"""This file demonstrates one way to create a mirror effect in Panda.
Call :func:`setupMirror()` to create a mirror in the world that reflects
everything in front of it.
The approach taken here is to create an offscreen buffer with its own
camera that renders its view into a texture, which is then applied to
the mirror geometry. The mirror's camera is repositioned each frame
with a task to keep it always on the opposite side of the mirror from
the main camera.
This demonstrates the basic interface for offscreen
render-to-a-texture in Panda. Similar approaches can be used for
related effects, such as a remote spy camera presenting its view onto
a closed-circuit television screen.
In this example the mirror itself is always perfectly flat--it's just
a single polygon, after all--but small distortions of the mirror
surface are possible, like a funhouse mirror. However, the reflection
itself is always basically planar; for more accurate convex
reflections, you will need to use a sphere map or a cube map."""
__all__ = ['setupMirror', 'showFrustum']
from panda3d.core import *
from direct.task import Task
[docs]def setupMirror(name, width, height, rootCamera = None,
bufferSize = 256, clearColor = None):
# The return value is a NodePath that contains a rectangle that
# reflects render. You can reparent, reposition, and rotate it
# anywhere you like.
if rootCamera is None:
rootCamera = base.camera
root = render.attachNewNode(name)
# Create a polygon to be the visible representation of the mirror.
cm = CardMaker('mirror')
cm.setFrame(width / 2.0, -width / 2.0, -height / 2.0, height / 2.0)
cm.setHasUvs(1)
card = root.attachNewNode(cm.generate())
# Create a PlaneNode to represent the mirror's position, for
# computing where the mirror's camera belongs each frame.
plane = Plane(Vec3(0, 1, 0), Point3(0, 0, 0))
planeNode = PlaneNode('mirrorPlane')
planeNode.setPlane(plane)
planeNP = root.attachNewNode(planeNode)
# Now create an offscreen buffer for rendering the mirror's point
# of view. The parameters here control the resolution of the
# texture.
buffer = base.win.makeTextureBuffer(name, bufferSize, bufferSize)
if clearColor is None:
buffer.setClearColor(base.win.getClearColor())
#buffer.setClearColor(VBase4(0, 0, 1, 1))
else:
buffer.setClearColor(clearColor)
# Set up a display region on this buffer, and create a camera.
dr = buffer.makeDisplayRegion()
camera = Camera('mirrorCamera')
lens = PerspectiveLens()
lens.setFilmSize(width, height)
camera.setLens(lens)
cameraNP = planeNP.attachNewNode(camera)
dr.setCamera(cameraNP)
# Since the reflection matrix will reverse the vertex-winding
# order of all the polygons in the world, we have to tell the
# camera to reverse the direction of its face culling. We also
# tell it not to draw (that is, to clip) anything behind the
# mirror plane.
dummy = NodePath('dummy')
dummy.setAttrib(CullFaceAttrib.makeReverse())
dummy.setClipPlane(planeNP)
camera.setInitialState(dummy.getState())
# Create a visible representation of the camera so we can see it.
#cameraVis = loader.loadModel('camera.egg')
#if not cameraVis.isEmpty():
# cameraVis.reparentTo(cameraNP)
# Spawn a task to keep that camera on the opposite side of the
# mirror.
def moveCamera(task, cameraNP = cameraNP, plane = plane,
planeNP = planeNP, card = card, lens = lens,
width = width, height = height, rootCamera = rootCamera):
# Set the camera to the mirror-image position of the main camera.
cameraNP.setMat(rootCamera.getMat(planeNP) * plane.getReflectionMat())
# Set the cameras roll to the roll of the mirror. Otherwise
# mirrored objects will be moved unexpectedly
cameraNP.setR(planeNP.getR()-180)
# And reset the frustum to exactly frame the mirror's corners.
# This is a minor detail, but it helps to provide a realistic
# reflection and keep the subject centered.
ul = cameraNP.getRelativePoint(card, Point3(-width / 2.0, 0, height / 2.0))
ur = cameraNP.getRelativePoint(card, Point3(width / 2.0, 0, height / 2.0))
ll = cameraNP.getRelativePoint(card, Point3(-width / 2.0, 0, -height / 2.0))
lr = cameraNP.getRelativePoint(card, Point3(width / 2.0, 0, -height / 2.0))
# get the distance from the mirrors camera to the mirror plane
camvec = planeNP.getPos() - cameraNP.getPos()
camdist = camvec.length()
# set the discance on the mirrors corners so it will keep correct
# sizes of the mirrored objects
ul.setY(camdist)
ur.setY(camdist)
ll.setY(camdist)
lr.setY(camdist)
lens.setFrustumFromCorners(ul, ur, ll, lr, Lens.FCCameraPlane | Lens.FCOffAxis | Lens.FCAspectRatio)
return Task.cont
# Add it with a fairly high priority to make it happen late in the
# frame, after the avatar controls (or whatever) have been applied
# but before we render.
taskMgr.add(moveCamera, name, priority = 40)
# Now apply the output of this camera as a texture on the mirror's
# visible representation.
card.setTexture(buffer.getTexture())
return root
[docs]def showFrustum(np):
# Utility function to reveal the frustum for a particular camera.
cameraNP = np.find('**/+Camera')
camera = cameraNP.node()
lens = camera.getLens()
geomNode = GeomNode('frustum')
geomNode.addGeom(lens.makeGeometry())
cameraNP.attachNewNode(geomNode)
if __name__ == "__main__":
from direct.showbase.ShowBase import ShowBase
base = ShowBase()
panda = loader.loadModel("panda")
panda.setH(180)
panda.setPos(0, 10, -2.5)
panda.setScale(0.5)
panda.reparentTo(render)
myMirror = setupMirror("mirror", 10, 10, bufferSize=1024, clearColor=(0, 0, 1, 1))
myMirror.setPos(0, 15, 2.5)
myMirror.setH(180)
# Uncomment this to show the frustum of the camera in the mirror
#showFrustum(render)
base.run()
