| /* |
| * Copyright 2013 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #ifndef SkPerlinNoiseShader2_DEFINED |
| #define SkPerlinNoiseShader2_DEFINED |
| |
| #include "SkShader.h" |
| |
| /** \class SkPerlinNoiseShader2 |
| |
| SkPerlinNoiseShader2 creates an image using the Perlin turbulence function. |
| |
| It can produce tileable noise if asked to stitch tiles and provided a tile size. |
| In order to fill a large area with repeating noise, set the stitchTiles flag to |
| true, and render exactly a single tile of noise. Without this flag, the result |
| will contain visible seams between tiles. |
| |
| The algorithm used is described here : |
| http://www.w3.org/TR/SVG/filters.html#feTurbulenceElement |
| */ |
| class SK_API SkPerlinNoiseShader2 : public SkShader { |
| public: |
| struct StitchData; |
| struct PaintingData; |
| |
| /** |
| * About the noise types : the difference between the first 2 is just minor tweaks to the |
| * algorithm, they're not 2 entirely different noises. The output looks different, but once the |
| * noise is generated in the [1, -1] range, the output is brought back in the [0, 1] range by |
| * doing : |
| * kFractalNoise_Type : noise * 0.5 + 0.5 |
| * kTurbulence_Type : abs(noise) |
| * Very little differences between the 2 types, although you can tell the difference visually. |
| * "Improved" is based on the Improved Perlin Noise algorithm described at |
| * http://mrl.nyu.edu/~perlin/noise/. It is quite distinct from the other two, and the noise is |
| * a 2D slice of a 3D noise texture. Minor changes to the Z coordinate will result in minor |
| * changes to the noise, making it suitable for animated noise. |
| */ |
| enum Type { |
| kFractalNoise_Type, |
| kTurbulence_Type, |
| kImprovedNoise_Type, |
| kFirstType = kFractalNoise_Type, |
| kLastType = kImprovedNoise_Type |
| }; |
| /** |
| * This will construct Perlin noise of the given type (Fractal Noise or Turbulence). |
| * |
| * Both base frequencies (X and Y) have a usual range of (0..1). |
| * |
| * The number of octaves provided should be fairly small, although no limit is enforced. |
| * Each octave doubles the frequency, so 10 octaves would produce noise from |
| * baseFrequency * 1, * 2, * 4, ..., * 512, which quickly yields insignificantly small |
| * periods and resembles regular unstructured noise rather than Perlin noise. |
| * |
| * If tileSize isn't NULL or an empty size, the tileSize parameter will be used to modify |
| * the frequencies so that the noise will be tileable for the given tile size. If tileSize |
| * is NULL or an empty size, the frequencies will be used as is without modification. |
| */ |
| static sk_sp<SkShader> MakeFractalNoise(SkScalar baseFrequencyX, SkScalar baseFrequencyY, |
| int numOctaves, SkScalar seed, |
| const SkISize* tileSize = NULL); |
| static sk_sp<SkShader> MakeTurbulence(SkScalar baseFrequencyX, SkScalar baseFrequencyY, |
| int numOctaves, SkScalar seed, |
| const SkISize* tileSize = NULL); |
| /** |
| * Creates an Improved Perlin Noise shader. The z value is roughly equivalent to the seed of the |
| * other two types, but minor variations to z will only slightly change the noise. |
| */ |
| static sk_sp<SkShader> MakeImprovedNoise(SkScalar baseFrequencyX, SkScalar baseFrequencyY, |
| int numOctaves, SkScalar z); |
| /** |
| * Create alias for CreateTurbulunce until all Skia users changed |
| * its code to use the new naming |
| */ |
| static sk_sp<SkShader> MakeTubulence(SkScalar baseFrequencyX, SkScalar baseFrequencyY, |
| int numOctaves, SkScalar seed, |
| const SkISize* tileSize = NULL) { |
| return MakeTurbulence(baseFrequencyX, baseFrequencyY, numOctaves, seed, tileSize); |
| } |
| |
| class PerlinNoiseShaderContext : public SkShader::Context { |
| public: |
| PerlinNoiseShaderContext(const SkPerlinNoiseShader2& shader, const ContextRec&); |
| virtual ~PerlinNoiseShaderContext(); |
| |
| void shadeSpan(int x, int y, SkPMColor[], int count) override; |
| |
| private: |
| SkPMColor shade(const SkPoint& point, StitchData& stitchData) const; |
| SkScalar calculateTurbulenceValueForPoint( |
| int channel, |
| StitchData& stitchData, const SkPoint& point) const; |
| SkScalar calculateImprovedNoiseValueForPoint(int channel, const SkPoint& point) const; |
| SkScalar noise2D(int channel, |
| const StitchData& stitchData, const SkPoint& noiseVector) const; |
| |
| SkMatrix fMatrix; |
| PaintingData* fPaintingData; |
| |
| typedef SkShader::Context INHERITED; |
| }; |
| |
| #if SK_SUPPORT_GPU |
| const GrFragmentProcessor* asFragmentProcessor(GrContext* context, const SkMatrix& viewM, |
| const SkMatrix*, SkFilterQuality) const override; |
| #endif |
| |
| SK_TO_STRING_OVERRIDE() |
| SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkPerlinNoiseShader2) |
| |
| protected: |
| void flatten(SkWriteBuffer&) const override; |
| size_t onContextSize(const ContextRec&) const override; |
| Context* onCreateContext(const ContextRec&, void* storage) const override; |
| |
| private: |
| SkPerlinNoiseShader2(SkPerlinNoiseShader2::Type type, SkScalar baseFrequencyX, |
| SkScalar baseFrequencyY, int numOctaves, SkScalar seed, |
| const SkISize* tileSize); |
| virtual ~SkPerlinNoiseShader2(); |
| |
| const SkPerlinNoiseShader2::Type fType; |
| const SkScalar fBaseFrequencyX; |
| const SkScalar fBaseFrequencyY; |
| const int fNumOctaves; |
| const SkScalar fSeed; |
| const SkISize fTileSize; |
| const bool fStitchTiles; |
| |
| typedef SkShader INHERITED; |
| }; |
| |
| #endif |