koobas.hobune.stream
Find point of top of rotated sprite
So, I have this object that 'orbits' around a planet object. I need to determine if the top of the object is closer to the epicentre of the planet or if the bottom of the object is closer. I have the following code, however it is simply not working:
Bounds theBounds = spriteRenderer.bounds;
//float angle = transform.rotation.eulerAngles.z;
float angle = Mathf.Deg2Rad*transform.rotation.eulerAngles.z;
Vector2 topBus = new Vector2(transform.position.x * Mathf.Cos(angle), transform.position.y+theBounds.extents.y * Mathf.Sin(angle));
Vector2 bottomBus = new Vector2(transform.position.x * Mathf.Cos(angle), transform.position.y-theBounds.extents.y * Mathf.Sin(angle));
if(Vector2.Distance(topBus,planet.transform.position) < Vector2.Distance(bottomBus,planet.transform.position))
{
rotationDirection = -90;
}
else
{
rotationDirection = 90;
}
I am completely stumped over why this is not working. I was wondering if I could get a pointer over what's wrong or alternative code that would work.
Thanks a lot!
Best Answer
I have found a solution to my problem after a great deal of Google searching. There was a mistake in the formula used to calculate the actual points.
The correct code is:
//Class to hold the function in for simplicity´s sake.
public class SpriteTools
{
//float angle: the angle of rotation (if any) for our sprite.
//Vector 2 pivot: the pivot from which the sprite is rotating (usually the transform)
//Vector2 point: the point (using relative sprite x and y) that we wish to calculate.
public static Vector2 returnWorldSpacePointFromSprite(Vector2 pivot,Vector2 point,float angle = 0.0f)
{
return new Vector2((point.x - pivot.x) * Mathf.Cos(angle) - (point.y - pivot.y) * Mathf.Sin(angle) + pivot.x,(point.y - pivot.y) * Mathf.Cos(angle) + (point.x - pivot.x) * Mathf.Sin(angle) + pivot.y);
}
}
Example usage:
Bounds theBounds = spriteRenderer.bounds;
float angle = Mathf.Deg2Rad*transform.rotation.eulerAngles.z;
Vector2 topBus = SpriteTools.returnWorldSpacePointFromSprite((Vector2)transform.position,new Vector2(transform.position.x,transform.position.y+theBounds.extents.y),angle);
Vector2 bottomBus = SpriteTools.returnWorldSpacePointFromSprite((Vector2)transform.position,new Vector2(transform.position.x,transform.position.y-theBounds.extents.y),angle);
if(Vector2.Distance(topBus,planet.transform.position) > Vector2.Distance(bottomBus,planet.transform.position))
{
rotationDirection = -90;
}
else
{
rotationDirection = 90;
}
Do note that this code won't account for sprites that are scaled up or down but it can be easily modified to do so.
