INTERFACE Pov;  

(*
   This module contains common procedures used with the POVray tracer.

   Last Modification: 17-05-00 by lozada.
*)

IMPORT R3, LR3, Wr;

PROCEDURE WritePOVPoint(wr: Wr.T; READONLY p: LR3.T);
  (* Writes a 3D point in POVray format. *)

PROCEDURE WritePOVColor(wr: Wr.T; READONLY cr: R3.T);
  (* Writes a rgb color in POVray format. *)

PROCEDURE WritePOVCylinder(
  wr: Wr.T;
  READONLY o,d: LR3.T;
  radius: REAL;
  READONLY cr: R3.T;
  tr: REAL;
  tag1, tag2: TEXT := "";
  );
  (* Defines a finity length cylinder without parallel end caps.*)	      

PROCEDURE WritePOVSphere(
  wr: Wr.T;
  READONLY p: LR3.T;
  radius: REAL;
  READONLY cr: R3.T;
  tr: REAL;
  tag1, tag2: TEXT := "";
  );
  (* 
    Defines a sphere with center in "p" and radius "radius". POVray has a
    highly optimized sphere primitive which renders much more quickly that
    the corresponding polynomial quadric shape.
  *)		   

PROCEDURE WritePOVTriangle(
  wr: Wr.T;
  READONLY a,b,c: LR3.T;
  READONLY cr: R3.T;
  tr: REAL;
  tag1, tag2: TEXT := "";
  );
  (* 
    Defines a triangle. Because triangle are perfectly flat surfaces it
    would requiere extremely large numbers of very smal triangles to appro-
    ximate a smooth, curved surface.
  *)		     		     

PROCEDURE WritePOVTriangleTex(
  wr: Wr.T;
  READONLY a,b,c: LR3.T;
  <* UNUSED *> READONLY cr: R3.T;
  <* UNUSED *> tr: REAL;
  );
  (* 
    Defines a triangle as above but with a some predefined texture face. 
  *)		     		     

PROCEDURE WritePOVSquare(
  wr: Wr.T;
  READONLY a,b,c,d: LR3.T;
  READONLY cr: R3.T;
  tr: REAL;
  );
  (* *************************************************************************
  // builds a square by the union of two triangular faces, adjacent
  // to one common edge.
  // 
  //                  /\ d
  //                 /  \
  //              a /____\ c
  //                \    /
  //                 \  /
  //                b \/
  //**********************************************************************
  *)

PROCEDURE WritePOVTetrahedron(
  wr: Wr.T;
  READONLY u,v,w,x: LR3.T;
  READONLY du,dv,dw,dx: LONGREAL;
  color : R3.T;
  trans : REAL;
  );
  (* *************************************************************************
  // builds a tetrahedron sby the union of four triangular faces.
  // to one common edge.
  //                   v          
  //                  /|\        
  //                 / | \        
  //              x /__|__\ w    
  //                \  |  /      
  //                 \ | /       
  //                  \|/
  //                   u
  //**********************************************************************
  *)

PROCEDURE WritePOVSmoothTriangle(
  wr: Wr.T;
  READONLY a, an: LR3.T;
  READONLY b, bn: LR3.T;
  READONLY c, cn: LR3.T; 
  READONLY cr: R3.T; 
  tr: REAL
  );
  (* 
    Much of our perception of smooth surfaces is dependent upon the way
    ligth and shading is done. By artificially modifying the surface normals
    we can simulate a triangle to be a smooth curved surface. The Smooth-
    Triangle primitive used the phong shading or interpolation of normals to
    calculate the surface normal for any point on the triangle based on nor-
    mal vectors which you define for the three corners. These normal vectors
    are prohibitivily difficult to computed by hand. Therefore smoothtrian-
    gles are almost always generated by utility programs.
  *)

(*
/****************************************************************************
// Define a pentagon build by the union of three triangular faces, adjacent
// to pairs to one common edge. 
//                  
//                  .b
//                 / \
//              c /___\a
//                |  /|
//                | / |
//                |/__|
//               d     e
//****************************************************************************/
*)

PROCEDURE WritePOVPenta(
  wr: Wr.T;
  READONLY a,b,c,d,e: LR3.T;
  READONLY cr: R3.T;
  tr: REAL;
  );

END Pov.

(**************************************************************************)
(*                                                                        *)
(* Copyright (C) 2000     Universidade Estadual de Campinas (UNICAMP)     *)
(*                                                                        *)
(* Authors:                                                               *)
(*   L. P. Lozada  & J. Stolfi   - UNICAMP <lozada@dcc.unicamp.br>        *)
(*                                                                        *)
(* This file can be freely used, distributed, and modified, provided that *)
(* this copyright and authorship notice is included in every copy or      *)
(* derived version.                                                       *)
(*                                                                        *)
(* DISCLAIMER: This software is offered ``as is'', without any guarantee  *)
(*   as to fitness for any particular purpose.  Neither the copyright     *)
(*   holder nor the authors or their employers can be held responsible    *)
(*   for any damages that may result from its use.                        *)
(*                                                                        *)
(**************************************************************************)