frustumCullTest method

CullResult frustumCullTest(Frustum frustum)

Test this AABB against a frustum and return a CullResult.

• CullResult.outside: the AABB is fully outside at least one plane.
• CullResult.inside: the AABB is fully inside all planes.
• CullResult.intersecting: the AABB straddles at least one plane.

Implementation

CullResult frustumCullTest(Frustum frustum) {
  var allInside = true;

  for (final plane in [
    frustum.plane0,
    frustum.plane1,
    frustum.plane2,
    frustum.plane3,
    frustum.plane4,
    frustum.plane5,
  ]) {
    final normal = plane.normal;
    final constant = plane.constant;

    // Positive vertex: the AABB corner farthest along the plane normal.
    final px = normal.x >= 0.0 ? max.x : min.x;
    final py = normal.y >= 0.0 ? max.y : min.y;
    final pz = normal.z >= 0.0 ? max.z : min.z;

    // Negative vertex: the AABB corner nearest along the plane normal.
    final nx = normal.x >= 0.0 ? min.x : max.x;
    final ny = normal.y >= 0.0 ? min.y : max.y;
    final nz = normal.z >= 0.0 ? min.z : max.z;

    final d1 = normal.x * px + normal.y * py + normal.z * pz + constant;
    final d2 = normal.x * nx + normal.y * ny + normal.z * nz + constant;

    // If positive vertex is outside, entire AABB is outside this plane.
    if (d1 < 0) {
      return CullResult.outside;
    }

    // If negative vertex is outside, AABB straddles this plane.
    if (d2 < 0) {
      allInside = false;
    }
  }

  return allInside ? CullResult.inside : CullResult.intersecting;
}