Function visible

tools/bloom-reference/src/main.rs:1692–1701

Test whether a point can see a given direction without being occluded. Returns true if no triangle blocks the ray from `origin` going toward `direction_to_light` within `max_distance`. The origin should already be offset along the surface normal to avoid self-intersection.

(ray_origin: Vec3, direction_to_light: Vec3, max_distance: f32, scene: &Scene, bvh: &Bvh)

/// The origin should already be offset along the surface normal to
/// avoid self-intersection.
fn visible(ray_origin: Vec3, direction_to_light: Vec3, max_distance: f32, scene: &Scene, bvh: &Bvh) -> bool {
    let ray = Ray::new(ray_origin, direction_to_light);
    // We only need to know if ANY triangle is hit before max_distance;
    // a specialized "any-hit" traversal would be faster than
    // closest-hit, but the closest-hit cost is acceptable for Phase 3.
    match intersect_bvh(&ray, scene, bvh) {
        Some(hit) => hit.t >= max_distance,
        None => true,
    }
}

// ============================================================
// Path tracer