mujoco

<mujoco model="touchtest">
  <compiler autolimits="true"/>
   <option sdf_initpoints="20"/>

  <extension>
    <plugin plugin="mujoco.sdf.gear">
      <instance name="gear">
        <config key="alpha" value="0"/>
      </instance>
    </plugin>
  </extension>

  <asset>
    <texture name="grid" type="2d" builtin="checker" rgb1=".1 .2 .3" rgb2=".2 .3 .4"
             width="300" height="300" mark="edge" markrgb=".2 .3 .4"/>
    <material name="grid" texture="grid" texrepeat="3 1" texuniform="true"/>
    <mesh name="gear">
      <plugin instance="gear"/>
    </mesh>
    <mesh name="sphere" builtin="wedge" params="37 37 45 45 0" scale=".3 .3 .3"/>
    <mesh name="box" builtin="plate" params="37 37" scale=".3 .5 .2"/>
  </asset>

  <visual>
      <headlight ambient=".7 .7 .7" diffuse=".2 .2 .2" specular="0.1 0.1 0.1"/>
      <map znear="0.01"/>
      <scale contactwidth=".02" contactheight=".5"/>
  </visual>

  <default>
    <geom friction="0.4" solimp="0 0.95 0.02"/>
  </default>

  <statistic center="0 0 1" extent="1" meansize=".1"/>

  <worldbody>
    <light pos="1 0 .3" dir="-1 0 -.3"/>
    <light pos="-1 0 .3" dir="1 0 -.3"/>
    <geom name="floor" pos="0 0 -0.01" type="plane" size="3 3 .01"/>

    <geom type="sdf" name="gear" mesh="gear" rgba="0.4 0.4 0.4 1" pos="-1.3 0 0">
      <plugin instance="gear"/>
    </geom>

    <body name="ball" pos="-1 1 1">
      <joint name="x" type="slide" axis="1 0 0" damping="1"/>
      <joint name="y" type="slide" axis="0 1 0" damping="1"/>
      <joint name="z" type="slide" axis="0 0 1"/>
      <joint name="rx" axis="1 0 0" springdamper="0.2 1"/>
      <joint name="ry" axis="0 1 0" springdamper="0.2 1"/>
      <geom type="sphere" size=".3" mass="0.1" rgba=".5 .5 .5 .3"/>
      <geom name="ball" type="mesh" mesh="sphere" mass="0" contype="0" conaffinity="0" rgba=".5 .5 .5 0"/>
    </body>

    <body name="finger" pos="0 0 1">
      <freejoint/>
      <geom type="box" size=".3 .5 .2" mass="0.1" rgba=".5 .5 .5 .3"/>
      <geom name="finger" type="mesh" mesh="box" mass="0" contype="0" conaffinity="0" rgba=".5 .5 .5 0"/>
    </body>
  </worldbody>

  <sensor>
    <tactile geom="ball" mesh="sphere"/>
    <tactile geom="finger" mesh="box"/>
  </sensor>
</mujoco>