drwr’s new draw callback feature opened up a world of opportunities.
I couldn’t resist playing with it so I ended up applying GLSL shaders to Panda objects. To my big surprise, it worked. 
Here’s some very simple code that applies a GLSL shader to the Panda model, using pyOpenGL.
The shader just shows the texture that’s applied, but inverted. Not much special, but it at least shows that texture and coords work correctly.
from pandac.PandaModules import PythonCallbackObject
from pandac.PandaModules import CallbackNode, VBase3
from direct.directbase import DirectStart
from OpenGL.GL import *
import sys
VSHADER = """
void main() {
gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
}
"""
FSHADER = """
uniform sampler2D tex;
void main() {
gl_FragColor.rgb = 1.0 - texture2D(tex,gl_TexCoord[0].st).rgb;
}
"""
def init(cbdata):
"""We'll be compiling & assigning the shader here.
This method will only be called once."""
v = glCreateShader(GL_VERTEX_SHADER)
f = glCreateShader(GL_FRAGMENT_SHADER)
glShaderSource(v, VSHADER)
glShaderSource(f, FSHADER)
glCompileShader(v)
glCompileShader(f)
program = glCreateProgram()
glAttachShader(program,v)
glAttachShader(program,f)
glLinkProgram(program)
glUseProgram(program)
glDeleteShader(v)
glDeleteShader(f)
# We don't need to set the shader again. Clear the callback.
cbnode.clearDrawCallback()
# Make sure we're using da OpenGL.
if base.pipe.getInterfaceName() != "OpenGL":
print "This program requires OpenGL."
sys.exit(1)
# Set up the callback object
cbnode = CallbackNode("cbnode")
cbnode.setDrawCallback(PythonCallbackObject(init))
cbnp = render.attachNewNode(cbnode)
# Load the panda and reparent it to the callback object.
panda = loader.loadModel("panda")
panda.reparentTo(cbnp)
# Let it rotate to show that transforms work well too.
panda.hprInterval(2.0, VBase3(360, 0, 0)).loop()
# Put the camera where it will be able to actually see something.
base.trackball.node().setPos(0, 30, -7)
run()The code will only run with latest CVS version of panda (or wait till 1.6.0).
Thanks so much drwr, for adding the callback feature to Panda.
PS. This made me realize how easy it would be if such a system would be implemented into Panda. Maybe one day panda will support GLSL without the need for this hacky pyOpenGL callback 
