48 lines
1.1 KiB
C
48 lines
1.1 KiB
C
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// mathx.h
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#ifndef __INCLUDE_MATHX
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#define __INCLUDE_MATHX
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#ifdef __cplusplus
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extern "C"
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{
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#endif
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int Arctan2(int y, int x);
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int Distance(int dX, int dY);
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#define DISTANCE_POINT(a,b) Distance((a).x - (b).x, (a).y - (b).y)
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#define CROSS_PRODUCT(a,b) (((long) (a).x) * ((long) (b).y) - ((long) (a).y) * ((long) (b).x))
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// Calculate difference between two angles and bring into range -180 < angle <= 180.
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#define ANGLEDIFF(a,b,c) { \
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c = b - a; \
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if (c > 180) { \
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c -= 360; \
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} else if (c <= -180) { \
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c += 360; \
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} \
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}
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// Calc d = the angle betw (the extension of rgxy[a]:rgxy[b]) and
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// (rgxy[b]:rgxy[c]). The sign of d reflects clockwise vs
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// counterclockwise turns.
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// LEFT FOR A RAINY DAY: make this more efficient
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#define CALCANGLE(a,b,c,d) \
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ANGLEDIFF(Arctan2(rgxy[b].y - rgxy[a].y, rgxy[b].x - rgxy[a].x), \
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Arctan2(rgxy[c].y - rgxy[b].y, rgxy[c].x - rgxy[b].x), \
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d);
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#define CALCANGLEPT(a,b,c,d) \
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ANGLEDIFF(Arctan2(b.y - a.y, b.x - a.x), \
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Arctan2(c.y - b.y, c.x - b.x), \
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d);
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#ifdef __cplusplus
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};
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#endif
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#endif //__INCLUDE_MATHX
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