basic spring simulation - two point masses connected by a spring

simplespring.py

import sys, time, math
from pyglet.gl import *
from euclid import *

window = pyglet.window.Window(512,512)

point0 = Vector2(100, 240)
velocity0 = Vector2(0, 0)
mass0 = 1
point1 = Vector2(300, 240)
velocity1 = Vector2(0, 0)
mass1 = 1

springConstant = 100
restLength = 150

triangle = pyglet.graphics.vertex_list(3, ('v2f', [-8,-8, 8,-8, 0,8]))
line = pyglet.graphics.vertex_list(2, ('v2f', [point0[0], point0[1], point1[0], point1[1]]))


@window.event
def on_draw():
    glClear(GL_COLOR_BUFFER_BIT)
    glColor3f(1,0.5,0)
    glPushMatrix()
    glTranslatef(point0[0], point0[1], 0)
    triangle.draw(GL_TRIANGLES)
    glPopMatrix()
    glColor3f(0,0.5,1)
    glPushMatrix()
    glTranslatef(point1[0], point1[1], 0)
    triangle.draw(GL_TRIANGLES)
    glPopMatrix()
    glColor3f(1,0,0)
    line.vertices = point0[0:2] + point1[0:2]
    line.draw(GL_LINES)


def update(dt):
    global velocity0, velocity1, point0, point1
    v = point1 - point0
    displacement = v.magnitude() - restLength
    v = v.normalized()
    force = springConstant * displacement * v
    accel = force / mass0
    velocity0 += accel * dt
    point0 += velocity0 * dt
    accel = -force / mass1
    velocity1 += accel * dt
    point1 += velocity1 * dt

pyglet.clock.schedule_interval(update,1/60.0)
pyglet.app.run()