Question

I am drawing a triangle with the following code

int x = x coordinate for center; int ax = x coordinate for left; int bx = x coordinate for right; int top = y coordinate for top; int bottom = y coordinate for bottom;  //           (x, top) //(ax, bottom)      (bx, bottom)   GraphicsPath path = new GraphicsPath(); // _ path.AddLine(ax, bottom, bx, bottom); // / path.AddLine(ax, bottom, x, top); // \ path.AddLine(bx, bottom, x, top); // order of drawing is _ / \ (bottom line, left side, right side) 

When I call DrawPath, it always draws my lines, no matter the order. But when I call FillPath, it does nothing. Only when my order is / _ \ or \ _ / does my triangle actually fill. Why is this?

Answer 1

It turns out that the answer I posted originally didn’t really solve the problem and that it worked on my machine because of an additional change I introduced, which is to change the FillMode:

GraphicsPath path = new GraphicsPath(FillMode.Winding); 

When you use the Winding mode, the algorithm will detect a closed path even if you didn’t add the lines in order.