:orphan:

spring_pendulum
---------------


3D animation of a spring pendulum

.. raw:: html

  <video width="558" height="558" controls autoplay>
    <source src="../_static/examples/spring_pendulum.mov" type="video/mp4">
    <source src="../_static/examples/spring_pendulum.ogg" type="video/ogg">
  </video>

----

.. code-block:: python
    
    
    
    import math
    import gr
    import gr3
    
    gr.setviewport(0, 1, 0, 1)
    gr3.setbackgroundcolor(1, 1, 1, 1)
    
    for t in range(200):
        f = 0.0375 * (math.cos(t * 0.2) * 0.995 ** t + 1.3)
        n = 90
        points = [
            (math.sin(i * math.pi / 8), n * 0.035 - i * f, math.cos(i * math.pi / 8))
            for i in range(n - 5)
        ]
        points.append((0, points[-1][1], 0))
        points.append((0, points[-1][1] - 0.5, 0))
        points.append((0, points[-1][1] - 1, 0))
        points.insert(0, (0, points[0][1], 0))
        points.insert(0, (0, points[0][1] + 2, 0))
        colors = [(1, 1, 1)] * n
        radii = [0.1] * n
        gr3.clear()
        gr3.drawtubemesh(n, points, colors, radii)
        gr3.drawspheremesh(1, points[-1], colors, 0.75)
        gr.clearws()
        gr3.drawimage(0, 1, 0, 1, 500, 500, gr3.GR3_Drawable.GR3_DRAWABLE_GKS)
        gr.updatews()