Revert "chore: clean up aabb"

This reverts commit d246e6e.
Walther · Nov 2, 2023 · c7b300a · c7b300a
1 parent d246e6e
commit c7b300a
Showing 1 changed file with 49 additions and 6 deletions.
diff --git a/clovers/src/aabb.rs b/clovers/src/aabb.rs
@@ -43,13 +43,56 @@ impl AABB {
     #[must_use]
     pub fn hit(&self, ray: &Ray, mut tmin: Float, mut tmax: Float) -> bool {
         // TODO: Create an improved hit method with more robust handling of zeroes. See https://github.com/RayTracing/raytracing.github.io/issues/927
+        // Both methods below are susceptible for NaNs and infinities, and have subtly different edge cases.
+
+        // "New method"
+        // for axis in 0..3 {
+        //     let a = (self.axis(axis).min - ray.origin[axis]) / ray.direction[axis];
+        //     let b = (self.axis(axis).max - ray.origin[axis]) / ray.direction[axis];
+        //     let t0: Float = a.min(b);
+        //     let t1: Float = a.max(b);
+        //     tmin = t0.max(tmin);
+        //     tmax = t1.min(tmax);
+        //     if tmax <= tmin {
+        //         return false;
+        //     }
+        // }
+
+        // "Old method"
+        // for axis in 0..3 {
+        //     let invd = 1.0 / ray.direction[axis];
+        //     let mut t0: Float = (self.axis(axis).min - ray.origin[axis]) * invd;
+        //     let mut t1: Float = (self.axis(axis).max - ray.origin[axis]) * invd;
+        //     if invd < 0.0 {
+        //         core::mem::swap(&mut t0, &mut t1);
+        //     }
+        //     tmin = if t0 > tmin { t0 } else { tmin };
+        //     tmax = if t1 < tmax { t1 } else { tmax };
+        //     if tmax <= tmin {
+        //         return false;
+        //     }
+        // }
+
+        // "My adjusted method" - possibly more zero-resistant?
+        // TODO: validate
         for axis in 0..3 {
-            let a = (self.axis(axis).min - ray.origin[axis]) / ray.direction[axis];
-            let b = (self.axis(axis).max - ray.origin[axis]) / ray.direction[axis];
-            let t0: Float = a.min(b);
-            let t1: Float = a.max(b);
-            tmin = t0.max(tmin);
-            tmax = t1.min(tmax);
+            // If ray direction component is 0, invd becomes infinity.
+            // Ignore? False positive hit for aabb is probably better than false negative; the actual object can still be hit more accurately
+            let invd = 1.0 / ray.direction[axis];
+            if !invd.is_normal() {
+                continue;
+            }
+            // If the value in parenthesis ends up as zero, 0*inf can be NaN
+            let mut t0: Float = (self.axis(axis).min - ray.origin[axis]) * invd;
+            let mut t1: Float = (self.axis(axis).max - ray.origin[axis]) * invd;
+            if !t0.is_normal() || !t1.is_normal() {
+                continue;
+            }
+            if invd < 0.0 {
+                core::mem::swap(&mut t0, &mut t1);
+            }
+            tmin = if t0 > tmin { t0 } else { tmin };
+            tmax = if t1 < tmax { t1 } else { tmax };
             if tmax <= tmin {
                 return false;
             }