omnidirectional lines

graphics.c

@@ -38,32 +38,42 @@ void dot(Canvas* c, uint x, uint y){
  * Draws a line from (start_x, start_y) to (end_x, end_y)
  */
 void line(Canvas* c, uint start_x, uint start_y, uint end_x, uint end_y){
-#ifndef abs
-#define abs(x) ((x<0)?(-x):(x))
-	int dx = abs(end_x - start_x);
-	int dy = abs(end_y - start_y);
+	int dx = end_x - start_x;
+	int dy = end_y - start_y;
+	if (dx<0) dx *= -1;
+	if (dy<0) dy *= -1;
+	dx++;
+	dy++;
+
+	if((dx>=dy && start_x>end_x) || ( dx<dy && start_y>end_y)){
+			int temp;
+
+			temp = end_x;
+			end_x = start_x;
+			start_x = temp;
+			
+			temp = end_y;
+			end_y = start_y;
+			start_y = temp;
+	}
 
 	int direction_x = start_x < end_x ? 1 : -1;
 	int direction_y = start_y < end_y ? 1 : -1;
 
-	printf("dx:%i dy:%i direction:%i,%i  \n", dx, dy, direction_x, direction_y);
-
 	if(dx>=dy){
 		float small = direction_y * (float)dy/(float)dx;
 		
-		for(int i=0; i<dx+1; i++){
+		for(int i=0; i<dx; i++){
 			dot(c, start_x + i*direction_x, start_y + i*small);
 		}
 	}else{
 		float small = direction_x * (float)dx/(float)dy;
 		
-		for(int i=0; i<dy+1; i++){
+		for(int i=0; i<dy; i++){
 			dot(c, start_x + i*small, start_y + i*direction_y);
 		}
 	}
 
-#undef abs
-#endif
 }
 
 
@@ -83,11 +93,10 @@ int main(){
 	Canvas a = {10, 10, data};
 
 	//line(&a, 1, 1, 8, 8);
-	line(&a, 8, 8, 1, 1);
-	//line(&a, 5, 5, 8, 8);
+	//line(&a, 8, 8, 1, 1);
+	//line(&a, 0, 5, 8, 8);
+	line(&a, 8, 8, 0, 5);
 
-	dot(&a, 0, 0);
-	dot(&a, 9, 9);
 
 	render(&a);