#!/usr/bin/env python

import sys
from PyOSG import Producer
from PyOSG import osg
from PyOSG import osgDB
from PyOSG import osgUtil
from PyOSG import osgGA
from PyOSG import osgProducer

def decorate_with_clip_node(subgraph):
    rootnode =  osg.Group()

    # create wireframe view of the model so the user can see
    # what parts are being culled away.
    stateset = osg.StateSet()
    # material = osg.Material()
    polymode = osg.PolygonMode()
    polymode.setMode(osg.PolygonMode.FRONT_AND_BACK,osg.PolygonMode.LINE)
    stateset.setAttributeAndModes(polymode,osg.StateAttribute.OVERRIDE|osg.StateAttribute.ON)

    wireframe_subgraph =  osg.Group()
    wireframe_subgraph.setStateSet(stateset)
    wireframe_subgraph.addChild(subgraph)
    rootnode.addChild(wireframe_subgraph)

    """
    # simple approach to adding a clipnode above a subrgaph.

    # create clipped part.
    clipped_subgraph =  osg.ClipNode()

    bs = subgraph.getBound()
    bs.radius( bs.radius() * 0.4)

    bb = osg.BoundingBox()
    bb.expandBy(bs)


    clipped_subgraph.createClipBox(bb)
    clipped_subgraph.addChild(subgraph)
    rootnode.addChild(clipped_subgraph)
    """



    # more complex approach to managing ClipNode, allowing
    # ClipNode node to be transformed independantly from the subgraph
    # that it is clipping.

    transform = osg.MatrixTransform()

    nc = osgUtil.newTransformCallback(subgraph.getBound().center(),osg.Vec3(0.0,0.0,1.0),osg.inDegrees(45.0))
    transform.setUpdateCallback(nc)

    clipnode =  osg.ClipNode()
    bs = subgraph.getBound()
    bs.radius(bs.radius() * 0.4)

    bb = osg.BoundingBox()
    bb.expandBy(bs)

    clipnode.createClipBox(bb)
    clipnode.setCullingActive(False)

    transform.addChild(clipnode)
    rootnode.addChild(transform)


    # create clipped part.
    clipped_subgraph =  osg.Group()

    clipped_subgraph.setStateSet(clipnode.getStateSet())
    clipped_subgraph.addChild(subgraph)
    rootnode.addChild(clipped_subgraph)

    return rootnode


def main(argv):
    # use an ArgumentParser object to manage the program arguments.
    arguments = osg.ArgumentParser(argv)

    # set up the usage document, in case we need to print out how to use this program.
    arguments.getApplicationUsage().setDescription(arguments.getApplicationName()+" is the example which demonstrates use multi-pass and osg.ClipNode to clip parts of the scene away..")
    arguments.getApplicationUsage().setCommandLineUsage(arguments.getApplicationName()+" [options] filename ...")
    arguments.getApplicationUsage().addCommandLineOption("-h or --help","Display this information")

    # initialize the viewer.
    viewer = osgProducer.Viewer(arguments)

    # set up the value with sensible default event handlers.
    viewer.setUpViewer(osgProducer.Viewer.STANDARD_SETTINGS)

    # get details on keyboard and mouse bindings used by the viewer.
    viewer.getUsage(arguments.getApplicationUsage())

    # if user request help write it out to cout.
    if arguments.read("-h") or arguments.read("--help"):
        arguments.getApplicationUsage().write()
        return 1


    # any option left unread are converted into errors to write out later.
    arguments.reportRemainingOptionsAsUnrecognized()

    # report any errors if they have occured when parsing the program aguments.
    if arguments.errors():
        arguments.writeErrorMessages()
        return 1


    if arguments.argc()<=1:
        arguments.getApplicationUsage().write(osg.ApplicationUsage.COMMAND_LINE_OPTION)
        return 1


    # load the nodes from the commandline arguments.
    loadedModel = osgDB.readNodeFiles(arguments)
    if not loadedModel:
        return 1

    # decorate the scenegraph with a clip node.
    rootnode = decorate_with_clip_node(loadedModel)

    # run optimization over the scene graph
    optimzer = osgUtil.Optimizer()
    optimzer.optimize(rootnode)

    # set the scene to render
    viewer.setSceneData(rootnode)

    # create the windows and run the threads.
    viewer.realize()

    while not viewer.done():

        # wait for all cull and draw threads to complete.
        viewer.sync()

        # update the scene by traversing it with the the update visitor which will
        # call all node update callbacks and animations.
        viewer.update()

        # fire off the cull and draw traversals of the scene.
        viewer.frame()

    # wait for all cull and draw threads to complete before exit.
    viewer.sync()

    return 0

if __name__ == "__main__":
    main(sys.argv)