1 // sphere.cxx -- build an ssg sphere object
3 // Pulled straight out of MesaGLU/quadratic.c
5 // Original gluSphere code is Copyright (C) 1999-2000 Brian Paul and
6 // licensed under the GPL
8 // This library is free software; you can redistribute it and/or
9 // modify it under the terms of the GNU Library General Public
10 // License as published by the Free Software Foundation; either
11 // version 2 of the License, or (at your option) any later version.
13 // This library is distributed in the hope that it will be useful,
14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 // Library General Public License for more details.
18 // You should have received a copy of the GNU General Public License
19 // along with this program; if not, write to the Free Software
20 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
24 #include <simgear/compiler.h>
25 #include <simgear/constants.h>
26 #include <simgear/debug/logstream.hxx>
32 #include <osg/Geometry>
37 // return a sphere object as an ssgBranch
39 SGMakeSphere(double radius, int slices, int stacks)
41 float rho, drho, dtheta;
45 osg::Geode* geode = new osg::Geode;
47 drho = SGD_PI / (float) stacks;
48 dtheta = SGD_2PI / (float) slices;
50 /* texturing: s goes from 0.0/0.25/0.5/0.75/1.0 at +y/+x/-y/-x/+y
51 axis t goes from -1.0/+1.0 at z = -radius/+radius (linear along
52 longitudes) cannot use triangle fan on texturing (s coord. at
53 top/bottom tip varies) */
57 t = 1.0; /* because loop now runs from 0 */
61 /* build slices as quad strips */
62 for ( i = imin; i < imax; i++ ) {
63 osg::Geometry* geometry = new osg::Geometry;
64 osg::Vec3Array* vl = new osg::Vec3Array;
65 osg::Vec3Array* nl = new osg::Vec3Array;
66 osg::Vec2Array* tl = new osg::Vec2Array;
70 for ( j = 0; j <= slices; j++ ) {
71 double theta = (j == slices) ? 0.0 : j * dtheta;
72 double x = -sin(theta) * sin(rho);
73 double y = cos(theta) * sin(rho);
74 double z = nsign * cos(rho);
76 // glNormal3f( x*nsign, y*nsign, z*nsign );
77 osg::Vec3 normal(x*nsign, y*nsign, z*nsign);
79 nl->push_back(normal);
82 tl->push_back(osg::Vec2(s, t));
84 // glVertex3f( x*radius, y*radius, z*radius );
85 vl->push_back(osg::Vec3(x*radius, y*radius, z*radius));
87 x = -sin(theta) * sin(rho+drho);
88 y = cos(theta) * sin(rho+drho);
89 z = nsign * cos(rho+drho);
91 // glNormal3f( x*nsign, y*nsign, z*nsign );
92 normal = osg::Vec3(x*nsign, y*nsign, z*nsign);
94 nl->push_back(normal);
96 // glTexCoord2f(s,t-dt);
97 tl->push_back(osg::Vec2(s, t-dt));
100 // glVertex3f( x*radius, y*radius, z*radius );
101 vl->push_back(osg::Vec3(x*radius, y*radius, z*radius));
104 if ( vl->size() != nl->size() ) {
105 SG_LOG( SG_EVENT, SG_ALERT, "bad sphere1");
108 if ( vl->size() != tl->size() ) {
109 SG_LOG( SG_EVENT, SG_ALERT, "bad sphere2");
114 osg::Vec4Array* cl = new osg::Vec4Array;
115 cl->push_back(osg::Vec4(1, 1, 1, 1));
117 geometry->setUseDisplayList(false);
118 geometry->setVertexArray(vl);
119 geometry->setNormalArray(nl);
120 geometry->setNormalBinding(osg::Geometry::BIND_PER_VERTEX);
121 geometry->setTexCoordArray(0, tl);
122 geometry->setColorArray(cl);
123 geometry->setColorBinding(osg::Geometry::BIND_OVERALL);
124 geometry->addPrimitiveSet(new osg::DrawArrays(GL_TRIANGLE_STRIP, 0, vl->size()));
125 geode->addDrawable(geometry);