# coding: utf-8
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"""This module provides the base scene structure.
This module provides the classes for describing a tree structure with
rendering and picking API.
All nodes inherit from :class:`Base`.
Nodes with children are provided with :class:`PrivateGroup` and
:class:`Group` classes.
Leaf rendering nodes should inherit from :class:`Elem`.
"""
from __future__ import absolute_import, division, unicode_literals
__authors__ = ["T. Vincent"]
__license__ = "MIT"
__date__ = "25/07/2016"
import itertools
import weakref
import numpy
from . import event
from . import transform
from .viewport import Viewport
# Nodes #######################################################################
[docs]class Base(event.Notifier):
"""A scene node with common features."""
def __init__(self):
super(Base, self).__init__()
self._visible = True
self._pickable = False
self._parentRef = None
self._transforms = transform.TransformList()
self._transforms.addListener(self._transformChanged)
# notifying properties
visible = event.notifyProperty('_visible',
doc="Visibility flag of the node")
pickable = event.notifyProperty('_pickable',
doc="True to make node pickable")
# Access to tree path
@property
def parent(self):
"""Parent or None if no parent"""
return None if self._parentRef is None else self._parentRef()
def _setParent(self, parent):
"""Set the parent of this node.
For internal use.
:param Base parent: The parent.
"""
if parent is not None and self._parentRef is not None:
raise RuntimeError('Trying to add a node at two places.')
# Alternative: remove it from previous children list
self._parentRef = None if parent is None else weakref.ref(parent)
@property
def path(self):
"""Tuple of scene nodes, from the tip of the tree down to this node.
If this tree is attached to a :class:`Viewport`,
then the :class:`Viewport` is the first element of path.
"""
if self.parent is None:
return self,
elif isinstance(self.parent, Viewport):
return self.parent, self
else:
return self.parent.path + (self, )
@property
def viewport(self):
"""The viewport this node is attached to or None."""
root = self.path[0]
return root if isinstance(root, Viewport) else None
@property
def objectToNDCTransform(self):
"""Transform from object to normalized device coordinates.
Do not forget perspective divide.
"""
# Using the Viewport's transforms property to proxy the camera
path = self.path
assert isinstance(path[0], Viewport)
return transform.StaticTransformList(elem.transforms for elem in path)
@property
def objectToSceneTransform(self):
"""Transform from object to scene.
Combine transforms up to the Viewport (not including it).
"""
path = self.path
if isinstance(path[0], Viewport):
path = path[1:] # Remove viewport to remove camera transforms
return transform.StaticTransformList(elem.transforms for elem in path)
# transform
@property
def transforms(self):
"""List of transforms defining the frame of this node relative
to its parent."""
return self._transforms
@transforms.setter
def transforms(self, iterable):
self._transforms.removeListener(self._transformChanged)
if isinstance(iterable, transform.TransformList):
# If it is a TransformList, do not create one to enable sharing.
self._transforms = iterable
else:
assert hasattr(iterable, '__iter__')
self._transforms = transform.TransformList(iterable)
self._transforms.addListener(self._transformChanged)
def _transformChanged(self, source):
self.notify() # Broadcast transform notification
# Bounds
_CUBE_CORNERS = numpy.array(list(itertools.product((0., 1.), repeat=3)),
dtype=numpy.float32)
"""Unit cube corners used to transform bounds"""
def _bounds(self, dataBounds=False):
"""Override in subclass to provide bounds in object coordinates"""
return None
[docs] def bounds(self, transformed=False, dataBounds=False):
"""Returns the bounds of this node aligned with the axis,
with or without transform applied.
:param bool transformed: False to give bounds in object coordinates
(the default), True to apply this object's
transforms.
:param bool dataBounds: False to give bounds of vertices (the default),
True to give bounds of the represented data.
:return: The bounds: ((xMin, yMin, zMin), (xMax, yMax, zMax)) or None
if no bounds.
:rtype: numpy.ndarray of float
"""
bounds = self._bounds(dataBounds)
if transformed and bounds is not None:
bounds = self.transforms.transformBounds(bounds)
return bounds
# Rendering
[docs] def prepareGL2(self, ctx):
"""Called before the rendering to prepare OpenGL resources.
Override in subclass.
"""
pass
[docs] def renderGL2(self, ctx):
"""Called to perform the OpenGL rendering.
Override in subclass.
"""
pass
[docs] def render(self, ctx):
"""Called internally to perform rendering."""
if self.visible:
ctx.pushTransform(self.transforms)
self.prepareGL2(ctx)
self.renderGL2(ctx)
ctx.popTransform()
[docs] def postRender(self, ctx):
"""Hook called when parent's node render is finished.
Called in the reverse of rendering order (i.e., last child first).
Meant for nodes that modify the :class:`RenderContext` ctx to
reset their modifications.
"""
pass
[docs] def pick(self, ctx, x, y, depth=None):
"""True/False picking, should be fast"""
if self.pickable:
pass
[docs] def pickRay(self, ctx, ray):
"""Picking returning list of ray intersections."""
if self.pickable:
pass
[docs]class Elem(Base):
"""A scene node that does some rendering."""
def __init__(self):
super(Elem, self).__init__()
# self.showBBox = False # Here or outside scene graph?
# self.clipPlane = None # This needs to be handled in the shader
[docs]class PrivateGroup(Base):
"""A scene node that renders its (private) childern.
:param iterable children: :class:`Base` nodes to add as children
"""
[docs] class ChildrenList(event.NotifierList):
"""List of children with notification and children's parent update."""
def _listWillChangeHook(self, methodName, *args, **kwargs):
super(PrivateGroup.ChildrenList, self)._listWillChangeHook(
methodName, *args, **kwargs)
for item in self:
item._setParent(None)
def _listWasChangedHook(self, methodName, *args, **kwargs):
for item in self:
item._setParent(self._parentRef())
super(PrivateGroup.ChildrenList, self)._listWasChangedHook(
methodName, *args, **kwargs)
def __init__(self, parent, children):
self._parentRef = weakref.ref(parent)
super(PrivateGroup.ChildrenList, self).__init__(children)
def __init__(self, children=()):
super(PrivateGroup, self).__init__()
self.__children = PrivateGroup.ChildrenList(self, children)
self.__children.addListener(self._updated)
@property
def _children(self):
"""List of children to be rendered.
This private attribute is meant to be used by subclass.
"""
return self.__children
@_children.setter
def _children(self, iterable):
self.__children.removeListener(self._updated)
for item in self.__children:
item._setParent(None)
del self.__children # This is needed
self.__children = PrivateGroup.ChildrenList(self, iterable)
self.__children.addListener(self._updated)
self.notify()
def _updated(self, source, *args, **kwargs):
"""Listen for updates"""
if source is not self: # Avoid infinite recursion
self.notify(*args, **kwargs)
def _bounds(self, dataBounds=False):
"""Compute the bounds from transformed children bounds"""
bounds = []
for child in self._children:
if child.visible:
childBounds = child.bounds(
transformed=True, dataBounds=dataBounds)
if childBounds is not None:
bounds.append(childBounds)
if len(bounds) == 0:
return None
else:
bounds = numpy.array(bounds, dtype=numpy.float32)
return numpy.array((bounds[:, 0, :].min(axis=0),
bounds[:, 1, :].max(axis=0)),
dtype=numpy.float32)
def prepareGL2(self, ctx):
pass
[docs] def renderGL2(self, ctx):
"""Render all children"""
for child in self._children:
child.render(ctx)
for child in reversed(self._children):
child.postRender(ctx)
[docs]class Group(PrivateGroup):
"""A scene node that renders its (public) children."""
@property
def children(self):
"""List of children to be rendered."""
return self._children
@children.setter
def children(self, iterable):
self._children = iterable
