C
C Program SRFWRL to convert triangulated or polygonated surface into
C Virtual Reality Modeling Language
C
C Version: 5.40
C Date: 2000, February 11
C
C Coded by: Ludek Klimes
C     Department of Geophysics, Charles University Prague,
C     Ke Karlovu 3, 121 16 Praha 2, Czech Republic,
C     E-mail: klimes@seis.karlov.mff.cuni.cz
C
C References:
C     
C     VRML (Virtual Reality Modeling Language) version 1.0C
C     
C     VRML97 (Virtual Reality Modeling Language ISO/IEC 14772)
C     
C     GOCAD
C     
C     Persistence of Vision scene description language, version 3.1
C
C.......................................................................
C                                                    
C Description of data files:
C
C Input data read from the standard input device (*):
C     The data are read by the list directed input (free format) and
C     consist of a single string 'SEP':
C     'SEP'...String in apostrophes containing the name of the input
C             SEP parameter or history file with the input data.
C     No default, 'SEP' must be specified and cannot be blank.
C
C                                                     
C Input data file 'SEP':
C     File 'SEP' has the form of the SEP
C     parameter file.  The parameters, which do not differ from their
C     defaults, need not be specified in file 'SEP'.
C Data specifying input files:
C     VRTX='string'... Name of the file with vertices of the polygons.
C             Description of file VRTX
C             Default: VRTX='vrtx.out'
C     TRGL='string'... Name of the file describing the triangles or
C             polygons.  Triangles are recommended (and obligatory if
C             VRML='GOCAD').
C             Description of file TRGL
C             Default: TRGL='trgl.out'
C     COLORS='string'... Name of the file containing the data describing
C             the colour map.
C             Description of file COLORS
C             Not used if VRML='GOCAD'.
C             Default: COLORS='hsv.dat'
C Input/output file:
C     WRL='string'... Name of the file to be supplemented with surfaces
C             or to be copied to the beginning of the output file.
C             If the filename is blank, output file starts from a
C             scratch (mostly not reasonable).
C             The default name of the output file is equal to WRL.
C             It is recommended to specify WRL rather than to use
C             the default name.
C             Default: WRL='out.wrl'
C     WRLOUT='string'... Name of the output file if different from WRL.
C             Default: WRLOUT=WRL
C Data specifying the form of the output file:
C     VRML='string'... Virtual reality scene description language.
C             VRML='VRML1': VRML (Virtual Reality Modeling Language)
C                           version 1.0.
C             VRML='VRML2': VRML97 according to ISO/IEC 14772 standard.
C             VRML='GOCAD': GOCAD description of surfaces (TSurf).
C             VRML='POV':   POV (Persistence Of Vision) scene
C                           description language, version 3.1.
C             Default: VRML='VRML2' (recommended)
C     NAME='string'... String containing the GOCAD name of the surface.
C             Used only if VRML='GOCAD'.  Obligatory parameter, must be
C             specified and cannot be blank if VRML='GOCAD'.
C Data specifying the values to be scaled in colours:
C     KOLPOS=integer... If zero, all surfaces will have the same colour
C             given by parameters R, G, B.  If positive, the values in
C             KOLPOS-th column of input file VRTX will be colour-coded
C             at each vertex on the positive side of each triangle or
C             polygon of the surface.
C             Not used if VRML='GOCAD'.
C             Default: KOLPOS=7
C     KOLNEG=integer... If zero, all surfaces will have the same colour
C             given by parameters R, G, B.  If positive, the values in
C             KOLNEG-th column of input file VRTX will be colour-coded
C             at each vertex on the negative side of each triangle or
C             polygon of the surface.
C             Not used if VRML='GOCAD'.
C             Default: KOLNEG=7
C     PROPERTIES='string'... String containing names of properties
C             corresponding to values Z1,Z2,Z3,V1,...,VN (see file
C             VRTX) which may be used to control the
C             colour of the surface.  If the number of names is smaller
C             than the number of values, the leftmost values are
C             considered.  If PROPERTIES=' ', no values are considered
C             and GOCAD atom VRTX is used for the vertices (otherwise,
C             GOCAD atom PVRTX is used).
C             Used only if VRML='GOCAD'.
C             Default: PROPERTIES=' '
C Data specifying the colour scale (not used if VRML='GOCAD'):
C     VADD=real, VMUL=real, VPER=real, VREF=real, CREF=real, CREF1=real,
C     CREF2=real, CREF3=real, etc... Refer to file
C             colors.for.
C     R=real, G=real, B=real... Float numbers between 0 and 1 specifying
C             the colour of the surfaces if KOLPOS=0 or
C             KOLNEG=0.
C             Defaults: R=1, G=1, B=1 (white)
C     TRANSP=real... Transparency of the surfaces (sometimes called
C             transmit).  Values from 0 to 1.
C             Default: TRANSP=0.
C     AMBIENT=real... Float number between 0 and 1 specifying the
C             intensity of the ambient light.  The colour of the ambient
C             light is assumed white.  Applied to the surfaces only if
C             VRML='vrml1'.  Otherwise, the ambient light source of
C             intensity AMBIENT is prescribed by program
C             iniwrl.for.
C             Default:  AMBIENT=0.20 (default for VRML materials)
C     SPECULAR=real... Intensity of the specular reflections from
C             glossy surfaces.  Values from 0 to 1.
C             Default: SPECULAR=0 (default for VRML materials)
C     SHININESS=real... Shininess of the surfaces (sometimes called
C             transmit).  Values from 0 to 1.
C             Default: SHININESS=0.20 (default for VRML materials)
C
C                                                    
C Input file VRTX with the vertices:
C (1) None to several strings terminated by / (a slash)
C (2) For each vertex data (2.1):
C (2.1) 'NAME',X1,X2,X3,Z1,Z2,Z3,V1,...,VN/
C     'NAME'... Name of the vertex.  Not considered.  May be blank.
C     X1,X2,X3... Coordinates of the vertex.
C     Z1,Z2,Z3... Normal to the surface at the vertex.
C     V1,...,VN...Optional values which may be used to control the
C             colour of the surface.
C     /...    None to several values terminated by a slash.
C (3) / or end of file.
C
C                                                    
C Input file TRGL with the triangles or polygons:
C (1) For each triangle data (1.1), or for each polygon data (1.2):
C (1.1) I1,I2,I3,/
C     I1,I2,I3... Indices of 3 vertices of the triangle, right-handed
C             with respect to the given surface normals.
C             The vertices in file VRTX are indexed by positive integers
C             according to their order.
C             For polygon, three indices I1,I2,I3 are replaced with more
C             ones.
C     /...    List of vertices is terminated by a slash.
C (1.2) I1,I2,...,IN,/
C     I1,I2,...,IN... Indices of N vertices of the polygon.
C             The vertices in file VRTX are indexed by positive integers
C             according to their order.
C     /...    List of vertices must be terminated by a slash.
C (2) / or end of file.
C
C=======================================================================
C
C Common block /RAMC/:
      INCLUDE 'ram.inc'
C     ram.inc
C
      INTEGER IRAM(MRAM)
      EQUIVALENCE (IRAM,RAM)
C
C.......................................................................
C
C     External functions and subroutines:
      EXTERNAL LENGTH,RSEP1,RSEP3T,RSEP3I,ERROR,FORM2,COLOR1,COLOR2
      INTEGER  LENGTH
C
C     Filenames and parameters:
      CHARACTER*80 FSEP,FVRTX,FTRGL,FCOLS,FIN,FOUT
      INTEGER LU1,LU2,IUNDEF,MVRTX,MQ
      PARAMETER (LU1=1,LU2=2,IUNDEF=-999999,MVRTX=99,MQ=30)
C     MVRTX...  Maximum number of vertices of a single polygon.
C
C     Other variables:
      CHARACTER*(8+8*MQ) FORMAT
      CHARACTER*5   VRML
      CHARACTER*255 TEXT
      LOGICAL LNORM
      INTEGER KOLPOS,KOLNEG,KQ,NQ
      INTEGER NVRTX,NPLGN,IREF,IRGB,I1,I2,I,N
      REAL AMBI,TRANSP,SPEC,SHIN,RED,GREEN,BLUE
      REAL OUTMIN(MQ),OUTMAX(MQ),R,G,B,AUX
C     LNORM.. Says whether the surface normals are specified.
C
C.......................................................................
C
C     Reading main input data:
      WRITE(*,'(A)') '+SRFWRL: Enter input filename: '
      FSEP=' '
      READ (*,*) FSEP
      IF(FSEP.EQ.' ') THEN
C       SRFWRL-07
        CALL ERROR('SRFWRL-07: No input file specified')
C       Input file in the form of the SEP (Stanford Exploration Project)
C       parameter or history file must be specified.
C       There is no default filename.
      END IF
      WRITE(*,'(A)') '+SRFWRL: Working...            '
C
C     Reading input and output filenames:
      CALL RSEP1(LU1,FSEP)
      CALL RSEP3T('VRTX'  ,FVRTX,'vrtx.out')
      CALL RSEP3T('TRGL'  ,FTRGL,'trgl.out')
      CALL RSEP3T('COLORS',FCOLS,'hsv.dat' )
      CALL RSEP3T('WRL'   ,FIN  ,'out.wrl' )
      CALL RSEP3T('WRLOUT',FOUT ,FIN       )
      CALL RSEP3T('VRML'  ,VRML ,'VRML2'   )
      CALL LOWER(VRML)
      CALL RSEP3I('KOLPOS',KOLPOS,7)
      CALL RSEP3I('KOLNEG',KOLNEG,7)
C
C     Beginning of the output file:
      OPEN(LU2,FILE=FOUT)
      CALL WRL1(LU1,LU2,FIN,FOUT,VRML)
C
C     Writing the prolog for the GOCAD surface:
      IF (VRML.EQ.'gocad') THEN
        WRITE(LU2,'(A)')
     *   'GOCAD TSurf'
        CALL RSEP3T('NAME',TEXT,' ')
        IF (TEXT.NE.' ') THEN
          I=LENGTH(TEXT)
          WRITE(LU2,'(2A)')
     *     'HDR name:',TEXT(1:I)
        ELSE
C         SRFWRL-09
          CALL ERROR('SRFWRL-09: No name of GOCAD object')
C         Name of the GOCAD object (set of points) must be specified.
        END IF
        CALL RSEP3T('PROPERTIES',TEXT,' ')
        IF (TEXT.NE.' ') THEN
          I=LENGTH(TEXT)
          WRITE(LU2,'(2A)')
     *     'PROPERTIES ',TEXT(1:I)
          KOLNEG=4
          DO 11 I=1,I-2
            IF (TEXT(I:I).NE.' '.AND.TEXT(I+1:I+1).EQ.' ') THEN
              KOLNEG=KOLNEG+1
            END IF
   11     CONTINUE
        ELSE
          KOLNEG=0
        END IF
        KOLPOS=KOLNEG
      END IF
C
C     Reading vertices:
      LNORM=.TRUE.
      KQ=MAX0(6,KOLPOS,KOLNEG)
      IF(VRML.EQ.'gocad') THEN
        NQ=KQ
      ELSE IF(KOLPOS.EQ.0.AND.KOLNEG.EQ.0) THEN
        NQ=6
      ELSE IF(KOLPOS.EQ.KOLNEG) THEN
        NQ=7
      ELSE
        NQ=8
      END IF
      IF(NQ.GT.MQ) THEN
C       SRFWRL-10
        CALL ERROR('SRFWRL-10: Too small arrays OUTMIN and OUTMAX')
      END IF
      OPEN(LU1,FILE=FVRTX)
      READ(LU1,*) (TEXT,I=1,20)
      NVRTX=0
   20 CONTINUE
        IF(NVRTX+KQ.GT.MRAM) THEN
C         SRFWRL-01
          CALL ERROR('SRFWRL-01: Too small array RAM')
        END IF
        TEXT='$'
        DO 21 I=NVRTX+2,NVRTX+KQ
          RAM(I)=0.
   21   CONTINUE
        READ(LU1,*,END=29) TEXT,(RAM(I),I=NVRTX+1,NVRTX+KQ)
        IF(TEXT.EQ.'$') THEN
          GO TO 29
        END IF
C       Shifting the values to be displayed to the 7th and 8th columns
        IF(KOLNEG.GT.0) THEN
          AUX=RAM(NVRTX+KOLNEG)
        END IF
        IF(KOLPOS.GT.0) THEN
          RAM(NVRTX+7)=RAM(NVRTX+KOLPOS)
        END IF
        IF(KOLNEG.GT.0.AND.KOLPOS.NE.KOLNEG) THEN
          RAM(NVRTX+8)=AUX
        END IF
C       Normalizing the normal
        AUX=SQRT(RAM(NVRTX+4)**2+RAM(NVRTX+5)**2+RAM(NVRTX+6)**2)
        IF(AUX.GT.0.) THEN
          AUX=0.999/AUX
          RAM(NVRTX+4)=RAM(NVRTX+4)*AUX
          RAM(NVRTX+5)=RAM(NVRTX+5)*AUX
          RAM(NVRTX+6)=RAM(NVRTX+6)*AUX
        ELSE
          LNORM=.FALSE.
        END IF
        IF(NVRTX.EQ.0) THEN
          DO 22 I=1,NQ
            OUTMIN(I)=RAM(NVRTX+I)
            OUTMAX(I)=RAM(NVRTX+I)
   22     CONTINUE
        ELSE
          DO 23 I=1,NQ
            OUTMIN(I)=AMIN1(OUTMIN(I),RAM(NVRTX+I))
            OUTMAX(I)=AMAX1(OUTMAX(I),RAM(NVRTX+I))
   23     CONTINUE
        END IF
        NVRTX=NVRTX+NQ
      GO TO 20
   29 CONTINUE
      CLOSE(LU1)
      IF(NQ.GE.8) THEN
        OUTMIN(7)=AMIN1(OUTMIN(7),OUTMIN(8))
        OUTMAX(7)=AMAX1(OUTMAX(7),OUTMAX(8))
      END IF
C     Values to be displayed have been shifted to the 7th or 8th columns
      IF(VRML.NE.'gocad') THEN
        IF(KOLNEG.NE.0) THEN
          IF(KOLPOS.EQ.KOLNEG) THEN
            KOLNEG=7
          ELSE
            KOLNEG=8
          END IF
        END IF
        IF(KOLPOS.NE.0) THEN
          KOLPOS=7
        END IF
      END IF
C
C     Reading input parameters for surface appearance:
      CALL RSEP3R('AMBIENT'  ,AMBI  ,0.20)
      CALL RSEP3R('TRANSP'   ,TRANSP,0.00)
      CALL RSEP3R('SPECULAR' ,SPEC  ,0.00)
      CALL RSEP3R('SHININESS',SHIN  ,0.20)
      CALL RSEP3R('R'        ,RED   ,1.)
      CALL RSEP3R('G'        ,GREEN ,1.)
      CALL RSEP3R('B'        ,BLUE  ,1.)
C
C     Determining the colour map:
      IF(KOLPOS.GT.0.OR.KOLNEG.GT.0) THEN
        CALL COLOR1(LU1,MRAM-NVRTX,IRAM(NVRTX+1),RAM(NVRTX+1),
     *                                            1,OUTMIN(7),OUTMAX(7))
        IF (VRML.EQ.'pov') THEN
          AUX=0.01/SHININ
          WRITE(LU2,'(A)')
     *     '#default {'
          WRITE(LU2,'(A,2(F4.2,A))')
     *     '  finish { ambient 1.00 specular ',SPEC,
     *                                            ' roughness ',AUX,' }'
          WRITE(LU2,'(A)')
     *     '  pigment {'
     *    ,'    color_map {'
          CALL COLOR3(MRAM-NVRTX,IRAM(NVRTX+1),RAM(NVRTX+1),1,IREF,IRGB)
          I=NVRTX+1+IRAM(NVRTX+1)
          IREF=NVRTX+IREF
          IRGB=NVRTX+IRGB
          DO 57 I2=1,IRAM(NVRTX+2)-IRAM(NVRTX+1)
            WRITE(LU2,'(A,F8.6,A,4(F4.2,A))')
     *       '      [',RAM(I+I2),' rgbt <',
     *                     (RAM(IRGB+I1),',',I1=3*I2-2,3*I2),TRANSP,'>]'
   57     CONTINUE
          WRITE(LU2,'(A)')
     *     '    }'
     *    ,'  }'
     *    ,'}'
          WRITE(LU2,'(A,G13.6,A)')
     *     '#declare CREF = ',RAM(IREF+1),';'
     *    ,'#declare VREF = ',RAM(IREF+2),';'
     *    ,'#declare VPER = ',RAM(IREF+3),';'
        END IF
      END IF
C
C     Writing the prolog for the surface:
      IF (VRML.EQ.'vrml1') THEN
        WRITE(LU2,'(A)')
     *   'DEF SurfaceMaterial Material {'
        WRITE(LU2,'(3(A,F4.2))')
     *   '  diffuseColor    ',RED,' ',GREEN,' ',BLUE
     *  ,'  ambientColor    ',RED*AMBI,' ',GREEN*AMBI,' ',BLUE*AMBI
     *  ,'  specularColor   ',SPEC,' ',SPEC,' ',SPEC
        WRITE(LU2,'(A,F4.2)')
     *   '  shininess       ',SHIN
     *  ,'  transparency    ',TRANSP
        WRITE(LU2,'(A)')
     *   '  emissiveColor    0.00 0.00 0.00'
     *  ,'}'
        WRITE(LU2,'(A)')
     *   'Separator {'
     *  ,'USE SurfaceMaterial'
        IF(LNORM) THEN
          WRITE(LU2,'(A)') 'NormalBinding { value PER_VERTEX }'
        ELSE
          WRITE(LU2,'(A)') 'NormalBinding { value PER_FACE }'
        END IF
      ELSE IF (VRML.EQ.'vrml2') THEN
        WRITE(LU2,'(A)')
     *   'Shape {'
     *  ,'  appearance DEF SurfaceAppearance Appearance {'
     *  ,'    material Material {'
        WRITE(LU2,'(3(A,F4.2))')
     *   '      diffuseColor     ',RED,' ',GREEN,' ',BLUE
     *  ,'      specularColor    ',SPEC,' ',SPEC,' ',SPEC
        WRITE(LU2,'(A,F4.2)')
     *   '      shininess        ',SHIN
     *  ,'      transparency     ',TRANSP
        WRITE(LU2,'(A)')
     *   '      ambientIntensity 1.00'
     *  ,'      emissiveColor    0.00 0.00 0.00'
     *  ,'    }'
     *  ,'  }'
     *  ,'}'
     *  ,'Surface {'
     *  ,'appearance USE SurfaceAppearance'
      ELSE IF (VRML.EQ.'gocad') THEN
        CONTINUE
      ELSE IF (VRML.EQ.'pov') THEN
        WRITE(LU2,'(A,I6,A)')
     *   '#declare NVRTX =',NVRTX/NQ,';'
        WRITE(LU2,'(A)')
     *   '#declare PTS = array[NVRTX][7]'
     *  ,'#declare IVRTX = 0;'
     *  ,'#macro VRTX(X1,X2,X3,Z1,Z2,Z3,V1)'
     *  ,'  #declare PTS[IVRTX][0] = X1;'
     *  ,'  #declare PTS[IVRTX][1] = X2;'
     *  ,'  #declare PTS[IVRTX][2] = X3;'
     *  ,'  #declare PTS[IVRTX][3] = Z1;'
     *  ,'  #declare PTS[IVRTX][4] = Z2;'
     *  ,'  #declare PTS[IVRTX][5] = Z3;'
     *  ,'  #declare PTS[IVRTX][6] = V1;'
     *  ,'  #declare IVRTX = IVRTX + 1;'
     *  ,'#end'
     *  ,'#macro TRGL(I1,I2,I3)'
     *  ,'  #local X1=;'
     *  ,'  #local X2=;'
     *  ,'  #local X3=;'
     *  ,'  #local Z1=;'
     *  ,'  #local Z2=;'
     *  ,'  #local Z3=;'
     *  ,'  #local V1=PTS[I1][6]-PTS[I3][6];'
     *  ,'  #local V2=PTS[I2][6]-PTS[I3][6];'
     *  ,'  #local V3=           PTS[I3][6];'
     *  ,'  #if (V1=0 & V2=0)'
     *  ,'    #local V1=VPER/999999;'
     *  ,'  #end'
     *  ,'  #local D1=X1-X3;'
     *  ,'  #local D2=X2-X3;'
     *  ,'  #local D11=vdot(D1,D1);'
     *  ,'  #local D12=vdot(D1,D2);'
     *  ,'  #local D22=vdot(D2,D2);'
     *  ,'  #local D  =D11*D22-D12*D12;'
     *  ,'  #local G =(D1*(D22*V1-D12*V2)+D2*(-D12*V1+D11*V2))/D;'
     *  ,'  #local GN= vlength(G);'
     *  ,'  #local G0= G*VPER/GN/GN;'
     *  ,'  #local G1= V2*D1-V1*D2;'
     *  ,'  #local G2= vcross(G0,G1);'
     *  ,'  smooth_triangle {'
     *  ,'    X1,Z1,X2,Z2,X3,Z3'
     *  ,'    texture {'
     *  ,'      pigment {'
     *  ,'        gradient x'
     *  ,'        translate ((VREF-V3)/VPER-CREF-100)*x'
     *  ,'        matrix '
     *  ,'        translate X3'
     *  ,'      }'
     *  ,'    }'
     *  ,'  }'
     *  ,'#end'
      ELSE
C       SRFWRL-08
        CALL ERROR('SRFWRL-08: No valid string in VRML')
C       Valid string specifying the form of the output file is:
C       VRML='VRML1' or 'VRML2' or 'POV'. Default and recommended
C       value is 'VRML2'.
      END IF
C
C     Writing the vertices:
      IF (VRML.EQ.'vrml1') THEN
        WRITE(LU2,'(A)') 'Coordinate3 { point ['
      ELSE IF (VRML.EQ.'vrml2') THEN
        WRITE(LU2,'(A)') 'point ['
      END IF
C     ------
      IF (VRML.EQ.'vrml1'.OR.VRML.EQ.'vrml2') THEN
        FORMAT='('
        CALL FORM2(3,OUTMIN(1),OUTMAX(1),FORMAT(2:25))
        DO 60 I=1,NVRTX,NQ
          WRITE(LU2,FORMAT) RAM(I),' ',RAM(I+1),' ',RAM(I+2),','
   60   CONTINUE
      ELSE IF (VRML.EQ.'gocad') THEN
C       Writing the vertices with normals and values:
        FORMAT='(A,I0,A,'
        FORMAT(5:5)=CHAR(ICHAR('1')+INT(ALOG10(FLOAT(NVRTX/NQ)+0.5)))
        IF (KOLNEG.EQ.0) THEN
          CALL FORM2(3,OUTMIN(1),OUTMAX(1),FORMAT(9:8+8*3))
          DO 62 I=1,NVRTX,NQ
            WRITE(LU2,FORMAT) 'VRTX ',I/NQ+1,(' ',RAM(J),J=I,I+2)
   62     CONTINUE
        ELSE
          CALL FORM2(NQ,OUTMIN(1),OUTMAX(1),FORMAT(9:8+8*NQ))
          DO 63 I=1,NVRTX,NQ
            WRITE(LU2,FORMAT) 'PVRTX ',I/NQ+1,(' ',RAM(J),J=I,I+NQ-1)
   63     CONTINUE
        END IF
      ELSE IF (VRML.EQ.'pov') THEN
C       Writing the vertices with normals and values:
        IF(KOLNEG.NE.KOLPOS) THEN
C         SRFWRL-51
          CALL WARN('SRFWRL-51: POV surface sides differently coloured')
C         POV scene description language does not allow for different
C         colours at the positive and negative side of a surface.
        END IF
        FORMAT='(A,'
        CALL FORM2(3,OUTMIN(1),OUTMAX(1),FORMAT(4:27))
        FORMAT(27:38)=',3(F5.3,A),'
        CALL FORM2(1,OUTMIN(7),OUTMAX(7),FORMAT(39:46))
        DO 65 I=1,NVRTX,NQ
          WRITE(LU2,FORMAT) 'VRTX(',(RAM(I1),',',I1=I,I+5),RAM(I+6),')'
   65   CONTINUE
      END IF
C     ------
      IF (VRML.EQ.'vrml1') THEN
        WRITE(LU2,'(A)') '] }'
      ELSE IF (VRML.EQ.'vrml2') THEN
        WRITE(LU2,'(A)') ']'
      END IF
C
C     Writing the right-handed normals (positive surface side):
      IF(LNORM) THEN
        IF (VRML.EQ.'vrml1') THEN
          WRITE(LU2,'(A)') 'DEF SurfaceNormal Normal { vector ['
        ELSE IF (VRML.EQ.'vrml2') THEN
          WRITE(LU2,'(A)') 'normalPos Normal { vector ['
        END IF
C       ------
        IF (VRML.EQ.'vrml1'.OR.VRML.EQ.'vrml2') THEN
          FORMAT='(3(F5.3,A))'
          DO 66 I=4,NVRTX,NQ
            WRITE(LU2,FORMAT) RAM(I),' ',RAM(I+1),' ',RAM(I+2),','
   66     CONTINUE
        END IF
C       ------
        IF (VRML.EQ.'vrml1') THEN
          WRITE(LU2,'(A)') '] }'
        ELSE IF (VRML.EQ.'vrml2') THEN
          WRITE(LU2,'(A)') '] }'
        END IF
      END IF
C
C     Writing the left-handed normals (negative surface side):
      IF(LNORM) THEN
        IF (VRML.EQ.'vrml1') THEN
          WRITE(LU2,'(A)') 'Normal { vector ['
        ELSE IF (VRML.EQ.'vrml2') THEN
          WRITE(LU2,'(A)') 'normalNeg Normal { vector ['
        END IF
C       ------
        IF (VRML.EQ.'vrml1'.OR.VRML.EQ.'vrml2') THEN
          DO 67 I=4,NVRTX,NQ
            WRITE(LU2,FORMAT) -RAM(I),' ',-RAM(I+1),' ',-RAM(I+2),','
   67     CONTINUE
        END IF
C       ------
        IF (VRML.EQ.'vrml1') THEN
          WRITE(LU2,'(A)') '] }'
        ELSE IF (VRML.EQ.'vrml2') THEN
          WRITE(LU2,'(A)') '] }'
        END IF
      END IF
C
C     Writing the colours of the positive surface side:
      IF(KOLPOS.GT.0) THEN
        IF (VRML.EQ.'vrml1') THEN
          WRITE(LU2,'(A)') 'DEF SurfaceColor Material { diffuseColor ['
        ELSE IF (VRML.EQ.'vrml2') THEN
          WRITE(LU2,'(A)') 'colorPos DEF SurfaceColor Color { color ['
        END IF
C       ------
        IF (VRML.EQ.'vrml1'.OR.VRML.EQ.'vrml2') THEN
          DO 71 I=KOLPOS,NVRTX,NQ
            CALL COLOR2(MRAM-NVRTX,IRAM(NVRTX+1),RAM(NVRTX+1),
     *                                                   1,RAM(I),R,G,B)
            WRITE(LU2,'(3(F4.2,A))') R,' ',G,' ',B,','
   71     CONTINUE
        END IF
C       ------
        IF (VRML.EQ.'vrml1') THEN
          WRITE(LU2,'(A)') '] }'
        ELSE IF (VRML.EQ.'vrml2') THEN
          WRITE(LU2,'(A)') '] }'
        END IF
      END IF
C
C     Writing the colours of the negative surface side:
      IF(KOLNEG.GT.0) THEN
        IF(KOLNEG.EQ.KOLPOS) THEN
          IF (VRML.EQ.'vrml1') THEN
            CONTINUE
          ELSE IF (VRML.EQ.'vrml2') THEN
            WRITE(LU2,'(A)') 'colorNeg USE SurfaceColor'
          END IF
        ELSE
          IF (VRML.EQ.'vrml1') THEN
            WRITE(LU2,'(A)') 'Material { diffuseColor ['
          ELSE IF (VRML.EQ.'vrml2') THEN
            WRITE(LU2,'(A)') 'colorNeg Color { color ['
          ELSE IF (VRML.EQ.'pov') THEN
          END IF
C         ------
          IF (VRML.EQ.'vrml1'.OR.VRML.EQ.'vrml2') THEN
            DO 72 I=KOLNEG,NVRTX,NQ
              CALL COLOR2(MRAM-NVRTX,IRAM(NVRTX+1),RAM(NVRTX+1),
     *                                                   1,RAM(I),R,G,B)
              WRITE(LU2,'(3(F4.2,A))') R,' ',G,' ',B,','
   72       CONTINUE
          END IF
C         ------
          IF (VRML.EQ.'vrml1') THEN
            WRITE(LU2,'(A)') '] }'
          ELSE IF (VRML.EQ.'vrml2') THEN
            WRITE(LU2,'(A)') '] }'
          END IF
        END IF
      END IF
C
C     Reading the polygons (usually triangles):
      DO 81 I=1,MRAM
        IRAM(I)=0
   81 CONTINUE
      OPEN(LU1,FILE=FTRGL)
      NPLGN=0
   82 CONTINUE
        IF(NPLGN+MVRTX+1.GT.MRAM) THEN
C         SRFWRL-02
          CALL ERROR('SRFWRL-02: Too small array RAM')
        END IF
        IRAM(NPLGN+1)=IUNDEF
        READ(LU1,*,END=89) (IRAM(I),I=NPLGN+1,NPLGN+MVRTX+1)
        IF(IRAM(NPLGN+1).EQ.IUNDEF) THEN
          GO TO 89
        END IF
        DO 83 I=NPLGN+1,NPLGN+MVRTX+1
          IF(IRAM(I).LE.0) THEN
C           Number of polygon vertices
            N=I-1-NPLGN
            GO TO 84
          ELSE IF(IRAM(I).GT.NVRTX/NQ) THEN
C           SRFWRL-03
            WRITE(TEXT,'(A,I6)')'SRFWRL-03: Wrong vertex index:',IRAM(I)
            CALL ERROR(TEXT(1:LENGTH(TEXT)))
          END IF
   83   CONTINUE
C         SRFWRL-04
          CALL ERROR('SRFWRL-04: Too many vertices in polygons')
   84   CONTINUE
        IF(N.LT.3) THEN
C         SRFWRL-52
          CALL WARN('SRFWRL-52: Polygon of less than 3 vertices')
        END IF
C       Checking vertex indices:
        DO 86 I2=NPLGN+1,NPLGN+N
          DO 85 I1=I2+1,NPLGN+N
          IF(IRAM(I2).EQ.IRAM(I1)) THEN
C           SRFWRL-05
            WRITE(TEXT,'(A,I6)')
     *        'SRFWRL-05: The same vertex twice in a polygon:',IRAM(I2)
            CALL ERROR(TEXT(1:LENGTH(TEXT)))
C           All vertices of a polygon must be different.
          END IF
   85     CONTINUE
   86   CONTINUE
C       Terminating polygon by zero
        IF(N.GE.3) THEN
          NPLGN=NPLGN+N+1
          IRAM(NPLGN)=0
        END IF
      GO TO 82
   89 CONTINUE
      CLOSE(LU1)
C
C     Writing the polygons (usually triangles):
      IF(VRML.EQ.'vrml1') THEN
        IF(KOLNEG.GT.0) THEN
          WRITE(LU2,'(A)') 'MaterialBinding { value PER_VERTEX }'
        ELSE
          WRITE(LU2,'(A)') 'MaterialBinding { value OVERALL }'
        END IF
        WRITE(LU2,'(A)') 'ShapeHints {'
        WRITE(LU2,'(A)') '  vertexOrdering CLOCKWISE'
        WRITE(LU2,'(A)') '  shapeType SOLID'
        WRITE(LU2,'(A)') '}'
        WRITE(LU2,'(A)') 'DEF Surface IndexedFaceSet { coordIndex ['
      ELSE IF(VRML.EQ.'vrml2') THEN
        WRITE(LU2,'(A)') 'coordIndex ['
      END IF
C     ------
      N=0
      IF(VRML.EQ.'vrml1'.OR.VRML.EQ.'vrml2') THEN
        FORMAT='(99(I0,A))'
        I=INT(ALOG10(FLOAT(NVRTX/NQ)-0.5))+1
        FORMAT(6:6)=CHAR(ICHAR('0')+I)
        DO 91 I2=1,NPLGN
          IF(IRAM(I2).LE.0) THEN
            WRITE(LU2,FORMAT)
     *                (IRAM(I1)-1,', ',I1=N+1,I2-2),IRAM(I2-1)-1,', -1,'
            N=I2
          END IF
   91   CONTINUE
      ELSE IF (VRML.EQ.'gocad') THEN
        FORMAT='(A,3(A,I0))'
        I=INT(ALOG10(FLOAT(NVRTX/NQ)+0.5))+1
        FORMAT(9:9)=CHAR(ICHAR('0')+I)
        DO 92 I2=1,NPLGN
          IF(IRAM(I2).LE.0) THEN
            IF(I2-N.GT.4) THEN
C             SRFWRL-10
              CALL ERROR('SRFWRL-10: More than 3 vertices in polygon')
C             In this version of the SRFWRL program, only triangles are
C             allowed for GOCAD.  Polygons should be divided into
C             triangles using program 'trgl.for'.
            END IF
            WRITE(LU2,FORMAT) 'TRGL',(' ',IRAM(I1),I1=N+1,I2-1)
            N=I2
          END IF
   92   CONTINUE
      ELSE IF(VRML.EQ.'pov') THEN
        FORMAT='(99(A,I0))'
        I=INT(ALOG10(FLOAT(NVRTX/NQ)-0.5))+1
        FORMAT(8:8)=CHAR(ICHAR('0')+I)
        DO 93 I2=1,NPLGN
          IF(IRAM(I2).LE.0) THEN
            IF(I2-N.GT.4) THEN
C             SRFWRL-06
              CALL ERROR('SRFWRL-06: More than 3 vertices in polygon')
C             In this version of the SRFWRL program, only triangles are
C             allowed for the POV scene description language.  Polygons
C             should be divided into triangles using program 'trgl.for'.
            END IF
            WRITE(LU2,FORMAT)
     *             'TRGL(',(IRAM(I1)-1,',',I1=N+1,I2-2),IRAM(I2-1)-1,')'
            N=I2
          END IF
   93   CONTINUE
      END IF
C     ------
      IF(VRML.EQ.'vrml1') THEN
        WRITE(LU2,'(A)') '] }'
        IF(LNORM) THEN
          WRITE(LU2,'(A)') 'USE SurfaceNormal'
        END IF
        IF(KOLPOS.GT.0) THEN
          WRITE(LU2,'(A)') 'USE SurfaceColor'
          WRITE(LU2,'(A)') 'MaterialBinding { value PER_VERTEX }'
        ELSE
          WRITE(LU2,'(A)') 'MaterialBinding { value OVERALL }'
        END IF
        WRITE(LU2,'(A)') 'ShapeHints {'
        WRITE(LU2,'(A)') '  vertexOrdering COUNTERCLOCKWISE'
        WRITE(LU2,'(A)') '  shapeType SOLID'
        WRITE(LU2,'(A)') '}'
        WRITE(LU2,'(A)') 'USE Surface'
      ELSE IF(VRML.EQ.'vrml2') THEN
        WRITE(LU2,'(A)') ']'
      END IF
C
C     Writing the trailor for the surface:
      IF (VRML.EQ.'vrml1') THEN
        WRITE(LU2,'(A)') '}'
      ELSE IF (VRML.EQ.'vrml2') THEN
        WRITE(LU2,'(A)') '}'
      ELSE IF (VRML.EQ.'gocad') THEN
        WRITE(LU2,'(A)') 'END'
      END IF
      CLOSE(LU2)
      WRITE(*,'(A)') '+SRFWRL: Done.                 '
      STOP
      END
C
C=======================================================================
C
      INCLUDE 'error.for'
C     error.for
      INCLUDE 'sep.for'
C     sep.for
      INCLUDE 'length.for'
C     length.for
      INCLUDE 'forms.for'
C     forms.for
      INCLUDE 'colors.for'
C     colors.for
      INCLUDE 'wrl.for'
C     wrl.for
C
C=======================================================================
C