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#ifndef lint |
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static const char RCSid[] = "$Id$"; |
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#endif |
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/* |
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* hermite.c - routines for 3D hermite curves. |
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* |
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* 10/29/85 |
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*/ |
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#include <stdio.h> |
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hermite3(hp, p0, p1, r0, r1, t) /* compute point on hermite curve */ |
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double hp[3]; /* returned hermite point */ |
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double p0[3]; /* first endpoint */ |
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double p1[3]; /* second endpoint */ |
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double r0[3]; /* tangent at p0 */ |
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double r1[3]; /* tangent at p1 */ |
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double t; /* position parameter */ |
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{ |
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register int i; |
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double tmh[4]; |
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tmh[0] = (2.0*t - 3.0)*t*t + 1.0; |
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tmh[1] = (-2.0*t + 3.0)*t*t; |
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tmh[2] = ((t - 2.0)*t + 1.0)*t; |
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tmh[3] = (t - 1.0)*t*t; |
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for (i = 0; i < 3; i++) |
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hp[i] = p0[i]*tmh[0] + p1[i]*tmh[1] + |
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r0[i]*tmh[2] + r1[i]*tmh[3]; |
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} |
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htan3(ht, p0, p1, r0, r1, t) /* compute tangent on hermite curve */ |
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double ht[3]; /* returned hermite tangent */ |
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double p0[3]; /* first endpoint */ |
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double p1[3]; /* second endpoint */ |
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double r0[3]; /* tangent at p0 */ |
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double r1[3]; /* tangent at p1 */ |
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double t; /* position parameter */ |
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{ |
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register int i; |
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double tpmh[4]; |
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tpmh[0] = (6.0*t - 6.0)*t; |
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tpmh[1] = (-6.0*t + 6.0)*t; |
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tpmh[2] = (3.0*t - 4.0)*t + 1.0; |
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tpmh[3] = (3.0*t - 2.0)*t; |
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for (i = 0; i < 3; i++) |
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ht[i] = p0[i]*tpmh[0] + p1[i]*tpmh[1] + |
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r0[i]*tpmh[2] + r1[i]*tpmh[3]; |
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} |