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      1 /*
      2  * Copyright (C) 2010 Google Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  *
      8  * 1.  Redistributions of source code must retain the above copyright
      9  *     notice, this list of conditions and the following disclaimer.
     10  * 2.  Redistributions in binary form must reproduce the above copyright
     11  *     notice, this list of conditions and the following disclaimer in the
     12  *     documentation and/or other materials provided with the distribution.
     13  *
     14  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
     15  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     16  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     17  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
     18  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
     19  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     20  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
     21  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     24  */
     25 
     26 // Cubic curve classification algorithm from "Rendering Vector Art on
     27 // the GPU" by Loop and Blinn, GPU Gems 3, Chapter 25:
     28 // http://http.developer.nvidia.com/GPUGems3/gpugems3_ch25.html .
     29 
     30 #ifndef LoopBlinnClassifier_h
     31 #define LoopBlinnClassifier_h
     32 
     33 #include <wtf/Noncopyable.h>
     34 
     35 namespace WebCore {
     36 
     37 class FloatPoint;
     38 
     39 // Classifies cubic curves into specific types.
     40 class LoopBlinnClassifier {
     41     WTF_MAKE_NONCOPYABLE(LoopBlinnClassifier);
     42 public:
     43     // The types of cubic curves.
     44     enum CurveType {
     45         kSerpentine,
     46         kCusp,
     47         kLoop,
     48         kQuadratic,
     49         kLine,
     50         kPoint
     51     };
     52 
     53     // The result of the classifier.
     54     struct Result {
     55     public:
     56         Result(CurveType inputCurveType, float inputD1, float inputD2, float inputD3)
     57             : curveType(inputCurveType)
     58             , d1(inputD1)
     59             , d2(inputD2)
     60             , d3(inputD3) { }
     61 
     62         CurveType curveType;
     63 
     64         // These are coefficients used later in the computation of
     65         // texture coordinates per vertex.
     66         float d1;
     67         float d2;
     68         float d3;
     69     };
     70 
     71     // Classifies the given cubic bezier curve starting at c0, ending
     72     // at c3, and affected by control points c1 and c2.
     73     static Result classify(const FloatPoint& c0,
     74                            const FloatPoint& c1,
     75                            const FloatPoint& c2,
     76                            const FloatPoint& c3);
     77 
     78 private:
     79     // This class does not need to be instantiated.
     80     LoopBlinnClassifier() { }
     81 };
     82 
     83 } // namespace WebCore
     84 
     85 #endif // LoopBlinnClassifier_h
     86