Games [XUI2D] Newton's Cradle Example

[Erel]

A simple example:


1. It loads the objects.
2. Creates the rope joints.
3. That's it. Everything just happens.

A bit of code is required to draw the ropes.

Note that the restitution is set to 1.02 which is larger than the maximum value. This helps with preserving the motion energy.

It is included in the examples pack.

https://www.b4x.com/android/forum/threads/xui2d-example-pack.96454/

 

[Marvel]

Why did we subtract the top vector from the hinge vector and then set it as the ropes LocalPointA vector?

Dim TopPosition As B2Vec2 = hinge.BodyDef.Position.CreateCopy
            
'Subtract top bar body positiojn from hinge position
TopPosition.SubtractFromThis(top.Body.Position)
            
'Tie top bar with marble body with a ropeJoint
rope.Initialize(top.Body, bw.Body, TopPosition, X2.CreateVec2(0, 0), 1.5)

 

[Erel]

The connection point is local to the body. In this case body A is the top bar, not the hinge. To get the relative position of the hinge we need to subtract the "top bar" position from the hinge position.