[Data/Submesh] Tangents can be computed on submeshes

- It will allow computing them for each individual submesh instead of the whole mesh

include/RaZ/Data/Mesh.hpp

@@ -41,7 +41,7 @@ class Mesh : public Component {
   /// Computes & updates the mesh's bounding box by computing the submeshes' ones.
   /// \return Mesh's bounding box.
   const AABB& computeBoundingBox();
-  /// Computes the mesh's tangents.
+  /// Computes the tangents for each of the mesh's vertices.
   void computeTangents();
 
   Mesh& operator=(const Mesh&) = delete;

include/RaZ/Data/Submesh.hpp

@@ -48,6 +48,8 @@ class Submesh {
   /// Computes & updates the submesh's bounding box.
   /// \return Submesh's bounding box.
   const AABB& computeBoundingBox();
+  /// Computes the tangents for each of the submesh's vertices.
+  void computeTangents();
 
   Submesh& operator=(const Submesh&) = delete;
   Submesh& operator=(Submesh&&) noexcept = default;

src/RaZ/Data/Mesh.cpp

@@ -6,25 +6,6 @@
 
 namespace Raz {
 
-namespace {
-
-constexpr Vec3f computeTangent(const Vertex& firstVert, const Vertex& secondVert, const Vertex& thirdVert) noexcept {
-  const Vec3f firstEdge  = secondVert.position - firstVert.position;
-  const Vec3f secondEdge = thirdVert.position - firstVert.position;
-
-  const Vec2f firstUvDiff  = secondVert.texcoords - firstVert.texcoords;
-  const Vec2f secondUvDiff = thirdVert.texcoords - firstVert.texcoords;
-
-  const float denominator = (firstUvDiff.x() * secondUvDiff.y() - secondUvDiff.x() * firstUvDiff.y());
-
-  if (denominator == 0.f)
-    return Vec3f(0.f);
-
-  return (firstEdge * secondUvDiff.y() - secondEdge * firstUvDiff.y()) / denominator;
-}
-
-} // namespace
-
 Mesh::Mesh(const Plane& plane, float width, float depth) {
   const float height = plane.computeCentroid().y();
 
@@ -257,32 +238,8 @@ void Mesh::computeTangents() {
     return;
 
   Threading::parallelize(m_submeshes, [] (const auto& range) noexcept {
-    for (Submesh& submesh : range) {
-      for (Vertex& vertex : submesh.getVertices())
-        vertex.tangent = Vec3f(0.f, 0.f, 0.f);
-
-      for (std::size_t i = 0; i < submesh.getTriangleIndexCount(); i += 3) {
-        Vertex& firstVert  = submesh.getVertices()[submesh.getTriangleIndices()[i    ]];
-        Vertex& secondVert = submesh.getVertices()[submesh.getTriangleIndices()[i + 1]];
-        Vertex& thirdVert  = submesh.getVertices()[submesh.getTriangleIndices()[i + 2]];
-
-        const Vec3f tangent = computeTangent(firstVert, secondVert, thirdVert);
-
-        // Adding the computed tangent to each vertex; they will be normalized later
-        firstVert.tangent  += tangent;
-        secondVert.tangent += tangent;
-        thirdVert.tangent  += tangent;
-      }
-
-      // Normalizing the accumulated tangents
-      for (Vertex& vert : submesh.getVertices()) {
-        // Avoiding NaNs by preventing normalization of a 0 vector
-        if (vert.tangent.strictlyEquals(Vec3f(0.f)))
-          continue;
-
-        vert.tangent = (vert.tangent - vert.normal * vert.tangent.dot(vert.normal)).normalize();
-      }
-    }
+    for (Submesh& submesh : range)
+      submesh.computeTangents();
   });
 }
 

src/RaZ/Data/Submesh.cpp

@@ -2,6 +2,25 @@
 
 namespace Raz {
 
+namespace {
+
+constexpr Vec3f computeTangent(const Vertex& firstVert, const Vertex& secondVert, const Vertex& thirdVert) noexcept {
+  const Vec3f firstEdge  = secondVert.position - firstVert.position;
+  const Vec3f secondEdge = thirdVert.position - firstVert.position;
+
+  const Vec2f firstUvDiff  = secondVert.texcoords - firstVert.texcoords;
+  const Vec2f secondUvDiff = thirdVert.texcoords - firstVert.texcoords;
+
+  const float denominator = (firstUvDiff.x() * secondUvDiff.y() - secondUvDiff.x() * firstUvDiff.y());
+
+  if (denominator == 0.f)
+    return Vec3f(0.f);
+
+  return (firstEdge * secondUvDiff.y() - secondEdge * firstUvDiff.y()) / denominator;
+}
+
+} // namespace
+
 const AABB& Submesh::computeBoundingBox() {
   Vec3f minPos(std::numeric_limits<float>::max());
   Vec3f maxPos(std::numeric_limits<float>::lowest());
@@ -20,4 +39,31 @@ const AABB& Submesh::computeBoundingBox() {
   return m_boundingBox;
 }
 
+void Submesh::computeTangents() {
+  for (Vertex& vert : m_vertices)
+    vert.tangent = Vec3f(0.f, 0.f, 0.f);
+
+  for (std::size_t i = 0; i < m_triangleIndices.size(); i += 3) {
+    Vertex& firstVert  = m_vertices[m_triangleIndices[i    ]];
+    Vertex& secondVert = m_vertices[m_triangleIndices[i + 1]];
+    Vertex& thirdVert  = m_vertices[m_triangleIndices[i + 2]];
+
+    const Vec3f tangent = computeTangent(firstVert, secondVert, thirdVert);
+
+    // Adding the computed tangent to each vertex; they will be normalized later
+    firstVert.tangent  += tangent;
+    secondVert.tangent += tangent;
+    thirdVert.tangent  += tangent;
+  }
+
+  // Normalizing the accumulated tangents
+  for (Vertex& vert : m_vertices) {
+    // Avoiding NaNs by preventing the normalization of a 0 vector
+    if (vert.tangent.strictlyEquals(Vec3f(0.f)))
+      continue;
+
+    vert.tangent = (vert.tangent - vert.normal * vert.tangent.dot(vert.normal)).normalize();
+  }
+}
+
 } // namespace Raz