From 468cba97b31c042800a96d8f3749df2147cc729b Mon Sep 17 00:00:00 2001
From: Bill Thiede <git@xinu.tv>
Date: Wed, 18 Jan 2023 20:17:05 -0800
Subject: [PATCH] rtiow: remove unused ray/triangle intersection
 implementations.

---
 rtiow/renderer/src/triangles.rs | 87 +--------------------------------
 1 file changed, 2 insertions(+), 85 deletions(-)

diff --git a/rtiow/renderer/src/triangles.rs b/rtiow/renderer/src/triangles.rs
index 7a5d528..1fef141 100644
--- a/rtiow/renderer/src/triangles.rs
+++ b/rtiow/renderer/src/triangles.rs
@@ -71,7 +71,7 @@ where
 }
 
 /// Based on https://www.scratchapixel.com/lessons/3d-basic-rendering/ray-tracing-rendering-a-triangle/moller-trumbore-ray-triangle-intersection.html
-fn ray_triangle_intersect_moller_trumbore1(r: Ray, tri: &Triangle) -> Option<RayTriangleResult> {
+fn ray_triangle_intersect_moller_trumbore(r: Ray, tri: &Triangle) -> Option<RayTriangleResult> {
     // #ifdef MOLLER_TRUMBORE
     //     Vec3f v0v1 = v1 - v0;
     //     Vec3f v0v2 = v2 - v0;
@@ -133,88 +133,6 @@ fn ray_triangle_intersect_moller_trumbore1(r: Ray, tri: &Triangle) -> Option<Ray
     None
 }
 
-// From https://en.wikipedia.org/wiki/M%C3%B6ller%E2%80%93Trumbore_intersection_algorithm
-fn ray_triangle_intersect_moller_trumbore2(r: Ray, tri: &Triangle) -> Option<RayTriangleResult> {
-    let v0 = tri.verts[0];
-    let v1 = tri.verts[1];
-    let v2 = tri.verts[2];
-
-    let edge1 = v1 - v0;
-    let edge2 = v2 - v0;
-    let h = cross(r.direction, edge2);
-    let a = dot(edge1, h);
-    if a < EPSILON {
-        return None;
-    }
-
-    let f = 1. / a;
-    let s = r.origin - v0;
-    let u = f * dot(s, h);
-    if u < 0. || u > 1. {
-        return None;
-    }
-    let q = cross(s, edge1);
-    let v = f * dot(r.direction, q);
-    if v < 0. || u + v > 1. {
-        return None;
-    }
-    // At this stage we can compute t to find out where the intersection point is on the line.
-    let t = f * dot(edge2, q);
-    // ray intersection
-    if t > EPSILON {
-        return Some(RayTriangleResult {
-            t,
-            p: r.origin + r.direction * t,
-        });
-    }
-    // This means that there is a line intersection but not a ray intersection.
-    None
-}
-/// Based on https://www.scratchapixel.com/lessons/3d-basic-rendering/ray-tracing-rendering-a-triangle/ray-triangle-intersection-geometric-solution.html
-fn ray_triangle_intersect_geometric(r: Ray, tri: &Triangle) -> Option<RayTriangleResult> {
-    let n = tri.normal;
-
-    // close enough to parallel, won't hit
-    let n_dot_dir = dot(n, r.direction);
-    if n_dot_dir < EPSILON {
-        return None;
-    }
-
-    let v0 = tri.verts[0];
-    let v1 = tri.verts[1];
-    let v2 = tri.verts[2];
-    let d = -dot(n, v0);
-    let t = -(dot(n, r.origin) + d) / n_dot_dir;
-    // check if the triangle is behind the ray
-    if t < 0. {
-        return None;
-    }
-
-    let p = r.origin + t * r.direction;
-
-    let edge0 = v1 - v0;
-    let edge1 = v2 - v1;
-    let edge2 = v0 - v2;
-    let vp0 = p - v0;
-    let c = cross(edge0, vp0);
-    if dot(n, c) < 0. {
-        return None;
-    }
-
-    let vp1 = p - v1;
-    let c = cross(edge1, vp1);
-    if dot(n, c) < 0. {
-        return None;
-    }
-
-    let vp2 = p - v2;
-    let c = cross(edge2, vp2);
-    if dot(n, c) < 0. {
-        return None;
-    }
-    Some(RayTriangleResult { t, p })
-}
-
 impl<M> Hit for Triangles<M>
 where
     M: Material,
@@ -222,8 +140,7 @@ where
     fn hit(&self, r: Ray, _t_min: f32, _t_max: f32) -> Option<HitRecord> {
         // TODO(wathiede): add an acceleration structure to more cheaply skip some triangles.
         for tri in &self.triangles {
-            if let Some(RayTriangleResult { t, p }) =
-                ray_triangle_intersect_moller_trumbore1(r, tri)
+            if let Some(RayTriangleResult { t, p }) = ray_triangle_intersect_moller_trumbore(r, tri)
             {
                 //if let Some(RayTriangleResult { t, p }) = ray_triangle_intersect_geometric(r, tri) {
                 // We don't support UV (yet?).