The Tor Browser: gfx/skia/trunk/include/effects/SkPerlinNoiseShader.h@129ffea94266

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     1 /*

     2  * Copyright 2013 Google Inc.

     3  *

     4  * Use of this source code is governed by a BSD-style license that can be

     5  * found in the LICENSE file.

     6  */

     8 #ifndef SkPerlinNoiseShader_DEFINED

     9 #define SkPerlinNoiseShader_DEFINED

    11 #include "SkShader.h"

    13 /** \class SkPerlinNoiseShader

    15     SkPerlinNoiseShader creates an image using the Perlin turbulence function.

    17     It can produce tileable noise if asked to stitch tiles and provided a tile size.

    18     In order to fill a large area with repeating noise, set the stitchTiles flag to

    19     true, and render exactly a single tile of noise. Without this flag, the result

    20     will contain visible seams between tiles.

    22     The algorithm used is described here :

    23     http://www.w3.org/TR/SVG/filters.html#feTurbulenceElement

    24 */

    25 class SK_API SkPerlinNoiseShader : public SkShader {

    26     struct PaintingData;

    27 public:

    28     struct StitchData;

    30     /**

    31      *  About the noise types : the difference between the 2 is just minor tweaks to the algorithm,

    32      *  they're not 2 entirely different noises. The output looks different, but once the noise is

    33      *  generated in the [1, -1] range, the output is brought back in the [0, 1] range by doing :

    34      *  kFractalNoise_Type : noise * 0.5 + 0.5

    35      *  kTurbulence_Type   : abs(noise)

    36      *  Very little differences between the 2 types, although you can tell the difference visually.

    37      */

    38     enum Type {

    39         kFractalNoise_Type,

    40         kTurbulence_Type,

    41         kFirstType = kFractalNoise_Type,

    42         kLastType = kTurbulence_Type

    43     };

    44     /**

    45      *  This will construct Perlin noise of the given type (Fractal Noise or Turbulence).

    46      *

    47      *  Both base frequencies (X and Y) have a usual range of (0..1).

    48      *

    49      *  The number of octaves provided should be fairly small, although no limit is enforced.

    50      *  Each octave doubles the frequency, so 10 octaves would produce noise from

    51      *  baseFrequency * 1, * 2, * 4, ..., * 512, which quickly yields insignificantly small

    52      *  periods and resembles regular unstructured noise rather than Perlin noise.

    53      *

    54      *  If tileSize isn't NULL or an empty size, the tileSize parameter will be used to modify

    55      *  the frequencies so that the noise will be tileable for the given tile size. If tileSize

    56      *  is NULL or an empty size, the frequencies will be used as is without modification.

    57      */

    58     static SkShader* CreateFractalNoise(SkScalar baseFrequencyX, SkScalar baseFrequencyY,

    59                                         int numOctaves, SkScalar seed,

    60                                         const SkISize* tileSize = NULL);

    61     static SkShader* CreateTubulence(SkScalar baseFrequencyX, SkScalar baseFrequencyY,

    62                                      int numOctaves, SkScalar seed,

    63                                      const SkISize* tileSize = NULL);

    65     virtual bool setContext(const SkBitmap& device, const SkPaint& paint,

    66                             const SkMatrix& matrix);

    67     virtual void shadeSpan(int x, int y, SkPMColor[], int count) SK_OVERRIDE;

    68     virtual void shadeSpan16(int x, int y, uint16_t[], int count) SK_OVERRIDE;

    70     virtual GrEffectRef* asNewEffect(GrContext* context, const SkPaint&) const SK_OVERRIDE;

    72     SK_TO_STRING_OVERRIDE()

    73     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkPerlinNoiseShader)

    75 protected:

    76     SkPerlinNoiseShader(SkReadBuffer&);

    77     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;

    79 private:

    80     SkPerlinNoiseShader(SkPerlinNoiseShader::Type type, SkScalar baseFrequencyX,

    81                         SkScalar baseFrequencyY, int numOctaves, SkScalar seed,

    82                         const SkISize* tileSize);

    83     virtual ~SkPerlinNoiseShader();

    85     SkScalar noise2D(int channel, const PaintingData& paintingData,

    86                      const StitchData& stitchData, const SkPoint& noiseVector) const;

    88     SkScalar calculateTurbulenceValueForPoint(int channel, const PaintingData& paintingData,

    89                                               StitchData& stitchData, const SkPoint& point) const;

    91     SkPMColor shade(const SkPoint& point, StitchData& stitchData) const;

    93     // TODO (scroggo): Once all SkShaders are created from a factory, and we have removed the

    94     // constructor that creates SkPerlinNoiseShader from an SkReadBuffer, several fields can

    95     // be made constant.

    96     /*const*/ SkPerlinNoiseShader::Type fType;

    97     /*const*/ SkScalar                  fBaseFrequencyX;

    98     /*const*/ SkScalar                  fBaseFrequencyY;

    99     /*const*/ int                       fNumOctaves;

   100     /*const*/ SkScalar                  fSeed;

   101     /*const*/ SkISize                   fTileSize;

   102     /*const*/ bool                      fStitchTiles;

   103     // TODO (scroggo): Once setContext creates a new object, place this on that object.

   104     SkMatrix fMatrix;

   106     PaintingData* fPaintingData;

   108     typedef SkShader INHERITED;

   109 };

   111 #endif

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gfx/skia/trunk/include/effects/SkPerlinNoiseShader.h@129ffea94266

gfx/skia/trunk/include/effects/SkPerlinNoiseShader.h