Function rayIntersectsTriangle

src/math/index.ts:400–426

(
  ray: Ray, v0: Vec3, v1: Vec3, v2: Vec3,
)

// Ray-triangle intersection (Moller-Trumbore algorithm)

export function rayIntersectsTriangle(
  ray: Ray, v0: Vec3, v1: Vec3, v2: Vec3,
): RayHit {
  const EPSILON = 1e-8;
  const edge1: Vec3 = { x: v1.x - v0.x, y: v1.y - v0.y, z: v1.z - v0.z };
  const edge2: Vec3 = { x: v2.x - v0.x, y: v2.y - v0.y, z: v2.z - v0.z };
  const h = vec3Cross(ray.direction, edge2);
  const a = vec3Dot(edge1, h);
  const noHit: RayHit = { hit: false, distance: 0, point: { x: 0, y: 0, z: 0 }, normal: { x: 0, y: 0, z: 0 } };
  if (a > -EPSILON && a < EPSILON) return noHit;
  const f = 1.0 / a;
  const s: Vec3 = { x: ray.position.x - v0.x, y: ray.position.y - v0.y, z: ray.position.z - v0.z };
  const u = f * vec3Dot(s, h);
  if (u < 0.0 || u > 1.0) return noHit;
  const q = vec3Cross(s, edge1);
  const v = f * vec3Dot(ray.direction, q);
  if (v < 0.0 || u + v > 1.0) return noHit;
  const t = f * vec3Dot(edge2, q);
  if (t <= EPSILON) return noHit;
  const point: Vec3 = {
    x: ray.position.x + ray.direction.x * t,
    y: ray.position.y + ray.direction.y * t,
    z: ray.position.z + ray.direction.z * t,
  };
  const normal = vec3Normalize(vec3Cross(edge1, edge2));
  return { hit: true, distance: t, point, normal };
}

export function getRayCollisionBox(ray: Ray, box_: BoundingBox): RayHit {
  const noHit: RayHit = { hit: false, distance: 0, point: { x: 0, y: 0, z: 0 }, normal: { x: 0, y: 0, z: 0 } };