From db9d393fddf657bef1d336024bc63c26d14e6cdc Mon Sep 17 00:00:00 2001
From: Elkantor <vic03@live.fr>
Date: Mon, 21 Dec 2020 15:11:06 +0100
Subject: [PATCH]  Rework the declaration of the 'Vector2LineIntersect'
 function, and add the 'Vector2SegmentIntersect' function

---
 src/raymath.h | 38 +++++++++++++++++++++++++++++++-------
 1 file changed, 31 insertions(+), 7 deletions(-)

diff --git a/src/raymath.h b/src/raymath.h
index d57a7ba78..b32807a87 100644
--- a/src/raymath.h
+++ b/src/raymath.h
@@ -336,19 +336,43 @@ RMDEF Vector2 Vector2MoveTowards(Vector2 v, Vector2 target, float maxDistance)
     return result;
 }
 
-// Get the intersection point of two lines A and B defined by A(p1, p2) and B(p3, p4)
-RMDEF Vector2 Vector2LineIntersect(Vector2 p1, Vector2 p2, Vector2 p3, Vector2 p4)
+// Get the intersection point of two lines A and B defined by A(p1, p2) and B(p3, p4), return true if it exists, else false
+RMDEF _Bool Vector2 Vector2LineIntersect(Vector2 p1, Vector2 p2, Vector2 p3, Vector2 p4, Vector2* pointIntersection)
 {
-    Vector2 result = { 0 };
     const float div = (p4.y - p3.y)*(p2.x - p1.x) - (p4.x -p3.x)*(p2.y - p1.y);
 
-    if (div == 0.f) return result;
+    if (div == 0.f) return false;
 
     const float coeff = ((p4.x - p3.x)*(p1.y - p3.y) - (p4.y - p3.y)*(p1.x - p3.x)) / div;
 
-    result.x = p1.x + (p2.x - p1.x) * coeff;
-    result.y = p1.y + (p2.y - p1.y) * coeff; 
-    return result;
+    if (pointIntersection)
+    {
+        pointIntersection.x = p1.x + (p2.x - p1.x) * coeff;
+        pointIntersection.y = p1.y + (p2.y - p1.y) * coeff;
+    }
+    return true;
+}
+
+// Get the intersection point of two segments A and B defined by A(p1, p2) and B(P3, p4), return true if it exists, else false
+RMDEF _Bool Vector2SegmentIntersect(Vector2 p1, Vector2 p2, Vector2 p3, Vector2 p4, Vector2* pointIntersection)
+{
+    const float div = (p4.y - p3.y)*(p2.x - p1.x) - (p4.x -p3.x)*(p2.y - p1.y);
+
+    if (div == 0.f) return false;
+
+    const float xi = ((p3.x - p3.x)*(p1.x * p2.y - p1.y * p2.x) - (p1.x - p2.x)*(p3.x * p4.y - p3.y * p4.x)) / div;
+    const float yi = ((p3.y - p4.y)*(p1.x * p2.y - p1.y * p2.x) - (p1.y - p2.y)*(p3.x * p4.y - p3.y * p4.x)) / div;
+
+    if (xi < fminf(x1, x2) || xi > fmaxf(x1, x2)) return false;
+    if (xi < fminf(x3, x4) || xi > fmaxf(x3, x4)) return false;
+	if (yi < fminf(y1, y2) || yi > fmaxf(y1, y2)) return false;
+	if (yi < fminf(y3, y4) || yi > fmaxf(y3, y4)) return false;
+    if (pointIntersection)
+    {
+        pointIntersection->x = xi;
+        pointIntersection->y = yi;
+    }
+    return true;
 }
 
 //----------------------------------------------------------------------------------