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@ -1,3 +1,5 @@
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use bevy::{math::Vec3A, render::primitives::Aabb};
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use crate::prelude::*;
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/// Hit data for 3d objects in Global (not Local) space and the distance from the Camera
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@ -49,64 +51,112 @@ impl Triangle {
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}
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}
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pub(crate) fn intersects_aabb_3d(ray: &Ray3d, aabb: &Aabb, gt: &GlobalTransform) -> Option<Hit3d> {
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let world_to_model = gt.compute_matrix().inverse();
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let ray_dir: Vec3A = world_to_model.transform_vector3(*ray.direction).into();
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let ray_origin: Vec3A = world_to_model.transform_point3(ray.origin).into();
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let t0 = (aabb.min() - ray_origin) / ray_dir;
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let t1 = (aabb.max() - ray_origin) / ray_dir;
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let t_min = t0.min(t1);
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let t_max = t0.max(t1);
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let mut hit_near = t_min.x;
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let mut hit_far = t_max.x;
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if hit_near > t_max.y || t_min.y > hit_far {
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return None;
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}
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if t_min.y > hit_near {
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hit_near = t_min.y;
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}
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if t_max.y < hit_far {
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hit_far = t_max.y;
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}
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if (hit_near > t_max.z) || (t_min.z > hit_far) {
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return None;
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}
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if t_min.z > hit_near {
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hit_near = t_min.z;
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}
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if t_max.z < hit_far {
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hit_far = t_max.z;
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}
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Some(Hit3d { distance: (hit_near + hit_far) / 2.0 })
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}
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/// Heavily synthesized from these two resources:
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/// * Textbook: https://www.scratchapixel.com/lessons/3d-basic-rendering/ray-tracing-rendering-a-triangle/ray-triangle-intersection-geometric-solution.html
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/// * Example: https://github.com/aevyrie/bevy_mod_raycast/blob/435d8ef100738797161ac3a9b910ea346a4ed6e6/src/raycast.rs#L43
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pub(crate) fn intersects3d(ray: &Ray3d, mesh: &Mesh, gt: &GlobalTransform) -> Option<Hit3d> {
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let attr = MeshVertexAttribute::new("Vertex_Position", 0, VertexFormat::Float32x3);
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if let Some(verts) = mesh.attribute(attr) {
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if let Some(idxs) = mesh.indices() {
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match verts {
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VertexAttributeValues::Float32x3(vals) => {
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idxs.iter()
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.array_chunks::<3>()
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// Convert arrays to vec3
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.map(|[x, y, z]| {
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[
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Vec3::from_array(vals[x]),
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Vec3::from_array(vals[y]),
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Vec3::from_array(vals[z]),
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]
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})
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// Transform each point by the global transform
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.map(|[a, b, c]| {
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[
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gt.transform_point(a),
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gt.transform_point(b),
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gt.transform_point(c),
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]
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})
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// Collect everything into a triangle for easy operations
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.map(|[v0, v1, v2]| Triangle { v0, v1, v2 })
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.filter_map(|triangle| {
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// Calculate the distance this ray hits the plane normal to the tri
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if let Some(d) =
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ray.intersect_plane(triangle.v0, triangle.normal_plane())
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{
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// Calculate the point on that plane which intersects
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let p = ray.get_point(d);
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// Inside out test
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let hit = {
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// Determine if p is w/in edge0
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let c0 = triangle.edge0().cross(p - triangle.v0);
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// Determine if p is w/in edge1
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let c1 = triangle.edge1().cross(p - triangle.v1);
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// Determine if p is w/in edge2
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let c2 = triangle.edge2().cross(p - triangle.v2);
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// Check all three at once
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triangle.normal().dot(c0) > 0.0
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&& triangle.normal().dot(c1) > 0.0
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&& triangle.normal().dot(c2) > 0.0
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};
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hit.then_some(Hit3d { distance: d })
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} else {
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None
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}
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})
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.min_by(|a, b| a.distance.total_cmp(&b.distance))
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// First do an Aabb intersection test
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if let Some(aabb) = mesh.compute_aabb() {
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// Do the Aabb test
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if let Some(_) = intersects_aabb_3d(ray, &aabb, gt) {
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// If it passes that do the real intersection test
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let attr = MeshVertexAttribute::new("Vertex_Position", 0, VertexFormat::Float32x3);
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if let Some(verts) = mesh.attribute(attr) {
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if let Some(idxs) = mesh.indices() {
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match verts {
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VertexAttributeValues::Float32x3(vals) => {
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idxs.iter()
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.array_chunks::<3>()
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// Convert arrays to vec3
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.map(|[x, y, z]| {
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[
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Vec3::from_array(vals[x]),
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Vec3::from_array(vals[y]),
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Vec3::from_array(vals[z]),
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]
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})
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// Transform each point by the global transform
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.map(|[a, b, c]| {
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[
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gt.transform_point(a),
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gt.transform_point(b),
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gt.transform_point(c),
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]
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})
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// Collect everything into a triangle for easy operations
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.map(|[v0, v1, v2]| Triangle { v0, v1, v2 })
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.filter_map(|triangle| {
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// Calculate the distance this ray hits the plane normal to the tri
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if let Some(d) =
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ray.intersect_plane(triangle.v0, triangle.normal_plane())
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{
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// Calculate the point on that plane which intersects
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let p = ray.get_point(d);
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// Inside out test
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let hit = {
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// Determine if p is w/in edge0
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let c0 = triangle.edge0().cross(p - triangle.v0);
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// Determine if p is w/in edge1
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let c1 = triangle.edge1().cross(p - triangle.v1);
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// Determine if p is w/in edge2
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let c2 = triangle.edge2().cross(p - triangle.v2);
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// Check all three at once
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triangle.normal().dot(c0) > 0.0
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&& triangle.normal().dot(c1) > 0.0
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&& triangle.normal().dot(c2) > 0.0
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};
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hit.then_some(Hit3d { distance: d })
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} else {
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None
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}
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})
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.min_by(|a, b| a.distance.total_cmp(&b.distance))
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}
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_ => None,
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}
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} else {
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None
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}
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_ => None,
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} else {
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None
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}
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} else {
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None
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Elijah C. Voigt
1 year ago