glTF Unlit Material Example

This example demonstrates unlit materials in glTF models.

Note

To run this example, you need a model from the source repo’s example folder. If you are running this example from a local copy of the code (dev install) no further actions are needed. Otherwise, you may have to replace the path below to point to the location of the model.

import os
from pathlib import Path

try:
    # modify this line if your model is located elsewhere
    model_dir = Path(__file__).parents[1] / "data"
except NameError:
    # compatibility with sphinx-gallery
    model_dir = Path(os.getcwd()).parent / "data"

Once the path is set correctly, you can use the model as follows:

import imageio.v3 as iio
from wgpu.gui.auto import WgpuCanvas, run
import pygfx as gfx
from wgpu.utils.imgui import ImguiRenderer
from imgui_bundle import imgui

# Init
canvas = WgpuCanvas(size=(1280, 720), title="gltf_unlit")
renderer = gfx.renderers.WgpuRenderer(canvas)
scene = gfx.Scene()

# Read cube image and turn it into a 3D image (a 4d array)
env_img = iio.imread("imageio:meadow_cube.jpg")
cube_size = env_img.shape[1]
env_img.shape = 6, cube_size, cube_size, env_img.shape[-1]

# Create environment map
env_tex = gfx.Texture(
    env_img, dim=2, size=(cube_size, cube_size, 6), generate_mipmaps=True
)

# Load meshes, and apply env map
# Note that this lights the helmet already
gltf_path = model_dir / "just_a_girl" / "scene.gltf"

gltf = gfx.load_gltf(gltf_path)
# gfx.print_scene_graph(gltf.scene)  # Uncomment to see the tree structure


def add_env_map(obj, env_map):
    if isinstance(obj, gfx.Mesh) and isinstance(obj.material, gfx.MeshStandardMaterial):
        obj.material.env_map = env_map


unlit_model = gltf.scene if gltf.scene else gltf.scenes[0]
unlit_model.local.position = (-100, 0, 0)
scene.add(unlit_model)


from pygfx.utils.load_gltf import _GLTF  # noqa

# Hack to remove the unlit plugin
parser = _GLTF()
del parser._plugins["KHR_materials_unlit"]

pbr_gltf = parser.load(gltf_path, quiet=True)
pbr_model = pbr_gltf.scene if pbr_gltf.scene else pbr_gltf.scenes[0]
pbr_model.traverse(lambda obj: add_env_map(obj, env_tex))
pbr_model.local.position = (100, 0, 0)
scene.add(pbr_model)

gui_renderer = ImguiRenderer(renderer.device, canvas)


state = {"ibl": True}


def draw_imgui():
    imgui.new_frame()
    imgui.set_next_window_size((250, 0), imgui.Cond_.always)
    imgui.set_next_window_pos(
        (gui_renderer.backend.io.display_size.x - 250, 0), imgui.Cond_.always
    )
    is_expand, _ = imgui.begin(
        "Controls",
        None,
        flags=imgui.WindowFlags_.no_move | imgui.WindowFlags_.no_resize,
    )
    if is_expand:
        _, direct_light.visible = imgui.checkbox(
            "Directional Light", direct_light.visible
        )

        _, ambient_light.visible = imgui.checkbox(
            "Ambient Light", ambient_light.visible
        )

        changed, state["ibl"] = imgui.checkbox("IBL", state["ibl"])
        if changed:
            if state["ibl"]:
                pbr_model.traverse(lambda obj: add_env_map(obj, env_tex))
            else:
                pbr_model.traverse(lambda obj: add_env_map(obj, None))

    imgui.end()
    imgui.end_frame()
    imgui.render()
    return imgui.get_draw_data()


gui_renderer.set_gui(draw_imgui)


# Add extra light more or less where the sun seems to be in the skybox
direct_light = gfx.DirectionalLight(intensity=2.5)
direct_light.local.position = (-5, 10, -10)
scene.add(direct_light)

ambient_light = gfx.AmbientLight(intensity=0.2)
scene.add(ambient_light)

# Create camera and controller
camera = gfx.PerspectiveCamera(45, 640 / 480)
camera.show_object(scene)
controller = gfx.OrbitController(camera, register_events=renderer)


def animate():
    renderer.render(scene, camera)
    gui_renderer.render()
    canvas.request_draw()


if __name__ == "__main__":
    renderer.request_draw(animate)
    run()