Help me solve a vector math puzzle - lining up 3 points

jackhen

there are 3 vector points.

point1 is stationary. point2 is the global_position of a 2dNode called movingNode. point3 is the global_position of a child of movingNode called movingNodeChild.

what can I set movingNode.rotation (in vectors) to so that all 3 points will be in a line?

cybereality

So a direction vector (which can alternatively be thought of as an angle) can be defined by two points. You have the two points, point 1 and point 2, which the vector from 1 to 2 defined the angle. From there you just set point 3 to that angle. It may be a little more complicated if point 2 also has a rotation (the angle 3 is a global angle) so you will need to add or subtract the point 3 angle from the point 2 angle.

These functions should help:

var angle = point1.angle_to_point(point2)
point3.rotation = angle - point2.rotation

jackhen

@cybereality said: So a direction vector (which can alternatively be thought of as an angle) can be defined by two points. You have the two points, point 1 and point 2, which the vector from 1 to 2 defined the angle. From there you just set point 3 to that angle. It may be a little more complicated if point 2 also has a rotation (the angle 3 is a global angle) so you will need to add or subtract the point 3 angle from the point 2 angle.

These functions should help:
var angle = point1.angle_to_point(point2)
point3.rotation = angle - point2.rotation

Thanks for the help! I was able to get it working!

cybereality

Oh, right. Maybe this then:

var angle = point1.angle_to_point(point2)
point2.rotation = angle

But that will only work if point3 is stationary (I believe directly to the right of point2 in local space). If point3 is also moving, then you will additionally have to take the position into account, which is more complex (but still possible with the same functions as above).