Implemented project(c,t) (project circle onto triangle via a ray). Updated a demo for testing

Author: Illia

TEST_Geometry2D.cpp

@@ -8,6 +8,7 @@
 #include "third_party/olcPGEX_QuickGUI.h"
 
 #include <variant>
+#include <optional>
 
 
 using namespace olc::utils::geom2d;
@@ -156,6 +157,29 @@ class Test_Geometry2D : public olc::PixelGameEngine
 		return std::visit(dispatch, s1, s2);
 	}
 
+	std::optional<olc::v_2d<float>> CheckProject(const ShapeWrap& s1, const ShapeWrap& s2, const ShapeWrap& s3)
+	{
+		const auto dispatch = overloads{
+			
+			[](const auto& s1, const auto& s2, const auto& s3)
+			{
+				return std::optional<olc::v_2d<float>>{};
+			},
+
+			[](const Circle& s1, const Rect& s2, const Ray& s3)
+			{
+				return project(make_internal(s1), make_internal(s2), make_internal(s3));
+			},
+
+			[](const Circle& s1, const Triangle& s2, const Ray& s3)
+			{
+				return project(make_internal(s1), make_internal(s2), make_internal(s3));
+			}
+		};
+
+		return std::visit(dispatch, s1, s2, s3);
+	}
+
 	std::optional<ray<float>> CheckReflect(const olc::utils::geom2d::ray<float>& s1, const ShapeWrap& s2)
 	{
 		const auto dispatch = overloads{
@@ -319,6 +343,9 @@ class Test_Geometry2D : public olc::PixelGameEngine
 
 
 		bool bRayMode = false;
+		std::vector<std::optional<olc::v_2d<float>>> projected_circle_left_ray;
+		std::vector<std::optional<olc::v_2d<float>>> projected_circle_right_ray;
+
 		if (GetMouse(1).bHeld)
 		{
 			// Enable Ray Mode
@@ -344,6 +371,15 @@ class Test_Geometry2D : public olc::PixelGameEngine
 			vIntersections.insert(vIntersections.end(), vPoints3.begin(), vPoints3.end());
 
 
+			for (const auto& shape : vecShapes)
+			{
+				if(std::holds_alternative<Rect>(shape) || std::holds_alternative<Triangle>(shape))
+				{
+					projected_circle_left_ray.push_back(CheckProject(Circle{ { { 130.0f, 20.0f }, {150.0f, 20.0f} } }, shape, ray1));
+					projected_circle_right_ray.push_back(CheckProject(Circle{ { { 130.0f, 20.0f }, {150.0f, 20.0f} } }, shape, ray2));
+				}
+			}
+			
 		}
 
 		// Draw All Shapes
@@ -373,6 +409,22 @@ class Test_Geometry2D : public olc::PixelGameEngine
 		{
 			DrawShape(ray1, olc::CYAN); 
 			DrawShape(ray2, olc::CYAN);
+
+			for(const auto& projection : projected_circle_left_ray)
+			{
+				if (projection.has_value())
+				{
+					DrawCircle(projection.value(), 20.0f, olc::CYAN);
+				}
+			}
+			
+			for (const auto& projection : projected_circle_right_ray)
+			{
+				if (projection.has_value())
+				{
+					DrawCircle(projection.value(), 20.0f, olc::RED);
+				}
+			}
 		}
 
 		// Laser beam		

olcUTIL_Geometry2D.h

@@ -164,7 +164,7 @@
              | closest      | closest      |              |              |              |              |
              | overlaps     | overlaps     | overlaps     | overlaps     | overlaps     |              |
              | intersects   | intersects   | intersects   | intersects   | intersects   |              |
-             | project      | project      |              | project      |              |              |
+             | project      | project      | project      | project      | project      |              |
     ---------+--------------+--------------+--------------+--------------+--------------+--------------+
     TRIANGLE | contains     | contains     | contains     | contains     | contains     |              |
              | closest      |              |              |              |              |              |
@@ -2184,8 +2184,35 @@ namespace olc::utils::geom2d
 	template<typename T1, typename T2, typename T3>
 	inline std::optional<olc::v_2d<T2>> project(const circle<T1>& c, const triangle<T2>& t, const ray<T3>& q)
 	{
-		// TODO:
-		return std::nullopt;
+		const auto s1 = project(c, t.side(0), q);
+		const auto s2 = project(c, t.side(1), q);
+		const auto s3 = project(c, t.side(2), q);
+
+		std::vector<olc::v_2d<T2>> vAllIntersections;
+		if (s1.has_value()) vAllIntersections.push_back(s1.value());
+		if (s2.has_value()) vAllIntersections.push_back(s2.value());
+		if (s3.has_value()) vAllIntersections.push_back(s3.value());
+
+		if (vAllIntersections.size() == 0)
+		{
+			// No intersections at all, so
+			return std::nullopt;
+		}
+
+		// Find closest
+		double dClosest = std::numeric_limits<double>::max();
+		olc::v_2d<T2> vClosest;
+		for (const auto& vContact : vAllIntersections)
+		{
+			double dDistance = (vContact - q.origin).mag2();
+			if (dDistance < dClosest)
+			{
+				dClosest = dDistance;
+				vClosest = vContact;
+			}
+		}
+
+		return vClosest;
 	}
 
 
@@ -2457,10 +2484,11 @@ namespace olc::utils::geom2d
 			if (s2 < 0)
 				return { q.origin + q.direction * s1 };
 
-			return { q.origin + q.direction * std::min(s1, s2) };
+			const auto& [min_dist, max_dist] = std::minmax(s1, s2);
+			return { q.origin + q.direction * min_dist, q.origin + q.direction * max_dist };
 		}
 	}
-
+	
 	// intersects(q,r)
 	// Get intersection points where a ray intersects a rectangle
 	template<typename T1, typename T2>