AoC2022_Day4/main.cpp

#define OLC_PGE_APPLICATION
#include "pixelGameEngine.h"
#include "olcutils.h"

using namespace olc;

class Example : public olc::PixelGameEngine
{
public:
	Example()
	{
		sAppName = "Example";
	}

public:
    bool RayVsRect(const vf2d ray_origin, const vf2d ray_dir, const olc::utils::geom2d::rect<float> target, vf2d&contact_point, vf2d&contact_normal, float&t_hit_near){

        contact_normal = { 0, 0 };
        contact_point = { 0, 0 };

        vf2d t_near = {(target.pos.x - ray_origin.x) / ray_dir.x, (target.pos.y - ray_origin.y) / ray_dir.y};
        vf2d t_far = {(target.pos.x + target.size.x - ray_origin.x) / ray_dir.x, (target.pos.y + target.size.y - ray_origin.y) / ray_dir.y};

        if (t_near.x > t_far.x) {float b; b = t_near.x; t_near.x = t_far.x; t_far.x = b;};
        if (t_near.y > t_far.y) {float b; b = t_near.y; t_near.y = t_far.y; t_far.y = b;};

        if (t_near.x > t_far.y || t_near.y > t_far.x) return false;

        t_hit_near = fmax(t_near.x, t_near.y);
        float t_hit_far = fmin(t_far.x, t_far.y);

        if (t_hit_far < 0) return false;

        contact_point.x = ray_origin.x + t_hit_near * ray_dir.x; 
        contact_point.y = ray_origin.y + t_hit_near * ray_dir.y;

        if (t_near.x > t_near.y)
            if ( 1.0f / ray_dir.x < 0)
                contact_normal = { 1, 0 };
            else
                contact_normal = { -1, 0};
        else 
        if ( t_near.x < t_near.y)
            if ( 1.0f / ray_dir.y < 0)
                contact_normal = { 0, 1 };
            else
                contact_normal = { 0, -1 };
        
        return true;

        
    }
    vf2d originPoint={16,16};
	bool OnUserCreate() override
	{
		// Called once at the start, so create things here
		return true;
	}

	bool OnUserUpdate(float fElapsedTime) override
	{
        vf2d velocity={(GetKey(D).bHeld-GetKey(A).bHeld)*20*fElapsedTime,(GetKey(S).bHeld-GetKey(W).bHeld)*20*fElapsedTime};
        vf2d contact_point;
        vf2d contact_normal;
        float t_hit_near;

		Clear(Pixel(64,64,255));
        if (!olc::utils::geom2d::overlaps(olc::utils::geom2d::circle<float>{originPoint+velocity,5},olc::utils::geom2d::rect<float>{{32,32},{64,32}})) {
            originPoint+=velocity;
            DrawCircle(originPoint,5);
        } else {
            DrawCircle(originPoint,5,RED);
        }
        DrawLine(originPoint,GetMousePos());

        DrawRect({32,32},{64,32},RayVsRect(originPoint, GetMousePos()-originPoint, olc::utils::geom2d::rect<float>{{32,32},{64,32}},contact_point,contact_normal,t_hit_near)&&t_hit_near<1?YELLOW:WHITE);
		return true;
	}
};


int main()
{
	Example demo;
	if (demo.Construct(128, 120, 8, 8))
		demo.Start();

	return 0;
}