| 1 |
greg |
2.1 |
#ifndef lint
|
| 2 |
greg |
2.2 |
static const char RCSid[] = "$Id: objtriangulate.c,v 2.1 2021/03/12 03:59:25 greg Exp $";
|
| 3 |
greg |
2.1 |
#endif
|
| 4 |
|
|
/*
|
| 5 |
|
|
* Turn all faces with > 3 sides to triangles in Wavefront .OBJ scene
|
| 6 |
|
|
*/
|
| 7 |
|
|
|
| 8 |
|
|
#include "copyright.h"
|
| 9 |
|
|
|
| 10 |
|
|
#include <stdio.h>
|
| 11 |
|
|
#include <stdlib.h>
|
| 12 |
|
|
#include "rterror.h"
|
| 13 |
|
|
#include "objutil.h"
|
| 14 |
|
|
#include "triangulate.h"
|
| 15 |
|
|
|
| 16 |
|
|
typedef struct {
|
| 17 |
|
|
Scene *sc;
|
| 18 |
|
|
Face *f;
|
| 19 |
greg |
2.2 |
int rev;
|
| 20 |
greg |
2.1 |
} SceneFace;
|
| 21 |
|
|
|
| 22 |
|
|
/* Callback to create new triangle */
|
| 23 |
|
|
static int
|
| 24 |
|
|
addtriangle(const Vert2_list *tp, int a, int b, int c)
|
| 25 |
|
|
{
|
| 26 |
|
|
SceneFace *sf = (SceneFace *)tp->p;
|
| 27 |
|
|
Face *f = sf->f;
|
| 28 |
|
|
VNDX triv[3];
|
| 29 |
|
|
|
| 30 |
greg |
2.2 |
if (sf->rev) { /* need to reverse triangle? */
|
| 31 |
|
|
int t = a;
|
| 32 |
|
|
a = c;
|
| 33 |
|
|
c = t;
|
| 34 |
|
|
}
|
| 35 |
greg |
2.1 |
triv[0][0] = f->v[a].vid;
|
| 36 |
|
|
triv[0][1] = f->v[a].tid;
|
| 37 |
|
|
triv[0][2] = f->v[a].nid;
|
| 38 |
|
|
triv[1][0] = f->v[b].vid;
|
| 39 |
|
|
triv[1][1] = f->v[b].tid;
|
| 40 |
|
|
triv[1][2] = f->v[b].nid;
|
| 41 |
|
|
triv[2][0] = f->v[c].vid;
|
| 42 |
|
|
triv[2][1] = f->v[c].tid;
|
| 43 |
|
|
triv[2][2] = f->v[c].nid;
|
| 44 |
|
|
|
| 45 |
|
|
f = addFace(sf->sc, triv, 3);
|
| 46 |
|
|
if (f == NULL)
|
| 47 |
|
|
return(0);
|
| 48 |
|
|
|
| 49 |
|
|
f->flags |= sf->f->flags;
|
| 50 |
|
|
f->grp = sf->f->grp;
|
| 51 |
|
|
f->mat = sf->f->mat;
|
| 52 |
|
|
return(1);
|
| 53 |
|
|
}
|
| 54 |
|
|
|
| 55 |
|
|
/* Callback to convert face to triangles */
|
| 56 |
|
|
static int
|
| 57 |
|
|
mktriangles(Scene *sc, Face *f, void *p)
|
| 58 |
|
|
{
|
| 59 |
|
|
Normal nrm;
|
| 60 |
|
|
int i, ax, ay;
|
| 61 |
|
|
Vert2_list *poly;
|
| 62 |
|
|
SceneFace mysf;
|
| 63 |
|
|
|
| 64 |
|
|
if (f->nv <= 3) /* already a triangle? */
|
| 65 |
|
|
return(0);
|
| 66 |
|
|
|
| 67 |
|
|
if (faceArea(sc, f, nrm) == 0) /* hidden degenerate? */
|
| 68 |
|
|
return(0);
|
| 69 |
|
|
/* identify major axis from normal */
|
| 70 |
|
|
i = (nrm[1]*nrm[1] > nrm[0]*nrm[0]);
|
| 71 |
|
|
if (nrm[2]*nrm[2] > nrm[i]*nrm[i]) i = 2;
|
| 72 |
|
|
ax = (i+1)%3;
|
| 73 |
|
|
ay = (i+2)%3;
|
| 74 |
|
|
/* assign 2-D vertices */
|
| 75 |
|
|
poly = polyAlloc(f->nv);
|
| 76 |
|
|
if (poly == NULL) {
|
| 77 |
|
|
error(SYSTEM, "Out of memory in mktriangles");
|
| 78 |
|
|
return(-1);
|
| 79 |
|
|
}
|
| 80 |
|
|
mysf.sc = sc;
|
| 81 |
|
|
mysf.f = f;
|
| 82 |
|
|
poly->p = &mysf;
|
| 83 |
|
|
for (i = 0; i < f->nv; i++) {
|
| 84 |
|
|
double *pt = sc->vert[f->v[i].vid].p;
|
| 85 |
|
|
poly->v[i].mX = pt[ax];
|
| 86 |
|
|
poly->v[i].mY = pt[ay];
|
| 87 |
|
|
}
|
| 88 |
greg |
2.2 |
mysf.rev = (polyArea(poly) < .0);
|
| 89 |
greg |
2.1 |
i = polyTriangulate(poly, addtriangle);
|
| 90 |
|
|
polyFree(poly);
|
| 91 |
|
|
/* flag face if replaced */
|
| 92 |
|
|
f->flags |= (i > 0)*FACE_DUPLICATE;
|
| 93 |
|
|
return(i);
|
| 94 |
|
|
}
|
| 95 |
|
|
|
| 96 |
|
|
/* Convert all faces with > 3 vertices to triangles */
|
| 97 |
|
|
int
|
| 98 |
|
|
triangulateScene(Scene *sc)
|
| 99 |
|
|
{
|
| 100 |
|
|
int orig_nfaces = sc->nfaces;
|
| 101 |
|
|
int nc = foreachFace(sc, mktriangles,
|
| 102 |
|
|
0, FACE_DUPLICATE|FACE_DEGENERATE, NULL);
|
| 103 |
|
|
|
| 104 |
|
|
if (nc < 0) /* bad (memory) error? */
|
| 105 |
|
|
return(-1);
|
| 106 |
|
|
if (nc > 0) /* else remove faces we split up */
|
| 107 |
|
|
deleteFaces(sc, FACE_DUPLICATE, 0);
|
| 108 |
|
|
|
| 109 |
|
|
return(sc->nfaces - orig_nfaces);
|
| 110 |
|
|
}
|
