[FEATURE] Add batched simulation of heterogeneous objects. (#2202)

Co-authored-by: Alexis Duburcq <alexis.duburcq@gmail.com>

Author: YilingQiao

examples/rigid/heterogeneous_simulation.py

@@ -0,0 +1,126 @@
+"""
+Heterogeneous Simulation Example
+================================
+
+This example demonstrates heterogeneous simulation, where different parallel
+environments can have different geometry variants for the same entity.
+
+Variant Assignment Rules:
+    When passing a list of morphs to scene.add_entity(), variants are distributed
+    across environments using the following rules:
+
+    1. When n_envs >= n_variants:
+       Balanced block assignment. Environments are divided into blocks, with each
+       block assigned to one variant. For example, with 4 variants and 8 environments:
+       - Environments 0-1 -> Variant 0
+       - Environments 2-3 -> Variant 1
+       - Environments 4-5 -> Variant 2
+       - Environments 6-7 -> Variant 3
+
+    2. When n_envs < n_variants:
+       Each environment i gets variant i (0-indexed). Variants beyond n_envs are
+       unused. For example, with 4 variants and 2 environments:
+       - Environment 0 -> Variant 0 (first morph in list)
+       - Environment 1 -> Variant 1 (second morph in list)
+       - Variants 2 and 3 are unused
+
+Usage:
+    python heterogeneous_simulation.py -v -n 4  # 4 environments (matches 4 variants)
+    python heterogeneous_simulation.py -v -n 8  # 8 environments (2 per variant)
+    python heterogeneous_simulation.py -v -n 2  # 2 environments (only first 2 variants used)
+"""
+
+import argparse
+
+import numpy as np
+import genesis as gs
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument("-v", "--vis", action="store_true", default=False)
+    parser.add_argument("-n", "--n_envs", type=int, default=4)
+    args = parser.parse_args()
+
+    ########################## init ##########################
+    gs.init(backend=gs.gpu, precision="32")
+    ########################## create a scene ##########################
+    scene = gs.Scene(
+        viewer_options=gs.options.ViewerOptions(
+            camera_pos=(3, -1, 1.5),
+            camera_lookat=(0.0, 0.0, 0.5),
+        ),
+        show_viewer=args.vis,
+    )
+
+    ########################## entities ##########################
+    plane = scene.add_entity(
+        gs.morphs.Plane(),
+    )
+    franka = scene.add_entity(
+        gs.morphs.MJCF(file="xml/franka_emika_panda/panda.xml"),
+    )
+
+    # Define 4 geometry variants - see module docstring for variant assignment rules
+    morphs_heterogeneous = [
+        gs.morphs.Box(size=(0.04, 0.04, 0.04), pos=(0.65, 0.0, 0.02)),  # Variant 0
+        gs.morphs.Box(size=(0.02, 0.02, 0.02), pos=(0.65, 0.0, 0.02)),  # Variant 1
+        gs.morphs.Sphere(radius=0.015, pos=(0.65, 0.0, 0.02)),  # Variant 2
+        gs.morphs.Sphere(radius=0.025, pos=(0.65, 0.0, 0.02)),  # Variant 3
+    ]
+    grasping_object = scene.add_entity(
+        morph=morphs_heterogeneous,
+    )
+    ########################## build ##########################
+    scene.build(n_envs=args.n_envs, env_spacing=(1, 1))
+
+    motors_dof = np.arange(7)
+    fingers_dof = np.arange(7, 9)
+    l_qpos = [-1.0124, 1.5559, 1.3662, -1.6878, -1.5799, 1.7757, 1.4602, 0.04, 0.04]
+    if args.n_envs == 0:
+        franka.set_qpos(np.array(l_qpos))
+    else:
+        franka.set_qpos(np.array([l_qpos] * args.n_envs))
+    scene.step()
+
+    AABB = grasping_object.get_AABB()
+    mass = grasping_object.get_mass()
+    print("heterogeneous AABB", AABB)
+    print("heterogeneous mass", mass)
+
+    end_effector = franka.get_link("hand")
+    qpos = franka.inverse_kinematics(
+        link=end_effector,
+        pos=np.array([[0.65, 0.0, 0.135]] * args.n_envs),
+        quat=np.array([[0, 1, 0, 0]] * args.n_envs),
+    )
+    franka.control_dofs_position(qpos[..., :-2], motors_dof)
+
+    # hold
+    for i in range(100):
+        print("hold", i)
+        scene.step()
+
+    # grasp
+    finder_pos = 0.0
+    for i in range(100):
+        print("grasp", i)
+        franka.control_dofs_position(qpos[..., :-2], motors_dof)
+        franka.control_dofs_position(np.array([[finder_pos, finder_pos]] * args.n_envs), fingers_dof)
+        scene.step()
+
+    # lift
+    qpos = franka.inverse_kinematics(
+        link=end_effector,
+        pos=np.array([[0.65, 0.0, 0.3]] * args.n_envs),
+        quat=np.array([[0, 1, 0, 0]] * args.n_envs),
+    )
+    for i in range(200):
+        print("lift", i)
+        franka.control_dofs_position(qpos[..., :-2], motors_dof)
+        franka.control_dofs_position(np.array([[finder_pos, finder_pos]] * args.n_envs), fingers_dof)
+        scene.step()
+
+
+if __name__ == "__main__":
+    main()