Create Collision_-_Get_Lines_Intersect.c

Collision_-_Get_Lines_Intersect.c

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+
+#include "raylib.h"
+
+bool get_line_intersect(float p0_x, float p0_y, float p1_x, float p1_y, float p2_x ,float p2_y, float p3_x, float p3_y);
+
+int main(void)
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    const int screenWidth = 800;
+    const int screenHeight = 450;
+
+    InitWindow(screenWidth, screenHeight, "raylib example.");
+
+    // Create 4 vectors for 2 lines..
+    Vector2 line1a=(Vector2){100,100};
+    Vector2 line1b=(Vector2){200,200};
+    Vector2 line2a;
+    Vector2 line2b;
+ 
+    SetTargetFPS(60);               // Set our game to run at 60 frames-per-second
+    //--------------------------------------------------------------------------------------
+
+    // Main game loop
+    while (!WindowShouldClose())    // Detect window close button or ESC key
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+        
+        // The second line is below the mouse pointer.
+        line2a.x = GetMouseX();
+        line2a.y = GetMouseY();
+        line2b.x = line2a.x - 100;
+        line2b.y = line2a.y + 100;
+        
+        //----------------------------------------------------------------------------------
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+            ClearBackground(RAYWHITE);
+                    
+               
+            // Here we draw the first line.
+            DrawLine(line1a.x,line1a.y,line1b.x,line1b.y,RED);
+            // Here we draw the second line, the one below the mouse pointer.
+            DrawLine(line2a.x,line2a.y,line2b.x,line2b.y,GREEN);
+            
+            // Here we check if the two lines on the screen touch each other.
+            if(get_line_intersect(line1a.x,line1a.y,line1b.x,line1b.y,line2a.x,line2a.y,line2b.x,line2b.y)){
+                DrawText("Collision between lines!!",0,0,40,RED); // Let the user know there has been a collision.
+            }else{ // If no lines touch then show a message.
+                DrawText("Move the mouse line on the other line!!",0,0,20,BLACK);
+            }
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+    CloseWindow();        // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+
+
+}
+
+// This function was originally by andre la moth.
+bool get_line_intersect(float p0_x, float p0_y, float p1_x, float p1_y, float p2_x ,float p2_y, float p3_x, float p3_y){
+    float s1_x;
+    float s1_y; 
+    float s2_x; 
+    float s2_y;
+    
+    s1_x = p1_x - p0_x;     
+    s1_y = p1_y - p0_y;
+    s2_x = p3_x - p2_x;
+    s2_y = p3_y - p2_y;
+
+    float s;
+    float t;
+    
+    s = (-s1_y * (p0_x - p2_x) + s1_x * (p0_y - p2_y)) / (-s2_x * s1_y + s1_x * s2_y);
+    t = ( s2_x * (p0_y - p2_y) - s2_y * (p0_x - p2_x)) / (-s2_x * s1_y + s1_x * s2_y);
+
+    if(s >= 0 && s <= 1 && t >= 0 && t <= 1) return true;
+    
+    return false; // No collision    
+}