squared distance in comments

Summary: Comments were describing squared distance as absolute distance in a few places.

Reviewed By: nikhilaravi

Differential Revision: D20426020

fbshipit-source-id: 009946867c4a98f61f5ce7158542d41e22bf8346

pytorch3d/csrc/rasterize_meshes/geometry_utils.cuh

@@ -218,14 +218,15 @@ BarycentricPerspectiveCorrectionBackward(
   return thrust::make_tuple(grad_bary, grad_z0, grad_z1, grad_z2);
 }
 
-// Return minimum distance between line segment (v1 - v0) and point p.
+// Calculate minimum squared distance between a line segment (v1 - v0) and a
+// point p.
 //
 // Args:
 //     p: Coordinates of a point.
 //     v0, v1: Coordinates of the end points of the line segment.
 //
 // Returns:
-//     non-square distance to the boundary of the triangle.
+//     squared distance to the boundary of the triangle.
 //
 __device__ inline float
 PointLineDistanceForward(const float2& p, const float2& a, const float2& b) {
@@ -284,7 +285,7 @@ PointLineDistanceBackward(
 //     v0, v1, v2: Coordinates of the three triangle vertices.
 //
 // Returns:
-//     shortest absolute distance from a point to a triangle.
+//     shortest squared distance from a point to a triangle.
 //
 __device__ inline float PointTriangleDistanceForward(
     const float2& p,

pytorch3d/csrc/rasterize_meshes/geometry_utils.h

@@ -241,14 +241,15 @@ inline std::tuple<vec3<T>, T, T, T> BarycentricPerspectiveCorrectionBackward(
   return std::make_tuple(grad_bary, grad_z0, grad_z1, grad_z2);
 }
 
-// Calculate minimum distance between a line segment (v1 - v0) and point p.
+// Calculate minimum squared distance between a line segment (v1 - v0) and a
+// point p.
 //
 // Args:
 //     p: Coordinates of a point.
 //     v0, v1: Coordinates of the end points of the line segment.
 //
 // Returns:
-//     non-square distance of the point to the line.
+//     squared distance of the point to the line.
 //
 // Consider the line extending the segment - this can be parameterized as:
 // v0 + t (v1 - v0).
@@ -322,7 +323,7 @@ inline std::tuple<vec2<T>, vec2<T>, vec2<T>> PointLineDistanceBackward(
 //     v0, v1, v2: Coordinates of the three triangle vertices.
 //
 // Returns:
-//     shortest absolute distance from a point to a triangle.
+//     shortest squared distance from a point to a triangle.
 //
 //
 template <typename T>

pytorch3d/csrc/rasterize_meshes/rasterize_meshes_cpu.cpp

@@ -214,14 +214,15 @@ RasterizeMeshesNaiveCpu(
             continue; // Point is behind the image plane so ignore.
           }
 
-          // Compute absolute distance of the point to the triangle.
+          // Compute squared distance of the point to the triangle.
-          // If the point is inside the triangle then the distance
-          // is negative.
           const float dist = PointTriangleDistanceForward(pxy, v0, v1, v2);
 
           // Use the bary coordinates to determine if the point is
           // inside the face.
           const bool inside = bary.x > 0.0f && bary.y > 0.0f && bary.z > 0.0f;
+
+          // If the point is inside the triangle then signed_dist
+          // is negative.
           const float signed_dist = inside ? -dist : dist;
 
           // Check if pixel is outside blur region