michael@0: /*
michael@0:  * Copyright 2013 Google Inc.
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: 
michael@0: #ifndef SkPerlinNoiseShader_DEFINED
michael@0: #define SkPerlinNoiseShader_DEFINED
michael@0: 
michael@0: #include "SkShader.h"
michael@0: 
michael@0: /** \class SkPerlinNoiseShader
michael@0: 
michael@0:     SkPerlinNoiseShader creates an image using the Perlin turbulence function.
michael@0: 
michael@0:     It can produce tileable noise if asked to stitch tiles and provided a tile size.
michael@0:     In order to fill a large area with repeating noise, set the stitchTiles flag to
michael@0:     true, and render exactly a single tile of noise. Without this flag, the result
michael@0:     will contain visible seams between tiles.
michael@0: 
michael@0:     The algorithm used is described here :
michael@0:     http://www.w3.org/TR/SVG/filters.html#feTurbulenceElement
michael@0: */
michael@0: class SK_API SkPerlinNoiseShader : public SkShader {
michael@0:     struct PaintingData;
michael@0: public:
michael@0:     struct StitchData;
michael@0: 
michael@0:     /**
michael@0:      *  About the noise types : the difference between the 2 is just minor tweaks to the algorithm,
michael@0:      *  they're not 2 entirely different noises. The output looks different, but once the noise is
michael@0:      *  generated in the [1, -1] range, the output is brought back in the [0, 1] range by doing :
michael@0:      *  kFractalNoise_Type : noise * 0.5 + 0.5
michael@0:      *  kTurbulence_Type   : abs(noise)
michael@0:      *  Very little differences between the 2 types, although you can tell the difference visually.
michael@0:      */
michael@0:     enum Type {
michael@0:         kFractalNoise_Type,
michael@0:         kTurbulence_Type,
michael@0:         kFirstType = kFractalNoise_Type,
michael@0:         kLastType = kTurbulence_Type
michael@0:     };
michael@0:     /**
michael@0:      *  This will construct Perlin noise of the given type (Fractal Noise or Turbulence).
michael@0:      *
michael@0:      *  Both base frequencies (X and Y) have a usual range of (0..1).
michael@0:      *
michael@0:      *  The number of octaves provided should be fairly small, although no limit is enforced.
michael@0:      *  Each octave doubles the frequency, so 10 octaves would produce noise from
michael@0:      *  baseFrequency * 1, * 2, * 4, ..., * 512, which quickly yields insignificantly small
michael@0:      *  periods and resembles regular unstructured noise rather than Perlin noise.
michael@0:      *
michael@0:      *  If tileSize isn't NULL or an empty size, the tileSize parameter will be used to modify
michael@0:      *  the frequencies so that the noise will be tileable for the given tile size. If tileSize
michael@0:      *  is NULL or an empty size, the frequencies will be used as is without modification.
michael@0:      */
michael@0:     static SkShader* CreateFractalNoise(SkScalar baseFrequencyX, SkScalar baseFrequencyY,
michael@0:                                         int numOctaves, SkScalar seed,
michael@0:                                         const SkISize* tileSize = NULL);
michael@0:     static SkShader* CreateTubulence(SkScalar baseFrequencyX, SkScalar baseFrequencyY,
michael@0:                                      int numOctaves, SkScalar seed,
michael@0:                                      const SkISize* tileSize = NULL);
michael@0: 
michael@0:     virtual bool setContext(const SkBitmap& device, const SkPaint& paint,
michael@0:                             const SkMatrix& matrix);
michael@0:     virtual void shadeSpan(int x, int y, SkPMColor[], int count) SK_OVERRIDE;
michael@0:     virtual void shadeSpan16(int x, int y, uint16_t[], int count) SK_OVERRIDE;
michael@0: 
michael@0:     virtual GrEffectRef* asNewEffect(GrContext* context, const SkPaint&) const SK_OVERRIDE;
michael@0: 
michael@0:     SK_TO_STRING_OVERRIDE()
michael@0:     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkPerlinNoiseShader)
michael@0: 
michael@0: protected:
michael@0:     SkPerlinNoiseShader(SkReadBuffer&);
michael@0:     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
michael@0: 
michael@0: private:
michael@0:     SkPerlinNoiseShader(SkPerlinNoiseShader::Type type, SkScalar baseFrequencyX,
michael@0:                         SkScalar baseFrequencyY, int numOctaves, SkScalar seed,
michael@0:                         const SkISize* tileSize);
michael@0:     virtual ~SkPerlinNoiseShader();
michael@0: 
michael@0:     SkScalar noise2D(int channel, const PaintingData& paintingData,
michael@0:                      const StitchData& stitchData, const SkPoint& noiseVector) const;
michael@0: 
michael@0:     SkScalar calculateTurbulenceValueForPoint(int channel, const PaintingData& paintingData,
michael@0:                                               StitchData& stitchData, const SkPoint& point) const;
michael@0: 
michael@0:     SkPMColor shade(const SkPoint& point, StitchData& stitchData) const;
michael@0: 
michael@0:     // TODO (scroggo): Once all SkShaders are created from a factory, and we have removed the
michael@0:     // constructor that creates SkPerlinNoiseShader from an SkReadBuffer, several fields can
michael@0:     // be made constant.
michael@0:     /*const*/ SkPerlinNoiseShader::Type fType;
michael@0:     /*const*/ SkScalar                  fBaseFrequencyX;
michael@0:     /*const*/ SkScalar                  fBaseFrequencyY;
michael@0:     /*const*/ int                       fNumOctaves;
michael@0:     /*const*/ SkScalar                  fSeed;
michael@0:     /*const*/ SkISize                   fTileSize;
michael@0:     /*const*/ bool                      fStitchTiles;
michael@0:     // TODO (scroggo): Once setContext creates a new object, place this on that object.
michael@0:     SkMatrix fMatrix;
michael@0: 
michael@0:     PaintingData* fPaintingData;
michael@0: 
michael@0:     typedef SkShader INHERITED;
michael@0: };
michael@0: 
michael@0: #endif