dspline.h File Reference

#include "common.h"
#include "vmath.h"
#include "rt/defines.h"

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Functions
void	rt_dspline_matrix (mat_t m, const char *type, const double tension, const double bias)
double	rt_dspline4 (mat_t m, double a, double b, double c, double d, double alpha)
void	rt_dspline4v (double *pt, const mat_t m, const double *a, const double *b, const double *c, const double *d, const int depth, const double alpha)
void	rt_dspline_n (double *r, const mat_t m, const double *knots, const int n, const int depth, const double alpha)

Function Documentation

rt_dspline_matrix()

void rt_dspline_matrix	(	mat_t	m,
		const char *	type,
		const double	tension,
		const double	bias
	)

Initialize a spline matrix for a particular spline type.

rt_dspline4()

double rt_dspline4	(	mat_t	m,
		double	a,
		double	b,
		double	c,
		double	d,
		double	alpha
	)

m spline matrix (see rt_dspline4_matrix) a, b, c, d knot values alpha: 0..1 interpolation point

Evaluate a 1-dimensional spline at a point "alpha" on knot values a, b, c, d.

rt_dspline4v()

void rt_dspline4v	(	double *	pt,
		const mat_t	m,
		const double *	a,
		const double *	b,
		const double *	c,
		const double *	d,
		const int	depth,
		const double	alpha
	)

pt vector to receive the interpolation result m spline matrix (see rt_dspline4_matrix) a, b, c, d knot values alpha: 0..1 interpolation point

Evaluate a spline at a point "alpha" between knot pts b & c. The knots and result are all vectors with "depth" values (length).

rt_dspline_n()

void rt_dspline_n	(	double *	r,
		const mat_t	m,
		const double *	knots,
		const int	n,
		const int	depth,
		const double	alpha
	)

Interpolate n knot vectors over the range 0..1

"knots" is an array of "n" knot vectors. Each vector consists of "depth" values. They define an "n" dimensional surface which is evaluated at the single point "alpha". The evaluated point is returned in "r"

Example use:

double result[MAX_DEPTH], knots[MAX_DEPTH*MAX_KNOTS]; mat_t m; int knot_count, depth;

knots = bu_malloc(sizeof(double) * knot_length * knot_count); result = bu_malloc(sizeof(double) * knot_length);

rt_dspline4_matrix(m, "Catmull", (double *)NULL, 0.0);

for (i=0; i < knot_count; i++) get a knot(knots, i, knot_length);

rt_dspline_n(result, m, knots, knot_count, knot_length, alpha);