#!/usr/bin/env python
# C++ source file - (C) 2003 Robert Osfield, released under the OSGPL.
#
# Simple example of use of Producer.RenderSurface to create an OpenGL
# graphics window, and OSG for rendering.

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

def main(argv):
    if len(argv)<2:
        print argv[0], ": requires filename argument."
        return 1

    # load the scene.
    loadedModel = osgDB.readNodeFile(argv[1])
    if not loadedModel:
        print argv[0], ": No data loaded."
        return 1

    # create the window to draw to.
    renderSurface = Producer.RenderSurface()
    renderSurface.setWindowName("osgsimple")
    renderSurface.setWindowRectangle(100,100,800,600)
    renderSurface.useBorder(True)
    renderSurface.realize()

    # create the view of the scene.
    sceneView = osgUtil.SceneView()
    sceneView.setDefaults()
    sceneView.setSceneData(loadedModel)

    # initialize the view to look at the center of the scene graph
    bs = loadedModel.getBound()
    viewMatrix = osg.Matrix()
    viewMatrix.makeLookAt(bs.center()-osg.Vec3(0.0,2.0*bs.radius(),0.0),bs.center(),osg.Vec3(0.0,0.0,1.0))

    # record the timer tick at the start of rendering.
    start_tick = osg.Timer.instance().tick()

    frameNum = 0

    # main loop (note, window toolkits which take control over the main loop will require a window redraw callback containing the code below.)
    while( renderSurface.isRealized() ):
        # set up the frame stamp for current frame to record the current time and frame number so that animtion code can advance correctly
        frameStamp = osg.FrameStamp()
        frameStamp.setReferenceTime(osg.Timer.instance().delta_s(start_tick,osg.Timer.instance().tick()))
        frameStamp.setFrameNumber(frameNum)
        frameNum += 1

        # pass frame stamp to the SceneView so that the update, cull and draw traversals all use the same FrameStamp
        sceneView.setFrameStamp(frameStamp)

        # update the viewport dimensions, incase the window has been resized.
        sceneView.setViewport(0,0,renderSurface.getWindowWidth(),renderSurface.getWindowHeight())

        # set the view
        sceneView.setViewMatrix(viewMatrix)

        # do the update traversal the scene graph - such as updating animations
        sceneView.update()

        # do the cull traversal, collect all objects in the view frustum into a sorted set of rendering bins
        sceneView.cull()

        # draw the rendering bins.
        sceneView.draw()

        # Swap Buffers
        renderSurface.swapBuffers()

    return 0

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