My goal is to detect the different regions within a simple drawing constructed of various lines. Please click the following link to view a visual example of my goal for clarification. I am of course able to get the position of the drawn lines, but since one line can cross multiple 'regions' I don't think this information alone will be sufficient.
Any ideas, suggestions or points to other websites are welcome. I am using C# in combination with WPF - I am not certain which search words might lead to an answer to this problem. I did come across this shape checker article from AForge, but it seems to focus on detecting shapes that are already there, not so much on regions that still have to be 'discovered'. As a side note, I hope to find a solution that works not only with rectangles but also with other types of shapes.
Thank you very much in advance.
Update:
foreach (Line canvasObject in DrawingCanvas.Children.OfType<Line>())
{
LineGeometry lineGeometry1 = new LineGeometry();
lineGeometry1.StartPoint = new Point(canvasObject.X1, canvasObject.Y1);
lineGeometry1.EndPoint = new Point(canvasObject.X2, canvasObject.Y2);
if (canvasObject.X1 != canvasObject.X2) {
foreach (Line canvasObject2 in DrawingCanvas.Children.OfType<Line>()) {
if (canvasObject.X1 == canvasObject2.X1 && canvasObject.X2 == canvasObject2.X2 &&
canvasObject2.Y1 == canvasObject2.Y2 && canvasObject.Y2 == canvasObject2.Y2) {
return;
// prevent the system from 'colliding' the same two lines
}
LineGeometry lineGeometry2 = new LineGeometry {
StartPoint = new Point(canvasObject2.X1, canvasObject2.Y1),
EndPoint = new Point(canvasObject2.X2, canvasObject2.Y2)
};
if (lineGeometry1.FillContainsWithDetail(lineGeometry2).ToString() != "Empty") {
//collision detected
Rectangle rectangle = new Rectangle {
Width = Math.Abs(canvasObject.X2 - canvasObject.X1),
Height = 20,
Fill = Brushes.Red
};
//rectangle.Height = Math.Abs(canvasObject.Y2 - canvasObject.Y1);
DrawingCanvas2.Children.Add(rectangle);
Canvas.SetTop(rectangle, canvasObject.Y1);
Canvas.SetLeft(rectangle, canvasObject.X1);
}
}
}
}
I have experimented with the following code - to give you an impression of how I tried to tackle this problem. Initially I thought I had found a partial solution, by checking for collision between lines. Unfortunately I just created a second line of each line (which of course collided 'with itself'). After I added a simple if check (see below) this no longer occurs, but now I don't get any collisions anymore.. so will probably need a new technique.
Update 2:
After some more digging and searching the internet for solutions, I have a new potential solution in mind. Hopefully this can also be of use to anyone looking for answers in the future. Using a flood-fill algorithm I am able to 'fill' each region with a specific color - much like the paint bucket tool in an image editing application. Summarized, this done by taking a 'screenshot' of the Canvas element, starting at a certain pixel and expanding over and over until a pixel with a different color is found (these would be the lines). It works pretty well and is able to return an image with the various regions. However - my current problem is accessing these regions as 'objects' in C#/WPF. I would like to draw the regions myself (using polyobject or something similar?) - making it possible to use the objects for further calculations or interactions.
I have tried saving the position of the smallest and largest X and Y positions in the FloodFill algorithm after each pixel check, but this makes the algorithm work very very slow. If anyone has an idea, I would love to know. :)
