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1 | /* |
2 | * extrude.c - Perform the extrusion |
3 | * |
4 | * Written 2011 by Werner Almesberger |
5 | * Copyright 2011 by Werner Almesberger |
6 | * |
7 | * This program is free software; you can redistribute it and/or modify |
8 | * it under the terms of the GNU General Public License as published by |
9 | * the Free Software Foundation; either version 2 of the License, or |
10 | * (at your option) any later version. |
11 | */ |
12 | |
13 | /* |
14 | * Known bugs: |
15 | * |
16 | * - negative x coordinates in shape produce overlapping faces |
17 | */ |
18 | |
19 | |
20 | #include <stdlib.h> |
21 | #include <math.h> |
22 | #include <assert.h> |
23 | |
24 | #include "ptrude.h" |
25 | #include "path.h" |
26 | #include "extrude.h" |
27 | |
28 | |
29 | static void cvt_3d(struct point *p, const struct vertex *v, double z) |
30 | { |
31 | p->x = v->x; |
32 | p->y = v->y; |
33 | p->z = z; |
34 | } |
35 | |
36 | |
37 | static void size(const struct path *p) |
38 | { |
39 | const struct vertex *v, *next; |
40 | double s = 0, sl = 0; |
41 | int n = 0; |
42 | |
43 | if (!debug) |
44 | return; |
45 | for (v = p->vertices; v; v = next) { |
46 | next = v->next; |
47 | if (next) |
48 | s += hypot(v->x-next->x, v->y-next->y); |
49 | sl += v->len; |
50 | n++; |
51 | } |
52 | fprintf(stderr, "%d virt %g real %g\n", n, sl, s); |
53 | |
54 | } |
55 | |
56 | |
57 | static void mesh(const struct path *pa, double za, |
58 | const struct path *pb, double zb, |
59 | void (*face)(void *data, struct point a, struct point b, struct point c), |
60 | void *data) |
61 | { |
62 | const struct vertex *a = pa->vertices; |
63 | const struct vertex *b = pb->vertices; |
64 | double sa = 0, sb = 0; /* total distance traveled on path */ |
65 | double da, db; |
66 | struct point a3, b3, n; |
67 | |
68 | cvt_3d(&a3, a, za); |
69 | cvt_3d(&b3, b, zb); |
70 | |
71 | while (a->next || b->next) { |
72 | da = fabs(sa+a->len-sb); |
73 | db = fabs(sb+b->len-sa); |
74 | if ((a->next && da < db) || !b->next) { |
75 | cvt_3d(&n, a->next, za); |
76 | face(data, a3, n, b3); |
77 | a3 = n; |
78 | sa += a->len; |
79 | a = a->next; |
80 | } else { |
81 | cvt_3d(&n, b->next, zb); |
82 | face(data, b3, a3, n); |
83 | b3 = n; |
84 | sb += b->len; |
85 | b = b->next; |
86 | } |
87 | } |
88 | } |
89 | |
90 | |
91 | void extrude(const struct path *path, const struct path *shape, |
92 | double r, double d, |
93 | void (*face)(void *data, struct point a, struct point b, struct point c), |
94 | void *data) |
95 | { |
96 | const struct vertex *v, *next; /* current and next vertex */ |
97 | struct path *prev, *curr; /* previous and current path */ |
98 | struct path *tmp; |
99 | |
100 | if (!path->vertices || !path->vertices->next) |
101 | return; |
102 | |
103 | v = shape->vertices; |
104 | if (!v || !v->next) |
105 | return; |
106 | |
107 | tmp = stretch_path(path, v->x, r); |
108 | size(tmp); |
109 | prev = round_path(tmp, r, d); |
110 | free_path(tmp); |
111 | size(prev); |
112 | |
113 | while (v->next) { |
114 | next = v->next; |
115 | tmp = stretch_path(path, next->x, r); |
116 | size(tmp); |
117 | curr = round_path(tmp, r, d); |
118 | size(curr); |
119 | free_path(tmp); |
120 | |
121 | mesh(prev, v->y, curr, next->y, face, data); |
122 | |
123 | free_path(prev); |
124 | prev = curr; |
125 | v = next; |
126 | } |
127 | |
128 | free_path(prev); |
129 | } |
130 |
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