Scaling and Rotating objects in real time

[Qluxzz]

Hi there, I'm working on a level editor and have gotten stuck. I know how to drag and drop the objects, but not how to scale them or rotate the objects according to the users mouse input.

For example I have a video of another persons level editor.


I imagine it's not that difficult but I just can't think of how so all help is appreciated.

Thanks in advance Qluxzz

[zsbzsb]

Video isn't loading for me. But if I think I know what you are talking about. For scaling - it depends on the distance from the initial mouse button press to the current mouse position. For rotation - you need to use atan2 to calculate the rotation from the initial button press to the current mouse position. 

[Nexus]

I would do it as follows:

• When pressing the mouse button, compute the vector v from the object's center to the mouse position.
  
• As long as the mouse button is held down, check the position every frame. Compute another vector w from the center to the new mouse position. Then, the scale factor is length(w) / length(v) and the rotation is signedAngle(v, w) -- these functions already exist in Thor.Vectors (just include the header, no need to link).
• When releasing the mouse button, apply both scale and rotation relatively to their current values.