InstancedNode sample (requires latest master branch)

instancing.py

from direct.directbase import TestStart
from panda3d.core import *
from random import random

shader = Shader.make(Shader.SL_GLSL, """
#version 150

in vec4 p3d_Vertex;
in vec4 p3d_Color;
in vec2 p3d_MultiTexCoord0;

in mat4x3 p3d_InstanceMatrix;

uniform mat4 p3d_ModelViewProjectionMatrix;
uniform vec4 p3d_ColorScale;

out vec2 texcoord;
out vec4 color;

void main() {
  gl_Position = p3d_ModelViewProjectionMatrix * vec4(p3d_InstanceMatrix * p3d_Vertex, 1);
  texcoord = p3d_MultiTexCoord0;
  color = p3d_Color * p3d_ColorScale;
}
""", """
#version 150

in vec2 texcoord;
in vec4 color;
out vec4 p3d_FragColor;
uniform sampler2D p3d_Texture0;

void main() {
  p3d_FragColor = texture(p3d_Texture0, texcoord);
  p3d_FragColor *= color;
}
""")

inst = InstancedNode("inst")
#inst.instances.append(pos=(2, 0, 0), hpr=(30, 0, 0))
inst.instances.append(pos=(12, 0, 0), hpr=(30, 0, 0))
inst.instances.append(pos=(22, 0, 0), hpr=(30, 0, 0))
inst.instances.append(pos=(32, 0, 0), hpr=(30, 0, 0))
inst.set_bounds_type(BoundingVolume.BT_best)
inst_path = render.attach_new_node(inst)
#inst_path.show_bounds()

sattr = ShaderAttrib.make(shader)
# Comment this out to get regular instancing
sattr = sattr.set_flag(ShaderAttrib.F_hardware_instancing, True)
inst_path.set_attrib(sattr)

# Load the node that is to be instanced
panda = loader.load_model("panda")
panda.reparent_to(inst_path)
panda.flatten_strong() # flattening highly recommended
#panda.show_tight_bounds()
#panda.show_bounds()

# Test that nested instancing works, by giving each panda a baby panda.
# I don't think this is as efficient as simply having a single InstancedNode
# with a giant list of instances, though, but it should nonetheless DTRT.
if False:
    inst2 = InstancedNode("inst2")
    inst2.instances.append(pos=(0, 0, 0))
    inst2.instances.append(pos=(0, -2.5, 0), hpr=(0, 0, 0), scale=0.3)
    inst2_path = inst_path.attach_new_node(inst2)
    panda.reparent_to(inst2_path)

def spawn_instance():
    inst.instances.append(pos=(random() * 50, random() * 50, 0), hpr=(30, 0, 0), scale=random() + 0.5)

base.accept('a', spawn_instance)
base.accept('o', base.oobe_cull)

base.trackball.node().set_pos(0, 50, 0)

base.run()