collision.hpp

/*
    KTech, Kaup's C++ 2D terminal game engine library.
    Copyright (C) 2023-2025 Ethan Kaufman (AKA Kaup)
 
    This file is part of KTech.
 
    KTech is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    any later version.
 
    KTech is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
    along with KTech. If not, see <https://www.gnu.org/licenses/>.
*/
 
#pragma once
 
#define KTECH_DEFINITION
#include "../ktech.hpp"
#undef KTECH_DEFINITION
#include "../world/object.hpp"
 
#include <vector>
 
class KTech::Collision
{
public:
    enum class CR : uint8_t
    {
        B,  
        P,  
        O   
    };
 
    std::vector<std::vector<CR>> colliderTypes{
        { CR::B, CR::P, CR::O }, // Unpushable - 0
        { CR::B, CR::P, CR::O }, // Pushable - 1
        { CR::O, CR::O, CR::O } // Overlapping - 2
    };
 
    auto MoveObject(const ID<Object>& object, Point direction) -> bool;
 
private:
    Engine& engine;
 
    struct CollisionData{
        ID<Object> activeObject;
        ID<Object> passiveObject;
        size_t activeCollider;
        size_t passiveCollider;
    };
 
    inline Collision(Engine& engine)
        : engine(engine) {};
 
    auto GetPotentialCollisionResult(uint8_t type1, uint8_t type2) -> CR;
    // Warning: `position1` and `position2` override `collider1.m_rPos` and `collider2.m_rPos` respectively
    static auto AreCollidersOverlapping(const Collider& collider1, const Point& position1, const Collider& collider2, const Point& position2) -> bool;
    static auto AreSimpleCollidersOverlapping(const Collider& collider1, const Point& position1, const Collider& collider2, const Point& position2) -> bool;
    static auto AreSimpleAndComplexCollidersOverlapping(const Collider& complex, const Point& complexPosition, const Collider& simple, const Point& simplePosition) -> bool;
    static auto AreComplexCollidersOverlapping(const Collider& collider1, const Point& position1, const Collider& collider2, const Point& position2) -> bool;
    void ExpandMovementTree(const ID<Object>& thisObject, Point direction,
        std::vector<CollisionData>& pushData,
        std::vector<CollisionData>& blockData,
        std::vector<CollisionData>& overlapData,
        std::vector<CollisionData>& exitOverlapData);
 
    friend class Engine;
};