#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# C++ version Copyright (c) 2006-2007 Erin Catto http://www.box2d.org
# Python version by Ken Lauer / sirkne at gmail dot com
# 
# This software is provided 'as-is', without any express or implied
# warranty.  In no event will the authors be held liable for any damages
# arising from the use of this software.
# Permission is granted to anyone to use this software for any purpose,
# including commercial applications, and to alter it and redistribute it
# freely, subject to the following restrictions:
# 1. The origin of this software must not be misrepresented; you must not
# claim that you wrote the original software. If you use this software
# in a product, an acknowledgment in the product documentation would be
# appreciated but is not required.
# 2. Altered source versions must be plainly marked as such, and must not be
# misrepresented as being the original software.
# 3. This notice may not be removed or altered from any source distribution.

from framework import *
from math import sin

class MotorJoint (Framework):
    name="MotorJoint"
    description = 'g to stop/go'
    count = 800
    def __init__(self):
        Framework.__init__(self)
        
        ground = self.world.CreateStaticBody(
                shapes=[b2EdgeShape(vertices=[(-20,0),( 20, 0)])],
                )
       
        # Define motorized body
        body = self.world.CreateDynamicBody(
                position=(0, 8),
                allowSleep=False,
                fixtures=b2FixtureDef(density=2.0, friction=0.6, 
                                      shape=b2PolygonShape(box=(2.0, 0.5)),),
                )
        
        self.joint = self.world.CreateMotorJoint(bodyA=ground, bodyB=body,
                                                 maxForce=1000, maxTorque=1000)

        self.go = False
        self.time = 0.0

    def Keyboard(self, key):
         if key == Keys.K_g:
             self.go = not self.go

    def Step(self, settings):
        Framework.Step(self, settings)

        if self.go and settings.hz > 0.0:
            self.time += 1.0 / settings.hz

        linear_offset = (6 * sin(2.0 * self.time), 8.0 + 4.0 * sin(1.0 * self.time))
        angular_offset = 4.0 * self.time

        self.joint.linearOffset = linear_offset
        self.joint.angularOffset = angular_offset
       
        renderer = self.renderer
        renderer.DrawPoint(renderer.to_screen(linear_offset), 4, b2Color(0.9,0.9,0.9))

if __name__=="__main__":
     main(MotorJoint)

