//  Button shape based on superelliptic balls and cylinders
//
//  The button shape is a cylindroidical "stem", topped by 
//  hemispheroidical "caps".  The whole thing is centered on the origin,
//  with the front capped end towards +Y.  The whole thing fits inside the box
//
//     [-HX .. +HX] x [-HY .. +HY] x [-HZ .. +HZ]
//
//  where HX = button_shape_HX, HY = button_shape_HY
//  and HZ = button_shape_HZ
//
//  Assumes defined:
//
//    button_cyl = the "stem" shape, 
//      an infinite cylinder to use as stem, centered on the Y axis,
//      with max |X| = max |Z| = 1 and convex cross-section.
//
//    button_ball = the "cap" shape,
//      a bounded blob with same XZ section as button_cyl and max |Y| = 1
//
//    button_shape_HX
//    button_shape_HY
//    button_shape_HZ
// 
//    button_shape_cap_HY = Y extent of cap ( <= button_shape_HY )
//
//  Defines
//  
//    button_shape = the thing
//

#declare button_shape_stem_HY = button_shape_HY - button_shape_cap_HY

#declare button_shape =
  merge{
    object{ button_ball 
      scale < 1, button_shape_cap_HY, 1 >
      translate < 0, +button_shape_stem_HY, 0 >
    }
    object{ button_ball 
      scale < 1, button_shape_cap_HY, 1 >
      translate < 0, -button_shape_stem_HY, 0 >
    }
    intersection{
      object{ button_cyl }
      plane{ < 0,  1, 0 >, button_shape_stem_HY }
      plane{ < 0, -1, 0 >, button_shape_stem_HY }
    }
    bounded_by{ box{
      1.001 * < -1,-button_shape_HY,-1 >,
      1.001 * < +1,+button_shape_HY,+1 >
    } }
    scale < button_shape_HX, 1, button_shape_HZ >
  }