5 * Vertices in strip are numbered as follows:
7 * ___ X-2 ___ X-1 ___ 0 ___ 1 ___ 2 ___ 3 ___ 4 __
9 * / \ / \ / \ / \ / \ / \ / \
10 * / \ / \ / \ / \ / \ / \ / \
11 * X-3 ___ X-2 ___ X-1 ___ 0 ___ 1 ___ 2 ___ 3 ___ 4
12 * Y-2 Y-2 Y-2 1 1 1 1 1
13 * \ / \ / \ / \ / \ / \ / \ /
14 * \ / \ / \ / \ / \ / \ / \ /
15 * ___ X-3 ___ X-2 ___ X-1 ___ 0 ___ 1 ___ 2 ___ 3 __
18 * . . . . . . . . . . . . . . .
20 * X-4 ___ X-3 ___ X-2 ___ X-1 ___ 0 ___ 1 ___ 2 ___ 3
21 * 1 1 1 1 Y-2 Y-2 Y-2 Y-2
22 * \ / \ / \ / \ / \ / \ / \ /
23 * \ / \ / \ / \ / \ / \ / \ /
24 * ___ X-4 ___ X-3 ___ X-2 ___ X-1 ___ 0 ___ 1 ___ 2 __
28 * 0 <= x < X x = distance along
29 * 0 <= y < Y y = distance across
31 * Vertices are in reading order from diagram above ie x varies fastest.
33 * Y must be even. The actual location opposite (0,0) is (X-(Y-1)/2,0),
34 * and likewise opposite (0,Y-1) is ((Y-1)/2,0).
36 * We label edges as follows:
56 /* vertex number: 0000 | y | x
63 #define Y1 (1 << YSHIFT)
64 #define YMASK ((Y-1) << YSHIFT)
70 #define FOR_VERTEX(v) \
71 for ((v)=0; (v)<N; (v)++)
73 #define FOR_VPEDGE(v,e) \
74 for ((e)=0; (e)<V6; (e)++)
76 extern int edge_end2(unsigned v1, int e);
77 #define EDGE_END2 edge_end2
79 #define FOR_VEDGE_X(v1,e,v2,init,otherwise) \
80 FOR_VPEDGE((v1),(e)) \
81 if (((v2)= EDGE_END2((v1),(e)), \
83 (v2)) < 0) { otherwise; } else
85 #define NOTHING ((void)0)
87 #define FOR_VEDGE(v1,e,v2) \
88 FOR_VEDGE_X(v1,e,v2,NOTHING,NOTHING)
90 #define FOR_EDGE(v1,e,v2) \
92 FOR_VEDGE((v1),(e),(v2))
94 #define FOR_RIM_VERTEX(vy,vx,v) \
95 for ((vy)=0; (vy)<Y; (vy)+=Y-1) \
96 for ((vx)=0; (v)= (vy)<<YSHIFT | (vx), (vx)<X; (vx)++)
98 typedef double Vertices[N][D3];