xref: /external/webkit/Source/WebCore/platform/graphics/gpu/LoopBlinnTextureCoords.h

/*
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#ifndef LoopBlinnTextureCoords_h
#define LoopBlinnTextureCoords_h

#include "FloatPoint3D.h"
#include "LoopBlinnClassifier.h"
#include "LoopBlinnConstants.h"

#include <wtf/Noncopyable.h>

namespace WebCore {

// Computes three-dimensional texture coordinates for the control
// points of a cubic curve for rendering via the shader in "Rendering
// Vector Art on the GPU" by Loop and Blinn, GPU Gems 3, Chapter 25.
class LoopBlinnTextureCoords {
public:
    // Container for the cubic texture coordinates and other associated
    // information.
    struct Result {
        Result()
            : isLineOrPoint(false)
            , hasRenderingArtifact(false)
            , subdivisionParameterValue(0.0f) { }

        // The (k, l, m) texture coordinates that are to be associated
        // with the four control points of the cubic curve.
        FloatPoint3D klmCoordinates[4];

        // Indicates whether the curve is a line or a point, in which case
        // we do not need to add its triangles to the mesh.
        bool isLineOrPoint;

        // For the loop case, indicates whether a rendering artifact was
        // detected, in which case the curve needs to be further
        // subdivided.
        bool hasRenderingArtifact;

        // If a rendering artifact will occur for the given loop curve,
        // this is the parameter value (0 <= value <= 1) at which the
        // curve needs to be subdivided to fix the artifact.
        float subdivisionParameterValue;
    };

    // Computes the texture coordinates for a cubic curve segment's
    // control points, given the classification of the curve as well as
    // an indication of which side is to be filled.
    static Result compute(const LoopBlinnClassifier::Result& classification,
                          LoopBlinnConstants::FillSide sideToFill);

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

} // namespace WebCore

#endif // LoopBlinnTextureCoords_h