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/*************************************************************************
* Copyright (C) 2009-2013 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
* Cones/cylinders.
*/
#include "dimension.h"
#include <math.h>
/** Cone payload type. */
typedef struct dmnsn_cone_payload {
double r1, r2;
} dmnsn_cone_payload;
/** Intersection callback for a cone. */
static bool
dmnsn_cone_intersection_fn(const dmnsn_object *cone, dmnsn_line l,
dmnsn_intersection *intersection)
{
const dmnsn_cone_payload *payload = cone->ptr;
double r1 = payload->r1, r2 = payload->r2;
/* Solve (x0 + nx*t)^2 + (z0 + nz*t)^2
== (((r2 - r1)*(y0 + ny*t) + r1 + r2)/2)^2 */
double poly[3], x[2];
poly[2] = l.n.x*l.n.x + l.n.z*l.n.z - l.n.y*l.n.y*(r2 - r1)*(r2 - r1)/4.0;
poly[1] = 2.0*(l.n.x*l.x0.x + l.n.z*l.x0.z)
- l.n.y*(r2 - r1)*(l.x0.y*(r2 - r1) + r2 + r1)/2.0;
poly[0] = l.x0.x*l.x0.x + l.x0.z*l.x0.z
- (l.x0.y*(r2 - r1) + r2 + r1)*(l.x0.y*(r2 - r1) + r2 + r1)/4.0;
size_t n = dmnsn_polynomial_solve(poly, 2, x);
if (n > 0) {
double t = x[0];
dmnsn_vector p;
if (n == 2) {
t = dmnsn_min(t, x[1]);
p = dmnsn_line_point(l, t);
if (p.y <= -1.0 || p.y >= 1.0) {
t = dmnsn_max(x[0], x[1]);
p = dmnsn_line_point(l, t);
}
} else {
p = dmnsn_line_point(l, t);
}
if (t >= 0.0 && p.y >= -1.0 && p.y <= 1.0) {
double r = ((r2 - r1)*p.y + r1 + r2)/2.0;
dmnsn_vector norm = dmnsn_new_vector(p.x, -r*(r2 - r1)/2.0, p.z);
intersection->t = t;
intersection->normal = norm;
return true;
}
}
return false;
}
/** Inside callback for a cone. */
static bool
dmnsn_cone_inside_fn(const dmnsn_object *cone, dmnsn_vector point)
{
const dmnsn_cone_payload *payload = cone->ptr;
double r1 = payload->r1, r2 = payload->r2;
double r = (point.y*(r2 - r1) + r1 + r2)/2.0;
return point.x*point.x + point.z*point.z < r*r
&& point.y > -1.0 && point.y < 1.0;
}
/** Cone cap intersection function. */
static bool
dmnsn_cone_cap_intersection_fn(const dmnsn_object *cap, dmnsn_line l,
dmnsn_intersection *intersection)
{
if (l.n.y != 0.0) {
double *rptr = cap->ptr, r = *rptr;
double t = -l.x0.y/l.n.y;
dmnsn_vector p = dmnsn_line_point(l, t);
if (t >= 0.0 && p.x*p.x + p.z*p.z <= r*r) {
intersection->t = t;
intersection->normal = dmnsn_new_vector(0.0, -1.0, 0.0);
return true;
}
}
return false;
}
/** Inside callback for a cone cap. */
static bool
dmnsn_cone_cap_inside_fn(const dmnsn_object *cone, dmnsn_vector point)
{
return false;
}
/** Allocate a new cone cap. */
dmnsn_object *
dmnsn_new_cone_cap(double r)
{
dmnsn_object *cap = dmnsn_new_object();
cap->intersection_fn = dmnsn_cone_cap_intersection_fn;
cap->inside_fn = dmnsn_cone_cap_inside_fn;
cap->bounding_box.min = dmnsn_new_vector(-r, 0.0, -r);
cap->bounding_box.max = dmnsn_new_vector(+r, 0.0, +r);
double *payload = dmnsn_malloc(sizeof(double));
*payload = r;
cap->ptr = payload;
cap->free_fn = dmnsn_free;
return cap;
}
/* Allocate a new cone object */
dmnsn_object *
dmnsn_new_cone(double r1, double r2, bool open)
{
dmnsn_object *cone = dmnsn_new_object();
cone->intersection_fn = dmnsn_cone_intersection_fn;
cone->inside_fn = dmnsn_cone_inside_fn;
double rmax = dmnsn_max(r1, r2);
cone->bounding_box.min = dmnsn_new_vector(-rmax, -1.0, -rmax);
cone->bounding_box.max = dmnsn_new_vector(rmax, 1.0, rmax);
dmnsn_cone_payload *payload = dmnsn_malloc(sizeof(dmnsn_cone_payload));
payload->r1 = r1;
payload->r2 = r2;
cone->ptr = payload;
cone->free_fn = dmnsn_free;
/* Implement closed cones as a union with the caps */
if (!open) {
dmnsn_object *cap1 = dmnsn_new_cone_cap(r1);
dmnsn_object *cap2 = dmnsn_new_cone_cap(r2);
cap1->intrinsic_trans = dmnsn_translation_matrix(
dmnsn_new_vector(0.0, -1.0, 0.0)
);
cap2->intrinsic_trans = dmnsn_translation_matrix(
dmnsn_new_vector(0.0, +1.0, 0.0)
);
/* Flip the normal around for the top cap */
cap2->intrinsic_trans.n[1][1] = -1.0;
dmnsn_array *withcaps = dmnsn_new_array(sizeof(dmnsn_object *));
dmnsn_array_push(withcaps, &cone);
dmnsn_array_push(withcaps, &cap1);
dmnsn_array_push(withcaps, &cap2);
cone = dmnsn_new_csg_union(withcaps);
dmnsn_delete_array(withcaps);
}
return cone;
}
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