100 lines
2.1 KiB
C
100 lines
2.1 KiB
C
/*
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* stl.c - Genererate STL slice from polygon set
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*
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* Written 2013 by Werner Almesberger
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* Copyright 2013 Werner Almesberger
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <stdlib.h>
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#include <stdio.h>
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#include <math.h>
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#include "poly2d.h"
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#include "path.h"
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#include "stl.h"
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static void facet(FILE *file, const struct f2d *f, int a, int b, int c,
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double za, double zb, double zc, double nx, double ny, double nz)
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{
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double d;
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d = sqrt(nx*nx+ny*ny+nz*nz);
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if (!d)
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d = 1;
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fprintf(file, "facet normal %e %e %e\n", nx/d, ny/d, nz/d);
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fprintf(file, "\touter loop\n");
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fprintf(file, "\t\tvertex %e %e %e\n", f->x[a], f->y[a], za);
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fprintf(file, "\t\tvertex %e %e %e\n", f->x[b], f->y[b], zb);
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fprintf(file, "\t\tvertex %e %e %e\n", f->x[c], f->y[c], zc);
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fprintf(file, "\tendloop\n");
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fprintf(file, "endfacet\n");
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}
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static void surface(FILE *file, const struct f2d *f)
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{
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facet(file, f, 0, 1, 2, 1, 1, 1, 0, 0, 1);
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facet(file, f, 2, 1, 0, 0, 0, 0, 0, 0, -1);
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}
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static void side(FILE *file, const struct f2d *f, int a, int b)
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{
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double nx, ny;
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nx = f->y[b]-f->y[a];
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ny = f->x[a]-f->x[b];
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facet(file, f, a, b, b, 0, 0, 1, nx, ny, 0);
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facet(file, f, b, a, a, 1, 1, 0, nx, ny, 0);
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}
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static void stl_write(FILE *file, const struct path *paths)
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{
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struct p2d *polys;
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struct f2d *faces;
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const struct f2d *f;
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int i;
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fprintf(file, "solid cameo\n");
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polys = paths_to_polys(paths);
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faces = f2d_tri(polys);
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for (f = faces; f; f = f->next) {
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surface(file, f);
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for (i = 0; i != 3; i++)
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if (f->side[i])
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side(file, f, i, (i+1) % 3);
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}
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p2d_free_all(polys);
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f2d_free_all(faces);
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fprintf(file, "endsolid cameo\n");
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}
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void stl(const char *name, const struct path *paths)
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{
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FILE *file = stdout;
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if (name) {
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file = fopen(name, "w");
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if (!file) {
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perror(name);
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exit(1);
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}
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}
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stl_write(file, paths);
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if (name && fclose(file)) {
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perror(name);
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exit(1);
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}
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}
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