135 lines
3.7 KiB
C++
135 lines
3.7 KiB
C++
// sphere.cxx -- build an ssg sphere object
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//
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// Pulled straight out of MesaGLU/quadratic.c
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//
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// Original gluSphere code is Copyright (C) 1999-2000 Brian Paul and
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// licensed under the GPL
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Library General Public
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// License as published by the Free Software Foundation; either
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// version 2 of the License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Library General Public License for more details.
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//
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// You should have received a copy of the GNU Library General Public
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// License along with this library; if not, write to the
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// Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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// Boston, MA 02111-1307, USA.
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//
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// $Id$
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#include <simgear/compiler.h>
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#include STL_IOSTREAM
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#include <plib/sg.h>
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#include <plib/ssg.h>
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#if !defined (SG_HAVE_NATIVE_SGI_COMPILERS)
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SG_USING_STD(cout);
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SG_USING_STD(endl);
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#endif
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// return a sphere object as an ssgBranch
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ssgBranch *ssgMakeSphere( ssgSimpleState *state, ssgColourArray *cl,
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double radius, int slices, int stacks,
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ssgCallback predraw, ssgCallback postdraw )
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{
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float rho, drho, theta, dtheta;
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float x, y, z;
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float s, t, ds, dt;
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int i, j, imin, imax;
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float nsign = 1.0;
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ssgBranch *sphere = new ssgBranch;
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sgVec2 vec2;
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sgVec3 vec3;
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drho = SGD_PI / (float) stacks;
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dtheta = 2.0 * SGD_PI / (float) slices;
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/* texturing: s goes from 0.0/0.25/0.5/0.75/1.0 at +y/+x/-y/-x/+y
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axis t goes from -1.0/+1.0 at z = -radius/+radius (linear along
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longitudes) cannot use triangle fan on texturing (s coord. at
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top/bottom tip varies) */
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ds = 1.0 / slices;
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dt = 1.0 / stacks;
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t = 1.0; /* because loop now runs from 0 */
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imin = 0;
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imax = stacks;
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/* build slices as quad strips */
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for ( i = imin; i < imax; i++ ) {
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ssgVertexArray *vl = new ssgVertexArray();
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ssgNormalArray *nl = new ssgNormalArray();
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ssgTexCoordArray *tl = new ssgTexCoordArray();
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rho = i * drho;
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s = 0.0;
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for ( j = 0; j <= slices; j++ ) {
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theta = (j == slices) ? 0.0 : j * dtheta;
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x = -sin(theta) * sin(rho);
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y = cos(theta) * sin(rho);
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z = nsign * cos(rho);
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// glNormal3f( x*nsign, y*nsign, z*nsign );
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sgSetVec3( vec3, x*nsign, y*nsign, z*nsign );
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sgNormalizeVec3( vec3 );
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nl->add( vec3 );
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// glTexCoord2f(s,t);
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sgSetVec2( vec2, s, t );
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tl->add( vec2 );
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// glVertex3f( x*radius, y*radius, z*radius );
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sgSetVec3( vec3, x*radius, y*radius, z*radius );
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vl->add( vec3 );
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x = -sin(theta) * sin(rho+drho);
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y = cos(theta) * sin(rho+drho);
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z = nsign * cos(rho+drho);
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// glNormal3f( x*nsign, y*nsign, z*nsign );
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sgSetVec3( vec3, x*nsign, y*nsign, z*nsign );
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sgNormalizeVec3( vec3 );
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nl->add( vec3 );
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// glTexCoord2f(s,t-dt);
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sgSetVec2( vec2, s, t-dt );
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tl->add( vec2 );
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s += ds;
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// glVertex3f( x*radius, y*radius, z*radius );
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sgSetVec3( vec3, x*radius, y*radius, z*radius );
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vl->add( vec3 );
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}
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ssgLeaf *slice =
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new ssgVtxTable ( GL_TRIANGLE_STRIP, vl, nl, tl, cl );
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if ( vl->getNum() != nl->getNum() ) {
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cout << "bad sphere1" << endl;
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exit(-1);
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}
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if ( vl->getNum() != tl->getNum() ) {
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cout << "bad sphere2" << endl;
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exit(-1);
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}
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slice->setState( state );
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slice->setCallback( SSG_CALLBACK_PREDRAW, predraw );
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slice->setCallback( SSG_CALLBACK_POSTDRAW, postdraw );
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sphere->addKid( slice );
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t -= dt;
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}
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return sphere;
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}
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