/* 
 * line.sl 1.0 by Andrew Osiow
 *
 * Line is based on small modification to wire.sl which is distributed with Pixar's RMS or Mtor
 * Instead of setting Opacity, it sets line_color based on UV space
 *  
 */
#define HALF 0.5

surface line( float hwidth=0.0075,smult = 1.0,tmult = 1.0;
              color line_color = 0.0;)
  {
    float rim;
    float s_mid,t_mid,mid;
    color C;
    float val;

    rim = 2*hwidth; 

    Oi = Os;
    C  = Cs;

    s_mid = length(dPdu)*(HALF - abs(mod(s*smult,1.0) - HALF))/smult;
    t_mid = length(dPdv)*(HALF - abs(mod(t*tmult,1.0) - HALF))/tmult;
    mid = (s_mid > t_mid) ? t_mid : s_mid;
										    
    if (mid < hwidth)
      C = line_color;
    else if ( mid < (hwidth+rim))
      C = mix (line_color,Cs,(mid-hwidth)/rim);
    Ci = Oi * C;
  }