Create Example_-_Orientation_PointvsLine.c

Example_-_Orientation_PointvsLine.c

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+
+#include "raylib.h"
+#include <math.h>
+
+int orientation(int ax,int ay,int bx, int by, int cx, int cy);
+
+int main(void)
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    const int screenWidth = 800;
+    const int screenHeight = 450;
+
+    InitWindow(screenWidth, screenHeight, "raylib example.");
+ 
+    SetTargetFPS(60);               // Set our game to run at 60 frames-per-second
+    //--------------------------------------------------------------------------------------
+
+    Vector2 line1a=(Vector2){200,100};
+    Vector2 line1b=(Vector2){100,200};
+    Vector2 point = (Vector2){300,150};
+
+    // Main game loop
+    while (!WindowShouldClose())    // Detect window close button or ESC key
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+        // Put the point below the mouse.
+        point = GetMousePosition();
+        //----------------------------------------------------------------------------------
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+            ClearBackground(RAYWHITE);
+                
+            // Here we draw the first line.
+            DrawLine(line1a.x,line1a.y,line1b.x,line1b.y,RED);
+            // Draw the Point under the mouse.
+            DrawCircle(point.x,point.y,10,RED);
+
+            // Here we check if the mouse if left or right or on the same path of the line.
+            // line starts at a.xy to b.xy.
+            // This orientation function could be useful for turrets etc.
+            if(orientation(line1a.x,line1a.y,line1b.x,line1b.y,point.x,point.y)==-1)DrawText("left",0,0,20,RED);
+            if(orientation(line1a.x,line1a.y,line1b.x,line1b.y,point.x,point.y)==0)DrawText("Same",0,0,20,RED);
+            if(orientation(line1a.x,line1a.y,line1b.x,line1b.y,point.x,point.y)==1)DrawText("right",0,0,20,RED);
+
+
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+    CloseWindow();        // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+
+
+}
+
+//
+// This is the orientation function. It returns -1 if the point is left of the inputted line.
+// 0 if on the same and 1 if on the right of the line.
+// aa,bb,point
+int orientation(int ax,int ay,int bx, int by, int cx, int cy){
+	if(((bx-ax)*(cy-ay)-(by-ay)*(cx-ax))<0)return -1;
+    if(((bx-ax)*(cy-ay)-(by-ay)*(cx-ax))>0)return 1;
+    return 0;
+}