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authorTavian Barnes <tavianator@gmail.com>2009-07-01 04:44:51 +0000
committerTavian Barnes <tavianator@gmail.com>2009-07-01 04:44:51 +0000
commite957408cb8cd200696a081b4f5c749c5294110ec (patch)
tree3777bb33f7c49786eaced2a50f8196e295428647 /libdimension/objects.c
parent5dcc62e9f198094e3fd49be1847871853c1449bc (diff)
downloaddimension-e957408cb8cd200696a081b4f5c749c5294110ec.tar.xz
Sphere and cube C++ wrappers.
Diffstat (limited to 'libdimension/objects.c')
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1 files changed, 181 insertions, 0 deletions
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+/*************************************************************************
+ * 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;
+}