Create Collision_-_PolyvsPoly_Collide.c

Collision_-_PolyvsPoly_Collide.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);
+bool polypolycollide(Vector2 poly1[],int as1, Vector2 poly2[], int as2);
+
+int debug=0;
+
+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
+    //--------------------------------------------------------------------------------------
+
+    // Main game loop
+    while (!WindowShouldClose())    // Detect window close button or ESC key
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+        
+        
+        //----------------------------------------------------------------------------------
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+            ClearBackground(RAYWHITE);
+            //
+            // Create a Vector2 array and create some points in it
+            //
+            Vector2 pol1[3];
+            pol1[0] = (Vector2){200,100};
+            pol1[1] = (Vector2){20,300};
+            pol1[2] = (Vector2){280,300};
+            
+            Vector2 pol2[3];
+            pol2[0] = (Vector2){50+GetMouseX()-50,50+GetMouseY()-50};
+            pol2[1] = (Vector2){20+GetMouseX()-50,150+GetMouseY()-50};
+            pol2[2] = (Vector2){90+GetMouseX()-50,150+GetMouseY()-50};
+
+            if(polypolycollide(     pol1,sizeof(pol1)/sizeof(pol1[0]),
+                                    pol2,sizeof(pol2)/sizeof(pol2[0]))==true){
+                DrawText(FormatText("Collision"),0,0,20,RED);
+            }
+
+            DrawText(FormatText("%i",debug),0,20,20,RED);
+            
+            DrawTriangle(pol1[0],pol1[1],pol1[2],RED);
+            DrawTriangle(pol2[0],pol2[1],pol2[2],YELLOW);
+
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+    CloseWindow();        // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+
+
+}
+
+bool polypolycollide(Vector2 poly1[],int as1, Vector2 poly2[], int as2){
+    
+	//'first check if the second polygon is inside the first polygon
+	int x=-5000;
+    int y=-5000;
+	int cnt=0;
+	for(int i=1;i<as1;i++){
+        if(get_line_intersect(  x,
+                                y,
+                                poly2[0].x,
+                                poly2[0].y,
+                                poly1[i-1].x,
+                                poly1[i-1].y,
+                                poly1[i].x,
+                                poly1[i].y))cnt++;
+	}
+    if(get_line_intersect(      x,y,
+                                poly2[0].x,poly2[0].y,
+                                poly1[as1-1].x,poly1[as1-1].y,
+                                poly1[0].x,poly1[0].y))cnt++;
+    
+    if( (cnt % 2) > 0 )return true;
+    
+    
+
+	//'Now check if the first polygon is inside the second polygon
+	x=-5000;
+	y=-5000;
+	cnt=0;
+	for(int i=1;i<as2;i++){
+		if(get_line_intersect(      x,y,
+                                    poly1[0].x,poly1[0].y,
+                                    poly2[i-1].x,poly2[i-1].y,
+                                    poly2[i].x,poly2[i].y))cnt++;
+	}
+	if(get_line_intersect(      x,y,
+                                poly1[0].x,poly1[0].y,
+                                poly2[as2-1].x,
+                                poly2[as2-1].y,
+                                poly2[0].x,poly2[0].y))cnt++;
+	//'
+	if((cnt % 2) > 0)return true;
+
+	//'
+	//' Now check if any of the lines of the two polygons touch
+    for(int i=1;i<as1;i++){
+    for(int j=1;j<as2;j++){
+		if(get_line_intersect(      poly2[j-1].x,poly2[j-1].y,
+                                    poly2[j].x,poly2[j].y,
+                                    poly1[i-1].x,poly1[i-1].y,
+                                    poly1[i].x,poly1[i].y))return true;
+    }}
+    for(int j=1;j<as2;j++){
+		if(get_line_intersect(  poly2[j-1].x,poly2[j-1].y,
+                                poly2[j].x,poly2[j].y,
+                                poly1[0].x,poly1[0].y,
+                                poly1[as1-1].x,poly1[as1-1].y))return true;
+	}
+    for(int j=1;j<as1;j++){
+		if(get_line_intersect(  poly1[j-1].x,poly1[j-1].y,
+                                poly1[j].x,poly1[j].y,
+                                poly2[0].x,poly2[0].y,
+                                poly2[as2-1].x,poly2[as2-1].y))return true;
+    }
+	//'There was no Collision between the two polygons ___ Return
+	return false;
+}
+
+// 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    
+}