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- Trackball
class Trackball |
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Trackball mechanism for interactive rotation
Use the trackball utility to rotate a viewpoint
around a fixed world-space coordinate (center).
This trackball is a simple x/y grid of polar
coordinates. Dragging to the left rotates the
eye around the object to view the left side,
similarly for right, top, bottom.
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Methods defined here:
- __init__(self, position, quaternion, center, originalX, originalY, width, height, dragAngle=6.2831853071795862)
- Initialise the Trackball
position -- object-space original position (camera pos)
quaternion -- camera orientation as a quaternion
originalX, originalY -- the initial screen
coordinates of the drag
width, height -- the dimensions of the screen
(newX-originalX)/(fractional width) used by
trackball algorithm
center -- the x,y,z world coordinates around which
we are to rotate the application will need to
use some heuristic to determine the most appropriate
center of rotation. For instance, when the user
first clicks, check for an object in the "center" of
the display, use the center of that object (or
possibly the midpoint between the greatest and least
Z-buffer values) projected back into world space
coordinates. If there is no available object,
potentially use the maximum and minimum of the whole
Z buffer. If there are no rendered elements at all
then use some multiple of the near frustum (20 or
30, for example)
dragAngle -- maximum rotation angle for a drag
- cancel(self)
- Cancel drag rotation, return pos,quat to original values
- update(self, newX, newY)
- Update with new x,y drag coordinates
newX, newY -- the new screen coordinates for the drag
returns a new position and quaternion orientation
Data and non-method functions defined here:
- __doc__ = 'Trackball mechanism for interactive rotation\n\t\n\t...e left side,\n\tsimilarly for right, top, bottom.\n\t'
- __module__ = 'OpenGLContext.trackball'
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