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/*************************************************************************
* Copyright (C) 2009-2010 Tavian Barnes <tavianator@gmail.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/>. *
*************************************************************************/
#include "dimension.h"
#include <math.h>
/*
* Cylinder
*/
/* Cylinder callbacks */
static bool dmnsn_cylinder_intersection_fn(const dmnsn_object *cylinder,
dmnsn_line line,
dmnsn_intersection *intersection);
static bool dmnsn_cylinder_inside_fn(const dmnsn_object *cylinder,
dmnsn_vector point);
/* Allocate a new cylinder object */
dmnsn_object *
dmnsn_new_cylinder(bool open)
{
dmnsn_object *cylinder = dmnsn_new_object();
cylinder->intersection_fn = &dmnsn_cylinder_intersection_fn;
cylinder->inside_fn = &dmnsn_cylinder_inside_fn;
cylinder->bounding_box.min = dmnsn_new_vector(-1.0, -1.0, -1.0);
cylinder->bounding_box.max = dmnsn_new_vector(1.0, 1.0, 1.0);
if (open) {
cylinder->ptr = cylinder; /* (bool)cyliner->ptr == open */
}
return cylinder;
}
/* Intersections callback for a cylinder */
static bool
dmnsn_cylinder_intersection_fn(const dmnsn_object *cylinder, dmnsn_line line,
dmnsn_intersection *intersection)
{
dmnsn_line l = dmnsn_transform_line(cylinder->trans_inv, line);
/* Solve (x0 + nx*t)^2 + (z0 + nz*t)^2 == 1 */
double a, b, c, t;
a = l.n.x*l.n.x + l.n.z*l.n.z;
b = 2.0*(l.n.x*l.x0.x + l.n.z*l.x0.z);
c = l.x0.x*l.x0.x + l.x0.z*l.x0.z - 1.0;
if (b*b - 4.0*a*c >= 0.0) {
t = (-b - sqrt(b*b - 4.0*a*c))/(2.0*a);
dmnsn_vector p = dmnsn_line_point(l, t);
if (t < 0.0 || p.y <= -1.0 || p.y >= 1.0) {
t = (-b + sqrt(b*b - 4.0*a*c))/(2.0*a);
p = dmnsn_line_point(l, t);
}
if (!cylinder->ptr) {
/* Test for cap intersections */
double tcap = (-1.0 - l.x0.y)/l.n.y;
dmnsn_vector pcap = dmnsn_line_point(l, tcap);
dmnsn_vector norm = dmnsn_new_vector(0.0, -1.0, 0.0);
if (tcap < 0.0 || pcap.x*pcap.x + pcap.z*pcap.z >= 1.0) {
tcap = (+1.0 - l.x0.y)/l.n.y;
pcap = dmnsn_line_point(l, tcap);
norm = dmnsn_new_vector(0.0, 1.0, 0.0);
}
if (tcap >= 0.0
&& (tcap < t || p.y <= -1.0 || p.y >= 1.0)
&& pcap.x*pcap.x + pcap.z*pcap.z < 1.0)
{
intersection->ray = line;
intersection->t = tcap;
intersection->normal = dmnsn_transform_normal(cylinder->trans, norm);
intersection->texture = cylinder->texture;
intersection->interior = cylinder->interior;
return true;
}
}
if (t >= 0.0 && p.y > -1.0 && p.y < 1.0) {
p.y = 0;
intersection->ray = line;
intersection->t = t;
intersection->normal = dmnsn_transform_normal(cylinder->trans, p);
intersection->texture = cylinder->texture;
intersection->interior = cylinder->interior;
return true;
}
}
return false;
}
/* Inside callback for a cylinder */
static bool
dmnsn_cylinder_inside_fn(const dmnsn_object *cylinder, dmnsn_vector point)
{
point = dmnsn_transform_vector(cylinder->trans_inv, point);
return point.x*point.x + point.z*point.z < 1
&& point.y > -1.0 && point.y < 1.0;
}
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