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)

light = Light()

GravityAccel = Vector([0, -9.8, 0])
AirDrag = 1
BounceCoeff = 0.8

class Object:
	def __init__(self, pos=Vector([0,0,0]), vel=Vector([0,0,0]), mass=1.0, radius=1.0, material=Material()):
		self.pos = pos
		self.vel = vel
		self.mass = mass
		self.radius = radius
		self.material = material
		self.force = Vector([0, 0, 0])
		self.mobile = True
	def draw(self):
		self.material.apply()
		glPushMatrix()
		glTranslatef(self.pos[0], self.pos[1], self.pos[2])
		gluSphere(quadric, self.radius, 16, 8)
		glPopMatrix()
		self.material.disable()
	def calculateForce(self):
		self.force = Vector([0, 0, 0])
		self.force += self.mass * GravityAccel
		self.force -= self.vel * AirDrag
	def update(self, dt):
		if self.mobile:
			acc = self.force / self.mass
			self.vel += acc * dt
			self.pos += self.vel * dt
			if self.pos[1] < 0 and self.vel[1] < 0:
				self.vel[1] = -self.vel[1] * BounceCoeff

class Spring:
	def __init__(self, obj1, obj2, restLength=-1, k=1):
		self.obj1 = obj1
		self.obj2 = obj2
		if restLength >= 0:
			self.restLength = restLength
		else:
			self.restLength = obj1.pos.distance(obj2.pos)
		self.k = k
	def draw(self):
		Color.Red.apply()
		glBegin(GL_LINES)
		glVertex3fv(self.obj1.pos)
		glVertex3fv(self.obj2.pos)
		glEnd()
	def calculateForce(self):
		v = self.obj2.pos - self.obj1.pos
		displacement = v.length() - self.restLength
		v.normalize()
		force = self.k * displacement * v
		self.obj1.force += force
		self.obj2.force -= force

objects = []
objects.append(Object(pos=Vector([-8, 30, 0]), mass=30.0, radius=1.0, material=Material(diffuse=Color.Red)))
objects.append(Object(pos=Vector([0, 30, 0]), mass=10.0, radius=1.0, material=Material(diffuse=Color.Green)))
objects.append(Object(pos=Vector([8, 30, 0]), mass=10.0, radius=1.0, material=Material(diffuse=Color.Cyan)))
objects[0].mobile = False

springs = []
springs.append(Spring(objects[0],objects[1],k=10))
springs.append(Spring(objects[1],objects[2],k=10))

active = False

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

    light.apply()
    for o in objects: o.draw()
    for s in springs: s.draw()
    
    glutSwapBuffers()


def keyboard(key, x, y):
    global active
    if key == chr(27):
        sys.exit(0)
    elif key == ' ':
        active = not active
    elif key == 'r':
        objects[0].mobile = True

prevTime = time.time()

def update():
    global prevTime, active
    t = time.time()
    dt = t - prevTime
    prevTime = t
    if active:
        for o in objects: o.calculateForce()
        for s in springs: s.calculateForce()
        for o in objects: o.update(dt)
    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()