Circular Cursor Lock

[Ethan-Taylor]

Hey Guys,
I was wondering how I would make the cursor locked to a circle around my player?
So If you move your cursor around the cursor stays locked to a circle path around the player.

I should've listened to all those maths lessons XD

Anyway,
Thanks!

[bobbyjones]

I would just do two circle collision checks but I'm sure that is the hacky way of doing things. Another option would just be to use atan2 and the coord of the mouse and the coord of the player to get an angle. And then just use the radius, angle,sin and cos to get the new coords at the distance needed. I said this quite briefly as I haven't programmed in awhile and not at a pc to test. But I hope this is enough to help you figure it out.

[Ethan-Taylor]

I would just do two circle collision checks but I'm sure that is the hacky way of doing things. Another option would just be to use atan2 and the coord of the mouse and the coord of the player to get an angle. And then just use the radius, angle,sin and cos to get the new coords at the distance needed. I said this quite briefly as I haven't programmed in awhile and not at a pc to test. But I hope this is enough to help you figure it out.

Can you write a set of instructions?
Example :

xcursorlock = atan(blah blah blah blah) ...

Thanks

[s-ol]

You can try setting the mouse back into the circle every frame, but that can be laggy/glitchy/buggy. Alternatively enable relative mode and draw a virtual cursor yourself.

The math is rather easy, get the vector between center of the screen and mousepos, then clamp that to the radius.

[Ethan-Taylor]

You can try setting the mouse back into the circle every frame, but that can be laggy/glitchy/buggy. Alternatively enable relative mode and draw a virtual cursor yourself.

The math is rather easy, get the vector between center of the screen and mousepos, then clamp that to the radius.

Here's a diagram. The orange circle is the cursor and the black line is the path it's locked to.
The purple square is the player. When you move the cursor around it stays locked to the path.

Any code will help.

Thanks.

[micha]

Lets say the player is at coordinates (px,py) and the mouse at (mx,my) and the desired radius is r then you can calculate the coordinates you are looking for like this:

Code: Select all

function getPositionOnCircle(px,py,mx,my,r)
  local dx,dy = mx-px, my-py
  local dist = math.sqrt(dx^2+dy^2)
  if  dist > r then
    return px + dx/dist*r, py + dy/dist*r
  else
    return px,py
  end
end

You don't need trigonometry, only Pythagoras Theorem. The code basically calculates the distance between mouse and player and if it larger than the given radius, divides the distance vector by the distance and multiplies by the radius.

[bobbyjones]

micha what about less than?

[micha]

micha what about less than?

In that case, the function returns the actual mouse coordinates. That means that the mouse can freely move inside the circle, but if it is outside, the mouse position is corrected.

I noticed an error I made in the previous code snippet. This is the corrected version.

Code: Select all

function getPositionOnCircle(px,py,mx,my,r)
  local dx,dy = mx-px, my-py
  local dist = math.sqrt(dx^2+dy^2)
  if  dist > r then
    return px + dx/dist*r, py + dy/dist*r
  else
    return mx,my
  end
end

[Ethan-Taylor]

micha what about less than?

In that case, the function returns the actual mouse coordinates. That means that the mouse can freely move inside the circle, but if it is outside, the mouse position is corrected.

I noticed an error I made in the previous code snippet. This is the corrected version.

Code: Select all

function getPositionOnCircle(px,py,mx,my,r)
  local dx,dy = mx-px, my-py
  local dist = math.sqrt(dx^2+dy^2)
  if  dist > r then
    return px + dx/dist*r, py + dy/dist*r
  else
    return mx,my
  end
end

Thanks, This is what I was looking for