# Author: Shao Zhang and Phil Saltzman
# Last Updated: 4/19/2005
#
# This tutorial is intended as a initial panda scripting lesson going over
# display initialization, loading models, placing objects, and the scene graph.
#
# Step 4: In this step, we will load the rest of the planets up to Mars.
# In addition to loading them, we will organize how the planets are grouped
# hierarchically in the scene. This will help us rotate them in the next step
# to give a rough simulation of the solar system.  You can see them move by
# running step_5_complete_solar_system.py.

import direct.directbase.DirectStart
from pandac.PandaModules import *
from direct.gui.DirectGui import *
import sys

class World:
  def __init__(self):
    #This is the initialization we had before
    self.title = OnscreenText(          #Create the title
      text="Panda3D: Tutorial 1 - Solar System",
      style=1, fg=(1,1,1,1), pos=(0.8,-0.95), scale = .07)
  
    base.setBackgroundColor(0, 0, 0)    #Set the background to black
    base.disableMouse()                 #disable mouse control of the camera
    camera.setPos ( 0, 0, 45 )          #Set the camera position (X, Y, Z)
    camera.setHpr ( 0, -90, 0 )         #Set the camera orientation
                                        #(heading, pitch, roll) in degrees

    #This section has our variables. This time we are adding a variable to
    #control the relative size of the orbits.
    self.sizescale = 0.6                #relative size of planets
    self.orbitscale = 10                #relative size of orbits

    self.loadPlanets()                  #Load our models and make them render
    
  def loadPlanets(self):
    #Here is where we load all of the planets, and place them.
    #The first thing we do is create a dummy node for each planet. A dummy
    #node is simply a node path that does not have any geometry attached to it.
    #This is done by <NodePath>.attachNewNode('name_of_new_node')

    #We do this because positioning the planets around a circular orbit could
    #be done with a lot of messy sine and cosine operations. Instead, we define
    #our planets to be a given distance from a dummy node, and when we turn the
    #dummy, the planets will move along with it, kind of like turning the
    #center of a disc and having an object at its edge move. Most attributes,
    #like position, orientation, scale, texture, color, etc., are inherited
    #this way. Panda deals with the fact that the objects are not attached
    #directly to render (they are attached through other NodePaths to render),
    #and makes sure the attributes inherit.
    
    #This system of attaching NodePaths to each other is called the Scene Graph
    self.orbit_root_mercury = render.attachNewNode('orbit_root_mercury')
    self.orbit_root_venus = render.attachNewNode('orbit_root_venus')
    self.orbit_root_mars = render.attachNewNode('orbit_root_mars')
    self.orbit_root_earth = render.attachNewNode('orbit_root_earth')

    #orbit_root_moon is like all the other orbit_root dummy nodes except that
    #it will be parented to orbit_root_earth so that the moon will orbit the
    #earth instead of the sun. So, the moon will first inherit
    #orbit_root_moon's position and then orbit_root_earth's. There is no hard
    #limit on how many objects can inherit from each other.
    self.orbit_root_moon = (
      self.orbit_root_earth.attachNewNode('orbit_root_moon'))

    ###############################################################

    #These are the same steps used to load the sky model that we used in the
    #last step
    #Load the model for the sky
    self.sky = loader.loadModel("models/solar_sky_sphere")
    #Load the texture for the sky.
    self.sky_tex = loader.loadTexture("models/stars_1k_tex.jpg")
    #Set the sky texture to the sky model
    self.sky.setTexture(self.sky_tex, 1)
    #Parent the sky model to the render node so that the sky is rendered
    self.sky.reparentTo(render)
    #Scale the size of the sky.
    self.sky.setScale(40)

    #These are the same steps we used to load the sun in the last step.
    #Again, we use loader.loadModelCopy since we're using planet_sphere more
    #than once.
    self.sun = loader.loadModelCopy("models/planet_sphere")
    self.sun_tex = loader.loadTexture("models/sun_1k_tex.jpg")
    self.sun.setTexture(self.sun_tex, 1)
    self.sun.reparentTo(render)
    self.sun.setScale(2 * self.sizescale)
    
    #Now we load the planets, which we load using the same steps we used to
    #load the sun. The only difference is that the models are not parented
    #directly to render for the reasons described above.
    #The values used for scale are the ratio of the planet's radius to Earth's
    #radius, multiplied by our global scale variable. In the same way, the
    #values used for orbit are the ratio of the planet's orbit to Earth's
    #orbit, multiplied by our global orbit scale variable
    
    #Load mercury
    self.mercury = loader.loadModelCopy("models/planet_sphere")
    self.mercury_tex = loader.loadTexture("models/mercury_1k_tex.jpg")
    self.mercury.setTexture(self.mercury_tex, 1)
    self.mercury.reparentTo(self.orbit_root_mercury)
    #Set the position of mercury. By default, all nodes are pre assigned the
    #position (0, 0, 0) when they are first loaded. We didn't reposition the
    #sun and sky because they are centered in the solar system. Mercury,
    #however, needs to be offset so we use .setPos to offset the
    #position of mercury in the X direction with respect to its orbit radius.
    #We will do this for the rest of the planets.
    self.mercury.setPos( 0.38 * self.orbitscale, 0, 0)
    self.mercury.setScale(0.385 * self.sizescale)

    #Load Venus
    self.venus = loader.loadModelCopy("models/planet_sphere")
    self.venus_tex = loader.loadTexture("models/venus_1k_tex.jpg")
    self.venus.setTexture(self.venus_tex, 1)
    self.venus.reparentTo(self.orbit_root_venus)
    self.venus.setPos( 0.72 * self.orbitscale, 0, 0)
    self.venus.setScale(0.923 * self.sizescale)

    #Load Mars
    self.mars = loader.loadModelCopy("models/planet_sphere")
    self.mars_tex = loader.loadTexture("models/mars_1k_tex.jpg")
    self.mars.setTexture(self.mars_tex, 1)
    self.mars.reparentTo(self.orbit_root_mars)
    self.mars.setPos( 1.52 * self.orbitscale, 0, 0)
    self.mars.setScale(0.515 * self.sizescale)

    #Load Earth
    self.earth = loader.loadModelCopy("models/planet_sphere")
    self.earth_tex = loader.loadTexture("models/earth_1k_tex.jpg")
    self.earth.setTexture(self.earth_tex, 1)
    self.earth.reparentTo(self.orbit_root_earth)
    self.earth.setScale(self.sizescale)
    self.earth.setPos( self.orbitscale, 0, 0)

    #The center of the moon's orbit is exactly the same distance away from
    #The sun as the Earth's distance from the sun
    self.orbit_root_moon.setPos( self.orbitscale, 0, 0)
    
    #Load the moon
    self.moon = loader.loadModelCopy("models/planet_sphere")
    self.moon_tex = loader.loadTexture("models/moon_1k_tex.jpg")
    self.moon.setTexture(self.moon_tex, 1)
    self.moon.reparentTo(self.orbit_root_moon)
    self.moon.setScale(0.1 * self.sizescale)
    self.moon.setPos(0.1 * self.orbitscale, 0, 0)
  #end loadPlanets()

#end class world
    
w = World()
run()
