Added point vs polygon collision checking

src/raylib.h

@@ -1130,6 +1130,7 @@ RLAPI bool CheckCollisionPointRec(Vector2 point, Rectangle rec);
 RLAPI bool CheckCollisionPointCircle(Vector2 point, Vector2 center, float radius);                       // Check if point is inside circle
 RLAPI bool CheckCollisionPointTriangle(Vector2 point, Vector2 p1, Vector2 p2, Vector2 p3);               // Check if point is inside a triangle
 RLAPI bool CheckCollisionLines(Vector2 startPos1, Vector2 endPos1, Vector2 startPos2, Vector2 endPos2, Vector2 *collisionPoint); // Check the collision between two lines defined by two points each, returns collision point by reference
+RLAPI bool CheckCollisionPointPolygon(Vector2 polygon[], int vertexCount, Vector2 point);                // Check if point is inside a polygon
 RLAPI Rectangle GetCollisionRec(Rectangle rec1, Rectangle rec2);                                         // Get collision rectangle for two rectangles collision
 
 //------------------------------------------------------------------------------------

src/shapes.c

@@ -68,6 +68,9 @@
 // Module specific Functions Declaration
 //----------------------------------------------------------------------------------
 static float EaseCubicInOut(float t, float b, float c, float d);    // Cubic easing
+static bool OnSegment(Vector2 p, Vector2 q, Vector2 r);
+static int Orientation(Vector2 p, Vector2 q, Vector2 r); 
+static bool DoIntersect(Vector2 p1, Vector2 q1, Vector2 p2, Vector2 q2);
 
 //----------------------------------------------------------------------------------
 // Module Functions Definition
@@ -1521,6 +1524,40 @@ bool CheckCollisionLines(Vector2 startPos1, Vector2 endPos1, Vector2 startPos2,
     return true;
 }
 
+// Another function from GeeksForGeeks
+// Returns true if the point p lies inside the polygon[] with n vertices 
+bool CheckCollisionPointPolygon(Vector2 polygon[], int vertexCount, Vector2 point) 
+{ 
+    // There must be at least 3 vertices in polygon[] 
+    if (vertexCount < 3) return false; 
+ 
+    // Create a point for line segment from p to infinite 
+    Vector2 extreme = {10000, point.y}; 
+ 
+    // Count intersections of the above line with sides of polygon 
+    int count = 0, i = 0; 
+    do
+    { 
+        int next = (i+1)%vertexCount; 
+ 
+        // Check if the line segment from 'p' to 'extreme' intersects 
+        // with the line segment from 'polygon[i]' to 'polygon[next]' 
+        if (DoIntersect(polygon[i], polygon[next], point, extreme)) 
+        { 
+            // If the point 'p' is colinear with line segment 'i-next', 
+            // then check if it lies on segment. If it lies, return true, 
+            // otherwise false 
+            if (Orientation(polygon[i], point, polygon[next]) == 0) return OnSegment(polygon[i], point, polygon[next]); 
+ 
+            count++; 
+        } 
+        i = next; 
+    } while (i != 0); 
+ 
+    // Return true if count is odd, false otherwise 
+    return count&1; // Same as (count%2 == 1) 
+}
+
 // Get collision rectangle for two rectangles collision
 Rectangle GetCollisionRec(Rectangle rec1, Rectangle rec2)
 {
@@ -1602,3 +1639,64 @@ static float EaseCubicInOut(float t, float b, float c, float d)
 
     return 0.5f*c*(t*t*t + 2.0f) + b;
 }
+
+// Point inside polygon checking code
+// Credit to https://www.geeksforgeeks.org/how-to-check-if-a-given-point-lies-inside-a-polygon/
+
+#define INF 10000 
+// Given three colinear points p, q, r, the function checks if 
+// point q lies on line segment 'pr' 
+static bool OnSegment(Vector2 p, Vector2 q, Vector2 r) 
+{ 
+    if (q.x <= fmaxf(p.x, r.x) && q.x >= fminf(p.x, r.x) && 
+            q.y <= fmaxf(p.y, r.y) && q.y >= fminf(p.y, r.y)) 
+        return true; 
+    return false; 
+} 
+ 
+// To find orientation of ordered triplet (p, q, r). 
+// The function returns following values 
+// 0 --> p, q and r are colinear 
+// 1 --> Clockwise 
+// 2 --> Counterclockwise 
+static int Orientation(Vector2 p, Vector2 q, Vector2 r) 
+{ 
+    int val = (q.y - p.y) * (r.x - q.x) - 
+            (q.x - p.x) * (r.y - q.y); 
+ 
+    if (val == 0) return 0; // colinear 
+    return (val > 0)? 1: 2; // clock or counterclock wise 
+} 
+ 
+// The function that returns true if line segment 'p1q1' 
+// and 'p2q2' intersect. 
+static bool DoIntersect(Vector2 p1, Vector2 q1, Vector2 p2, Vector2 q2) 
+{ 
+    // Find the four orientations needed for general and 
+    // special cases 
+    int o1 = Orientation(p1, q1, p2); 
+    int o2 = Orientation(p1, q1, q2); 
+    int o3 = Orientation(p2, q2, p1); 
+    int o4 = Orientation(p2, q2, q1); 
+ 
+    // General case 
+    if (o1 != o2 && o3 != o4) 
+        return true; 
+ 
+    // Special Cases 
+    // p1, q1 and p2 are colinear and p2 lies on segment p1q1 
+    if (o1 == 0 && OnSegment(p1, p2, q1)) return true; 
+ 
+    // p1, q1 and p2 are colinear and q2 lies on segment p1q1 
+    if (o2 == 0 && OnSegment(p1, q2, q1)) return true; 
+ 
+    // p2, q2 and p1 are colinear and p1 lies on segment p2q2 
+    if (o3 == 0 && OnSegment(p2, p1, q2)) return true; 
+ 
+    // p2, q2 and q1 are colinear and q1 lies on segment p2q2 
+    if (o4 == 0 && OnSegment(p2, q1, q2)) return true; 
+ 
+    return false; // Doesn't fall in any of the above cases 
+} 
+
+// End of GeeksForGeeks code