CODEWITHSUNDEEP
c#wpftelerik
nafarkash
nafarkash

Reputation: 359

Get points on arc with center, start and end points given

I'm trying to find a simple solution for getting a set of points on arc.
My program runs with c#, wpf and telerik.

In my program I have a map, with camera's FOV (field of view) on it.
Till now I had triangular fov , but client wants it with an arc.
I have a center point (camera's origin) with two points representing left and right FOV boundaries.
The points are represented as coordinates.

A draw of what I wish to accomplish

My goal is to gather a set of points on top of the arc which connects the FOV limits (left and right points), which then I'll send to telerik to draw.

some remarks:

  1. I know telerik can draw arc, but it has weird binding problems
  2. I saw some answers (not really helpful) saying to calculate the circle equation and continue from there. I wish to avoid it if possible.

Does c# and Math class has some tools which can help? I tried calculating it by myself, but it got too complicated for me to handle.

Thanks, Naor.

Upvotes: 1

Views: 1528

Answers (1)

Clemens
Clemens

Reputation: 128062

You could use a Path control with an appropriate PathGeometry that contains an ArcSegment.

In the example below, (100,100) is the center point and (50,50) and (150,50) are the start and end points of the arc. Note that the arc is a segment of an ellipse, where the Size property of the ArcSegment specifies the ellipse radii. Here it is a circle of radius 50*sqrt(2).

<Path Stroke="Black">
    <Path.Data>
        <PathGeometry>
            <PathFigure StartPoint="100,100" IsClosed="True">
                <LineSegment Point="50,50"/>
                <ArcSegment Point="150,50" Size="70.7,70.7" SweepDirection="Clockwise"/>
            </PathFigure>
        </PathGeometry>
    </Path.Data>
</Path>

Or shorter:

<Path Stroke="Black" Data="M100,100 L50,50 A70.7,70.7 0 0 1 150,50Z" />

Assuming that your view model has four properties that describe the arc figure like

public Point Center { get; private set; } = new Point(100, 100);
public Point Start { get; private set; } = new Point(50, 50);
public Point End { get; private set; } = new Point(150, 50);
public Size Size { get; private set; } = new Size(70.7, 70.7);

you could write the XAML with Bindings like this:

<PathFigure StartPoint="{Binding Center}" IsClosed="True">
    <LineSegment Point="{Binding Start}"/>
    <ArcSegment Point="{Binding End}" Size="{Binding Size}" SweepDirection="Clockwise"/>
</PathFigure>

You can of course also create such a geometry in code behind.

Upvotes: 1

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