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optimization

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orange
2026-02-26 16:19:54 +03:00
parent 74dc2234f7
commit 211e4c3d9b
1 changed files with 20 additions and 9 deletions
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29
include/omath/collision/mesh_collider.hpp
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@@ -46,16 +46,27 @@ namespace omath::collision
[[nodiscard]]
const VertexType& find_furthest_vertex(const VectorType& direction) const
{
// Compare vertices in world space so rotation and non-uniform scale are
// accounted for correctly. Without this the comparator uses local-space
// positions against a world-space direction, which yields the wrong support
// vertex whenever a non-identity transform is applied to the mesh.
// The support query arrives in world space, but vertex positions are stored
// in local space. We need argmax_v { world(v) · d }.
//
// 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.at(0, 0) * direction.x + m.at(1, 0) * direction.y + m.at(2, 0) * direction.z,
m.at(0, 1) * direction.x + m.at(1, 1) * direction.y + m.at(2, 1) * direction.z,
m.at(0, 2) * direction.x + m.at(1, 2) * direction.y + m.at(2, 2) * direction.z,
};
return *std::ranges::max_element(
m_mesh.m_vertex_buffer, [&](const auto& first, const auto& second)
{
return m_mesh.vertex_position_to_world_space(first.position).dot(direction)
< m_mesh.vertex_position_to_world_space(second.position).dot(direction);
});
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;
};