diff options
| -rw-r--r-- | dimension/tests/Makefile.am | 7 | ||||
| -rw-r--r-- | dimension/tests/ellipsoid.dmnsn | 67 | ||||
| -rw-r--r-- | libdimension/sphere.c | 68 |
3 files changed, 136 insertions, 6 deletions
diff --git a/dimension/tests/Makefile.am b/dimension/tests/Makefile.am index 684b2aa..b5b6882 100644 --- a/dimension/tests/Makefile.am +++ b/dimension/tests/Makefile.am @@ -1,5 +1,5 @@ ########################################################################### -## Copyright (C) 2009-2011 Tavian Barnes <tavianator@tavianator.com> ## +## Copyright (C) 2009-2014 Tavian Barnes <tavianator@tavianator.com> ## ## ## ## This file is part of The Dimension Build Suite. ## ## ## @@ -17,8 +17,9 @@ ## along with this program. If not, see <http://www.gnu.org/licenses/>. ## ########################################################################### -TESTS = demo.dmnsn \ - cube.dmnsn +TESTS = cube.dmnsn \ + demo.dmnsn \ + ellipsoid.dmnsn TEST_EXTENSIONS = .dmnsn DMNSN_LOG_COMPILER = $(top_srcdir)/dimension/dimension AM_DMNSN_LOG_FLAGS = --strict -v diff --git a/dimension/tests/ellipsoid.dmnsn b/dimension/tests/ellipsoid.dmnsn new file mode 100644 index 0000000..9b5e08e --- /dev/null +++ b/dimension/tests/ellipsoid.dmnsn @@ -0,0 +1,67 @@ +######################################################################### +# Copyright (C) 2010-2014 Tavian Barnes <tavianator@tavianator.com> # +# # +# This file is part of The Dimension Test Suite. # +# # +# The Dimension Test Suite is free software; you can redistribute it # +# and/or modify it under the terms of the GNU 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 Test Suite 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 # +# General Public License for more details. # +# # +# You should have received a copy of the GNU General Public License # +# along with this program. If not, see <http://www.gnu.org/licenses/>. # +######################################################################### + +camera = PerspectiveCamera(location = -7*Z, look_at = 0) + +background = 0.5*sRGB(0.73, 0.90, 0.97) + +lights.append(PointLight(location = (0, 7, -7), color = White)) + +objects.append( + Plane( + normal = Y, distance = -4, + + texture = Texture( + pigment = sRGB(0.73, 0.90, 0.97), + finish = Ambient(sRGB(0.5)), + ) + ) +) + +objects.append( + Sphere( + center = 0, + radius = 1, + + pigment = White + ) + .translate(-3*X) +) + +objects.append( + Sphere( + center = 0, + radius = 1, + + pigment = White + ) + .scale(1.25, 0.75, 0.75) +) + +objects.append( + Sphere( + center = 0, + radius = 1, + + pigment = White + ) + .scale(1.25, 0.75, 0.75) + .rotate(45*Z) + .translate(3*X) +) diff --git a/libdimension/sphere.c b/libdimension/sphere.c index 5555499..8f1e1a7 100644 --- a/libdimension/sphere.c +++ b/libdimension/sphere.c @@ -63,9 +63,71 @@ dmnsn_sphere_inside_fn(const dmnsn_object *sphere, dmnsn_vector point) static dmnsn_bounding_box dmnsn_sphere_bounding_fn(const dmnsn_object *object, dmnsn_matrix trans) { - // TODO: tighter bound - dmnsn_bounding_box box = dmnsn_symmetric_bounding_box(dmnsn_new_vector(1.0, 1.0, 1.0)); - return dmnsn_transform_bounding_box(trans, box); + // Get a tight bound using the conic representation of a sphere: + // + // S = [ 1 0 0 0 ] + // [ 0 1 0 0 ] + // [ 0 0 1 0 ] + // [ 0 0 0 -1 ]. + // + // The surface is defined by + // p^T * S * p = 0, + // and the tangent planes are defined by + // q * S^-1 * q^T = 0. + // Note that S = S^-1. + // + // The symmetric matrix R, defined by + // R = M * S^-1 * M^T, + // characterizes the tangent planes. Specifically, + // min.x = (R[0,3] - sqrt(R[0,3]^2 - R[0,0]*R[3,3]))/R[3,3] + // max.x = (R[0,3] + sqrt(R[0,3]^2 - R[0,0]*R[3,3]))/R[3,3] + // min.y = (R[1,3] - sqrt(R[1,3]^2 - R[1,1]*R[3,3]))/R[3,3] + // max.y = (R[1,3] + sqrt(R[1,3]^2 - R[1,1]*R[3,3]))/R[3,3] + // min.z = (R[2,3] - sqrt(R[2,3]^2 - R[2,2]*R[3,3]))/R[3,3] + // max.z = (R[2,3] + sqrt(R[2,3]^2 - R[2,2]*R[3,3]))/R[3,3] + // + // Unfortunately, we can't use dmnsn_matrix because the matrices are not + // affine + + // MS = M * S^-1 = M * S + // Last row is [ 0 0 0 -1 ] implicitly + double MS[3][4]; + for (int i = 0; i < 3; ++i) { + for (int j = 0; j < 3; ++j) { + MS[i][j] = trans.n[i][j]; + } + MS[i][3] = -trans.n[i][3]; + } + + // R = MS * M^T + // We only compute the upper triangular portion + // R[3][3] is implicitly -1 + double R[4][4]; + for (int i = 0; i < 3; ++i) { + for (int j = i; j < 3; ++j) { + R[i][j] = 0.0; + for (int k = 0; k < 4; ++k) { + R[i][j] += MS[i][k]*trans.n[j][k]; + } + } + R[i][3] = MS[i][3]; + } + + dmnsn_bounding_box box; + + double dx = sqrt(R[0][3]*R[0][3] + R[0][0]); + box.min.x = -R[0][3] - dx; + box.max.x = -R[0][3] + dx; + + double dy = sqrt(R[1][3]*R[1][3] + R[1][1]); + box.min.y = -R[1][3] - dy; + box.max.y = -R[1][3] + dy; + + double dz = sqrt(R[2][3]*R[2][3] + R[2][2]); + box.min.z = -R[2][3] - dz; + box.max.z = -R[2][3] + dz; + + return box; } /// Sphere vtable. |