prism.cpp

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/*
 * prism.cpp
 *
 * Copyright (C) 2010  Thomas A. Vaughan
 * All rights reserved.
 *
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the <organization> nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THOMAS A. VAUGHAN ''AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THOMAS A. VAUGHAN BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *
 * Geometry methods specific to 3D prisms (see prism.h)
 */

// includes --------------------------------------------------------------------
#include "prism.h"              // always include our own header first




////////////////////////////////////////////////////////////////////////////////
//
//      static helper methods
//
////////////////////////////////////////////////////////////////////////////////


////////////////////////////////////////////////////////////////////////////////
//
//      public API
//
////////////////////////////////////////////////////////////////////////////////

void
createRegularPrism
(
IN int nSides,
IN float radius,
IN float height,
IO point3d_t * points
)
{
        ASSERT(nSides > 2, "Polygon must have at least 3 sides: %d", nSides);
        ASSERT(radius > 0, "prism base must have radius > 0: %f", radius);
        ASSERT(height > 0, "prism must have positive height: %f", height);
        ASSERT(points, "null");

        // loop through and construct n-sided regular polygon
        float dPhi = 2 * M_PI / nSides;
        float phi = 0;
        point3d_t * p = points;
        for (int i = 0; i < nSides; ++i, phi += dPhi, p += 2) {
                point3d_t& base = *p;
                point3d_t& top = *(p + 1);

                base.x = radius * sin(phi);
                base.z = radius * cos(phi);
                base.y = 0.0;

                top.x = base.x;
                top.z = base.z;
                top.y = height;
        }
}