import sys, time, math
from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.GLUT import *
from dmsgl import *

camera = OrthoCamera(-25,25, 0,50, -25,25)

point0 = Vector([-10, 25, 0])
velocity0 = Vector([0, 0, 0])
mass0 = 1
point1 = Vector([10, 25, 0])
velocity1 = Vector([0, 0, 0])
mass1 = 1

springConstant = 1
restLength = 15

light = Light()
material = Material(diffuse=Color.Grey70)
ball0Xform = SimpleTransform(translate=point0)
ball1Xform = SimpleTransform(translate=point1)

active = False

def draw():
    Color.Black.clear()
    camera.apply()

    light.apply()
    material.apply()
    ball0Xform.pushApply()
    gluSphere(quadric, 1.0, 32, 16)
    ball0Xform.pop()
    ball1Xform.pushApply()
    gluSphere(quadric, 1.0, 32, 16)
    ball1Xform.pop()
    material.disable()
    Color.Red.apply()
    glBegin(GL_LINES)
    glVertex3fv(point0)
    glVertex3fv(point1)
    glEnd()
    
    glutSwapBuffers()


def keyboard(key, x, y):
    global active
    if key == chr(27):
        sys.exit(0)
    elif key == ' ':
        active = not active

prevTime = time.time()

def update():
    global prevTime, active, velocity0, velocity1, point0, point1, ballXform0, ballXform1
    t = time.time()
    dt = t - prevTime
    prevTime = t
    if active:
        v = point1 - point0
        displacement = v.length() - restLength
        v.normalize()
        force = springConstant * displacement * v
        accel = force / mass0
        velocity0 += accel * dt
        point0 += velocity0 * dt
        ball0Xform.translate = point0
        accel = -force / mass1
        velocity1 += accel * dt
        point1 += velocity1 * dt
        ball1Xform.translate = point1
    glutPostRedisplay()

glutInit([])
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH)
glutInitWindowSize(400,400)
glutCreateWindow(sys.argv[0])
glutDisplayFunc(draw)
glutKeyboardFunc(keyboard)
glutIdleFunc(update)
glEnable(GL_DEPTH_TEST)
quadric = gluNewQuadric()
glutMainLoop()