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#ifndef lint |
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static const char RCSid[] = "$Id$"; |
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static const char RCSid[] = "$Id$"; |
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#endif |
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/* |
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* Compute 4-byte direction code (assume this fits into int) |
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* Compute a 4-byte direction code (externals defined in rtmath.h). |
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* |
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* Mean accuracy is 0.0022 degrees, with a maximum error of 0.0058 degrees. |
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*/ |
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#include "standard.h" |
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#include "rtmath.h" |
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#define DCSCALE 11585.2 /* (1<<13)*sqrt(2) */ |
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#define FXNEG 01 |
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#define F2SFT 18 |
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#define FMASK 0x1fff |
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int4 |
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encodedir(dv) /* encode a normalized direction vector */ |
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FVECT dv; |
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int32 |
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encodedir(FVECT dv) /* encode a normalized direction vector */ |
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{ |
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register int4 dc = 0; |
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int32 dc = 0; |
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int cd[3], cm; |
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register int i; |
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int i; |
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for (i = 0; i < 3; i++) |
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if (dv[i] < 0.) { |
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cd[i] = dv[i] * -DCSCALE; |
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cd[i] = (int)(dv[i] * -DCSCALE); |
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dc |= FXNEG<<i; |
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} else |
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cd[i] = dv[i] * DCSCALE; |
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cd[i] = (int)(dv[i] * DCSCALE); |
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if (!(cd[0] | cd[1] | cd[2])) |
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return(0); /* zero normal */ |
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if (cd[0] <= cd[1]) { |
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dc |= F1X | cd[0] << F1SFT; |
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cm = cd[1]; |
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dc |= F2Z | cd[2] << F2SFT; |
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else |
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dc |= cm << F2SFT; |
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if (!dc) /* don't generate 0 code normally */ |
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dc = F1X; |
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return(dc); |
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} |
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void |
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decodedir(dv, dc) /* decode a normalized direction vector */ |
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register FVECT dv; /* returned */ |
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register int4 dc; |
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decodedir(FVECT dv, int32 dc) /* decode a normalized direction vector */ |
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{ |
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double d1, d2, der; |
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if (!dc) { /* special code for zero normal */ |
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dv[0] = dv[1] = dv[2] = 0.; |
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return; |
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} |
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d1 = ((dc>>F1SFT & FMASK)+.5)*(1./DCSCALE); |
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d2 = ((dc>>F2SFT & FMASK)+.5)*(1./DCSCALE); |
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der = sqrt(1. - d1*d1 - d2*d2); |
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double |
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dir2diff(dc1, dc2) /* approx. radians^2 between directions */ |
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int4 dc1, dc2; |
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dir2diff(int32 dc1, int32 dc2) /* approx. radians^2 between directions */ |
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{ |
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FVECT v1, v2; |
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double |
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fdir2diff(dc1, v2) /* approx. radians^2 between directions */ |
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int4 dc1; |
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register FVECT v2; |
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fdir2diff(int32 dc1, FVECT v2) /* approx. radians^2 between directions */ |
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{ |
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FVECT v1; |
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