From 9b6ca3e20b1d0a9ab7f821963c63c9b2b3c4fc40 Mon Sep 17 00:00:00 2001 From: Tavian Barnes Date: Wed, 13 May 2009 22:58:44 +0000 Subject: Begin object type, with sphere example. --- libdimension/sphere.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 69 insertions(+) create mode 100644 libdimension/sphere.c (limited to 'libdimension/sphere.c') diff --git a/libdimension/sphere.c b/libdimension/sphere.c new file mode 100644 index 0000000..4b99eaf --- /dev/null +++ b/libdimension/sphere.c @@ -0,0 +1,69 @@ +/************************************************************************* + * Copyright (C) 2008 Tavian Barnes * + * * + * 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 * + * . * + *************************************************************************/ + +#include "dimension.h" +#include /* For malloc */ +#include /* For sqrt */ + +static dmnsn_array *dmnsn_sphere_intersections_fn(dmnsn_line line); +static int dmnsn_sphere_inside_fn(dmnsn_vector point); + +dmnsn_object * +dmnsn_new_sphere() +{ + dmnsn_object *sphere = dmnsn_new_object(); + sphere->intersections_fn = &dmnsn_sphere_intersections_fn; + sphere->inside_fn = &dmnsn_sphere_inside_fn; + return sphere; +} + +void +dmnsn_delete_sphere(dmnsn_object *sphere) +{ + dmnsn_delete_object(sphere); +} + +static dmnsn_array * +dmnsn_sphere_intersections_fn(dmnsn_line line) +{ + double a, b, c, t[2]; + dmnsn_array *array = dmnsn_new_array(sizeof(double)); + + // Solve (x0 + nx*t)^2 + (y0 + ny*t)^2 + (z0 + nz*t)^2 == 1 + + a = line.n.x*line.n.x + line.n.y*line.n.y + line.n.z*line.n.z; + b = 2.0*(line.n.x*line.x0.x + line.n.y*line.x0.y + line.n.z*line.x0.z); + c = line.x0.x*line.x0.x + line.x0.y*line.x0.y + line.x0.z*line.x0.z - 1.0; + + if (b*b - 4.0*a*c >= 0) { + t[0] = (-b + sqrt(b*b - 4.0*a*c))/(2*a); + t[1] = (-b - sqrt(b*b - 4.0*a*c))/(2*a); + dmnsn_array_set(array, 0, &t[0]); + dmnsn_array_set(array, 1, &t[1]); + } + + return array; +} + +static int +dmnsn_sphere_inside_fn(dmnsn_vector point) +{ + return sqrt(point.x*point.x + point.y*point.y + point.z*point.z) < 1.0; +} -- cgit v1.2.3