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#pragma once
#include <optional>
#include <variant>
#include <vector>
#include "api/BoxCollider.h"
#include "api/CircleCollider.h"
#include "api/Event.h"
#include "api/Metadata.h"
#include "api/Rigidbody.h"
#include "api/Transform.h"
#include "api/Vector2.h"
#include "Collider.h"
#include "System.h"
namespace crepe {
//! A system responsible for detecting and handling collisions between colliders.
class CollisionSystem : public System {
public:
using System::System;
private:
//! Enum representing movement directions during collision resolution.
enum class Direction {
//! No movement required.
NONE,
//! Movement in the X direction.
X_DIRECTION,
//! Movement in the Y direction.
Y_DIRECTION,
//! Movement in both X and Y directions.
BOTH
};
public:
//! Structure representing components of the collider
struct ColliderInfo {
Transform & transform;
Rigidbody & rigidbody;
Metadata & metadata;
};
/**
* \brief Structure representing detailed collision information between two colliders.
*
* Includes information about the colliding objects and the resolution data for handling the collision.
*/
struct CollisionInfo {
ColliderInfo self;
ColliderInfo other;
//! The resolution vector for the collision.
vec2 resolution;
//! The direction of movement for resolving the collision.
Direction resolution_direction = Direction::NONE;
CollisionInfo operator - () const;
};
private:
//! A variant type that can hold either a BoxCollider or a CircleCollider.
using collider_variant = std::variant<std::reference_wrapper<BoxCollider>,
std::reference_wrapper<CircleCollider>>;
//! Enum representing the types of collider pairs for collision detection.
enum class CollisionInternalType {
BOX_BOX,
CIRCLE_CIRCLE,
BOX_CIRCLE,
CIRCLE_BOX,
NONE,
};
/**
* \brief A structure to store the collision data of a single collider.
*
* This structure all components and id that are for needed within this system when calculating or handeling collisions.
* The transform and rigidbody are mostly needed for location and rotation.
* In rigidbody additional info is written about what the body of the object is,
* and how it should respond on a collision.
*/
struct CollisionInternal {
game_object_id_t id = 0;
collider_variant collider;
ColliderInfo info;
vec2 resolution;
Direction resolution_direction = Direction::NONE;
};
//! Structure of collider with addtitional components
struct BoxColliderInternal {
BoxCollider & collider;
Transform & transform;
Rigidbody & rigidbody;
};
//! Structure of collider with addtitional components
struct CircleColliderInternal {
CircleCollider & collider;
Transform & transform;
Rigidbody & rigidbody;
};
public:
//! Updates the collision system by checking for collisions between colliders and handling them.
void update() override;
private:
/**
* \brief Determines the type of collider pair from two colliders.
*
* Uses std::holds_alternative to identify the types of the provided colliders.
*
* \param collider1 First collider variant (BoxCollider or CircleCollider).
* \param collider2 Second collider variant (BoxCollider or CircleCollider).
* \return The combined type of the two colliders.
*/
CollisionInternalType get_collider_type(const collider_variant & collider1, const collider_variant & collider2) const;
private:
/**
* \brief Handles collision resolution between two colliders.
*
* Processes collision data and adjusts objects to resolve collisions and/or calls the user oncollision script function.
*
* \param data1 Collision data for the first collider.
* \param data2 Collision data for the second collider.
*/
CollisionInfo get_collision_info(const CollisionInternal & data1, const CollisionInternal & data2) const;
/**
* \brief Corrects the resolution of the collision
*
* This function corrects the resolution by fixing the x or y if it is empty.
* Besides this with the input of the resolution the direction is saved before correction.
*
* \param resolution resolution vector that needs to be corrected
* \param rigidbody rigidbody data used to correct resolution
* \return Direction of resolution
*/
Direction resolution_correction(vec2 & resolution,const Rigidbody::Data & rigidbody);
/**
* \brief Determines the appropriate collision handler for a collision.
*
* Decides the correct resolution process based on the dynamic or static nature of the colliders involved.
*
* \param info Collision information containing data about both colliders.
*/
void determine_collision_handler(const CollisionInfo & info);
/**
* \brief Calls both collision script
*
* Calls both collision script to let user add additonal handeling or handle full collision.
*
* \param info Collision information containing data about both colliders.
* \param info_inverted Collision information containing data about both colliders in opposite order.
*/
void call_collision_events(const CollisionInfo & info, const CollisionInfo & info_inverted);
/**
* \brief Handles collisions involving static objects.
*
* Resolves collisions by adjusting positions and modifying velocities if bounce is enabled.
*
* \param info Collision information containing data about both colliders.
*/
void static_collision_handler(const CollisionInfo & info);
/**
* \brief Handles collisions involving dynamic objects.
*
* Resolves collisions by adjusting positions and modifying velocities if bounce is enabled.
*
* \param info Collision information containing data about both colliders.
*/
void dynamic_collision_handler(const CollisionInfo & info);
private:
/**
* \brief Checks for collisions between colliders.
*
* Identifies collisions and generates pairs of colliding objects for further processing.
*
* \param colliders A collection of all active colliders.
* \return A list of collision pairs with their associated data.
*/
std::vector<std::pair<CollisionInternal, CollisionInternal>>
gather_collisions(std::vector<CollisionInternal> & colliders);
/**
* \brief Checks if the settings allow collision
*
* This function checks if there is any collison layer where each object is located in.
* After checking the layers it checks the names and at last the tags.
* if in all three sets nothing is found collision can not happen.
*
* \param this_rigidbody Rigidbody of first object
* \param other_rigidbody Rigidbody of second collider
* \param this_metadata Rigidbody of first object
* \param other_metadata Rigidbody of second object
* \return Returns true if there is at least one comparision found.
*/
bool should_collide(const CollisionInternal & self, const CollisionInternal & other) const; //done
/**
* \brief Checks for collision between two colliders.
*
* Calls the appropriate collision detection function based on the collider types.
*
* \param first_info Collision data for the first collider.
* \param second_info Collision data for the second collider.
* \param type The type of collider pair.
* \return True if a collision is detected, otherwise false.
*/
bool detect_collision(CollisionInternal & first_info, CollisionInternal & second_info, const CollisionInternalType & type);
/**
* \brief Detects collisions between two BoxColliders.
*
* \param box1 Information about the first BoxCollider.
* \param box2 Information about the second BoxCollider.
* \return returns resolution vector if collide otherwise returns {-1,-1}
*/
vec2 get_box_box_detection(const BoxColliderInternal & box1, const BoxColliderInternal & box2) const;
/**
* \brief Check collision for box on circle collider
*
* \param box1 Information about the BoxCollider.
* \param circle2 Information about the circleCollider.
* \return returns resolution vector if collide otherwise returns {-1,-1}
*/
vec2 get_box_circle_detection(const BoxColliderInternal & box1, const CircleColliderInternal & circle2) const;
/**
* \brief Check collision for circle on circle collider
*
* \param circle1 Information about the first circleCollider.
* \param circle2 Information about the second circleCollider.
* \return returns resolution vector if collide otherwise returns {-1,-1}
*
* \return status of collision
*/
vec2 get_circle_circle_detection(const CircleColliderInternal & circle1, const CircleColliderInternal & circle2) const;
};
/**
* \brief Event triggered during a collision between objects.
*/
class CollisionEvent : public Event {
public:
crepe::CollisionSystem::CollisionInfo info;
CollisionEvent(const crepe::CollisionSystem::CollisionInfo & collisionInfo)
: info(collisionInfo) {}
};
} // namespace crepe
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