the-world-engine/dist/esm/box2d.ts/build/collision/b2_collide_circle.js

three.js based, unity like game engine for browser

import { b2_maxFloat, b2_epsilon } from "../common/b2_settings.js";

import { b2Vec2, b2Transform } from "../common/b2_math.js";

import { b2ManifoldType } from "./b2_collision.js";

const b2CollideCircles_s_pA = new b2Vec2;

const b2CollideCircles_s_pB = new b2Vec2;

export function b2CollideCircles(e, o, c, n, l) {
    e.pointCount = 0;
    const b = b2Transform.MulXV(c, o.m_p, b2CollideCircles_s_pA);
    const s = b2Transform.MulXV(l, n.m_p, b2CollideCircles_s_pB);
    const i = b2Vec2.DistanceSquaredVV(b, s);
    const t = o.m_radius + n.m_radius;
    if (i > t * t) {
        return;
    }
    e.type = b2ManifoldType.e_circles;
    e.localPoint.Copy(o.m_p);
    e.localNormal.SetZero();
    e.pointCount = 1;
    e.points[0].localPoint.Copy(n.m_p);
    e.points[0].id.key = 0;
}

const b2CollidePolygonAndCircle_s_c = new b2Vec2;

const b2CollidePolygonAndCircle_s_cLocal = new b2Vec2;

const b2CollidePolygonAndCircle_s_faceCenter = new b2Vec2;

export function b2CollidePolygonAndCircle(e, o, c, n, l) {
    e.pointCount = 0;
    const b = b2Transform.MulXV(l, n.m_p, b2CollidePolygonAndCircle_s_c);
    const s = b2Transform.MulTXV(c, b, b2CollidePolygonAndCircle_s_cLocal);
    let i = 0;
    let t = -b2_maxFloat;
    const r = o.m_radius + n.m_radius;
    const V = o.m_count;
    const f = o.m_vertices;
    const _ = o.m_normals;
    for (let e = 0; e < V; ++e) {
        const o = b2Vec2.DotVV(_[e], b2Vec2.SubVV(s, f[e], b2Vec2.s_t0));
        if (o > r) {
            return;
        }
        if (o > t) {
            t = o;
            i = e;
        }
    }
    const C = i;
    const d = (C + 1) % V;
    const a = f[C];
    const m = f[d];
    if (t < b2_epsilon) {
        e.pointCount = 1;
        e.type = b2ManifoldType.e_faceA;
        e.localNormal.Copy(_[i]);
        b2Vec2.MidVV(a, m, e.localPoint);
        e.points[0].localPoint.Copy(n.m_p);
        e.points[0].id.key = 0;
        return;
    }
    const p = b2Vec2.DotVV(b2Vec2.SubVV(s, a, b2Vec2.s_t0), b2Vec2.SubVV(m, a, b2Vec2.s_t1));
    const y = b2Vec2.DotVV(b2Vec2.SubVV(s, m, b2Vec2.s_t0), b2Vec2.SubVV(a, m, b2Vec2.s_t1));
    if (p <= 0) {
        if (b2Vec2.DistanceSquaredVV(s, a) > r * r) {
            return;
        }
        e.pointCount = 1;
        e.type = b2ManifoldType.e_faceA;
        b2Vec2.SubVV(s, a, e.localNormal).SelfNormalize();
        e.localPoint.Copy(a);
        e.points[0].localPoint.Copy(n.m_p);
        e.points[0].id.key = 0;
    } else if (y <= 0) {
        if (b2Vec2.DistanceSquaredVV(s, m) > r * r) {
            return;
        }
        e.pointCount = 1;
        e.type = b2ManifoldType.e_faceA;
        b2Vec2.SubVV(s, m, e.localNormal).SelfNormalize();
        e.localPoint.Copy(m);
        e.points[0].localPoint.Copy(n.m_p);
        e.points[0].id.key = 0;
    } else {
        const o = b2Vec2.MidVV(a, m, b2CollidePolygonAndCircle_s_faceCenter);
        const c = b2Vec2.DotVV(b2Vec2.SubVV(s, o, b2Vec2.s_t1), _[C]);
        if (c > r) {
            return;
        }
        e.pointCount = 1;
        e.type = b2ManifoldType.e_faceA;
        e.localNormal.Copy(_[C]).SelfNormalize();
        e.localPoint.Copy(o);
        e.points[0].localPoint.Copy(n.m_p);
        e.points[0].id.key = 0;
    }
}