Skinning Animation

This example demonstrates how to animate a skinned mesh using a glTF animation clip.

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 pygfx as gfx
from rendercanvas.auto import RenderCanvas, loop

from wgpu.utils.imgui import ImguiRenderer
from imgui_bundle import imgui, hello_imgui, icons_fontawesome_4  # type: ignore

gltf_path = model_dir / "Michelle.glb"

canvas = RenderCanvas(
    size=(640, 480), update_mode="fastest", title="Skinnedmesh", vsync=False
)

renderer = gfx.WgpuRenderer(canvas)
camera = gfx.PerspectiveCamera(75, 640 / 480, depth_range=(0.1, 1000))
camera.local.position = (0, 100, 200)
camera.look_at((0, 80, 0))
scene = gfx.Scene()

scene.add(gfx.AmbientLight(), gfx.DirectionalLight())


gltf = gfx.load_gltf(gltf_path, quiet=True)

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

# Group[Scene]
# - WorldObject[Character]
# - - SkinnedMesh[Ch03]
# - - Bone[mixamorig:Hips]
# - - - ...

model_obj = gltf.scene.children[0]
model_obj.local.scale = (1, 1, 1)

action_clip = gltf.animations[0]

skeleton_helper = gfx.SkeletonHelper(model_obj)
scene.add(skeleton_helper)
scene.add(model_obj)

gfx.OrbitController(camera, register_events=renderer)

stats = gfx.Stats(viewport=renderer)

clock = gfx.Clock()

animation_mixer = gfx.AnimationMixer()
action = animation_mixer.clip_action(action_clip)

action.play()

gui_renderer = ImguiRenderer(renderer.device, canvas)

state = {"pause": False}

# Load pretty font and allow using font-awesome for icons
hello_imgui.load_font_ttf_with_font_awesome_icons("fonts/DroidSans.ttf", 14)


def draw_imgui():
    imgui.set_next_window_size(
        (gui_renderer.backend.io.display_size.x, 0), imgui.Cond_.always
    )
    imgui.set_next_window_pos(
        (0, gui_renderer.backend.io.display_size.y - 40), imgui.Cond_.always
    )
    imgui.begin(
        "player",
        True,
        flags=imgui.WindowFlags_.no_move
        | imgui.WindowFlags_.no_resize
        | imgui.WindowFlags_.no_collapse
        | imgui.WindowFlags_.no_title_bar,
    )

    duration = action_clip.duration

    if action.paused:
        if imgui.button(icons_fontawesome_4.ICON_FA_PLAY, size=(24, 24)):
            action.paused = False
    else:
        if imgui.button(icons_fontawesome_4.ICON_FA_PAUSE, size=(24, 24)):
            action.paused = True

    imgui.same_line()
    avail_size = imgui.get_content_region_avail()
    imgui.set_next_item_width(avail_size.x)
    changed, v = imgui.slider_float(" ", action.time, 0, duration, "%.2f")
    if changed:
        action.time = v
    imgui.end()


gui_renderer.set_gui(draw_imgui)


def animate():
    dt = clock.get_delta()

    animation_mixer.update(dt)

    with stats:
        renderer.render(scene, camera, flush=False)
    stats.render()
    gui_renderer.render()
    canvas.request_draw()


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

Interactive example

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