Does the rigid body class allow setting properties for each rigid body individually?

[codesbykhalil]

Does the rigid body class allow setting properties for each rigid body individually? I’m importing multiple different rigid bodies separately, and there are no links between them.

[duburcqa]

Yes. What do you want to do exactly?

[codesbykhalil]

I'm currently working on a visualization of rigid body motion. I want to start by importing multiple mesh files as rigid bodies, assign them different initial velocities, and let them scatter under the influence of gravity.
Below is my specific code.
import genesis as gs
import trimesh
import os
import time
import numpy as np

def main():
# 初始化Genesis
gs.init(backend=gs.gpu) # 使用GPU后端

# 创建场景，使用用户给定的参数
scene = gs.Scene(
    show_viewer    = True,
    viewer_options = gs.options.ViewerOptions(
        res           = (640, 480),  # 降低分辨率
        camera_pos    = (20, 20, 20),  # 调整相机位置到更高的位置
        camera_lookat = (10, 10, 10),  # 看向物体下落的位置
        camera_fov    = 60,  # 增加视场角以看到更多场景
        max_FPS       = 30,  # 降低帧率
    ),
    vis_options = gs.options.VisOptions(
        show_world_frame = True, # 显示原点坐标系
        world_frame_size = 0.5, # 坐标系长度(米)
        show_link_frame  = False, # 不显示实体链接坐标系 
        show_cameras     = False, # 不显示相机网格和视锥
        plane_reflection = False, # 开启平面反射
        ambient_light    = (0.1, 0.1, 0.1), # 环境光
    ),
    renderer = gs.renderers.Rasterizer(), # 使用光栅化渲染器
    rigid_options=gs.options.RigidOptions(
        enable_collision=True,  # 启用碰撞
        gravity=(0, 0, -9.81),  # 添加重力
    ),
)

plane = scene.add_entity(
    gs.morphs.Plane(),
)
# 读取temp目录下前100个prism_xxx.obj文件
temp_dir = "examples/obj/temp/temp"
obj_files = sorted([f for f in os.listdir(temp_dir) if f.endswith('.obj')])[:5]
print(f"将渲染以下文件: {obj_files}")

# 保存物体引用，用于后续设置初始速度
prism_objects = []

for obj_file in obj_files:
    file_path = os.path.join(temp_dir, obj_file)
    # 计算三棱柱体积和质量（可选）
    mesh = trimesh.load(file_path)
    volume = mesh.volume
    mass = volume * 10.0  # 假设密度为10
    # 添加到场景
    obj = scene.add_entity(
        morph=gs.morphs.Mesh(
            file=file_path,
            pos=(10, 10, 10),  # 可根据需要调整位置
            fixed=False,     # 允许物理模拟
        ),
        surface=gs.surfaces.Default(
            color=(0.8, 0.8, 0.8),  # 浅灰色
            smooth=True,  # 平滑渲染
        ),
    )
    prism_objects.append(obj)

# 添加一个平面作为地面
# scene.add_entity(
#     morph=gs.morphs.Box(
#         pos=(0.0, 0.0, -0.5),  # 位置
#         size=(10.0, 10.0, 0.1),  # 大小
#         fixed=True,  # 固定地面
#     ),
#     surface=gs.surfaces.Default(
#         color=(0.8, 0.8, 0.8),  # 浅灰色
#         smooth=True,
#     ),
# )

# 添加坐标轴
# X轴（红色）
scene.add_entity(
    gs.morphs.Cylinder(
        pos=(0.5, 0.0, 0.0),
        radius=0.005,
        height=1.0,
        euler=(0, 90, 0),  # 绕Y轴旋转90度
        fixed=True,
    ),
    surface=gs.surfaces.Default(color=(1.0, 0.0, 0.0)),  # 红色
)

# Y轴（绿色）
scene.add_entity(
    gs.morphs.Cylinder(
        pos=(0.0, 0.5, 0.0),
        radius=0.005,
        height=1.0,
        euler=(90, 0, 0),  # 绕X轴旋转90度
        fixed=True,
    ),
    surface=gs.surfaces.Default(color=(0.0, 1.0, 0.0)),  # 绿色
)

# Z轴（蓝色）
scene.add_entity(
    gs.morphs.Cylinder(
        pos=(0.0, 0.0, 0.5),
        radius=0.005,
        height=1.0,
        fixed=True,
    ),
    surface=gs.surfaces.Default(color=(0.0, 0.0, 1.0)),  # 蓝色
)

# 添加录屏相机（必须在scene.build()之前）
cam = scene.add_camera(
    res    = (1280, 960),
    pos    = (20, 15, 15),
    lookat = (10, 10, 10),
    fov    = 40,
    GUI    = False,
)

# 构建场景
scene.build()

# 为所有物体设置相同的初始速度
v_obj_init = gs.tensor([0.0, -1.0, 0.0], requires_grad=True)
for obj in prism_objects:
    obj.set_velocity(v_obj_init)
print(f"已为{len(prism_objects)}个物体设置初始速度: [0.0, -1.0, 0.0]")

# 录屏主循环
cam.start_recording()
steps = 30 * 10  # 10秒，30帧每秒
for i in range(steps):
    scene.step()
    cam.render()
cam.stop_recording(save_to_filename='examples/obj/prism_simulation.mp4', fps=30)
print('录屏已结束，视频已保存。')

# 继续交互式运行（可选）
while True:
    scene.step()

if name == "main":
main()
It seems that only the Robotics Engine allows the use of the obj.set_velocity(v_obj_init) attribute.

[codesbykhalil]

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