(newbie) group2D rotation issue

[Phil_Taz]

Hi all, I am learning with a project to simulate a car with steering.
I have the wheels as rectshapes, they work fine, I can rotate them.
I built the frame with 7 ‘nodes’ indicating the corners of the car, each node is an ovalshape and I have grouped them in a group2D along with the wheels.
Now the problem…

I want to rotate the whole ‘vehicle’ (ie the group2D called ‘car’) and also to move it about on the canvas using sliders to change the origin of ‘drawing the car group2D’.

Problem is that if I rotate the items inside the group2D and then move the origin in a single axis, it is fine on the X axis but on the Y axis it moves at an angle… (in both axes even though the X axis value is static).

I can rotate the ‘wheels’ (rectshapes) and the ‘car’ can be shifted X or Y no problem, but if I rotate the ‘nodes’ (frame of car), the XY slide rotates too.

[Phil_Taz]

It’s that last bit, I would understand if both axes rotated but why only one?

[DerkJ]

Seems like abug since here
https://documentation.xojo.com/api/graphics/object2d.html#object2d-rotation

Is being said that rotation is around it’s anchor point (center).

Can you output the x,y values of all the objects and make a new video showing them during the rotation?

[DerkJ]

More info here

Rotating Object2D around rotation origin

You can add the Object2D to a Group2D at a specific offset then use the group for transforming [code]dim shape As new RectShape shape.Width = 200 shape.Height = 80 shape.X = 100 shape.Y = 40 dim group As new Group2D group.Append(shape)[/code] Here the groups origin is at <0, 0>, which in the shapes reference frame is <-100, -40>. Rotating, scaling and translating the group effectively gives the shape the origin <-100, -40>. Or are you trying to reposition an already appended shape, that…

[Jeff_Tullin]

Are you moving all the objects with these sliders (apart from the wheel rotation)?
I thought you should add all objects to the Group2D, and just move that Group, by its centre

[Phil_Taz]

I am sorry guys, thanks for answering…

I found out that I was not understanding how the origin point in the group works.

Was applying the slider offset to the group, which was fine but also to the content zero point (which is now rotated) on one axis, so that secondary movement was on a different grid!

Duh!

I have a saying “When something really weird happened, it probably didn’t”…

Should listen to my own advice. Thanks again for reading.