LoopBlinnClassifier.h   [plain text]

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// Cubic curve classification algorithm from "Rendering Vector Art on
// the GPU" by Loop and Blinn, GPU Gems 3, Chapter 25:
// http://http.developer.nvidia.com/GPUGems3/gpugems3_ch25.html .

#ifndef LoopBlinnClassifier_h
#define LoopBlinnClassifier_h

#include <wtf/Noncopyable.h>

namespace WebCore {

class FloatPoint;

// Classifies cubic curves into specific types.
class LoopBlinnClassifier {
    WTF_MAKE_NONCOPYABLE(LoopBlinnClassifier);
public:
    // The types of cubic curves.
    enum CurveType {
        kSerpentine,
        kCusp,
        kLoop,
        kQuadratic,
        kLine,
        kPoint
    };

    // The result of the classifier.
    struct Result {
    public:
        Result(CurveType inputCurveType, float inputD1, float inputD2, float inputD3)
            : curveType(inputCurveType)
            , d1(inputD1)
            , d2(inputD2)
            , d3(inputD3) { }

        CurveType curveType;

        // These are coefficients used later in the computation of
        // texture coordinates per vertex.
        float d1;
        float d2;
        float d3;
    };

    // Classifies the given cubic bezier curve starting at c0, ending
    // at c3, and affected by control points c1 and c2.
    static Result classify(const FloatPoint& c0,
                           const FloatPoint& c1,
                           const FloatPoint& c2,
                           const FloatPoint& c3);

private:
    // This class does not need to be instantiated.
    LoopBlinnClassifier() { }
};

} // namespace WebCore

#endif // LoopBlinnClassifier_h