[SOLVED] Moving a model with key controls

[Anonymous]

I have a model (surgical scissors) which is made up of multiple meshes (base, connector, left & right scissors). I want to move the model as a whole at once using the keyboard, but I am not sure how to achieve this. I am trying to do it through python for now, by moving each mesh independently. Is there a better way of doing this?

[Hugo]

Hi Fayad,

What you can actually do is to create yourself an animation : using WriteState. WriteState saves all positions into a file. Once you register the animation, you could replay it using ReadState.

To create rotation/translation/scaling of an object, you can always use the TransformEngine.

Let me know if it helps.

Hugo

[Anonymous]

Can I get an example of a scene with a Rigid model and using TransformEngine.

Thanks,
Fayad

[Hugo]

Yes, take a look in examples/Components/engine/TransformEngine.scn

Hugo

[Anonymous]

Thanks Hugo, I know about this example but it uses vec3d for the template, and I want to use a rigid one, when I do that it does not seem to work. So can you show me how I can do the TransformEngine with a rigid object that has a collision model.

Thanks,
Fayad

[Damien Marchal]

Hi Fayad,

I tried in a small test to see how I would do a very simplified logic for a cissor.
Basically it is a “cissor” reference frame connected to two “child” frames to hold the local frames for each part of the cissor. The connection between the parent and child is done using a RigidRigidMapping. To any of these frame you can attach visual or collision models.

Then I made a python controller which actually connect the keypressed to actual transform of either the reference frame or the two sides when we open/close it.

It is quickly done and I have no idea if it is bullet proof… but here is the result, hoping you will find it useful.

# coding: utf-8
import Sofa

def translate(x, t):
        p = x[0:3]
        q = x[3:]
        return [p[0]+t[0], p[1]+t[1], p[2]+t[2]]+q

class CissorController(Sofa.PythonScriptController):
      '''Controller that handle open/close and movement of a cissor'''      
      def __init__(self, node, cissor):
           self.cissor = cissor
           
      def onKeyPressed(self, c):
           o = None
           p = None
           
           if c == '+':
                 o=0.1
           elif c == '-':
                 o=-0.1          
           elif c=='4':
                p = 0.1
           elif c=='6':
                p = -0.1
           
           if o is not None:
                 # Open/Close the cissor. 
                 q = self.cissor.right.transform.rest_position[0]
                 self.cissor.right.transform.rest_position = translate(q,[o,0.0,0.0])
                 q = self.cissor.left.transform.rest_position[0]
                 self.cissor.left.transform.rest_position = translate(q,[-o,0.0,0.0])

           if p is not None:
                 ## Move along X the cissor
                 q = self.cissor.transform.position[0]
                 self.cissor.transform.position = translate(q,[p,0.0,0.0])
                            
class MyCissor():
      '''A Sofa Prefab for a cissor.'''
      def __init__(self, node, name="MyCissor"):
            n = node.createChild(name)
            ## The reference transform to manipulate the whole cissor
            m = n.createObject("MechanicalObject", template="Rigid3", name="transform")
            
            ## The right side of the cissor with its own position/orientation. 
            r = n.createChild("right")
            r.createObject("MechanicalObject", name="transform", template="Rigid3", position=[1.0,0.5,0.0,0,0,0,1])
            r.createObject("RigidRigidMapping", name="map", initialPoints=r.transform.findData("rest_position").getLinkPath()) 
            
            ## The left side of the cissor with its own position/orientation. 
            l = n.createChild("left")
            l.createObject("MechanicalObject", name="transform", template="Rigid3", position=[-1.0,0.5,0.0,0,0,0,1])
            l.createObject("RigidRigidMapping", name="map", initialPoints=l.transform.findData("rest_position").getLinkPath()) 
            self.node = n
            
def createScene(root):
        root.createObject("EulerImplicit")
        root.createObject("CGLinearSolver")
        
        c = MyCissor(root).node
        CissorController(c,c)
        
        c.transform.showObject=True
        c.right.transform.showObject=True
        c.left.transform.showObject=True

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