#!/bin/env python

# Copyright (C) 2002-2003 Gideon May (gideon@computer.org)
#
# Permission to copy, use, sell and distribute this software is granted
# provided this copyright notice appears in all copies.
# Permission to modify the code and to distribute modified code is granted
# provided this copyright notice appears in all copies, and a notice
# that the code was modified is included with the copyright notice.
#
# This software is provided "as is" without express or implied warranty,
# and with no claim as to its suitability for any purpose.

# -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2003 Robert Osfield 
#
# This application is open source and may be redistributed and/or modified   
# freely and without restriction, both in commericial and non commericial applications,
# as long as this copyright notice is maintained.
# 
# This application is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
#

from PyOSG import osg
from PyOSG import osgDB
import math
import OpenGL

def makeSky():
    lev = ( -5, -1.0, 1.0, 15.0, 30.0, 60.0, 90.0  )
    cc = (
        ( 0.0, 0.0, 0.15 ),
        ( 0.0, 0.0, 0.15 ),
        ( 0.4, 0.4, 0.7 ),
        ( 0.2, 0.2, 0.6 ),
        ( 0.1, 0.1, 0.6 ),
        ( 0.1, 0.1, 0.6 ),
        ( 0.1, 0.1, 0.6 )
    )

    radius = 20.0
    nlev = len(lev)

    geom = osg.Geometry()

    coords = osg.Vec3Array(19*nlev)
    colors = osg.Vec4Array(19*nlev)
    tcoords = osg.Vec2Array(19*nlev)

    ci = 0

    for  i in range(nlev):
        for j in range(19):
            alpha = osg.DegreesToRadians(lev[i])
            theta = osg.DegreesToRadians(j*20)

            x = radius * math.cos( alpha ) * math.cos( theta )
            y = radius * math.cos( alpha ) * -math.sin( theta )
            z = radius * math.sin( alpha )

            coords[ci][0] = x
            coords[ci][1] = y
            coords[ci][2] = z

            colors[ci][0] = cc[i][0]
            colors[ci][1] = cc[i][1]
            colors[ci][2] = cc[i][2]
            colors[ci][3] = 1.0

            tcoords[ci][0] = j/18.0
            tcoords[ci][0] = i/(nlev-1.0)

            ci += 1

    for i in range(nlev-1):
        drawElements = osg.DrawElementsUShort(osg.PrimitiveSet.TRIANGLE_STRIP)
        drawElements.reserve(38)

        for j in range(19):
            drawElements.push_back((i+1)*19+j)
            drawElements.push_back((i+0)*19+j)

        geom.addPrimitiveSet(drawElements)

    geom.setVertexArray( coords )
    geom.setTexCoordArray( 0, tcoords )

    geom.setColorArray( colors )
    geom.setColorBinding( osg.Geometry.BIND_PER_VERTEX )


    tex = osg.Texture2D()
    tex.setImage(osgDB.readImageFile("Images/white.rgb"))

    dstate = osg.StateSet()

    dstate.setTextureAttributeAndModes(0, tex, osg.StateAttribute.OFF )
    dstate.setTextureAttribute(0, osg.TexEnv())
    dstate.setMode( OpenGL.GL.GL_LIGHTING, osg.StateAttribute.OFF )
    dstate.setMode( OpenGL.GL.GL_CULL_FACE, osg.StateAttribute.ON )
    

    # clear the depth to the far plane.
    depth = osg.Depth()
    depth.setFunction(osg.Depth.ALWAYS)
    depth.setRange(1.0,1.0)
    dstate.setAttributeAndModes(depth,osg.StateAttribute.ON )

    dstate.setRenderBinDetails(-2,"RenderBin")

    geom.setStateSet( dstate )

    geode = osg.Geode()
    geode.addDrawable( geom )

    geode.setName( "Sky" )

    return geode

if __name__ == "__main__":
    sky = makeSky()

    from PyOSG import *

    viewer = osgProducer.Viewer()
    viewer.setUpViewer(osgProducer.Viewer.STANDARD_SETTINGS)

    viewer.setSceneData(sky)
    viewer.realize()

    while not viewer.done():
        viewer.sync()
        viewer.update()
        viewer.frame()
    viewer.sync()
    sys.exit(0)