1 files changed, 453 insertions, 1 deletions

diff --git a/src/crepe/system/CollisionSystem.cpp b/src/crepe/system/CollisionSystem.cpp
index c74ca1d..2d5ce9d 100644
--- a/src/crepe/system/CollisionSystem.cpp
+++ b/src/crepe/system/CollisionSystem.cpp
@@ -1,5 +1,457 @@
+#include <cmath>
+#include <algorithm>
+#include <cstddef>
+#include <functional>
+#include <utility>
+#include <variant>
+#include <optional>
+
+#include "api/Event.h"
+#include "api/EventManager.h"
+#include "api/BoxCollider.h"
+#include "api/CircleCollider.h"
+#include "api/Metadata.h"
+#include "api/Vector2.h"
+#include "api/Rigidbody.h"
+#include "api/Transform.h"
+
+#include "ComponentManager.h"
 #include "CollisionSystem.h"
+#include "Collider.h"
+#include "types.h"
+#include "util/OptionalRef.h"
 
 using namespace crepe;
 
-void CollisionSystem::update() {}
+void CollisionSystem::update() {
+	std::vector<CollisionInternal> all_colliders;
+	game_object_id_t id = 0;
+	RefVector<Rigidbody> rigidbodies = this->component_manager.get_components_by_type<Rigidbody>();
+	// Collisions can only happen on object with a rigidbody
+	for(Rigidbody& rigidbody : rigidbodies) {
+		if (!rigidbody.active) continue;
+		id = rigidbody.game_object_id;
+		Transform& transform = this->component_manager.get_components_by_id<Transform>(id).front().get();
+		// Check if the boxcollider is active and has the same id as the rigidbody.
+		RefVector<BoxCollider> boxcolliders	= this->component_manager.get_components_by_type<BoxCollider>();
+		for (BoxCollider& boxcollider : boxcolliders) {
+			if(boxcollider.game_object_id != id) continue;
+			if(!boxcollider.active) continue;
+			all_colliders.push_back(
+				{
+					.id = id,
+				  .collider = collider_variant{boxcollider},
+					.transform = transform,
+					.rigidbody = rigidbody
+					}
+				);
+		}
+		// Check if the circlecollider is active and has the same id as the rigidbody.
+		RefVector<CircleCollider> circlecolliders	= this->component_manager.get_components_by_type<CircleCollider>();
+		for (CircleCollider& circlecollider : circlecolliders) {
+			if(circlecollider.game_object_id != id) continue;
+			if(!circlecollider.active) continue;
+			all_colliders.push_back(
+				{
+					.id = id,
+				  .collider = collider_variant{circlecollider},
+					.transform = transform,
+					.rigidbody = rigidbody
+					}
+				);
+		}
+	}
+
+	// Check between all colliders if there is a collision
+	std::vector<std::pair<CollisionInternal,CollisionInternal>> collided = this->gather_collisions(all_colliders);
+
+	// For both objects call the collision handler 
+	for (auto& collision_pair : collided) {
+		this->collision_handler_request(collision_pair.first,collision_pair.second);
+		this->collision_handler_request(collision_pair.second,collision_pair.first);
+	}
+}
+
+void CollisionSystem::collision_handler_request(CollisionInternal& this_data,CollisionInternal& other_data){
+
+	CollisionInternalType type = this->get_collider_type(this_data.collider,other_data.collider);
+	std::pair<vec2,CollisionSystem::Direction> resolution_data = this->collision_handler(this_data,other_data,type);
+
+	OptionalRef<Metadata> this_metadata = this->component_manager.get_components_by_id<Metadata>(this_data.id).front().get();
+	OptionalRef<Metadata> other_metadata = this->component_manager.get_components_by_id<Metadata>(other_data.id).front().get();
+	OptionalRef<Collider> this_collider;
+	OptionalRef<Collider> other_collider;
+	switch (type) {
+		case CollisionInternalType::BOX_BOX:{
+			this_collider = std::get<std::reference_wrapper<BoxCollider>>(this_data.collider);
+			other_collider = std::get<std::reference_wrapper<BoxCollider>>(other_data.collider);
+			break;
+		}
+		case CollisionInternalType::BOX_CIRCLE:{
+			this_collider = std::get<std::reference_wrapper<BoxCollider>>(this_data.collider);
+			other_collider = std::get<std::reference_wrapper<CircleCollider>>(other_data.collider);
+			break;
+		}
+		case CollisionInternalType::CIRCLE_BOX:{
+			this_collider = std::get<std::reference_wrapper<CircleCollider>>(this_data.collider);
+			other_collider = std::get<std::reference_wrapper<BoxCollider>>(other_data.collider);
+			break;
+		}
+		case CollisionInternalType::CIRCLE_CIRCLE:{
+			this_collider = std::get<std::reference_wrapper<CircleCollider>>(this_data.collider);
+			other_collider = std::get<std::reference_wrapper<CircleCollider>>(other_data.collider);
+			break;
+		}
+	}
+
+	// collision info
+	crepe::CollisionSystem::CollisionInfo collision_info{
+						.this_collider = this_collider,
+						.this_transform = this_data.transform,
+						.this_rigidbody = this_data.rigidbody,
+						.this_metadata = this_metadata,
+						.other_collider = other_collider,
+						.other_transform = other_data.transform,
+						.other_rigidbody = other_data.rigidbody,
+						.other_metadata = other_metadata,
+						.resolution = resolution_data.first,
+						.resolution_direction = resolution_data.second,
+        };
+
+	// Determine if static needs to be called
+	this->determine_collision_handler(collision_info);	
+}
+
+
+std::pair<vec2,CollisionSystem::Direction> CollisionSystem::collision_handler(CollisionInternal& data1,CollisionInternal& data2,CollisionInternalType type) {
+	vec2 resolution;
+	switch (type) {
+		case CollisionInternalType::BOX_BOX:	{
+			const BoxCollider & collider1 = std::get<std::reference_wrapper<BoxCollider>>(data1.collider);
+			const BoxCollider & collider2 = std::get<std::reference_wrapper<BoxCollider>>(data2.collider);
+			vec2 collider_pos1 = this->get_current_position(collider1.offset, data1.transform, data1.rigidbody);
+			vec2 collider_pos2 = this->get_current_position(collider2.offset, data2.transform, data2.rigidbody);
+			resolution = this->get_box_box_resolution(collider1,collider2,collider_pos1,collider_pos2);
+			break;
+		}
+		case CollisionInternalType::BOX_CIRCLE: {
+			const BoxCollider & collider1 = std::get<std::reference_wrapper<BoxCollider>>(data1.collider);
+			const CircleCollider & collider2 = std::get<std::reference_wrapper<CircleCollider>>(data2.collider);
+			vec2 collider_pos1 = this->get_current_position(collider1.offset, data1.transform, data1.rigidbody);
+			vec2 collider_pos2 = this->get_current_position(collider2.offset, data2.transform, data2.rigidbody);
+			resolution = this->get_circle_box_resolution(collider2,collider1,collider_pos2,collider_pos1);
+			break;
+		}
+		case CollisionInternalType::CIRCLE_CIRCLE:	{
+			const CircleCollider & collider1 = std::get<std::reference_wrapper<CircleCollider>>(data1.collider);
+			const CircleCollider & collider2 = std::get<std::reference_wrapper<CircleCollider>>(data2.collider);
+			vec2 collider_pos1 = this->get_current_position(collider1.offset, data1.transform, data1.rigidbody);
+			vec2 collider_pos2 = this->get_current_position(collider2.offset, data2.transform, data2.rigidbody);
+			resolution = this->get_circle_circle_resolution(collider1,collider2,collider_pos1,collider_pos2);
+			break;
+		}
+		case CollisionInternalType::CIRCLE_BOX:	{
+			const CircleCollider & collider1 = std::get<std::reference_wrapper<CircleCollider>>(data1.collider);
+			const BoxCollider & collider2 = std::get<std::reference_wrapper<BoxCollider>>(data2.collider);
+			vec2 collider_pos1 = this->get_current_position(collider1.offset, data1.transform, data1.rigidbody);
+			vec2 collider_pos2 = this->get_current_position(collider2.offset, data2.transform, data2.rigidbody);
+			resolution = this->get_circle_box_resolution(collider1,collider2,collider_pos1,collider_pos2);
+			break;
+		}
+	}
+
+	Direction resolution_direction = Direction::NONE;
+	if(resolution.x != 0 && resolution.y > 0) {
+		resolution_direction = Direction::BOTH;
+	} else if (resolution.x != 0) {
+		resolution_direction = Direction::X_DIRECTION;
+		if(data1.rigidbody.data.linear_velocity.y != 0)	
+		resolution.y = data1.rigidbody.data.linear_velocity.y * (resolution.x/data1.rigidbody.data.linear_velocity.x);
+	} else if (resolution.y != 0) {
+		resolution_direction = Direction::Y_DIRECTION;
+		if(data1.rigidbody.data.linear_velocity.x != 0) 
+		resolution.x = data1.rigidbody.data.linear_velocity.x * (resolution.y/data1.rigidbody.data.linear_velocity.y);
+	}
+
+	return std::make_pair(resolution,resolution_direction);
+}
+
+vec2 CollisionSystem::get_box_box_resolution(const BoxCollider& box_collider1,const BoxCollider& box_collider2,const vec2& final_position1,const vec2& final_position2) const
+{
+	vec2 resolution; // Default resolution vector
+	vec2 delta = final_position2 - final_position1;
+
+	// Compute half-dimensions of the boxes
+	float half_width1 = box_collider1.dimensions.x / 2.0;
+	float half_height1 = box_collider1.dimensions.y / 2.0;
+	float half_width2 = box_collider2.dimensions.x / 2.0;
+	float half_height2 = box_collider2.dimensions.y / 2.0;
+
+	// Calculate overlaps along X and Y axes
+	float overlap_x = (half_width1 + half_width2) - std::abs(delta.x);
+	float overlap_y = (half_height1 + half_height2) - std::abs(delta.y);
+
+	// Check if there is a collision should always be true
+	if (overlap_x > 0 && overlap_y > 0) {
+		// Determine the direction of resolution
+		if (overlap_x < overlap_y) {
+			// Resolve along the X-axis (smallest overlap)
+			resolution.x = (delta.x > 0) ? -overlap_x : overlap_x;
+		} else if (overlap_y < overlap_x) {
+			// Resolve along the Y-axis (smallest overlap)
+			resolution.y = (delta.y > 0) ? -overlap_y : overlap_y;
+		} else {
+			// Equal overlap, resolve both directions with preference
+			resolution.x = (delta.x > 0) ? -overlap_x : overlap_x;
+			resolution.y = (delta.y > 0) ? -overlap_y : overlap_y;
+		}
+	}
+
+	return resolution;
+}
+
+vec2 CollisionSystem::get_circle_circle_resolution(const CircleCollider& circle_collider1, const CircleCollider& circle_collider2, const vec2& final_position1, const vec2& final_position2) const 
+{
+    vec2 delta = final_position2 - final_position1;
+
+    // Compute the distance between the two circle centers
+    float distance = std::sqrt(delta.x * delta.x + delta.y * delta.y);
+
+    // Compute the combined radii of the two circles
+    float combined_radius = circle_collider1.radius + circle_collider2.radius;
+
+    // Compute the penetration depth
+    float penetration_depth = combined_radius - distance;
+
+    // Normalize the delta vector to get the collision direction
+    vec2 collision_normal = delta / distance;
+
+    // Compute the resolution vector
+    vec2 resolution = collision_normal * penetration_depth;
+
+    return resolution;
+}
+
+vec2 CollisionSystem::get_circle_box_resolution(const CircleCollider& circle_collider, const BoxCollider& box_collider, const vec2& circle_position, const vec2& box_position) const 
+{
+    vec2 delta = circle_position - box_position;
+
+    // Compute half-dimensions of the box
+    float half_width = box_collider.dimensions.x / 2.0f;
+    float half_height = box_collider.dimensions.y / 2.0f;
+
+    // Clamp circle center to the nearest point on the box
+    vec2 closest_point;
+    closest_point.x = std::clamp(delta.x, -half_width, half_width);
+    closest_point.y = std::clamp(delta.y, -half_height, half_height);
+
+    // Find the vector from the circle center to the closest point
+    vec2 closest_delta = delta - closest_point;
+
+    // Normalize the delta to get the collision direction
+    float distance = std::sqrt(closest_delta.x * closest_delta.x + closest_delta.y * closest_delta.y);
+    vec2 collision_normal = closest_delta / distance;
+
+    // Compute penetration depth
+    float penetration_depth = circle_collider.radius - distance;
+
+    // Compute the resolution vector
+    vec2 resolution = collision_normal * penetration_depth;
+
+    return resolution;
+}
+
+
+void CollisionSystem::determine_collision_handler(CollisionInfo& info){
+	// Check rigidbody type for static
+	if(info.this_rigidbody.data.body_type == Rigidbody::BodyType::STATIC) return;
+	// If second body is static perform the static collision handler in this system
+	if(info.other_rigidbody.data.body_type == Rigidbody::BodyType::STATIC){
+		static_collision_handler(info);
+	}; 
+	// Call collision event for user
+	CollisionEvent data(info);
+	EventManager::get_instance().trigger_event<CollisionEvent>(data, info.this_collider.game_object_id);
+}
+
+void CollisionSystem::static_collision_handler(CollisionInfo& info){
+	// Move object back using calculate move back value 
+	info.this_transform.position += info.resolution;
+
+	// If bounce is enabled mirror velocity
+	if(info.this_rigidbody.data.elastisity_coefficient > 0) {
+		if(info.resolution_direction == Direction::BOTH)
+		{
+			info.this_rigidbody.data.linear_velocity.y = -info.this_rigidbody.data.linear_velocity.y * info.this_rigidbody.data.elastisity_coefficient;
+			info.this_rigidbody.data.linear_velocity.x = -info.this_rigidbody.data.linear_velocity.x * info.this_rigidbody.data.elastisity_coefficient;
+		}
+		else if(info.resolution_direction == Direction::Y_DIRECTION) {
+			info.this_rigidbody.data.linear_velocity.y = -info.this_rigidbody.data.linear_velocity.y * info.this_rigidbody.data.elastisity_coefficient;
+		}
+		else if(info.resolution_direction == Direction::X_DIRECTION){
+			info.this_rigidbody.data.linear_velocity.x = -info.this_rigidbody.data.linear_velocity.x * info.this_rigidbody.data.elastisity_coefficient;
+		}
+	}
+	// Stop movement if bounce is disabled
+	else {
+		info.this_rigidbody.data.linear_velocity = {0,0};
+	}
+}
+
+std::vector<std::pair<CollisionSystem::CollisionInternal,CollisionSystem::CollisionInternal>> CollisionSystem::gather_collisions(std::vector<CollisionInternal> & colliders) {
+	
+	
+	// TODO:
+	// If no colliders skip
+	// Check if colliders has rigidbody if not skip
+
+	// TODO:
+	// If amount is higer than lets say 16 for now use quadtree otwerwise skip
+	// Quadtree code
+	// Quadtree is placed over the input vector
+
+	// Return data of collided colliders which are variants
+	std::vector<std::pair<CollisionInternal,CollisionInternal>> collisions_ret;
+	//using visit to visit the variant to access the active and id.  
+	for (size_t i = 0; i < colliders.size(); ++i) {
+		for (size_t j = i + 1; j < colliders.size(); ++j) {
+			if(colliders[i].id == colliders[j].id) continue;
+				CollisionInternalType type = get_collider_type(colliders[i].collider,colliders[j].collider);
+				if(!get_collision({
+					.collider = colliders[i].collider,
+					.transform = colliders[i].transform,
+					.rigidbody = colliders[i].rigidbody,
+					},
+					{
+					.collider = colliders[j].collider,
+					.transform = colliders[j].transform,
+					.rigidbody = colliders[j].rigidbody,
+					},
+					type)) continue;
+				collisions_ret.emplace_back(colliders[i],colliders[j]);
+		}
+	}
+	
+	return collisions_ret;
+}
+
+CollisionSystem::CollisionInternalType CollisionSystem::get_collider_type(const collider_variant& collider1,const collider_variant& collider2) const{
+	if(std::holds_alternative<std::reference_wrapper<CircleCollider>>(collider1)){
+		if(std::holds_alternative<std::reference_wrapper<CircleCollider>>(collider2))
+		{
+			return CollisionInternalType::CIRCLE_CIRCLE;
+		}
+		else {
+			return CollisionInternalType::CIRCLE_BOX;
+		}
+	}
+	else {
+		if(std::holds_alternative<std::reference_wrapper<CircleCollider>>(collider2))
+		{
+			return CollisionInternalType::BOX_CIRCLE;
+		}
+		else {
+			return CollisionInternalType::BOX_BOX;
+		}
+	}
+}
+
+bool CollisionSystem::get_collision(const CollisionInternal& first_info,const CollisionInternal& second_info, CollisionInternalType type) const{
+	switch (type) {
+		case CollisionInternalType::BOX_BOX:	{
+			const BoxCollider & box_collider1 = std::get<std::reference_wrapper<BoxCollider>>(first_info.collider);
+			const BoxCollider & box_collider2 = std::get<std::reference_wrapper<BoxCollider>>(second_info.collider);
+			return this->get_box_box_collision(box_collider1,box_collider2,first_info.transform,second_info.transform,second_info.rigidbody,second_info.rigidbody);
+		}
+		case CollisionInternalType::BOX_CIRCLE: {
+			const BoxCollider & box_collider = std::get<std::reference_wrapper<BoxCollider>>(first_info.collider);
+			const CircleCollider & circle_collider = std::get<std::reference_wrapper<CircleCollider>>(second_info.collider);
+			return this->get_box_circle_collision(box_collider,circle_collider,first_info.transform,second_info.transform,second_info.rigidbody,second_info.rigidbody);
+		}
+		case CollisionInternalType::CIRCLE_CIRCLE:	{
+			const CircleCollider & circle_collider1 = std::get<std::reference_wrapper<CircleCollider>>(first_info.collider);
+			const CircleCollider & circle_collider2 = std::get<std::reference_wrapper<CircleCollider>>(second_info.collider);
+			return this->get_circle_circle_collision(circle_collider1,circle_collider2,first_info.transform,second_info.transform,second_info.rigidbody,second_info.rigidbody);
+		}
+		case CollisionInternalType::CIRCLE_BOX:	{
+			const CircleCollider & circle_collider = std::get<std::reference_wrapper<CircleCollider>>(first_info.collider);
+			const BoxCollider & box_collider = std::get<std::reference_wrapper<BoxCollider>>(second_info.collider);
+			return this->get_box_circle_collision(box_collider,circle_collider,first_info.transform,second_info.transform,second_info.rigidbody,second_info.rigidbody);
+		}
+	}
+	return false;
+}
+
+
+bool CollisionSystem::get_box_box_collision(const BoxCollider& box1, const BoxCollider& box2, const Transform& transform1, const Transform& transform2, const Rigidbody& rigidbody1, const Rigidbody& rigidbody2) const
+{
+	// Get current positions of colliders
+	vec2 final_position1 = this->get_current_position(box1.offset,transform1,rigidbody1);
+	vec2 final_position2 = this->get_current_position(box2.offset,transform2,rigidbody2);
+
+	// Calculate half-extents (half width and half height)
+	float half_width1 = box1.dimensions.x / 2.0;
+	float half_height1 = box1.dimensions.y / 2.0;
+	float half_width2 = box2.dimensions.x / 2.0;
+	float half_height2 = box2.dimensions.y / 2.0;
+
+	// Check if the boxes overlap along the X and Y axes
+	return (final_position1.x + half_width1 > final_position2.x - half_width2 &&
+        final_position1.x - half_width1 < final_position2.x + half_width2 &&
+        final_position1.y + half_height1 > final_position2.y - half_height2 &&
+        final_position1.y - half_height1 < final_position2.y + half_height2);
+}
+
+bool CollisionSystem::get_box_circle_collision(const BoxCollider& box1, const CircleCollider& circle2, const Transform& transform1, const Transform& transform2, const Rigidbody& rigidbody1, const Rigidbody& rigidbody2) const {
+	// Get current positions of colliders
+	vec2 final_position1 = this->get_current_position(box1.offset, transform1, rigidbody1);
+	vec2 final_position2 = this->get_current_position(circle2.offset, transform2, rigidbody2);
+
+	// Calculate box half-extents
+	float half_width = box1.dimensions.x / 2.0;
+	float half_height = box1.dimensions.y / 2.0;
+
+	// Find the closest point on the box to the circle's center
+	float closest_x = std::max(final_position1.x - half_width, std::min(final_position2.x, final_position1.x + half_width));
+	float closest_y = std::max(final_position1.y - half_height, std::min(final_position2.y, final_position1.y + half_height));
+
+	// Calculate the distance squared between the circle's center and the closest point on the box
+	float distance_x = final_position2.x - closest_x;
+	float distance_y = final_position2.y - closest_y;
+	float distance_squared = distance_x * distance_x + distance_y * distance_y;
+
+	// Compare distance squared with the square of the circle's radius
+	return distance_squared <= circle2.radius * circle2.radius;
+}
+
+bool CollisionSystem::get_circle_circle_collision(const CircleCollider& circle1, const CircleCollider& circle2, const Transform& transform1, const Transform& transform2, const Rigidbody& rigidbody1, const Rigidbody& rigidbody2) const {
+	// Get current positions of colliders
+	vec2 final_position1 = this->get_current_position(circle1.offset,transform1,rigidbody1);
+	vec2 final_position2 = this->get_current_position(circle2.offset,transform2,rigidbody2);
+
+	float distance_x = final_position1.x - final_position2.x;
+	float distance_y = final_position1.y - final_position2.y;
+	float distance_squared = distance_x * distance_x + distance_y * distance_y;
+
+	// Calculate the sum of the radii
+	float radius_sum = circle1.radius + circle2.radius;
+
+	// Check if the distance between the centers is less than or equal to the sum of the radii
+	return distance_squared <= radius_sum * radius_sum;
+}
+
+vec2 CollisionSystem::get_current_position(const vec2& collider_offset, const Transform& transform, const Rigidbody& rigidbody) const {
+	// Get the rotation in radians
+	float radians1 = transform.rotation * (M_PI / 180.0);
+
+	// Calculate total offset with scale
+	vec2 total_offset = (rigidbody.data.offset + collider_offset) * transform.scale;
+
+	// Rotate
+	float rotated_total_offset_x1 = total_offset.x * cos(radians1) - total_offset.y * sin(radians1);
+	float rotated_total_offset_y1 = total_offset.x * sin(radians1) + total_offset.y * cos(radians1);
+
+	// Final positions considering scaling and rotation
+	return(transform.position + vec2(rotated_total_offset_x1, rotated_total_offset_y1));
+
+}