264 lines
6.8 KiB
C++
264 lines
6.8 KiB
C++
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/*******************************************************************************
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This program generates a gridded quadrilateral of given dimensions, and writes
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the result as a VRML 1.0 or X-file formatted output stream. The resultant
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quadrilateral is in the XY plane, going from [-1,-1] to [+1,+1].
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*******************************************************************************/
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#include <stdio.h>
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#include <stdlib.h>
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void WriteVRML1 (int nrows, int ncols);
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void WriteXFILE (int nrows, int ncols);
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inline void print (char *string) { fputs (string, stdout); }
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/*****************************************************************************
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*****************************************************************************/
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int main (int argc, char *argv[])
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{
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enum { VRML, XFILE } filetype = VRML;
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int nrows = 0,
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ncols = 0;
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int argi;
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for (argi=1; argi < argc; ++argi)
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{
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if ((argv[argi][0] == '-') && (tolower(argv[argi][1]) == 'x'))
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{ filetype = XFILE;
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continue;
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}
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if (nrows == 0)
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nrows = atoi (argv[argi]);
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else
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ncols = atoi (argv[argi]);
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}
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if (nrows <= 0)
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{ fputs
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( "quadgrid: Generates VRML1 or X-file gridded quadrilateral\n"
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"Usage: quadgrid [-x] <rows> [columns]\n"
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"\n"
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"If [columns] is omitted, quadgrid uses the number of rows.\n"
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"Use the -x option to generate X files.\n\n",
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stderr
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);
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exit (-1);
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}
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if (ncols == 0)
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ncols = nrows;
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if (filetype == VRML)
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WriteVRML1 (nrows, ncols);
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else
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WriteXFILE (nrows, ncols);
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return 0;
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}
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/*****************************************************************************
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This procedure writes out a grid in VRML 1.0 format.
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*****************************************************************************/
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void WriteVRML1 (int nrows, int ncols)
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{
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// VRML 1.0 Header
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printf (
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"#VRML V1.0 ascii\n\n"
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"Separator {\n"
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"Info { string "
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"\"%d x %d gridded quadrilateral generated by quadgrid.\""
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" }\n",
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nrows, ncols
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);
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// Write out the vertex coordinates.
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print ("\nCoordinate3 { point [\n");
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// N 2N 3N ... (N+1)(M+1)-1 This is the vertex indexing
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// : : : : for the generated grid layout.
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// 3 (N+1)+3 2(N+1)+3 ... M(N+1)+3 This contains (N+1)(M+1)
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// 2 (N+1)+2 2(N+1)+2 ... M(N+1)+2 vertices, NM quadrilaterals,
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// 1 (N+1)+1 2(N+1)+1 M(N+1)+1 and 2NM triangles.
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// 0 (N+1) 2(N+1) ... M(N+1)
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int row, col;
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for (col=0; col <= ncols; ++col)
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{ for (row=0; row <= nrows; ++row)
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{ printf ("\t% g\t% g\t0,\n",
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(((col / double(ncols)) * 2) - 1),
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(((row / double(nrows)) * 2) - 1));
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}
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}
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print ("] } # Coordinate3\n");
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// Write out the texture coordinates.
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print ("\nTextureCoordinate2 { point [\n");
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for (col=0; col <= ncols; ++col)
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{ for (row=0; row <= nrows; ++row)
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{ printf ("\t%g\t%g,\n",
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(col / double (ncols)),
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(row / double (nrows)));
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}
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}
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print ("] } # TextureCoordinate2\n");
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// Write out the normal vectors.
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print
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( "\nNormal { vector [0 0 1] }\n"
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"NormalBinding { value OVERALL }\n"
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);
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// Lay out triangles column by column.
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print ("\nIndexedFaceSet { coordIndex [\n");
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int left = 0; // Lower Left Vertex Index
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int right = 1+nrows; // Lower Right Vertex Index
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for (col=0; col < ncols; ++col, ++left, ++right)
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{ for (row=0; row < nrows; ++row, ++left, ++right)
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{ printf ("\t%d,\t%d,\t%d,\t-1,\n", left, right, right+1);
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printf ("\t%d,\t%d,\t%d,\t-1,\n", left, right+1, left+1);
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}
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}
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// Epilogue
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print
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( "] } # IndexedFaceSet\n"
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"\n} # Separator\n"
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);
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}
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/*****************************************************************************
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This procedure writes out a grid in X-file format.
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*****************************************************************************/
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void WriteXFILE (int nrows, int ncols)
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{
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int nverts = (nrows+1) * (ncols+1);
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// Header
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printf
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( "xof 0302txt 0032\n\n"
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"# %d x %d gridded quadrilateral generated by 'quadgrid'\n\n"
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"Header { 1;0;1; }\n\n"
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"Mesh {\n\n",
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nrows, ncols
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);
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// Write out the vertex coordinates.
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print ("# Vertex Coordinates\n\n");
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// N 2N 3N ... (N+1)(M+1)-1 This is the vertex indexing
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// : : : : for the generated grid layout.
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// 3 (N+1)+3 2(N+1)+3 ... M(N+1)+3 This contains (N+1)(M+1)
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// 2 (N+1)+2 2(N+1)+2 ... M(N+1)+2 vertices, NM quadrilaterals,
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// 1 (N+1)+1 2(N+1)+1 M(N+1)+1 and 2NM triangles.
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// 0 (N+1) 2(N+1) ... M(N+1)
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printf ("%d;\n", nverts);
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int row, col;
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for (col=0; col <= ncols; ++col)
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{
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for (row=0; row <= nrows; ++row)
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{
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if (col || row) print (",\n");
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printf ("% f; % f; 0.0;",
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(((col / double(ncols)) * 2) - 1),
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(((row / double(nrows)) * 2) - 1));
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}
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}
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print (";\n\n");
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// Face Coordinate Indices
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printf ("# Faces\n\n%d;\n", 2 * nrows * ncols);
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int left = 0; // Lower Left Vertex Index
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int right = 1+nrows; // Lower Right Vertex Index
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for (col=0; col < ncols; ++col, ++left, ++right)
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{ for (row=0; row < nrows; ++row, ++left, ++right)
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{ if (row || col) print (",\n");
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printf ("3;%4d,%4d,%4d;,\n", left, right+1, right);
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printf ("3;%4d,%4d,%4d;", left, left+1, right+1);
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}
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}
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print (";\n\n");
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// Write out the texture coordinates.
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printf ("MeshTextureCoords { \n\t%d;\n", nverts);
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for (col=0; col <= ncols; ++col)
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{ for (row=0; row <= nrows; ++row)
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{ printf ("%s\t%.4f; %.4f;",
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((row || col) ? ",\n" : ""),
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(col / double (ncols)),
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(row / double (nrows)));
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}
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}
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print (";\n}\n\n");
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// Write out default material
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print
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( "MeshMaterialList {\n"
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" # Diffuse White\n"
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" 1;1;0;;\n"
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" Material {\n"
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" 1.0; 1.0; 1.0; 1.0;;\n"
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" 1.0;\n"
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" 0.0; 0.0; 0.0;\n"
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" 0.0; 0.0; 0.0;\n"
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" }\n"
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"}\n\n"
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);
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// Write out the normal vectors.
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print ("MeshNormals {\n\t1;\n\t0.0; 0.0; -1.0;;\n\n");
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// Face Normal Indices
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printf ("\t%d;\n", 2 * nrows * ncols);
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int i;
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for (i=0; i < (2*nrows*ncols); ++i)
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printf ("%s\t3;0,0,0;", (i ? ",\n" : ""));
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print (";\n}\n");
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// Epilogue
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print ("\n}\n");
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}
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