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Diffstat (limited to 'libdimension/objects.c')
| -rw-r--r-- | libdimension/objects.c | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/libdimension/objects.c b/libdimension/objects.c new file mode 100644 index 0000000..b5cf64c --- /dev/null +++ b/libdimension/objects.c @@ -0,0 +1,181 @@ +/************************************************************************* + * Copyright (C) 2008 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 <stdlib.h> /* For malloc */ +#include <math.h> /* For sqrt */ + +/* + * Sphere + */ + +/* Sphere object callbacks */ +static dmnsn_array *dmnsn_sphere_intersections_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->intersections_fn = &dmnsn_sphere_intersections_fn; + sphere->inside_fn = &dmnsn_sphere_inside_fn; + } + return sphere; +} + +/* Free a sphere */ +void +dmnsn_delete_sphere(dmnsn_object *sphere) +{ + dmnsn_delete_object(sphere); +} + +/* Return a list of insersections of `line' with a sphere */ +static dmnsn_array * +dmnsn_sphere_intersections_fn(const dmnsn_object *sphere, 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; +} + +/* 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; +} + +/* + * Cube + */ + +/* Cube callbacks */ +static dmnsn_array *dmnsn_cube_intersections_fn(const dmnsn_object *cube, + dmnsn_line line); +static int dmnsn_cube_inside_fn(const dmnsn_object *cube, + dmnsn_vector point); + +/* Allocate a new cube object */ +dmnsn_object * +dmnsn_new_cube() +{ + dmnsn_object *cube = dmnsn_new_object(); + if (cube) { + cube->intersections_fn = &dmnsn_cube_intersections_fn; + cube->inside_fn = &dmnsn_cube_inside_fn; + } + return cube; +} + +/* Delete a cube */ +void +dmnsn_delete_cube(dmnsn_object *cube) +{ + dmnsn_delete_object(cube); +} + +/* Intersections callback for a cube */ +static dmnsn_array * +dmnsn_cube_intersections_fn(const dmnsn_object *cube, dmnsn_line line) +{ + double t; + dmnsn_vector p; + dmnsn_array *array = dmnsn_new_array(sizeof(double)); + + /* Six ray-plane intersection tests (x, y, z) = +/- 1.0 */ + + if (line.n.x != 0.0) { + /* x = -1.0 */ + t = (-1.0 - line.x0.x)/line.n.x; + p = dmnsn_line_point(line, t); + if (p.y >= -1.0 && p.y <= 1.0 && p.z >= -1.0 && p.z <= 1.0) { + dmnsn_array_push(array, &t); + } + + /* x = 1.0 */ + t = (1.0 - line.x0.x)/line.n.x; + p = dmnsn_line_point(line, t); + if (p.y >= -1.0 && p.y <= 1.0 && p.z >= -1.0 && p.z <= 1.0) { + dmnsn_array_push(array, &t); + } + } + + if (line.n.y != 0.0) { + /* y = -1.0 */ + t = (-1.0 - line.x0.y)/line.n.y; + p = dmnsn_line_point(line, t); + if (p.x >= -1.0 && p.x <= 1.0 && p.z >= -1.0 && p.z <= 1.0) { + dmnsn_array_push(array, &t); + } + + /* y = 1.0 */ + t = (1.0 - line.x0.y)/line.n.y; + p = dmnsn_line_point(line, t); + if (p.x >= -1.0 && p.x <= 1.0 && p.z >= -1.0 && p.z <= 1.0) { + dmnsn_array_push(array, &t); + } + } + + if (line.n.z != 0.0) { + /* z = -1.0 */ + t = (-1.0 - line.x0.z)/line.n.z; + p = dmnsn_line_point(line, t); + if (p.x >= -1.0 && p.x <= 1.0 && p.y >= -1.0 && p.y <= 1.0) { + dmnsn_array_push(array, &t); + } + + /* z = 1.0 */ + t = (1.0 - line.x0.z)/line.n.z; + p = dmnsn_line_point(line, t); + if (p.x >= -1.0 && p.x <= 1.0 && p.y >= -1.0 && p.y <= 1.0) { + dmnsn_array_push(array, &t); + } + } + + return array; +} + +/* Inside callback for a cube */ +static int +dmnsn_cube_inside_fn(const dmnsn_object *cube, dmnsn_vector point) +{ + return point.x > -1.0 && point.x < 1.0 + && point.y > -1.0 && point.y < 1.0 + && point.z > -1.0 && point.z < 1.0; +} |