prism.cpp

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00001 /*
00002  * prism.cpp
00003  *
00004  * Copyright (C) 2010  Thomas A. Vaughan
00005  * All rights reserved.
00006  *
00007  *
00008  * Redistribution and use in source and binary forms, with or without
00009  * modification, are permitted provided that the following conditions are met:
00010  *     * Redistributions of source code must retain the above copyright
00011  *       notice, this list of conditions and the following disclaimer.
00012  *     * Redistributions in binary form must reproduce the above copyright
00013  *       notice, this list of conditions and the following disclaimer in the
00014  *       documentation and/or other materials provided with the distribution.
00015  *     * Neither the name of the <organization> nor the
00016  *       names of its contributors may be used to endorse or promote products
00017  *       derived from this software without specific prior written permission.
00018  *
00019  * THIS SOFTWARE IS PROVIDED BY THOMAS A. VAUGHAN ''AS IS'' AND ANY
00020  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
00021  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
00022  * DISCLAIMED. IN NO EVENT SHALL THOMAS A. VAUGHAN BE LIABLE FOR ANY
00023  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
00024  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
00025  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
00026  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
00027  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
00028  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
00029  *
00030  *
00031  * Geometry methods specific to 3D prisms (see prism.h)
00032  */
00033 
00034 // includes --------------------------------------------------------------------
00035 #include "prism.h"              // always include our own header first
00036 
00037 
00038 
00039 
00040 ////////////////////////////////////////////////////////////////////////////////
00041 //
00042 //      static helper methods
00043 //
00044 ////////////////////////////////////////////////////////////////////////////////
00045 
00046 
00047 ////////////////////////////////////////////////////////////////////////////////
00048 //
00049 //      public API
00050 //
00051 ////////////////////////////////////////////////////////////////////////////////
00052 
00053 void
00054 createRegularPrism
00055 (
00056 IN int nSides,
00057 IN float radius,
00058 IN float height,
00059 IO point3d_t * points
00060 )
00061 {
00062         ASSERT(nSides > 2, "Polygon must have at least 3 sides: %d", nSides);
00063         ASSERT(radius > 0, "prism base must have radius > 0: %f", radius);
00064         ASSERT(height > 0, "prism must have positive height: %f", height);
00065         ASSERT(points, "null");
00066 
00067         // loop through and construct n-sided regular polygon
00068         float dPhi = 2 * M_PI / nSides;
00069         float phi = 0;
00070         point3d_t * p = points;
00071         for (int i = 0; i < nSides; ++i, phi += dPhi, p += 2) {
00072                 point3d_t& base = *p;
00073                 point3d_t& top = *(p + 1);
00074 
00075                 base.x = radius * sin(phi);
00076                 base.z = radius * cos(phi);
00077                 base.y = 0.0;
00078 
00079                 top.x = base.x;
00080                 top.z = base.z;
00081                 top.y = height;
00082         }
00083 }
00084