From 4e2a6e40a77068492e3b63b84a18d0cc7f003fb7 Mon Sep 17 00:00:00 2001 From: Tavian Barnes Date: Wed, 6 Jan 2010 13:43:14 -0500 Subject: Split up objects, finishes, pigments, lights, cameras, etc. --- libdimension/sphere.c | 91 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 91 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..c61a46f --- /dev/null +++ b/libdimension/sphere.c @@ -0,0 +1,91 @@ +/************************************************************************* + * Copyright (C) 2009 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 */ + +/* + * Sphere + */ + +/* Sphere object callbacks */ + +static dmnsn_intersection * +dmnsn_sphere_intersection_fn(const dmnsn_object *sphere, dmnsn_line line); + +static int dmnsn_sphere_inside_fn(const dmnsn_object *sphere, + dmnsn_vector point); + +/* Allocate a new sphere */ +dmnsn_object * +dmnsn_new_sphere() +{ + dmnsn_object *sphere = dmnsn_new_object(); + if (sphere) { + sphere->intersection_fn = &dmnsn_sphere_intersection_fn; + sphere->inside_fn = &dmnsn_sphere_inside_fn; + sphere->min = dmnsn_new_vector(-1.0, -1.0, -1.0); + sphere->max = dmnsn_new_vector(1.0, 1.0, 1.0); + } + return sphere; +} + +/* Returns the closest intersection of `line' with `sphere' */ +static dmnsn_intersection * +dmnsn_sphere_intersection_fn(const dmnsn_object *sphere, dmnsn_line line) +{ + double a, b, c, t; + dmnsn_intersection *intersection = NULL; + + /* 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 = (-b - sqrt(b*b - 4.0*a*c))/(2*a); + if (t < 0.0) { + t = (-b + sqrt(b*b - 4.0*a*c))/(2*a); + } + + if (t >= 0.0) { + intersection = dmnsn_new_intersection(); + intersection->ray = line; + intersection->t = t; + intersection->normal = dmnsn_line_point(line, t); + intersection->texture = sphere->texture; + + /* Flip the normal if we're inside the sphere */ + if (dmnsn_vector_dot(line.n, intersection->normal) > 0.0) + intersection->normal = dmnsn_vector_negate(intersection->normal); + } + } + + return intersection; +} + +/* Return whether a point is inside a sphere (x**2 + y**2 + z**2 < 1.0) */ +static int +dmnsn_sphere_inside_fn(const dmnsn_object *sphere, dmnsn_vector point) +{ + return point.x*point.x + point.y*point.y + point.z*point.z < 1.0; +} -- cgit v1.2.3