pocket-physics
Version:
Verlet physics extracted from pocket-ces demos
45 lines (44 loc) • 1.82 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
exports.projectPointEdge = exports.createPointEdgeProjectionResult = void 0;
const v2_1 = require("./v2");
/**
* Create a pre-made result object for tests.
*/
function createPointEdgeProjectionResult() {
return {
distance: Number.MIN_SAFE_INTEGER,
similarity: 0,
u: Number.MIN_SAFE_INTEGER,
projectedPoint: (0, v2_1.v2)(),
edgeNormal: (0, v2_1.v2)(),
};
}
exports.createPointEdgeProjectionResult = createPointEdgeProjectionResult;
const edgeDelta = (0, v2_1.v2)();
const perp = (0, v2_1.v2)();
function projectPointEdge(point, endpoint1, endpoint2, result) {
(0, v2_1.sub)(edgeDelta, endpoint2, endpoint1);
if (edgeDelta.x === 0 && edgeDelta.y === 0) {
throw new Error("ZeroLengthEdge");
}
// http://paulbourke.net/geometry/pointlineplane/
// http://paulbourke.net/geometry/pointlineplane/DistancePoint.java
const u = ((point.x - endpoint1.x) * edgeDelta.x +
(point.y - endpoint1.y) * edgeDelta.y) /
(edgeDelta.x * edgeDelta.x + edgeDelta.y * edgeDelta.y);
result.u = u;
const proj = (0, v2_1.set)(result.projectedPoint, endpoint1.x + u * edgeDelta.x, endpoint1.y + u * edgeDelta.y);
result.distance = (0, v2_1.distance)(proj, point);
// given:
// E1----------------------E2 Proj
// | |
// | EdgeNorm | perp
// | Point
//
// What is the similarity (dot product) between EdgeNorm and Perp?
const edgeNorm = (0, v2_1.normal)(result.edgeNormal, endpoint1, endpoint2);
(0, v2_1.sub)(perp, point, proj);
result.similarity = (0, v2_1.dot)(edgeNorm, perp);
}
exports.projectPointEdge = projectPointEdge;