// Last edited on 2024-05-01 21:41:20 by stolfi

#include "retalho.inc"
#include "retalho_pos.inc"

#macro surface_generic_control_points()

  #local Z = array[4][4]

  #local Z[0][0] =   8.0; 
  #local Z[0][1] =   7.0; 
  #local Z[0][2] =   6.0; 
  #local Z[0][3] =   7.0; 

  #local Z[1][0] =   7.0; 
  #local Z[1][1] =   6.0; 
  #local Z[1][2] =  40.0; 
  #local Z[1][3] =   5.0; 

  #local Z[2][0] =   8.0; 
  #local Z[2][1] =  -9.0; 
  #local Z[2][2] =   7.0; 
  #local Z[2][3] =   6.0; 

  #local Z[3][0] =   8.0; 
  #local Z[3][1] =   7.0; 
  #local Z[3][2] =   6.0; 
  #local Z[3][3] =   7.0; 
  
  #local P = array[4][4]
  
  #for (i, 0, 3)
    #for (j, 0, 3)
      #local P[i][j] = < 4*i - 6, 4*j - 6, Z[i][j] >;
    #end
  #end

  P
#end

#macro surface_generic(P, tx)
  #local rad = 0;
  object{ retalho(P, rad, tx) }
#end

#macro surface_generic_norm_vec(P, U, V, tx)
  #local pos = retalho_pos(P, U, V);
  #local dir = retalho_normal(P, U, V);
  #local rad = rad_arrow;
  #debug concat("!! normal = ( ", str(dir.x,9,6), ", ", str(dir.y,9,6), ", ", str(dir.z,9,6), " )\n")
  union{
    sphere{ pos, 1.5*rad texture{ tx } }
    object{ garrow(pos, dir, tx) }
  }
#end