public static void DrawFlatArrow(UnityEngine.Vector3 center, UnityEngine.Vector3 direction, UnityEngine.Vector3 forward, float handleSize)
{
var matrix = SceneHandles.matrix;
SceneHandles.matrix = UnityEngine.Matrix4x4.identity;
center = matrix.MultiplyPoint(center);
var xdir = matrix.MultiplyVector(direction).normalized;
var ydir = Vector3.Cross(xdir, matrix.MultiplyVector(forward)).normalized;
ydir *= 0.3f * handleSize;
xdir *= handleSize;
arrowPoints[0] = center;
arrowPoints[1] = center + (xdir - ydir);
arrowPoints[2] = center + (xdir + ydir);
SceneHandles.DrawAAConvexPolygon(arrowPoints);
SceneHandles.matrix = matrix;
}