Trackball¶

class glumpy.transforms.Trackball(*args, **kwargs)¶

Bases: glumpy.transforms.transform.Transform

3D trackball transform

Parameters:

aspect (float) – Indicate what is the aspect ratio of the object displayed. This is necessary to convert pixel drag move in oject space coordinates. Default is None.
znear (float) – Near clip plane. Default is 2.
zfar (float) – Distance clip plane. Default is 1000.
theta (float) – Angle (in degrees) around the z axis. Default is 45.
phi (float) – Angle (in degrees) around the x axis. Default is 45.
distance (float) – Distance from the trackball to the object. Default is 8.
zoom (float) – Zoom level. Default is 35.

The trackball transform simulates a virtual trackball (3D) that can rotate around the origin using intuitive mouse gestures.

The transform is connected to the following events:

on_attach: Transform initialization

on_resize: Tranform update to maintain aspect

on_mouse_scroll: Zoom in & out (user action)

on_mouse_grab: Drag (user action)

Usage example:

vertex = '''
attribute vec2 position;
void main()
{
    gl_Position = <transform>(vec4(position, 0.0, 1.0));
} '''

...
window = app.Window(width=800, height=800)
program = gloo.Program(vertex, fragment, count=4)
...
program['transform'] = Trackball(aspect=1)
window.attach(program['transform'])
...

aspect¶: Projection aspect

distance¶: Distance from the trackball to the object

phi¶: Angle (in degrees) around the x axis

theta¶: Angle (in degrees) around the z axis

zoom¶: Angle (in degrees) around the x axis

Trackball¶

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