1 |
#ifndef lint |
2 |
static const char RCSid[] = "$Id: tmesh.c,v 2.3 2003/06/26 00:58:09 schorsch Exp $"; |
3 |
#endif |
4 |
/* |
5 |
* Compute and print barycentric coordinates for triangle meshes |
6 |
*/ |
7 |
|
8 |
#include <stdio.h> |
9 |
|
10 |
#include "fvect.h" |
11 |
|
12 |
#include "tmesh.h" |
13 |
|
14 |
#define ABS(x) ((x) >= 0 ? (x) : -(x)) |
15 |
|
16 |
|
17 |
int |
18 |
flat_tri(v1, v2, v3, n1, n2, n3) /* determine if triangle is flat */ |
19 |
FVECT v1, v2, v3, n1, n2, n3; |
20 |
{ |
21 |
double d1, d2, d3; |
22 |
FVECT vt1, vt2, vn; |
23 |
/* compute default normal */ |
24 |
VSUB(vt1, v2, v1); |
25 |
VSUB(vt2, v3, v2); |
26 |
VCROSS(vn, vt1, vt2); |
27 |
if (normalize(vn) == 0.0) |
28 |
return(DEGEN); |
29 |
/* compare to supplied normals */ |
30 |
d1 = DOT(vn, n1); d2 = DOT(vn, n2); d3 = DOT(vn, n3); |
31 |
if (d1 < 0 && d2 < 0 && d3 < 0) { |
32 |
if (d1 > -COSTOL || d2 > -COSTOL || d3 > -COSTOL) |
33 |
return(RVBENT); |
34 |
return(RVFLAT); |
35 |
} |
36 |
if (d1 < COSTOL || d2 < COSTOL || d3 < COSTOL) |
37 |
return(ISBENT); |
38 |
return(ISFLAT); |
39 |
} |
40 |
|
41 |
|
42 |
int |
43 |
comp_baryc(bcm, v1, v2, v3) /* compute barycentric vectors */ |
44 |
register BARYCCM *bcm; |
45 |
RREAL *v1, *v2, *v3; |
46 |
{ |
47 |
RREAL *vt; |
48 |
FVECT va, vab, vcb; |
49 |
double d; |
50 |
int ax0, ax1; |
51 |
register int i; |
52 |
/* compute major axis */ |
53 |
VSUB(vab, v1, v2); |
54 |
VSUB(vcb, v3, v2); |
55 |
VCROSS(va, vab, vcb); |
56 |
bcm->ax = ABS(va[0]) > ABS(va[1]) ? 0 : 1; |
57 |
bcm->ax = ABS(va[bcm->ax]) > ABS(va[2]) ? bcm->ax : 2; |
58 |
ax0 = (bcm->ax + 1) % 3; |
59 |
ax1 = (bcm->ax + 2) % 3; |
60 |
for (i = 0; i < 2; i++) { |
61 |
vab[0] = v1[ax0] - v2[ax0]; |
62 |
vcb[0] = v3[ax0] - v2[ax0]; |
63 |
vab[1] = v1[ax1] - v2[ax1]; |
64 |
vcb[1] = v3[ax1] - v2[ax1]; |
65 |
d = vcb[0]*vcb[0] + vcb[1]*vcb[1]; |
66 |
if (d <= FTINY*FTINY) |
67 |
return(-1); |
68 |
d = (vcb[0]*vab[0]+vcb[1]*vab[1])/d; |
69 |
va[0] = vab[0] - vcb[0]*d; |
70 |
va[1] = vab[1] - vcb[1]*d; |
71 |
d = va[0]*va[0] + va[1]*va[1]; |
72 |
if (d <= FTINY*FTINY) |
73 |
return(-1); |
74 |
d = 1.0/d; |
75 |
bcm->tm[i][0] = va[0] *= d; |
76 |
bcm->tm[i][1] = va[1] *= d; |
77 |
bcm->tm[i][2] = -(v2[ax0]*va[0]+v2[ax1]*va[1]); |
78 |
/* rotate vertices */ |
79 |
vt = v1; |
80 |
v1 = v2; |
81 |
v2 = v3; |
82 |
v3 = vt; |
83 |
} |
84 |
return(0); |
85 |
} |
86 |
|
87 |
|
88 |
void |
89 |
eval_baryc(wt, p, bcm) /* evaluate barycentric weights at p */ |
90 |
RREAL wt[3]; |
91 |
FVECT p; |
92 |
register BARYCCM *bcm; |
93 |
{ |
94 |
double u, v; |
95 |
|
96 |
u = p[(bcm->ax + 1) % 3]; |
97 |
v = p[(bcm->ax + 2) % 3]; |
98 |
wt[0] = u*bcm->tm[0][0] + v*bcm->tm[0][1] + bcm->tm[0][2]; |
99 |
wt[1] = u*bcm->tm[1][0] + v*bcm->tm[1][1] + bcm->tm[1][2]; |
100 |
wt[2] = 1. - wt[1] - wt[0]; |
101 |
} |
102 |
|
103 |
|
104 |
int |
105 |
get_baryc(wt, p, v1, v2, v3) /* compute barycentric weights at p */ |
106 |
RREAL wt[3]; |
107 |
FVECT p; |
108 |
FVECT v1, v2, v3; |
109 |
{ |
110 |
BARYCCM bcm; |
111 |
|
112 |
if (comp_baryc(&bcm, v1, v2, v3) < 0) |
113 |
return(-1); |
114 |
eval_baryc(wt, p, &bcm); |
115 |
return(0); |
116 |
} |
117 |
|
118 |
|
119 |
#if 0 |
120 |
int |
121 |
get_baryc(wt, p, v1, v2, v3) /* compute barycentric weights at p */ |
122 |
RREAL wt[3]; |
123 |
FVECT p; |
124 |
FVECT v1, v2, v3; |
125 |
{ |
126 |
FVECT ac, bc, pc, cros; |
127 |
double normf; |
128 |
/* area formula w/o 2-D optimization */ |
129 |
VSUB(ac, v1, v3); |
130 |
VSUB(bc, v2, v3); |
131 |
VSUB(pc, p, v3); |
132 |
VCROSS(cros, ac, bc); |
133 |
normf = DOT(cros,cros) |
134 |
if (normf <= 0.0) |
135 |
return(-1); |
136 |
normf = 1./sqrt(normf); |
137 |
VCROSS(cros, bc, pc); |
138 |
wt[0] = VLEN(cros) * normf; |
139 |
VCROSS(cros, ac, pc); |
140 |
wt[1] = VLEN(cros) * normf; |
141 |
wt[2] = 1. - wt[1] - wt[0]; |
142 |
return(0); |
143 |
} |
144 |
#endif |
145 |
|
146 |
|
147 |
void |
148 |
put_baryc(bcm, com, n) /* put barycentric coord. vectors */ |
149 |
register BARYCCM *bcm; |
150 |
register RREAL com[][3]; |
151 |
int n; |
152 |
{ |
153 |
double a, b; |
154 |
register int i; |
155 |
|
156 |
printf("%d\t%d\n", 1+3*n, bcm->ax); |
157 |
for (i = 0; i < n; i++) { |
158 |
a = com[i][0] - com[i][2]; |
159 |
b = com[i][1] - com[i][2]; |
160 |
printf("%14.8f %14.8f %14.8f\n", |
161 |
bcm->tm[0][0]*a + bcm->tm[1][0]*b, |
162 |
bcm->tm[0][1]*a + bcm->tm[1][1]*b, |
163 |
bcm->tm[0][2]*a + bcm->tm[1][2]*b + com[i][2]); |
164 |
} |
165 |
} |