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Diffstat (limited to 'libdimension/model/objects/cone.c')
| -rw-r--r-- | libdimension/model/objects/cone.c | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/libdimension/model/objects/cone.c b/libdimension/model/objects/cone.c new file mode 100644 index 0000000..26e59ca --- /dev/null +++ b/libdimension/model/objects/cone.c @@ -0,0 +1,207 @@ +/************************************************************************* + * Copyright (C) 2009-2014 Tavian Barnes <tavianator@tavianator.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/>. * + *************************************************************************/ + +/** + * @file + * Cones/cylinders. + */ + +#include "internal/polynomial.h" +#include "dimension/model.h" +#include <math.h> + +/// Cone type. +typedef struct dmnsn_cone { + dmnsn_object object; + double r1, r2; +} dmnsn_cone; + +/// Intersection callback for a cone. +static bool +dmnsn_cone_intersection_fn(const dmnsn_object *object, dmnsn_ray l, + dmnsn_intersection *intersection) +{ + const dmnsn_cone *cone = (const dmnsn_cone *)object; + double r1 = cone->r1, r2 = cone->r2; + + // Solve (x0 + nx*t)^2 + (z0 + nz*t)^2 == (((r2 - r1)*(y0 + ny*t) + r1 + r2)/2)^2 + double poly[3], x[2]; + poly[2] = l.n.x*l.n.x + l.n.z*l.n.z - l.n.y*l.n.y*(r2 - r1)*(r2 - r1)/4.0; + poly[1] = 2.0*(l.n.x*l.x0.x + l.n.z*l.x0.z) + - l.n.y*(r2 - r1)*(l.x0.y*(r2 - r1) + r2 + r1)/2.0; + poly[0] = l.x0.x*l.x0.x + l.x0.z*l.x0.z + - (l.x0.y*(r2 - r1) + r2 + r1)*(l.x0.y*(r2 - r1) + r2 + r1)/4.0; + + size_t n = dmnsn_polynomial_solve(poly, 2, x); + + if (n > 0) { + double t = x[0]; + dmnsn_vector p; + if (n == 2) { + t = dmnsn_min(t, x[1]); + p = dmnsn_ray_point(l, t); + + if (p.y <= -1.0 || p.y >= 1.0) { + t = dmnsn_max(x[0], x[1]); + p = dmnsn_ray_point(l, t); + } + } else { + p = dmnsn_ray_point(l, t); + } + + if (t >= 0.0 && p.y >= -1.0 && p.y <= 1.0) { + double r = ((r2 - r1)*p.y + r1 + r2)/2.0; + dmnsn_vector norm = dmnsn_new_vector(p.x, -r*(r2 - r1)/2.0, p.z); + intersection->t = t; + intersection->normal = norm; + return true; + } + } + + return false; +} + +/// Inside callback for a cone. +static bool +dmnsn_cone_inside_fn(const dmnsn_object *object, dmnsn_vector point) +{ + const dmnsn_cone *cone = (const dmnsn_cone *)object; + double r1 = cone->r1, r2 = cone->r2; + double r = (point.y*(r2 - r1) + r1 + r2)/2.0; + return point.x*point.x + point.z*point.z < r*r + && point.y > -1.0 && point.y < 1.0; +} + +/// Cone bounding callback. +static dmnsn_aabb +dmnsn_cone_bounding_fn(const dmnsn_object *object, dmnsn_matrix trans) +{ + const dmnsn_cone *cone = (const dmnsn_cone *)object; + + double rmax = dmnsn_max(cone->r1, cone->r2); + dmnsn_aabb box = dmnsn_symmetric_aabb(dmnsn_new_vector(rmax, 1.0, rmax)); + return dmnsn_transform_aabb(trans, box); +} + +/// Cone vtable. +static const dmnsn_object_vtable dmnsn_cone_vtable = { + .intersection_fn = dmnsn_cone_intersection_fn, + .inside_fn = dmnsn_cone_inside_fn, + .bounding_fn = dmnsn_cone_bounding_fn, +}; + +/// Cone cap type. +typedef struct dmnsn_cone_cap { + dmnsn_object object; + double r; +} dmnsn_cone_cap; + +/// Cone cap intersection function. +static bool +dmnsn_cone_cap_intersection_fn(const dmnsn_object *object, dmnsn_ray l, + dmnsn_intersection *intersection) +{ + if (l.n.y != 0.0) { + const dmnsn_cone_cap *cap = (const dmnsn_cone_cap *)object; + double r = cap->r; + double t = -l.x0.y/l.n.y; + dmnsn_vector p = dmnsn_ray_point(l, t); + if (t >= 0.0 && p.x*p.x + p.z*p.z <= r*r) { + intersection->t = t; + intersection->normal = dmnsn_new_vector(0.0, -1.0, 0.0); + return true; + } + } + + return false; +} + +/// Inside callback for a cone cap. +static bool +dmnsn_cone_cap_inside_fn(const dmnsn_object *object, dmnsn_vector point) +{ + return false; +} + +/// Cone cap bounding callback. +static dmnsn_aabb +dmnsn_cone_cap_bounding_fn(const dmnsn_object *object, dmnsn_matrix trans) +{ + const dmnsn_cone_cap *cap = (const dmnsn_cone_cap *)object; + dmnsn_aabb box = dmnsn_symmetric_aabb(dmnsn_new_vector(cap->r, 0.0, cap->r)); + return dmnsn_transform_aabb(trans, box); +} + +/// Cone cap vtable. +static const dmnsn_object_vtable dmnsn_cone_cap_vtable = { + .intersection_fn = dmnsn_cone_cap_intersection_fn, + .inside_fn = dmnsn_cone_cap_inside_fn, + .bounding_fn = dmnsn_cone_cap_bounding_fn, +}; + +/// Allocate a new cone cap. +dmnsn_object * +dmnsn_new_cone_cap(dmnsn_pool *pool, double r) +{ + dmnsn_cone_cap *cap = DMNSN_PALLOC(pool, dmnsn_cone_cap); + cap->r = r; + + dmnsn_object *object = &cap->object; + dmnsn_init_object(object); + object->vtable = &dmnsn_cone_cap_vtable; + return object; +} + +// Allocate a new cone object +dmnsn_object * +dmnsn_new_cone(dmnsn_pool *pool, double r1, double r2, bool open) +{ + dmnsn_cone *cone = DMNSN_PALLOC(pool, dmnsn_cone); + cone->r1 = r1; + cone->r2 = r2; + + dmnsn_object *object = &cone->object; + dmnsn_init_object(object); + object->vtable = &dmnsn_cone_vtable; + + if (open) { + return object; + } + + // Implement closed cones as a union with the caps + dmnsn_object *cap1 = dmnsn_new_cone_cap(pool, r1); + dmnsn_object *cap2 = dmnsn_new_cone_cap(pool, r2); + cap1->intrinsic_trans = dmnsn_translation_matrix( + dmnsn_new_vector(0.0, -1.0, 0.0) + ); + cap2->intrinsic_trans = dmnsn_translation_matrix( + dmnsn_new_vector(0.0, +1.0, 0.0) + ); + // Flip the normal around for the top cap + cap2->intrinsic_trans.n[1][1] = -1.0; + + dmnsn_array *withcaps = DMNSN_PALLOC_ARRAY(pool, dmnsn_object *); + dmnsn_array_push(withcaps, &cone); + dmnsn_array_push(withcaps, &cap1); + dmnsn_array_push(withcaps, &cap2); + dmnsn_object *cone_cap_union = dmnsn_new_csg_union(pool, withcaps); + + return cone_cap_union; +} |