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comparison: gfx/skia/trunk/include/effects/SkPerlinNoiseShader.h
gfx/skia/trunk/include/effects/SkPerlinNoiseShader.h
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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 */ | |
| 7 | |
| 8 #ifndef SkPerlinNoiseShader_DEFINED | |
| 9 #define SkPerlinNoiseShader_DEFINED | |
| 10 | |
| 11 #include "SkShader.h" | |
| 12 | |
| 13 /** \class SkPerlinNoiseShader | |
| 14 | |
| 15 SkPerlinNoiseShader creates an image using the Perlin turbulence function. | |
| 16 | |
| 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. | |
| 21 | |
| 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; | |
| 29 | |
| 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); | |
| 64 | |
| 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; | |
| 69 | |
| 70 virtual GrEffectRef* asNewEffect(GrContext* context, const SkPaint&) const SK_OVERRIDE; | |
| 71 | |
| 72 SK_TO_STRING_OVERRIDE() | |
| 73 SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkPerlinNoiseShader) | |
| 74 | |
| 75 protected: | |
| 76 SkPerlinNoiseShader(SkReadBuffer&); | |
| 77 virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE; | |
| 78 | |
| 79 private: | |
| 80 SkPerlinNoiseShader(SkPerlinNoiseShader::Type type, SkScalar baseFrequencyX, | |
| 81 SkScalar baseFrequencyY, int numOctaves, SkScalar seed, | |
| 82 const SkISize* tileSize); | |
| 83 virtual ~SkPerlinNoiseShader(); | |
| 84 | |
| 85 SkScalar noise2D(int channel, const PaintingData& paintingData, | |
| 86 const StitchData& stitchData, const SkPoint& noiseVector) const; | |
| 87 | |
| 88 SkScalar calculateTurbulenceValueForPoint(int channel, const PaintingData& paintingData, | |
| 89 StitchData& stitchData, const SkPoint& point) const; | |
| 90 | |
| 91 SkPMColor shade(const SkPoint& point, StitchData& stitchData) const; | |
| 92 | |
| 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; | |
| 105 | |
| 106 PaintingData* fPaintingData; | |
| 107 | |
| 108 typedef SkShader INHERITED; | |
| 109 }; | |
| 110 | |
| 111 #endif |
