(vBs, countB, radiusB);
  distanceInput.transformA.set(transformA);
  distanceInput.transformB.set(transformB2);
  distanceInput.useRadii = false;
  const simplexCache = new SimplexCache();
  simplexCache.count = 0;
  const distanceOutput = new DistanceOutput();

  Distance(distanceOutput, simplexCache, distanceInput);

  testbed.status({
    hit,
    iters: output.iterations,
    lambda: output.lambda,
    distance: distanceOutput.distance,
  });

  const vertices = new Array(Settings.maxPolygonVertices);

  for (let i = 0; i < countA; ++i) {
    vertices[i] = Transform.mul(transformA, vAs[i]);
  }
  if (countA == 1) {
    testbed.drawCircle(vertices[0], radiusA, testbed.color(0.9, 0.9, 0.9));
  } else {
    testbed.drawPolygon(vertices.slice(0, countA), testbed.color(0.9, 0.9, 0.9));
  }

  for (let i = 0; i < countB; ++i) {
    vertices[i] = Transform.mul(transformB, vBs[i]);
  }
  if (countB == 1) {
    testbed.drawCircle(vertices[0], radiusB, testbed.color(0.5, 0.9, 0.5));
  } else {
    testbed.drawPolygon(vertices.slice(0, countB), testbed.color(0.5, 0.9, 0.5));
  }

  for (let i = 0; i < countB; ++i) {
    vertices[i] = Transform.mul(transformB2, vBs[i]);
  }
  if (countB == 1) {
    testbed.drawCircle(vertices[0], radiusB, testbed.color(0.5, 0.7, 0.9));
  } else {
    testbed.drawPolygon(vertices.slice(0, countB), testbed.color(0.5, 0.7, 0.9));
  }

  if (hit) {
    const p1 = output.point;
    testbed.drawPoint(p1, 10.0, testbed.color(0.9, 0.3, 0.3));
    const p2 = Vec2.add(p1, output.normal);
    testbed.drawSegment(p1, p2, testbed.color(0.9, 0.3, 0.3));
  }
};