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cagd_lib
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cagdsrev.c
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C/C++ Source or Header
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1991-05-19
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95 lines
/******************************************************************************
* CagdSRev.c - Surface of revolution out of a given profile. *
*******************************************************************************
* Written by Gershon Elber, Mar. 91. *
******************************************************************************/
#ifdef __MSDOS__
#include <stdlib.h>
#include <string.h>
#include <alloc.h>
#endif /* __MSDOS__ */
#include "cagd_loc.h"
static int CircKnotVector[12] = { 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 4 };
/******************************************************************************
* Constructs a surface of revolution around the Z axis of the given profile *
* curve. Resulting surface will be a Bspline surface, while input may be *
* either a Bspline or a Bezier curve. Curve must be 3d (I.e. P3 or E3). *
******************************************************************************/
CagdSrfStruct *CagdSurfaceRev(CagdCrvStruct *Crv)
{
int i, j, i9,
Len = Crv -> Length;
CagdPointType
PType = Crv -> PType;
CagdRType **SrfPoints,
sin45 = sin( M_PI / 4.0 ),
**CrvPoints = Crv -> Points;
CagdSrfStruct
*Srf = BspSrfNew(9, Len, 3, Crv -> Order, CAGD_PT_P3_TYPE);
for (i = 0; i < 12; i++)
Srf -> UKnotVector[i] = (CagdRType) CircKnotVector[i];
switch (Crv -> GType) {
case CAGD_CBEZIER_TYPE:
BspKnotUniformOpen(Len, Crv -> Order, Srf -> VKnotVector);
break;
case CAGD_CBSPLINE_TYPE:
GEN_COPY(Srf -> VKnotVector, Crv -> KnotVector, sizeof(CagdRType) *
(Len + Crv -> Order));
break;
case CAGD_CPOWER_TYPE:
FATAL_ERROR(CAGD_ERR_POWER_NO_SUPPORT);
return NULL;
default:
FATAL_ERROR(CAGD_ERR_UNDEF_CRV);
return NULL;
}
SrfPoints = Srf -> Points;
/* For each control point in the original curve - generate 9 points that */
/* Form a circle perpendicular to the Z axis. */
for (i = i9 = 0; i < Len; i++, i9 += 9) {
SrfPoints[W][i9] = 1.0;
switch (PType) {
case CAGD_PT_P3_TYPE:
SrfPoints[W][i9] = CrvPoints[W][i];
case CAGD_PT_E3_TYPE:
SrfPoints[X][i9] = CrvPoints[X][i];
SrfPoints[Y][i9] = CrvPoints[Y][i];
SrfPoints[Z][i9] = CrvPoints[Z][i];
break;
default:
FATAL_ERROR(CAGD_ERR_UNSUPPORT_PT);
break;
}
/* Last point is exactly the same as first one in circle - copy it. */
for (j = W; j <= Z; j++) SrfPoints[j][i9 + 8] = SrfPoints[j][i9];
/* The Z components are identical in all circle, while the XY */
/* components are rotated 45 degrees at a time: */
for (j = 1; j < 8; j++) {
SrfPoints[W][i9 + j] = SrfPoints[W][i9];
SrfPoints[X][i9 + j] = SrfPoints[X][i9 + j - 1] * sin45 -
SrfPoints[Y][i9 + j - 1] * sin45;
SrfPoints[Y][i9 + j] = SrfPoints[X][i9 + j - 1] * sin45 +
SrfPoints[Y][i9 + j - 1] * sin45;
SrfPoints[Z][i9 + j] = SrfPoints[Z][i9];
}
/* And finally we need to compensate for the W's on every second pt. */
for (j = 1; j < 8; j += 2) {
SrfPoints[W][i9 + j] *= sin45;
SrfPoints[Z][i9 + j] *= sin45;
}
}
return Srf;
}