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/*
* 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
sk_sp<GrFragmentProcessor> asFragmentProcessor(const AsFPArgs&) const override;
#endif
SK_TO_STRING_OVERRIDE()
SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkPerlinNoiseShader2)
protected:
void flatten(SkWriteBuffer&) const override;
Context* onMakeContext(const ContextRec&, SkArenaAlloc*) 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
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