Group {
     children [
        DEF SENSOR PlaneSensor {
           minPosition 0 0
           maxPosition 10 10
           offset 10 10 0
        }
  
        DEF BUTTON Transform {
           translation 10 10 0
           children [
              Shape {
                 appearance Appearance {
                    material Material {
                       emissiveColor 1 0 0
                    }
                 }
                 geometry Sphere {
                    radius 0.1
                 }
              }
           ]
        }
     ]
  }