OverviewV-Play 2 Support (Qt 5)Distance joint length › Reply To: Distance joint length

OverviewV-Play 2 Support (Qt 5)Distance joint length › Reply To: Distance joint length

V-Play Team

Hi totalzero!

I looked into the matter. Within the DistanceJoint implementation, a certain scaleRatio is applied to the length value whenever a new length is set. If you set the length to a new value, everything works fine. But when you read the length at a later point, you get the modified length that is used internally.

For the moment, you can fix this problem by manually calculating the “real” length when you need it:

// ...
  property var myJoint
  property  real scaleRatio

// ...

  // Timer that keeps creating heavy balls that crash down on the building
  Timer {
   // ...
    onTriggered: {
      // ...

      myJoint = extraJoint.createObject(world,
                                            "bodyA": ball1.body,
                                            "bodyB": ball2.body,
                                            "world": world,
                                            "collideConnected": true,
                                            "length": 200

      // myJoint.length holds the modified value, as we know that the "real" value is 200,
      // we can calculate the scaleRatio that is applied within the distance joint
      scaleRatio = 200 / myJoint.length 


  Timer {
        id: togetherTimer
        // ...
        onTriggered: {
            var realJointLength = myJoint.length * scaleRatio
            console.debug("LENGTH: "+myJoint.length)
            console.debug("SCALE-RATIO: "+scaleRatio)
            console.debug("REAL LENGTH: "+realJointLength)
  //          if(myJoint.length > heavyBox.width/2 + lightBox.width/2){
              myJoint.length = realJointLength - 10
  //          }


This is just a workaround for now. I think we can fix this problem and include the correct version in the next V-Play update.
Thanks for reporting this issue!






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