Basic skinned meshes

docs/source/examples/23_smpl_visualizer_skinned.rst

@@ -0,0 +1,292 @@
+.. Comment: this file is automatically generated by `update_example_docs.py`.
+   It should not be modified manually.
+
+Visualizer for SMPL human body models. Requires a .npz model file.
+==========================================
+
+
+See here for download instructions:
+    https://github.com/vchoutas/smplx?tab=readme-ov-file#downloading-the-model
+
+
+
+.. code-block:: python
+        :linenos:
+
+
+        from __future__ import annotations
+
+        import time
+        from dataclasses import dataclass
+        from pathlib import Path
+        from typing import List, Tuple
+
+        import numpy as np
+        import numpy as onp
+        import tyro
+        import viser
+        import viser.transforms as tf
+
+
+        @dataclass(frozen=True)
+        class SmplOutputs:
+            vertices: np.ndarray
+            faces: np.ndarray
+            T_world_joint: np.ndarray  # (num_joints, 4, 4)
+            T_parent_joint: np.ndarray  # (num_joints, 4, 4)
+
+
+        class SmplHelper:
+            """Helper for models in the SMPL family, implemented in numpy."""
+
+            def __init__(self, model_path: Path) -> None:
+                assert model_path.suffix.lower() == ".npz", "Model should be an .npz file!"
+                body_dict = dict(**onp.load(model_path, allow_pickle=True))
+
+                self._J_regressor = body_dict["J_regressor"]
+                self._weights = body_dict["weights"]
+                self._v_template = body_dict["v_template"]
+                self._posedirs = body_dict["posedirs"]
+                self._shapedirs = body_dict["shapedirs"]
+                self._faces = body_dict["f"]
+
+                self.num_joints: int = self._weights.shape[-1]
+                self.num_betas: int = self._shapedirs.shape[-1]
+                self.parent_idx: np.ndarray = body_dict["kintree_table"][0]
+
+            def get_outputs(self, betas: np.ndarray, joint_rotmats: np.ndarray) -> SmplOutputs:
+                # Get shaped vertices + joint positions, when all local poses are identity.
+                v_tpose = self._v_template + np.einsum("vxb,b->vx", self._shapedirs, betas)
+                j_tpose = np.einsum("jv,vx->jx", self._J_regressor, v_tpose)
+
+                # Local SE(3) transforms.
+                T_parent_joint = np.zeros((self.num_joints, 4, 4)) + np.eye(4)
+                T_parent_joint[:, :3, :3] = joint_rotmats
+                T_parent_joint[0, :3, 3] = j_tpose[0]
+                T_parent_joint[1:, :3, 3] = j_tpose[1:] - j_tpose[self.parent_idx[1:]]
+
+                # Forward kinematics.
+                T_world_joint = T_parent_joint.copy()
+                for i in range(1, self.num_joints):
+                    T_world_joint[i] = T_world_joint[self.parent_idx[i]] @ T_parent_joint[i]
+
+                # Linear blend skinning.
+                pose_delta = (joint_rotmats[1:, ...] - np.eye(3)).flatten()
+                v_blend = v_tpose + np.einsum("byn,n->by", self._posedirs, pose_delta)
+                v_delta = np.ones((v_blend.shape[0], self.num_joints, 4))
+                v_delta[:, :, :3] = v_blend[:, None, :] - j_tpose[None, :, :]
+                v_posed = np.einsum(
+                    "jxy,vj,vjy->vx", T_world_joint[:, :3, :], self._weights, v_delta
+                )
+                return SmplOutputs(v_posed, self._faces, T_world_joint, T_parent_joint)
+
+
+        def main(model_path: Path) -> None:
+            server = viser.ViserServer()
+            server.scene.set_up_direction("+y")
+            server.gui.configure_theme(control_layout="collapsible")
+
+            # Main loop. We'll read pose/shape from the GUI elements, compute the mesh,
+            # and then send the updated mesh in a loop.
+            model = SmplHelper(model_path)
+            gui_elements = make_gui_elements(
+                server,
+                num_betas=model.num_betas,
+                num_joints=model.num_joints,
+                parent_idx=model.parent_idx,
+            )
+            smpl_outputs = model.get_outputs(
+                betas=np.array([x.value for x in gui_elements.gui_betas]),
+                joint_rotmats=onp.zeros((model.num_joints, 3, 3)) + onp.eye(3),
+            )
+
+            bone_wxyzs = np.array(
+                [tf.SO3.from_matrix(R).wxyz for R in smpl_outputs.T_world_joint[:, :3, :3]]
+            )
+            bone_positions = smpl_outputs.T_world_joint[:, :3, 3]
+
+            skinned_handle = server.scene.add_mesh_skinned(
+                "/human",
+                smpl_outputs.vertices,
+                smpl_outputs.faces,
+                bone_wxyzs=bone_wxyzs,
+                bone_positions=bone_positions,
+                skin_weights=model._weights,
+                wireframe=gui_elements.gui_wireframe.value,
+                color=gui_elements.gui_rgb.value,
+            )
+
+            while True:
+                # Do nothing if no change.
+                time.sleep(0.02)
+                if not gui_elements.changed:
+                    continue
+
+                gui_elements.changed = False
+
+                # Compute SMPL outputs.
+                smpl_outputs = model.get_outputs(
+                    betas=np.array([x.value for x in gui_elements.gui_betas]),
+                    joint_rotmats=np.stack(
+                        [
+                            tf.SO3.exp(np.array(x.value)).as_matrix()
+                            for x in gui_elements.gui_joints
+                        ],
+                        axis=0,
+                    ),
+                )
+
+                # Match transform control gizmos to joint positions.
+                for i, control in enumerate(gui_elements.transform_controls):
+                    control.position = smpl_outputs.T_parent_joint[i, :3, 3]
+                    print(control.position)
+
+                    skinned_handle.bones[i].wxyz = tf.SO3.from_matrix(
+                        smpl_outputs.T_world_joint[i, :3, :3]
+                    ).wxyz
+                    skinned_handle.bones[i].position = smpl_outputs.T_world_joint[i, :3, 3]
+
+
+        @dataclass
+        class GuiElements:
+            """Structure containing handles for reading from GUI elements."""
+
+            gui_rgb: viser.GuiInputHandle[Tuple[int, int, int]]
+            gui_wireframe: viser.GuiInputHandle[bool]
+            gui_betas: List[viser.GuiInputHandle[float]]
+            gui_joints: List[viser.GuiInputHandle[Tuple[float, float, float]]]
+            transform_controls: List[viser.TransformControlsHandle]
+
+            changed: bool
+            """This flag will be flipped to True whenever the mesh needs to be re-generated."""
+
+
+        def make_gui_elements(
+            server: viser.ViserServer,
+            num_betas: int,
+            num_joints: int,
+            parent_idx: np.ndarray,
+        ) -> GuiElements:
+            """Make GUI elements for interacting with the model."""
+
+            tab_group = server.gui.add_tab_group()
+
+            def set_changed(_) -> None:
+                out.changed = True  # out is define later!
+
+            # GUI elements: mesh settings + visibility.
+            with tab_group.add_tab("View", viser.Icon.VIEWFINDER):
+                gui_rgb = server.gui.add_rgb("Color", initial_value=(90, 200, 255))
+                gui_wireframe = server.gui.add_checkbox("Wireframe", initial_value=False)
+                gui_show_controls = server.gui.add_checkbox("Handles", initial_value=True)
+
+                gui_rgb.on_update(set_changed)
+                gui_wireframe.on_update(set_changed)
+
+                @gui_show_controls.on_update
+                def _(_):
+                    for control in transform_controls:
+                        control.visible = gui_show_controls.value
+
+            # GUI elements: shape parameters.
+            with tab_group.add_tab("Shape", viser.Icon.BOX):
+                gui_reset_shape = server.gui.add_button("Reset Shape")
+                gui_random_shape = server.gui.add_button("Random Shape")
+
+                @gui_reset_shape.on_click
+                def _(_):
+                    for beta in gui_betas:
+                        beta.value = 0.0
+
+                @gui_random_shape.on_click
+                def _(_):
+                    for beta in gui_betas:
+                        beta.value = onp.random.normal(loc=0.0, scale=1.0)
+
+                gui_betas = []
+                for i in range(num_betas):
+                    beta = server.gui.add_slider(
+                        f"beta{i}", min=-5.0, max=5.0, step=0.01, initial_value=0.0
+                    )
+                    gui_betas.append(beta)
+                    beta.on_update(set_changed)
+
+            # GUI elements: joint angles.
+            with tab_group.add_tab("Joints", viser.Icon.ANGLE):
+                gui_reset_joints = server.gui.add_button("Reset Joints")
+                gui_random_joints = server.gui.add_button("Random Joints")
+
+                @gui_reset_joints.on_click
+                def _(_):
+                    for joint in gui_joints:
+                        joint.value = (0.0, 0.0, 0.0)
+
+                @gui_random_joints.on_click
+                def _(_):
+                    for joint in gui_joints:
+                        # It's hard to uniformly sample orientations directly in so(3), so we
+                        # first sample on S^3 and then convert.
+                        quat = onp.random.normal(loc=0.0, scale=1.0, size=(4,))
+                        quat /= onp.linalg.norm(quat)
+                        joint.value = tf.SO3(wxyz=quat).log()
+
+                gui_joints: List[viser.GuiInputHandle[Tuple[float, float, float]]] = []
+                for i in range(num_joints):
+                    gui_joint = server.gui.add_vector3(
+                        label=f"Joint {i}",
+                        initial_value=(0.0, 0.0, 0.0),
+                        step=0.05,
+                    )
+                    gui_joints.append(gui_joint)
+
+                    def set_callback_in_closure(i: int) -> None:
+                        @gui_joint.on_update
+                        def _(_):
+                            transform_controls[i].wxyz = tf.SO3.exp(
+                                np.array(gui_joints[i].value)
+                            ).wxyz
+                            out.changed = True
+
+                    set_callback_in_closure(i)
+
+            # Transform control gizmos on joints.
+            transform_controls: List[viser.TransformControlsHandle] = []
+            prefixed_joint_names = []  # Joint names, but prefixed with parents.
+            for i in range(num_joints):
+                prefixed_joint_name = f"joint_{i}"
+                if i > 0:
+                    prefixed_joint_name = (
+                        prefixed_joint_names[parent_idx[i]] + "/" + prefixed_joint_name
+                    )
+                prefixed_joint_names.append(prefixed_joint_name)
+                controls = server.scene.add_transform_controls(
+                    f"/smpl/{prefixed_joint_name}",
+                    depth_test=False,
+                    scale=0.2 * (0.75 ** prefixed_joint_name.count("/")),
+                    disable_axes=True,
+                    disable_sliders=True,
+                    visible=gui_show_controls.value,
+                )
+                transform_controls.append(controls)
+
+                def set_callback_in_closure(i: int) -> None:
+                    @controls.on_update
+                    def _(_) -> None:
+                        axisangle = tf.SO3(transform_controls[i].wxyz).log()
+                        gui_joints[i].value = (axisangle[0], axisangle[1], axisangle[2])
+
+                set_callback_in_closure(i)
+
+            out = GuiElements(
+                gui_rgb,
+                gui_wireframe,
+                gui_betas,
+                gui_joints,
+                transform_controls=transform_controls,
+                changed=True,
+            )
+            return out
+
+
+        if __name__ == "__main__":
+            tyro.cli(main, description=__doc__)

docs/source/scene_handles.md

@@ -28,6 +28,10 @@ connected clients. When a scene node is added to a client (for example, via
 
 .. autoclass:: viser.MeshHandle
 
+.. autoclass:: viser.MeshSkinnedHandle
+
+.. autoclass:: viser.MeshSkinnedBoneHandle
+
 .. autoclass:: viser.PointCloudHandle
 
 .. autoclass:: viser.TransformControlsHandle