quad.h

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/*
 * quad.h
 *
 * Copyright (C) 2007   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.
 *
 *
 * Quadratic beziers
 */

#ifndef WAVEPACKET_BEZIER_QUAD_H__
#define WAVEPACKET_BEZIER_QUAD_H__

// includes --------------------------------------------------------------------
#include "bezier.h"


/// \ingroup bezier
/*@{*/

namespace bezier {


/// quadratic bezier curve
struct quad_bezier_t {
        void clear(void) throw() {
                        p0 = p1 = p2 = point_t(0.0, 0.0);
                }

        void setFromPointsAndSlope(IN const point_t& in_p0,
                                IN const point_t& in_p1,
                                IN const point_t& t0) throw() {
                        p0 = in_p0;                     // initial point
                        p2 = in_p1;                     // final point
                        p1.x = p0.x + 0.5 * t0.x;       // t0 = initial tangent
                        p1.y = p0.y + 0.5 * t0.y;
                }

        point_t getFinalTangent(void) const throw() {
                        return point_t(2.0 * (p2.x - p1.x),
                                       2.0 * (p2.y - p1.y));
                }

        point_t getPointAt(IN float t) const throw() {
                        ASSERT(t >= 0.0 && t <= 1.0, "Bad t: %f", t);
                        float alpha = 1.0 - t;
                        float beta = 2.0 * t * alpha;
                        alpha *= alpha;
                        float gamma = t * t;
                        return point_t(alpha * p0.x + beta * p1.x + gamma * p2.x,
                                       alpha * p0.y + beta * p1.y + gamma * p2.y);
                }

        void getBoundingRect(OUT rect_t& r) const throw();

        // data fields (control points)
        point_t         p0;
        point_t         p1;
        point_t         p2;
};



};      // bezier namespace

#endif  // WAVEPACKET_BEZIER_QUAD_H__