from OpenGL.GL import *
from dmsgl import *

class PointMass:
	def __init__(self, position=Vector([0,0,0]), velocity=Vector([0,0,0]), mass=1.0):
		self.position = position
		self.velocity = velocity
		self.mass = mass
		self.force = Vector([0, 0, 0])
		self.mobile = True
	def clearForce(self):
		self.force = Vector([0,0,0])
	def addForce(self, force):
		self.force += force
	def update(self, dt):
		if self.mobile:
			acc = self.force / self.mass
			self.velocity += acc * dt
			self.position += self.velocity * dt

class Spring:
	def __init__(self, point1, point2, restLength=-1, k=1):
		self.point1 = point1
		self.point2 = point2
		if restLength >= 0:
			self.restLength = restLength
		else:
			self.restLength = point1.position.distance(point2.position)
		self.k = k
	def calculateForce(self):
		v = self.point2.position - self.point1.position
		displacement = v.length() - self.restLength
		v.normalize()
		force = self.k * displacement * v
		self.point1.addForce(force)
		self.point2.addForce(-force)
	def draw(self):
		glBegin(GL_LINES)
		glVertex3fv(self.point1.position)
		glVertex3fv(self.point2.position)
		glEnd()