koobas.hobune.stream
How to keep an object within a circle/sphere (radius) - NO RECTANGLE
To limit movement in a rectangle, it is easy
if (newLocation.x > maxPosition)
{
newLocation.x = maxPosition;
}
else if (newLocation.x < -maxPosition)
{
newLocation.x = -maxPosition;
}
if (newLocation.z > maxPosition)
{
newLocation.z = maxPosition;
}
else if (newLocation.z < -maxPosition)
{
newLocation.z = -maxPosition;
}
However, whenever you want to keep these boundaries in a CIRCLE, rather than a RECTANGLE, it becomes mathematically complex (for those like me who haven't taken a math course in over a decade).
How do I limit movement in a circle, rather than a rectangle? Unity's functions don't see to help. I even tried complex things like using a SphereCollider and ClosestPointOnBounds (which returns for a rectangle...even when used with a SphereCollider)
float radius = 400; //radius of *black circle*
Vector3 centerPosition = transform.localPosition; //center of *black circle*
float distance = Vector3.Distance(newLocation, centerPosition); //distance from ~green object~ to *black circle*
if (distance > radius) //If the distance is less than the radius, it is already within the circle.
{
Vector3 fromOriginToObject = newLocation - centerPosition; //~GreenPosition~ - *BlackCenter*
fromOriginToObject *= radius / distance; //Multiply by radius //Divide by Distance
newLocation = centerPosition + fromOriginToObject; //*BlackCenter* + all that Math
}
If the distance is < radius, it is within the circle. No need for any calculations. If the distance is > radius, the object is outside the circle.
Determine the center position of the circle/radius. The radius of this circle is also the maximum limit.
Determine the distance between point A (circle/bounds) and B (object you want to limit; prevent movement outside of bounds A).
If the distance is greater than the radius, then do the following:
Get Vector3 U from B (object) minus A (circle). (U = B - A)
Multiply by Radius (U x Radius)
Divide by Distance (U / Distance)
Position = U + A (maxLocation = U + A)
Thanks so much!
Only one thing, at least for me, I needed to add
newLocation = centerPosition + fromOriginToObject; //*BlackCenter* + all that $$anonymous$$ath
//ADDED CODE
transform.position = newLocation;
I use mouse position to update green objects position. At first this didnt work, but I looked at logs and figured out I need to put void, that gets the mouse Input, in Update, not LateUpdate (I red that it needs to be in LateUpdate). Worked perfectly after that!
I've been struggling with this for a long time in unity 3d. With the help from CarterG81 and Edisyo (thanks!) I got the following code:
public Transform player; // get the player transform, or w/e object you want to limit in a circle
public Vector3 circleCenter; // this is a location that is set to the middle of my world, it will be the center of your circle.
Void Update()
{
float radius 20f; // this is the range you want the player to move without restriction
float dist = Vector3.Distance(player.position, circleCenter); // the distance from player current position to the circleCenter
if (dist > radius)
{
Vector3 fromOrigintoObject = player.position - circleCenter;
fromOrigintoObject *= radius / dist;
player.position = circleCenter + fromOrigintoObject;
transform.position = player.position;
}
}
}
Any chance we can get a working example of this? Like what if I wanted to place the object in a random position within this circle?
You can instantiate the object/objects from a random position inside the circle, with Random.Range
Well, don't use max / min positions as they define a rectangle. What you want is defining a center point and a radius. Then just use Vector3.ClampMagnitude on the relative vector:
// C#
Vector3 v = newLocation - circleCenter;
v = Vector3.ClampMagnitude(v, circleRadius);
newLocation = circleCenter + v;
If the circle center and your location is not on the same "height" (y value) you can do:
// C#
circleCenter.y = newLocation.y;
Vector3 v = newLocation - circleCenter;
v = Vector3.ClampMagnitude(v, circleRadius);
newLocation = circleCenter + v;
Thank you. Your answer was so incredibly quick, I wasn't able to put my own in fast enough. I was trying to document this for others, because I found this question difficult to answer but finally found an answer myself.
I apologize for this. Thank you for this alternative.
Thank you! You just mentioning Vector3.Clamp$$anonymous$$agnitude helped me so much, I managed to fix my issue!
Hi, I would simply check the distance. I´m correct in the assumption, that we´re in the two-dimensional-space?
Vector2 center;
Vector2 position;
float maxDistance;
float actualDistance = Vector2.Distance(center, position);
if (actualDistance > maxDistance)
{
Vector2 centerToPosition = position - center;
centerToPosition.Normalize();
position = center + centerToPosition * maxDistance;
}
I actually use this for 2D game in a 3D game world. It was to "build structures" in the game; a form of crafting or equivalent of a RTS game where you move your mouse around to place buildings down at specific coordinates.
It works fine in a 3D world, if you are able to handle your Y-Axis ($$anonymous$$e was always 0, so no problem here).
I initially needed to convert $$anonymous$$ouse Coordinates into 3D world coordinates. However Unity's conversion of $$anonymous$$ouse to World coordinates was very jittery. ($$anonymous$$oving the mouse wouldn't necessarily move the world coordinates, resulting in huge jumps in world coordinates, no matter what method I tried, including raycasting).
So I ended up just attaching an object to the player, and then attaching a sprite (of what the player is trying to build) to that object (what is in essence a gameobject that acts as a mouse cursor, but for joystick controllers). This "cursor gameobject" moves in the X/Z axis in 3D world space, based on the code I posted.
Eventually I will figure out how to get smooth mouse to world coordinate conversion, and then simply (if not a controller/joystick) move said "cursor gameobject" based on mouse coordinates.
