-
-
Notifications
You must be signed in to change notification settings - Fork 1.2k
/
csgtermnormalizer.cc
156 lines (139 loc) · 5.5 KB
/
csgtermnormalizer.cc
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
#include "csgtermnormalizer.h"
#include "csgterm.h"
#include "printutils.h"
/*!
NB! for e.g. empty intersections, this can normalize a tree to nothing and return NULL.
*/
shared_ptr<CSGTerm> CSGTermNormalizer::normalize(const shared_ptr<CSGTerm> &root,
size_t limit)
{
shared_ptr<CSGTerm> temp = root;
while (1) {
shared_ptr<CSGTerm> n = normalizePass(temp);
if (!n) return n; // If normalized to nothing
if (temp == n) break;
temp = n;
unsigned int num = count(temp);
#ifdef DEBUG
PRINTB("Normalize count: %d\n", num);
#endif
if (num > limit) {
PRINTB("WARNING: Normalized tree is growing past %d elements. Aborting normalization.\n", limit);
return root;
}
}
return temp;
}
shared_ptr<CSGTerm> CSGTermNormalizer::normalizePass(shared_ptr<CSGTerm> term)
{
// This function implements the CSG normalization
// Reference:
// Goldfeather, J., Molnar, S., Turk, G., and Fuchs, H. Near
// Realtime CSG Rendering Using Tree Normalization and Geometric
// Pruning. IEEE Computer Graphics and Applications, 9(3):20-28,
// 1989.
// http://www.cc.gatech.edu/~turk/my_papers/pxpl_csg.pdf
if (term->type == CSGTerm::TYPE_PRIMITIVE) {
return term;
}
do {
while (term && normalize_tail(term)) { }
if (!term || term->type == CSGTerm::TYPE_PRIMITIVE) return term;
if (term->left) term->left = normalizePass(term->left);
} while (term->type != CSGTerm::TYPE_UNION &&
((term->right && term->right->type != CSGTerm::TYPE_PRIMITIVE) ||
(term->left && term->left->type == CSGTerm::TYPE_UNION)));
term->right = normalizePass(term->right);
// FIXME: Do we need to take into account any transformation of item here?
if (!term->right) {
if (term->type == CSGTerm::TYPE_UNION || term->type == CSGTerm::TYPE_DIFFERENCE) return term->left;
else return term->right;
}
if (!term->left) {
if (term->type == CSGTerm::TYPE_UNION) return term->right;
else return term->left;
}
return term;
}
bool CSGTermNormalizer::normalize_tail(shared_ptr<CSGTerm> &term)
{
if (term->type == CSGTerm::TYPE_UNION || term->type == CSGTerm::TYPE_PRIMITIVE) return false;
// Part A: The 'x . (y . z)' expressions
shared_ptr<CSGTerm> x = term->left;
shared_ptr<CSGTerm> y = term->right->left;
shared_ptr<CSGTerm> z = term->right->right;
shared_ptr<CSGTerm> result = term;
// 1. x - (y + z) -> (x - y) - z
if (term->type == CSGTerm::TYPE_DIFFERENCE && term->right->type == CSGTerm::TYPE_UNION) {
term = CSGTerm::createCSGTerm(CSGTerm::TYPE_DIFFERENCE,
CSGTerm::createCSGTerm(CSGTerm::TYPE_DIFFERENCE, x, y),
z);
return true;
}
// 2. x * (y + z) -> (x * y) + (x * z)
else if (term->type == CSGTerm::TYPE_INTERSECTION && term->right->type == CSGTerm::TYPE_UNION) {
term = CSGTerm::createCSGTerm(CSGTerm::TYPE_UNION,
CSGTerm::createCSGTerm(CSGTerm::TYPE_INTERSECTION, x, y),
CSGTerm::createCSGTerm(CSGTerm::TYPE_INTERSECTION, x, z));
return true;
}
// 3. x - (y * z) -> (x - y) + (x - z)
else if (term->type == CSGTerm::TYPE_DIFFERENCE && term->right->type == CSGTerm::TYPE_INTERSECTION) {
term = CSGTerm::createCSGTerm(CSGTerm::TYPE_UNION,
CSGTerm::createCSGTerm(CSGTerm::TYPE_DIFFERENCE, x, y),
CSGTerm::createCSGTerm(CSGTerm::TYPE_DIFFERENCE, x, z));
return true;
}
// 4. x * (y * z) -> (x * y) * z
else if (term->type == CSGTerm::TYPE_INTERSECTION && term->right->type == CSGTerm::TYPE_INTERSECTION) {
term = CSGTerm::createCSGTerm(CSGTerm::TYPE_INTERSECTION,
CSGTerm::createCSGTerm(CSGTerm::TYPE_INTERSECTION, x, y),
z);
return true;
}
// 5. x - (y - z) -> (x - y) + (x * z)
else if (term->type == CSGTerm::TYPE_DIFFERENCE && term->right->type == CSGTerm::TYPE_DIFFERENCE) {
term = CSGTerm::createCSGTerm(CSGTerm::TYPE_UNION,
CSGTerm::createCSGTerm(CSGTerm::TYPE_DIFFERENCE, x, y),
CSGTerm::createCSGTerm(CSGTerm::TYPE_INTERSECTION, x, z));
return true;
}
// 6. x * (y - z) -> (x * y) - z
else if (term->type == CSGTerm::TYPE_INTERSECTION && term->right->type == CSGTerm::TYPE_DIFFERENCE) {
term = CSGTerm::createCSGTerm(CSGTerm::TYPE_DIFFERENCE,
CSGTerm::createCSGTerm(CSGTerm::TYPE_INTERSECTION, x, y),
z);
return true;
}
// Part B: The '(x . y) . z' expressions
x = term->left->left;
y = term->left->right;
z = term->right;
// 7. (x - y) * z -> (x * z) - y
if (term->left->type == CSGTerm::TYPE_DIFFERENCE && term->type == CSGTerm::TYPE_INTERSECTION) {
term = CSGTerm::createCSGTerm(CSGTerm::TYPE_DIFFERENCE,
CSGTerm::createCSGTerm(CSGTerm::TYPE_INTERSECTION, x, z),
y);
return true;
}
// 8. (x + y) - z -> (x - z) + (y - z)
else if (term->left->type == CSGTerm::TYPE_UNION && term->type == CSGTerm::TYPE_DIFFERENCE) {
term = CSGTerm::createCSGTerm(CSGTerm::TYPE_UNION,
CSGTerm::createCSGTerm(CSGTerm::TYPE_DIFFERENCE, x, z),
CSGTerm::createCSGTerm(CSGTerm::TYPE_DIFFERENCE, y, z));
return true;
}
// 9. (x + y) * z -> (x * z) + (y * z)
else if (term->left->type == CSGTerm::TYPE_UNION && term->type == CSGTerm::TYPE_INTERSECTION) {
term = CSGTerm::createCSGTerm(CSGTerm::TYPE_UNION,
CSGTerm::createCSGTerm(CSGTerm::TYPE_INTERSECTION, x, z),
CSGTerm::createCSGTerm(CSGTerm::TYPE_INTERSECTION, y, z));
return true;
}
return false;
}
unsigned int CSGTermNormalizer::count(const shared_ptr<CSGTerm> &term) const
{
if (!term) return 0;
return term->type == CSGTerm::TYPE_PRIMITIVE ? 1 : 0 + count(term->left) + count(term->right);
}