1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/gfx/skia/trunk/include/effects/SkPerlinNoiseShader.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,111 @@
1.4 +/*
1.5 + * Copyright 2013 Google Inc.
1.6 + *
1.7 + * Use of this source code is governed by a BSD-style license that can be
1.8 + * found in the LICENSE file.
1.9 + */
1.10 +
1.11 +#ifndef SkPerlinNoiseShader_DEFINED
1.12 +#define SkPerlinNoiseShader_DEFINED
1.13 +
1.14 +#include "SkShader.h"
1.15 +
1.16 +/** \class SkPerlinNoiseShader
1.17 +
1.18 + SkPerlinNoiseShader creates an image using the Perlin turbulence function.
1.19 +
1.20 + It can produce tileable noise if asked to stitch tiles and provided a tile size.
1.21 + In order to fill a large area with repeating noise, set the stitchTiles flag to
1.22 + true, and render exactly a single tile of noise. Without this flag, the result
1.23 + will contain visible seams between tiles.
1.24 +
1.25 + The algorithm used is described here :
1.26 + http://www.w3.org/TR/SVG/filters.html#feTurbulenceElement
1.27 +*/
1.28 +class SK_API SkPerlinNoiseShader : public SkShader {
1.29 + struct PaintingData;
1.30 +public:
1.31 + struct StitchData;
1.32 +
1.33 + /**
1.34 + * About the noise types : the difference between the 2 is just minor tweaks to the algorithm,
1.35 + * they're not 2 entirely different noises. The output looks different, but once the noise is
1.36 + * generated in the [1, -1] range, the output is brought back in the [0, 1] range by doing :
1.37 + * kFractalNoise_Type : noise * 0.5 + 0.5
1.38 + * kTurbulence_Type : abs(noise)
1.39 + * Very little differences between the 2 types, although you can tell the difference visually.
1.40 + */
1.41 + enum Type {
1.42 + kFractalNoise_Type,
1.43 + kTurbulence_Type,
1.44 + kFirstType = kFractalNoise_Type,
1.45 + kLastType = kTurbulence_Type
1.46 + };
1.47 + /**
1.48 + * This will construct Perlin noise of the given type (Fractal Noise or Turbulence).
1.49 + *
1.50 + * Both base frequencies (X and Y) have a usual range of (0..1).
1.51 + *
1.52 + * The number of octaves provided should be fairly small, although no limit is enforced.
1.53 + * Each octave doubles the frequency, so 10 octaves would produce noise from
1.54 + * baseFrequency * 1, * 2, * 4, ..., * 512, which quickly yields insignificantly small
1.55 + * periods and resembles regular unstructured noise rather than Perlin noise.
1.56 + *
1.57 + * If tileSize isn't NULL or an empty size, the tileSize parameter will be used to modify
1.58 + * the frequencies so that the noise will be tileable for the given tile size. If tileSize
1.59 + * is NULL or an empty size, the frequencies will be used as is without modification.
1.60 + */
1.61 + static SkShader* CreateFractalNoise(SkScalar baseFrequencyX, SkScalar baseFrequencyY,
1.62 + int numOctaves, SkScalar seed,
1.63 + const SkISize* tileSize = NULL);
1.64 + static SkShader* CreateTubulence(SkScalar baseFrequencyX, SkScalar baseFrequencyY,
1.65 + int numOctaves, SkScalar seed,
1.66 + const SkISize* tileSize = NULL);
1.67 +
1.68 + virtual bool setContext(const SkBitmap& device, const SkPaint& paint,
1.69 + const SkMatrix& matrix);
1.70 + virtual void shadeSpan(int x, int y, SkPMColor[], int count) SK_OVERRIDE;
1.71 + virtual void shadeSpan16(int x, int y, uint16_t[], int count) SK_OVERRIDE;
1.72 +
1.73 + virtual GrEffectRef* asNewEffect(GrContext* context, const SkPaint&) const SK_OVERRIDE;
1.74 +
1.75 + SK_TO_STRING_OVERRIDE()
1.76 + SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkPerlinNoiseShader)
1.77 +
1.78 +protected:
1.79 + SkPerlinNoiseShader(SkReadBuffer&);
1.80 + virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
1.81 +
1.82 +private:
1.83 + SkPerlinNoiseShader(SkPerlinNoiseShader::Type type, SkScalar baseFrequencyX,
1.84 + SkScalar baseFrequencyY, int numOctaves, SkScalar seed,
1.85 + const SkISize* tileSize);
1.86 + virtual ~SkPerlinNoiseShader();
1.87 +
1.88 + SkScalar noise2D(int channel, const PaintingData& paintingData,
1.89 + const StitchData& stitchData, const SkPoint& noiseVector) const;
1.90 +
1.91 + SkScalar calculateTurbulenceValueForPoint(int channel, const PaintingData& paintingData,
1.92 + StitchData& stitchData, const SkPoint& point) const;
1.93 +
1.94 + SkPMColor shade(const SkPoint& point, StitchData& stitchData) const;
1.95 +
1.96 + // TODO (scroggo): Once all SkShaders are created from a factory, and we have removed the
1.97 + // constructor that creates SkPerlinNoiseShader from an SkReadBuffer, several fields can
1.98 + // be made constant.
1.99 + /*const*/ SkPerlinNoiseShader::Type fType;
1.100 + /*const*/ SkScalar fBaseFrequencyX;
1.101 + /*const*/ SkScalar fBaseFrequencyY;
1.102 + /*const*/ int fNumOctaves;
1.103 + /*const*/ SkScalar fSeed;
1.104 + /*const*/ SkISize fTileSize;
1.105 + /*const*/ bool fStitchTiles;
1.106 + // TODO (scroggo): Once setContext creates a new object, place this on that object.
1.107 + SkMatrix fMatrix;
1.108 +
1.109 + PaintingData* fPaintingData;
1.110 +
1.111 + typedef SkShader INHERITED;
1.112 +};
1.113 +
1.114 +#endif
