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# The Original Code is the Python Computer Graphics Kit.
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# The Initial Developer of the Original Code is Matthias Baas.
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# $Id: glrenderer.py,v 1.3 2005/08/28 19:42:43 mbaas Exp $

## \file glrenderer.py
## Contains the GLRenderer class.

from _OpenGL.GL import *
from _OpenGL.GLU import *
from scene import getScene
import _core

# GLRenderInstance
class GLRenderInstance(_core.GLRenderInstance):
    """GLRenderInstance.

    """

#    protocols.advise(instancesProvide=[ISceneItem])
    
    def __init__(self):
        _core.GLRenderInstance.__init__(self)


    # pick
    def pick(self, x, y, dx=2, dy=2, root=None):
        """Do an OpenGL picking pass at the specified cursor position.

        \param x (\c float) X window coordinate where to pick
        \param y (\c float) Y window coordinate where to pick
        \param dx (\c float) Width of the picking region
        \param dy (\c float) Height of the picking region
        \param root (\c WorldObject) Only check this subtree (None=entire world).
        \return Returns a list of hits. Each hit entry is a 3-tuple (zmin, zmax, object).
        """
        
        scene = getScene()
        vpx,vpy,width,height = self.getViewport()
        if self.stereo_mode==1:
            width /= 2

        glSelectBuffer(50)
        glRenderMode(GL_SELECT)
        glInitNames()
        glPushName(0)

        glDisable(GL_DEPTH_TEST)
        glDisable(GL_LIGHTING)
        glDisable(GL_BLEND)
        glDisable(GL_NORMALIZE)

        # Projection
        glMatrixMode(GL_PROJECTION)
        glLoadIdentity()
        gluPickMatrix(x, height-y, dx, dy, [vpx,vpy,width,height])
        glMultMatrixd(self.getProjection().toList())

        # Viewing transformation
        glMatrixMode(GL_MODELVIEW)
        glLoadIdentity()
        if scene.handedness=='l':
            glScaled(-1,1,1)
        glRotated(180,0,1,0);
        glMultMatrixd(self.getViewTransformation().toList())

        # 'Render' scene
        lut = {}
        if root==None:
            root = scene.worldRoot()
        glPushMatrix()
        # Change to the coordinate system of the parent of the root
        # so that we can continue with the local system
        if root.parent!=None:
            glMultMatrixd(root.parent.worldtransform.toList())
        self._pick_node(root, 0, lut)
        glPopMatrix()

        # Get results
        buffer = glRenderMode(GL_RENDER)
        res = []
        for zmin,zmax,names in buffer:
            idx = names[0]
            res.append((zmin,zmax,lut[idx]))

        # Sort so that nearest object is first
        res.sort()
        return res

    def _pick_node(self, obj, idx, lut):
        """Helper method for the pick() method.

        Returns the current index to use for the object 'names'.
        """
        if not obj.visible:
            return idx

        glPushMatrix()
        glMultMatrixd(obj.localTransform().toList())

        geom = obj.geom
        if geom!=None:
            glLoadName(idx)
            lut[idx] = obj
            idx+=1
            geom.drawGL()

        for child in obj.iterChilds():
            idx = self._pick_node(child, idx, lut)

        glPopMatrix()
        return idx
