fixed potential deadlock

Feature/mesh improvement

include/omath/collision/gjk_algorithm.hpp

@@ -14,11 +14,15 @@ namespace omath::collision
         Simplex<VertexType> simplex; // valid only if hit == true and size==4
     };
 
+    struct GjkSettings final
+    {
+        float epsilon = 1e-6f;
+        std::size_t max_iterations = 64;
+    };
     template<class ColliderInterfaceType>
     class GjkAlgorithm final
     {
         using VectorType = ColliderInterfaceType::VectorType;
-
     public:
         [[nodiscard]]
         static VectorType find_support_vertex(const ColliderInterfaceType& collider_a,
@@ -36,7 +40,8 @@ namespace omath::collision
 
         [[nodiscard]]
         static GjkHitInfo<VectorType> is_collide_with_simplex_info(const ColliderInterfaceType& collider_a,
-                                                                   const ColliderInterfaceType& collider_b)
+                                                                   const ColliderInterfaceType& collider_b,
+                                                                   const GjkSettings& settings = {})
         {
             auto support = find_support_vertex(collider_a, collider_b, VectorType{1, 0, 0});
 
@@ -45,11 +50,11 @@ namespace omath::collision
 
             auto direction = -support;
 
-            while (true)
+            for (std::size_t iteration = 0; iteration < settings.max_iterations; ++iteration)
             {
                 support = find_support_vertex(collider_a, collider_b, direction);
 
-                if (support.dot(direction) <= 0.f)
+                if (support.dot(direction) <= settings.epsilon)
                     return {false, simplex};
 
                 simplex.push_front(support);
@@ -57,6 +62,7 @@ namespace omath::collision
                 if (simplex.handle(direction))
                     return {true, simplex};
             }
+            return {false, simplex};
         }
     };
 } // namespace omath::collision

include/omath/collision/mesh_collider.hpp

@@ -46,9 +46,26 @@ namespace omath::collision
         [[nodiscard]]
         const VertexType& find_furthest_vertex(const VectorType& direction) const
         {
-            return *std::ranges::max_element(
+            // The support query arrives in world space, but vertex positions are stored
-                    m_mesh.m_vertex_buffer, [&direction](const auto& first, const auto& second)
+            // in local space.  We need argmax_v { world(v) · d }.
-                    { return first.position.dot(direction) < second.position.dot(direction); });
+            //
+            // world(v) = M·v  (ignoring translation, which is constant across vertices)
+            // world(v) · d = v · Mᵀ·d
+            //
+            // So we transform the direction to local space once — O(1) — then compare
+            // raw local positions, which is far cheaper than calling
+            // vertex_position_to_world_space (full 4×4 multiply) for every vertex.
+            //
+            // d_local = upper-left 3×3 of M, transposed, times d_world:
+            //   d_local[j] = sum_i  M.at(i,j) * d[i]   (i.e. column j of M dotted with d)
+            const auto& m = m_mesh.get_to_world_matrix();
+            const VectorType d_local = {
+                    m[0, 0] * direction.x + m[1, 0] * direction.y + m[2, 0] * direction.z,
+                    m[0, 1] * direction.x + m[1, 1] * direction.y + m[2, 1] * direction.z,
+                    m[0, 2] * direction.x + m[1, 2] * direction.y + m[2, 2] * direction.z,
+            };
+            return *std::ranges::max_element(m_mesh.m_vertex_buffer, [&d_local](const auto& first, const auto& second)
+                                             { return first.position.dot(d_local) < second.position.dot(d_local); });
         }
         MeshType m_mesh;
     };