Tweening a point in a circular motion

[puggsoy]

I need to tween FlxPoints in circles, but CircularMotion tweens objects. I can think of ways to work around this, but is there a more proper method of tweening points that I don't know about?

[Gama11]

No, there's no simple way of doing this atm as CircularMotion takes a FlxObject as its argument. This would solvable if FlxObject had a position FlxPoint instead of a separate x and y coordinate...

You could probably achieve similar effects using FlxAngle.rotatePoint() or FlxAngle.getCartesianCoords() in conjunction with polar coordinates, but neither of them seem as convenient.

[puggsoy]

Well, I managed to make a fairly simple workaround by rotating the point using FlxPoint.rotate() every frame using a pre-calculated increment angle (the total angle divided by the framerate times the duration). Do you think such a tween is worth considering though? It would be convenient if anybody else needed it (and I'd definitely use it in this project as well).

[Will Blanton]

Hey - I made this method just for that a while ago: 

 /**
 * Places a child relative to a parent using degrees and angle from the center Point
 * @param CenterX Horizontal value of parent
 * @param CenterY Vertical value of parent
 * @param ANGLE Angle from parent
 * @param RADIUS Radius/Distance from parent
 * @return FlxPoint Position of child
 */
 public static function placeOnCircle(CenterX:Float, CenterY:Float, ANGLE:Float, RADIUS:Int):FlxPoint
 {
 var a:Float = ANGLE * (Math.PI / 180);

 return FlxPoint.get(CenterX + RADIUS * Math.cos(a), CenterY + RADIUS * Math.sin(a));
 }

So this might work for you if you have the center point already.

[puggsoy]

I think FlxPoint.rotate() pretty much does that? Although, that's in the dev branch so it's not in the current stable release.

On Tuesday, 15 July 2014 20:40:20 UTC+12, Will Blanton wrote:

Hey - I made this method just for that a while ago: 

 /**
 * Places a child relative to a parent using degrees and angle from the center Point
 * @param CenterX Horizontal value of parent
 * @param CenterY Vertical value of parent
 * @param ANGLE Angle from parent
 * @param RADIUS Radius/Distance from parent
 * @return FlxPoint Position of child
 */
 public static function placeOnCircle(CenterX:Float, CenterY:Float, ANGLE:Float, RADIUS:Int):FlxPoint
 {
 var a:Float = ANGLE * (Math.PI / 180);

 return FlxPoint.get(CenterX + RADIUS * Math.cos(a), CenterY + RADIUS * Math.sin(a));
 }

So this might work for you if you have the center point already.

On Monday, July 14, 2014 2:47:49 AM UTC-4, puggsoy wrote:

[Gama11]

FlxPoint#rotate() is the same as the current FlxAngle.rotatePoint() (except for some fixes) - it's just been moved.