From 21b7a0b2f61cdf579ba9189dc8514243c8ebf9a4 Mon Sep 17 00:00:00 2001
From: Syntriax <Syntriax@gmail.com>
Date: Wed, 6 Dec 2023 11:24:49 +0300
Subject: [PATCH] Updated Physics Methods

---
 Game/Physics2D/PhysicsMath.cs | 51 ++++++++++++++++++++++++-----------
 1 file changed, 36 insertions(+), 15 deletions(-)

diff --git a/Game/Physics2D/PhysicsMath.cs b/Game/Physics2D/PhysicsMath.cs
index 9986d33..54cf2cc 100644
--- a/Game/Physics2D/PhysicsMath.cs
+++ b/Game/Physics2D/PhysicsMath.cs
@@ -7,6 +7,7 @@ using Microsoft.Xna.Framework;
 namespace Syntriax.Engine.Physics2D;
 
 public record Line(Vector2 From, Vector2 To);
+public record LineEquation(float Slope, float OffsetY);
 public record Triangle(Vector2 A, Vector2 B, Vector2 C);
 public record Circle(Vector2 Center, double Radius);
 
@@ -16,14 +17,14 @@ public static class PhysicsMath
         => ((q0.X - p0.X) * (p1.Y - p0.Y) - (q0.Y - p0.Y) * (p1.X - p0.X)) /
             ((q1.Y - q0.Y) * (p1.X - p0.X) - (q1.X - q0.X) * (p1.Y - p0.Y));
 
-    public static float IntersectionParameterT(Line l1, Line l2)
+    public static float IntersectionParameterT(this Line l1, Line l2)
         => ((l2.From.X - l1.From.X) * (l1.To.Y - l1.From.Y) - (l2.From.Y - l1.From.Y) * (l1.To.X - l1.From.X)) /
             ((l2.To.Y - l2.From.Y) * (l1.To.X - l1.From.X) - (l2.To.X - l2.From.X) * (l1.To.Y - l1.From.Y));
 
-    public static Vector2 GetIntersectionPoint(Line l1, Line l2)
+    public static Vector2 IntersectionPoint(this Line l1, Line l2)
         => Vector2.Lerp(l1.From, l1.To, IntersectionParameterT(l1, l2));
 
-    public static Vector2 ClosestPointOnLine(Vector2 point, Line line)
+    public static Vector2 ClosestPointTo(this Line line, Vector2 point)
     {
         // Convert edge points to vectors
         var edgeVector = new Vector2(line.To.X - line.From.X, line.To.Y - line.From.Y);
@@ -42,14 +43,14 @@ public static class PhysicsMath
         return new Vector2((float)closestX, (float)closestY);
     }
 
-    public static double GetArea(Triangle triangle)
+    public static double GetArea(this Triangle triangle)
     {
         return Math.Abs((triangle.A.X * (triangle.B.Y - triangle.C.Y) +
                          triangle.B.X * (triangle.C.Y - triangle.A.Y) +
                          triangle.C.X * (triangle.A.Y - triangle.B.Y)) * .5f);
     }
 
-    public static bool IsInTriangle(Vector2 point, Triangle triangle)
+    public static bool IsPointInside(this Triangle triangle, Vector2 point)
     {
         double A = GetArea(triangle);
         /* Calculate area of triangle ABC */
@@ -99,7 +100,7 @@ public static class PhysicsMath
         return (val > 0) ? 1 : 2; // clock or counterclock wise 
     }
 
-    public static bool DoIntersect(Line l1, Line l2)
+    public static bool Intersects(this Line l1, Line l2)
     {
         int o1 = Orientation(l1.From, l1.To, l2.From);
         int o2 = Orientation(l1.From, l1.To, l2.To);
@@ -117,19 +118,19 @@ public static class PhysicsMath
         return false;
     }
 
-    public static bool DoIntersect(Line l1, Line l2, [NotNullWhen(returnValue: true)] out Vector2? point)
+    public static bool Intersects(this Line l1, Line l2, [NotNullWhen(returnValue: true)] out Vector2? point)
     {
         point = null;
 
-        bool result = DoIntersect(l1, l2);
+        bool result = Intersects(l1, l2);
 
         if (result)
-            point = GetIntersectionPoint(l1, l2);
+            point = IntersectionPoint(l1, l2);
 
         return result;
     }
 
-    public static Circle GetCircumCircle(Triangle triangle)
+    public static Circle ToCircumCircle(this Triangle triangle)
     {
         Vector2 midAB = (triangle.A + triangle.B) / 2;
         Vector2 midBC = (triangle.B + triangle.C) / 2;
@@ -150,7 +151,7 @@ public static class PhysicsMath
         return new(center, Vector2.Distance(center, triangle.A));
     }
 
-    public static Triangle GetSuperTriangle(IList<Vector2> vertices)
+    public static Triangle ToSuperTriangle(IList<Vector2> vertices)
     {
         double minX = double.MaxValue, minY = double.MaxValue;
         double maxX = double.MinValue, maxY = double.MinValue;
@@ -176,14 +177,14 @@ public static class PhysicsMath
         return new Triangle(p1, p2, p3);
     }
 
-    public static List<Line> GetLines(IList<Vector2> vertices)
+    public static List<Line> ToLines(IList<Vector2> vertices)
     {
         List<Line> lines = new List<Line>(vertices.Count - 1);
-        GetLines(vertices, lines);
+        ToLines(vertices, lines);
         return lines;
     }
 
-    public static void GetLines(IList<Vector2> vertices, IList<Line> lines)
+    public static void ToLines(IList<Vector2> vertices, IList<Line> lines)
     {
         lines.Clear();
         for (int i = 0; i < vertices.Count - 1; i++)
@@ -191,7 +192,7 @@ public static class PhysicsMath
         lines.Add(new(vertices[^1], vertices[0]));
     }
 
-    public static bool DoesLineExistInVertices(Line lineToCheck, List<Vector2> vertices)
+    public static bool ExistIn(Line lineToCheck, List<Vector2> vertices)
     {
         for (int i = 0; i < vertices.Count - 1; i++)
         {
@@ -207,4 +208,24 @@ public static class PhysicsMath
         if (lineToCheck.From == vertexLast && lineToCheck.To == vertexFirst) return true;
         return false;
     }
+
+    public static bool LaysOn(this Vector2 point, Line line)
+    {
+        LineEquation lineEquation = line.ToLineEquation();
+
+        // y = mx + b
+        float y = lineEquation.Slope * point.X + lineEquation.OffsetY;
+
+        return y == point.Y;
+    }
+
+    public static LineEquation ToLineEquation(this Line line)
+    {
+        Vector2 slopeVector = line.To - line.From;
+        float slope = slopeVector.Y / slopeVector.X;
+
+        float yOffset = line.From.Y - (slope * line.From.X);
+
+        return new LineEquation(slope, yOffset);
+    }
 }