Missing scene/camera sync with browser view after web page-mouse interaction. #85

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1. BruceSherwood commented on Feb 27, 2020

   

   BruceSherwood

   on Feb 27, 2020

   Last edited by BruceSherwood

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   I don't understand. Run the following code and you will see scene.forward and scene.camera.axis changing as you use the mouse to rotate:

   box()
   forward = label(pos=vec(0,.2,0), text='')
   axis = label(pos=vec(0,-.2,0), text='')
   while True:
       rate(50)
       forward.text = scene.forward
       axis.text = scene.camera.axis
   
2. nastasi commented on Feb 27, 2020

   

   nastasi

   on Feb 27, 2020

   Last edited by nastasi

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   Correct, instead scene.up remains to <0,1,0>, is it correct ?

   box()
   forward = label(pos=vec(0,.2,0), text='')
   axis = label(pos=vec(0,-.2,0), text='')
   up = label(pos=vec(0,-.4,0), text='')
   while True:
       rate(50)
       forward.text = scene.forward
       axis.text = scene.camera.axis
       up.text = scene.up
3. BruceSherwood commented on Feb 27, 2020

   

   BruceSherwood

   on Feb 27, 2020

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   That is how it currently works, though it could use some critical thought. I'm not entirely comfortable with this corner of the vpython world.
4. nastasi commented on Feb 28, 2020

   

   nastasi

   on Feb 28, 2020

   Last edited by nastasi

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   Using the test below things became a little more clear.
   I didn't yet understand how it works exactly but seems that up is a sort of gamma in the polar coordinates (alpha, beta , gamma).
   If you try to do a 360° using "right" button it return to <0,1,0> BUT if you move the scene with the mouse and try again to do 360° up components change differently than before.
   @BruceSherwood ideas ?
   (BTW: when you change the scene with the mouse just canvas and forward items are in the event list)

   from math import pi as PI
   from vpython import (box, label, vec, rate, scene)
   
   box()
   forward = label(pos=vec(0, .2, 0), text='')
   axis = label(pos=vec(0, -.2, 0), text='')
   up = label(pos=vec(0, -.4, 0), text='')
   
   
   def keydown(ev):
       if ev.key == 'right':
           print('rotate')
           scene.camera.rotate(PI / 8, axis=scene.camera.axis)
       if ev.key == 'left':
           print('rotate')
           scene.camera.rotate(-PI / 8, axis=scene.camera.axis)
   
   
   scene.bind('keydown', keydown)
   
   while True:
       rate(50)
       forward.text = "F: %.3f, %.3f, %.3f" % (scene.forward.x, scene.forward.y, scene.forward.z)
       axis.text = "A: %.3f, %.3f, %.3f" % (scene.camera.axis.x, scene.camera.axis.y, scene.camera.axis.z)
       up.text = "U: %.3f, %.3f, %.3f" % (scene.up.x, scene.up.y, scene.up.z)