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/*************************************************************************
* Copyright (C) 2009-2014 Tavian Barnes <tavianator@tavianator.com> *
* *
* This file is part of The Dimension Library. *
* *
* The Dimension Library is free software; you can redistribute it and/ *
* or modify it under the terms of the GNU Lesser General Public License *
* as published by the Free Software Foundation; either version 3 of the *
* License, or (at your option) any later version. *
* *
* The Dimension Library is distributed in the hope that it will be *
* useful, but WITHOUT ANY WARRANTY; without even the implied warranty *
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU *
* Lesser General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public *
* License along with this program. If not, see *
* <http://www.gnu.org/licenses/>. *
*************************************************************************/
/**
* @file
* Lines in 3-D space.
*/
#ifndef DMNSN_MATH_H
#error "Please include <dimension/math.h> instead of this header directly."
#endif
/** A line, or ray. */
typedef struct dmnsn_ray {
dmnsn_vector x0; /**< The origin of the ray. */
dmnsn_vector n; /**< The direction of the ray. */
} dmnsn_ray;
/** A standard format string for rays. */
#define DMNSN_RAY_FORMAT "(<%g, %g, %g> + t*<%g, %g, %g>)"
/** The appropriate arguements to printf() a ray. */
#define DMNSN_RAY_PRINTF(l) \
DMNSN_VECTOR_PRINTF((l).x0), DMNSN_VECTOR_PRINTF((l).n)
/**
* Construct a new ray.
* @param[in] x0 The origin of the ray.
* @param[in] n The direction of the ray.
* @return The new ray.
*/
DMNSN_INLINE dmnsn_ray
dmnsn_new_ray(dmnsn_vector x0, dmnsn_vector n)
{
dmnsn_ray l = { x0, n };
return l;
}
/**
* Return the point at \p t on a ray.
* The point is defined by \f$ l.\vec{x_0} + t \cdot l.\vec{n} \f$
*/
DMNSN_INLINE dmnsn_vector
dmnsn_ray_point(dmnsn_ray l, double t)
{
return dmnsn_vector_add(l.x0, dmnsn_vector_mul(t, l.n));
}
/** Add epsilon*l.n to l.x0, to avoid self-intersections. */
DMNSN_INLINE dmnsn_ray
dmnsn_ray_add_epsilon(dmnsn_ray l)
{
return dmnsn_new_ray(
dmnsn_vector_add(
l.x0,
dmnsn_vector_mul(1.0e3*dmnsn_epsilon, l.n)
),
l.n
);
}
/** Return whether a ray contains any NaN entries. */
DMNSN_INLINE bool
dmnsn_ray_isnan(dmnsn_ray l)
{
return dmnsn_vector_isnan(l.x0) || dmnsn_vector_isnan(l.n);
}
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