Add structured bindings to iou to prove that we're C++17-friendly. Also other minor improvements to bbox iou

Summary: Recently we removed C++14-only compilation, should work.

Reviewed By: bottler

Differential Revision: D38919607

fbshipit-source-id: 6a26fa7713f7ba2163364ccc673ad774aa3a5adb

Author: Krzysztof Chalupka

pytorch3d/csrc/iou_box3d/iou_box3d.cu

@@ -29,14 +29,17 @@ __global__ void IoUBox3DKernel(
   const size_t tid = blockIdx.x * blockDim.x + threadIdx.x;
   const size_t stride = gridDim.x * blockDim.x;
 
+  std::array<FaceVerts, NUM_TRIS> box1_tris{};
+  std::array<FaceVerts, NUM_TRIS> box2_tris{};
+  std::array<FaceVerts, NUM_PLANES> box1_planes{};
+  std::array<FaceVerts, NUM_PLANES> box2_planes{};
+
   for (size_t i = tid; i < N * M; i += stride) {
     const size_t n = i / M; // box1 index
     const size_t m = i % M; // box2 index
 
     // Convert to array of structs of face vertices i.e. effectively (F, 3, 3)
     // FaceVerts is a data type defined in iou_utils.cuh
-    FaceVerts box1_tris[NUM_TRIS];
-    FaceVerts box2_tris[NUM_TRIS];
     GetBoxTris(boxes1[n], box1_tris);
     GetBoxTris(boxes2[m], box2_tris);
 
@@ -46,9 +49,7 @@ __global__ void IoUBox3DKernel(
     const float3 box2_center = BoxCenter(boxes2[m]);
 
     // Convert to an array of face vertices
-    FaceVerts box1_planes[NUM_PLANES];
     GetBoxPlanes(boxes1[n], box1_planes);
-    FaceVerts box2_planes[NUM_PLANES];
     GetBoxPlanes(boxes2[m], box2_planes);
 
     // Get Box Volumes

pytorch3d/csrc/iou_box3d/iou_utils.cuh

@@ -39,25 +39,25 @@ const int MAX_TRIS = 100;
 // We will use struct arrays for representing
 // the data for each box and intersecting
 // triangles
-typedef struct {
+struct FaceVerts {
   float3 v0;
   float3 v1;
   float3 v2;
   float3 v3; // Can be empty for triangles
-} FaceVerts;
+};
 
-typedef struct {
+struct FaceVertsIdx {
   int v0;
   int v1;
   int v2;
   int v3; // Can be empty for triangles
-} FaceVertsIdx;
+};
 
 // This is used when deciding which faces to
 // keep that are not coplanar
-typedef struct {
+struct Keep {
   bool keep;
-} Keep;
+};
 
 __device__ FaceVertsIdx _PLANES[] = {
     {0, 1, 2, 3},
@@ -128,64 +128,64 @@ __device__ inline void GetBoxPlanes(
   }
 }
 
-// The normal of a plane spanned by vectors e0 and e1
+// The geometric center of a list of vertices.
 //
 // Args
-//    e0, e1: float3 vectors defining a plane
+//    vertices: A list of float3 vertices {v0, ..., vN}.
 //
 // Returns
-//    float3: normal of the plane
+//    float3: Geometric center of the vertices.
 //
-__device__ inline float3 GetNormal(const float3 e0, const float3 e1) {
-  float3 n = cross(e0, e1);
-  n = n / std::fmaxf(norm(n), kEpsilon);
-  return n;
+__device__ inline float3 FaceCenter(
+    std::initializer_list<const float3> vertices) {
+  auto sumVertices = float3{};
+  for (const auto& vertex : vertices) {
+    sumVertices = sumVertices + vertex;
+  }
+  return sumVertices / vertices.size();
 }
 
-// The center of a triangle defined by vertices (v0, v1, v2)
+// The normal of a plane spanned by vectors e0 and e1
 //
 // Args
-//    v0, v1, v2: float3 coordinates of the vertices of the triangle
+//    e0, e1: float3 vectors defining a plane
 //
 // Returns
-//    float3: center of the triangle
+//    float3: normal of the plane
 //
-__device__ inline float3
-TriCenter(const float3 v0, const float3 v1, const float3 v2) {
-  float3 ctr = (v0 + v1 + v2) / 3.0f;
-  return ctr;
+__device__ inline float3 GetNormal(const float3 e0, const float3 e1) {
+  float3 n = cross(e0, e1);
+  n = n / std::fmaxf(norm(n), kEpsilon);
+  return n;
 }
 
-// The normal of the triangle defined by vertices (v0, v1, v2)
+// The normal of a face with vertices (v0, v1, v2) or (v0, ..., v3).
 // We find the "best" edges connecting the face center to the vertices,
 // such that the cross product between the edges is maximized.
 //
 // Args
-//    v0, v1, v2: float3 coordinates of the vertices of the face
+//    vertices: a list of float3 coordinates of the vertices.
 //
 // Returns
-//    float3: normal for the face
+//    float3: center of the plane
 //
-__device__ inline float3
-TriNormal(const float3 v0, const float3 v1, const float3 v2) {
-  const float3 ctr = TriCenter(v0, v1, v2);
-
-  const float d01 = norm(cross(v0 - ctr, v1 - ctr));
-  const float d02 = norm(cross(v0 - ctr, v2 - ctr));
-  const float d12 = norm(cross(v1 - ctr, v2 - ctr));
-
-  float3 n = GetNormal(v0 - ctr, v1 - ctr);
-  float max_dist = d01;
-
-  if (d02 > max_dist) {
-    max_dist = d02;
-    n = GetNormal(v0 - ctr, v2 - ctr);
-  }
-  if (d12 > max_dist) {
-    n = GetNormal(v1 - ctr, v2 - ctr);
+__device__ inline float3 FaceNormal(
+    std::initializer_list<const float3> vertices) {
+  const auto faceCenter = FaceCenter(vertices);
+  auto normal = float3();
+  auto maxDist = -1;
+  for (auto v1 = vertices.begin(); v1 != vertices.end() - 1; ++v1) {
+    for (auto v2 = std::next(v1); v2 != vertices.end(); ++v2) {
+      const auto v1ToCenter = *v1 - faceCenter;
+      const auto v2ToCenter = *v2 - faceCenter;
+      const auto dist = norm(cross(v1ToCenter, v2ToCenter));
+      if (dist > maxDist) {
+        normal = GetNormal(v1ToCenter, v2ToCenter);
+        maxDist = dist;
+      }
+    }
   }
-
-  return n;
+  return normal;
 }
 
 // The area of the face defined by vertices (v0, v1, v2)
@@ -201,79 +201,10 @@ TriNormal(const float3 v0, const float3 v1, const float3 v2) {
 //
 __device__ inline float FaceArea(const FaceVerts& tri) {
   // Get verts for face 1
-  const float3 v0 = tri.v0;
-  const float3 v1 = tri.v1;
-  const float3 v2 = tri.v2;
-  const float3 n = cross(v1 - v0, v2 - v0);
+  const float3 n = cross(tri.v1 - tri.v0, tri.v2 - tri.v0);
   return norm(n) / 2.0;
 }
 
-// The center of a plane defined by vertices (v0, v1, v2, v3)
-//
-// Args
-//    v0, v1, v2, v3: float3 coordinates of the vertices of the plane
-//
-// Returns
-//    float3: center of the plane
-//
-__device__ inline float3 PlaneCenter(
-    const float3 v0,
-    const float3 v1,
-    const float3 v2,
-    const float3 v3) {
-  float3 ctr = (v0 + v1 + v2 + v3) / 4.0f;
-  return ctr;
-}
-
-// The normal of a planar face with vertices (v0, v1, v2, v3)
-// We find the "best" edges connecting the face center to the vertices,
-// such that the cross product between the edges is maximized.
-//
-// Args
-//    e0, e1: float3 coordinates of the vertices of the plane
-//
-// Returns
-//    float3: center of the plane
-//
-__device__ inline float3 PlaneNormal(
-    const float3 v0,
-    const float3 v1,
-    const float3 v2,
-    const float3 v3) {
-  const float3 ctr = PlaneCenter(v0, v1, v2, v3);
-
-  const float d01 = norm(cross(v0 - ctr, v1 - ctr));
-  const float d02 = norm(cross(v0 - ctr, v2 - ctr));
-  const float d03 = norm(cross(v0 - ctr, v3 - ctr));
-  const float d12 = norm(cross(v1 - ctr, v2 - ctr));
-  const float d13 = norm(cross(v1 - ctr, v3 - ctr));
-  const float d23 = norm(cross(v2 - ctr, v3 - ctr));
-
-  float max_dist = d01;
-  float3 n = GetNormal(v0 - ctr, v1 - ctr);
-
-  if (d02 > max_dist) {
-    max_dist = d02;
-    n = GetNormal(v0 - ctr, v2 - ctr);
-  }
-  if (d03 > max_dist) {
-    max_dist = d03;
-    n = GetNormal(v0 - ctr, v3 - ctr);
-  }
-  if (d12 > max_dist) {
-    max_dist = d12;
-    n = GetNormal(v1 - ctr, v2 - ctr);
-  }
-  if (d13 > max_dist) {
-    max_dist = d13;
-    n = GetNormal(v1 - ctr, v3 - ctr);
-  }
-  if (d23 > max_dist) {
-    n = GetNormal(v2 - ctr, v3 - ctr);
-  }
-  return n;
-}
-
 // The normal of a box plane defined by the verts in `plane` such that it
 // points toward the centroid of the box given by `center`.
 //
@@ -290,17 +221,12 @@ template <typename FaceVertsPlane>
 __device__ inline float3 PlaneNormalDirection(
     const FaceVertsPlane& plane,
     const float3& center) {
-  // The plane's vertices
-  const float3 v0 = plane.v0;
-  const float3 v1 = plane.v1;
-  const float3 v2 = plane.v2;
-  const float3 v3 = plane.v3;
-
   // The plane's center
-  const float3 plane_center = PlaneCenter(v0, v1, v2, v3);
+  const float3 plane_center =
+      FaceCenter({plane.v0, plane.v1, plane.v2, plane.v3});
 
   // The plane's normal
-  float3 n = PlaneNormal(v0, v1, v2, v3);
+  float3 n = FaceNormal({plane.v0, plane.v1, plane.v2, plane.v3});
 
   // We project the center on the plane defined by (v0, v1, v2, v3)
   // We can write center = plane_center + a * e0 + b * e1 + c * n
@@ -442,14 +368,8 @@ __device__ inline float3 PolyhedronCenter(
 //
 __device__ inline bool
 IsInside(const FaceVerts& plane, const float3& normal, const float3& point) {
-  // Vertices of the plane
-  const float3 v0 = plane.v0;
-  const float3 v1 = plane.v1;
-  const float3 v2 = plane.v2;
-  const float3 v3 = plane.v3;
-
   // The center of the plane
-  const float3 plane_ctr = PlaneCenter(v0, v1, v2, v3);
+  const float3 plane_ctr = FaceCenter({plane.v0, plane.v1, plane.v2, plane.v3});
 
   // Every point p can be written as p = plane_ctr + a e0 + b e1 + c n
   // Solving for c:
@@ -478,14 +398,8 @@ __device__ inline float3 PlaneEdgeIntersection(
     const float3& normal,
     const float3& p0,
     const float3& p1) {
-  // Vertices of the plane
-  const float3 v0 = plane.v0;
-  const float3 v1 = plane.v1;
-  const float3 v2 = plane.v2;
-  const float3 v3 = plane.v3;
-
   // The center of the plane
-  const float3 plane_ctr = PlaneCenter(v0, v1, v2, v3);
+  const float3 plane_ctr = FaceCenter({plane.v0, plane.v1, plane.v2, plane.v3});
 
   // The point of intersection can be parametrized
   // p = p0 + a (p1 - p0) where a in [0, 1]
@@ -548,30 +462,18 @@ __device__ inline std::tuple<float3, float3> ArgMaxVerts(
 __device__ inline bool IsCoplanarTriTri(
     const FaceVerts& tri1,
     const FaceVerts& tri2) {
-  // Get verts for face 1
-  const float3 v0_1 = tri1.v0;
-  const float3 v1_1 = tri1.v1;
-  const float3 v2_1 = tri1.v2;
+  const float3 tri1_ctr = FaceCenter({tri1.v0, tri1.v1, tri1.v2});
+  const float3 tri1_n = FaceNormal({tri1.v0, tri1.v1, tri1.v2});
 
-  const float3 tri1_ctr = TriCenter(v0_1, v1_1, v2_1);
-  const float3 tri1_n = TriNormal(v0_1, v1_1, v2_1);
-
-  // Get verts for face 2
-  const float3 v0_2 = tri2.v0;
-  const float3 v1_2 = tri2.v1;
-  const float3 v2_2 = tri2.v2;
-
-  const float3 tri2_ctr = TriCenter(v0_2, v1_2, v2_2);
-  const float3 tri2_n = TriNormal(v0_2, v1_2, v2_2);
+  const float3 tri2_ctr = FaceCenter({tri2.v0, tri2.v1, tri2.v2});
+  const float3 tri2_n = FaceNormal({tri2.v0, tri2.v1, tri2.v2});
 
   // Check if parallel
   const bool check1 = abs(dot(tri1_n, tri2_n)) > 1 - dEpsilon;
 
   // Compute most distant points
-  auto argvs =
+  const auto [v1m, v2m] =
       ArgMaxVerts({tri1.v0, tri1.v1, tri1.v2}, {tri2.v0, tri2.v1, tri2.v2});
-  const float3 v1m = std::get<0>(argvs);
-  const float3 v2m = std::get<1>(argvs);
 
   float3 n12m = v1m - v2m;
   n12m = n12m / fmaxf(norm(n12m), kEpsilon);
@@ -597,22 +499,15 @@ __device__ inline bool IsCoplanarTriPlane(
     const FaceVerts& tri,
     const FaceVerts& plane,
     const float3& normal) {
-  // Get verts for tri
-  const float3 v0t = tri.v0;
-  const float3 v1t = tri.v1;
-  const float3 v2t = tri.v2;
-
-  const float3 tri_ctr = TriCenter(v0t, v1t, v2t);
-  const float3 nt = TriNormal(v0t, v1t, v2t);
+  const float3 tri_ctr = FaceCenter({tri.v0, tri.v1, tri.v2});
+  const float3 nt = FaceNormal({tri.v0, tri.v1, tri.v2});
 
   // check if parallel
   const bool check1 = abs(dot(nt, normal)) > 1 - dEpsilon;
 
   // Compute most distant points
-  auto argvs = ArgMaxVerts(
+  const auto [v1m, v2m] = ArgMaxVerts(
       {tri.v0, tri.v1, tri.v2}, {plane.v0, plane.v1, plane.v2, plane.v3});
-  const float3 v1m = std::get<0>(argvs);
-  const float3 v2m = std::get<1>(argvs);
 
   float3 n12m = v1m - v2m;
   n12m = n12m / fmaxf(norm(n12m), kEpsilon);