#macro front_wall_car_gate( tag, g_dim, g_pass, show_new, g_open )

  // A car gate.
  
  // {tag}      tag for part identification.
  // {g_dim}    dimensions of gate.  The Y dim includes the frame, the X dim does not.
  // {g_pass}   if true, the right wing is a narrower person gate. 
  // {g_open}   if true, show gate half-open.
  // {show_new} if true, uses the highlighting texture.
  
  // Origin is at left bottom corner of the nominal box {g_dim}.
  // Note that the frame will extend outside that box in X (but not in Y).
  
  #local g_frame_sx = 80;  // X width of frame.
  #local g_frame_sy = 100; // Y width of frame.
  #local g_hinge_sy = 45;  // Y gap between frame and grille.
  
  #local g_wings_sy = g_dim.y - 2*(g_frame_sy + g_hinge_sy); // Total Y width of wings (mobile parts).

  // Opening angle:
  #local g_open_deg = 60*g_open;
  
  // Texture:
  #if (show_new)
    #local w_tx = tx_grille_new
  #else
    #local w_tx = tx_grille
  #end
  
  #if (g_pass)
    #local g_gap_sy = 0; // Y gap between wings.
    #local w1_sy = 770; // Y width of right (person) wing.
    #local w0_sy = g_wings_sy - g_gap_sy - w1_sy; // Y width of left wing.
    #local w0_rot = -g_open_deg;
    #local w1_rot = +g_open_deg;
  #else
    #local g_gap_sy = 15; // Y gap between wings.
    #local w0_sy = (g_wings_sy - g_gap_sy)/2; // Y width of left wing.
    #local w1_sy = w0_sy; // Y width of Y wing.
    #local w0_rot = -g_open_deg;
    #local w1_rot = -g_open_deg;
  #end

  // The left wing of the gate:
  #local w0_tag = concat(tag, ".w0")
  #local w0_dim = < g_dim.x, w0_sy, g_dim.z >;
  #local w0_hinge_dy = g_frame_sy + g_hinge_sy/2; // Y coord of left hinge
  #local w0 = object{ front_wall_grille( w0_tag, w0_dim ) texture { w_tx } }
  
  // The right wing the gate:
  #local w1_tag = concat(tag, ".w1")
  #local w1_dim = < g_dim.x, w1_sy, g_dim.z >;
  #local w1_hinge_dy = g_dim.y - (g_frame_sy + g_hinge_sy/2); // Y coord of right hinge.
  #local w1 = object{ front_wall_grille( w1_tag, w1_dim ) texture{ w_tx } }
  
  // The fixed part of the gate:
  #local g_frame = sphere{ g_dim/2, 20 texture{ tx_bug } } // !!! Define !!!
  
  #local gate = 
    union{
      object{ g_frame }
      object{ w0 
        translate + w0_dim.x/2*x + g_hinge_sy/2*y 
        rotate w0_rot*z
        translate - w0_dim.x/2*x + w0_hinge_dy*y
      }
      object{ w1 
        translate + w1_dim.x*x - (w1_dim.y + g_hinge_sy/2)*y 
        rotate -w1_rot*z 
        translate - w1_dim.x*x + w1_hinge_dy*y
      }
    }

  gate 
  
#end