Creating a circular bounding area for the cursor

[ac3raven]

I need to limit cursor movement using a circular bounding area.

Pixelthief: "using polar coordinates would be a good way to do it. Check the distance of the mouse against the center of the circle, and if its larger, find the angle to the center of the cirle, and set it to the maximum distance from the circle * the cosine/sin of that angle"

Where do I start?

[Looki]

I'll give you the mathematic stuff.

| Always
| * Set Distance to Sqr((CenterX-CursorX) pow 2 + (CenterY-CursorY) pow 2)
| Distance > MaxDistance ?
| * Set Angle to Atan2(CenterY-CursorY,CenterX-CursorX)
| * Set CursorX to CenterX+cos(Angle)*MaxDistance
| * Set CursorY to CenterY-sin(Angle)*MaxDistance

Distance, Angle etc. are just variables that could be stored using Global Values, Counters or whatever.

If the angle is wrong, experiment a bit. I'm not sure if it's "-sin" or "+sin" - I haven't tested the code.

[MuddyMole]

I'd use vectors rather than trig, but it doesn't make a lot of difference either way.

+ Always
-> Set Distance to Sqr(((XMouse - XCircle) pow 2) + ((YMouse - YCircle) pow 2))

+ Distance > CircleRadius
-> Set CursorX to XCircle + ((XMouse - XCircle) * CircleRadius / Distance)
-> Set CursorY to YCircle + ((YMouse - YCircle) * CircleRadius / Distance)

+ Distance <= CircleRadius
-> Set CursorX to MouseX
-> Set CursorY to MouseY

Instead of using an extension to move the mouse cursor, it's better to just hide the cursor, and use an active object instead.

[Looki]

Vectors, man. They do magic. I really got to get into them. That code is pretty simple but still, I never would have used something like that. Seems clever.

[ac3raven]

So what is "Distance"?, and where do I put all this math? And what is XCircle and YCircle? and Where do I put Circle Radius? Are all of these just alterable values? If so, I can't name an alterable value "distance" because it is apparently a reserved expression.

I get the math, but how do I do this in Fusion?

[MuddyMole]

Example:
http://cid-b1e7ee094271bbda.office.live.com/self.aspx/Public/mouselimit.mfa


"Distance" is just a temporary variable. Personally, I'd use an active object as a custom mouse cursor, and I'd make "Distance" one of its alterable values.
Alternatively, use a global value, counter, or whatever (it doesn't much matter).
The name is not important - call it "D" or "Dist" or whatever else you like.

"XCircle" and "YCircle" are the X and Y coordinates of a point at the center of the circle. I don't know exactly what you're trying to do, but I'd imagine the circle is probably centered on another object - in which case, you'd just use the X and Y position of that object.
Alternatively, use an alterable value, global value, or whatever (it doesn't much matter).

Assuming the radius is fixed, you can just replace the words "CircleRadius" with the actual value.
Alternatively, use an alterable value, global value, or whatever (it doesn't much matter).