main.py

from panda3d.core import *
from random import random

import direct.directbase.DirectStart

vertex_glsl = """
#version 400
in vec4 p3d_Vertex;
uniform mat4 p3d_ModelViewProjectionMatrix;

void main() {
    gl_Position = p3d_ModelViewProjectionMatrix * p3d_Vertex;
}
"""

fragment_glsl = """
#version 400

uniform struct {
    vec4 baseColor;
} p3d_Material;

out vec3 color;

void main() {
    color = p3d_Material.baseColor.xyz;
}

"""

smiley = loader.loadModel("smiley")
smiley.reparent_to(render)
material = Material()
smiley.set_material(material)

def reload_shaders():
    shader = Shader.make(Shader.SL_GLSL, vertex_glsl, fragment_glsl)
    render.set_shader(shader)

def change_material():
    material = Material(smiley.get_material())
    print(material) 
    material.set_base_color(Vec4(random(), random(), random(), 1)) # Assertion 
    

base.accept("r", reload_shaders)
base.accept("c", change_material)

base.disableMouse()
base.cam.setPos(10, 10, 10)
base.cam.lookAt(smiley)

reload_shaders()
run()