#ifndef COLLISION_MESH_CLASS
#define COLLISION_MESH_CLASS

#include <vector>

#include <glm/glm.hpp>

#include "Structures.h"

// Triangle soup for triangle by triangle collision, wrapped in a BVH.
// Triangles live in the body's unit space, so t.GetMatrix() takes them to world space
// the same way it does for a Mesh. Winding must be counter clockwise seen from outside.
class CollisionMesh {
public:
    CollisionMesh(const std::vector<Triangle>& meshTriangles);

    // The 12 triangles of a unit cube, used for any body without its own mesh
    static const CollisionMesh& UnitBox();

    const std::vector<Triangle>& GetTriangles() const { return triangles; }

    // Appends the index of every triangle whose BVH leaf could touch tri (same space as the mesh)
    void Query(const Triangle& tri, std::vector<int>& hits) const;

private:
    struct Node {
        glm::vec3 boundsMin;
        glm::vec3 boundsMax;
        int left = -1;   // -1 = leaf
        int right = -1;
        int start = 0;
        int count = 0;
    };

    int Build(int start, int count);

    std::vector<Triangle> triangles;
    std::vector<Node> nodes;
};

#endif