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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 SkPerlinNoiseShader_DEFINED
#define SkPerlinNoiseShader_DEFINED
#include "include/core/SkRefCnt.h"
#include "include/core/SkScalar.h"
#include "include/core/SkShader.h" // IWYU pragma: keep
#include "include/private/base/SkAPI.h"
struct SkISize;
/** \class SkPerlinNoiseShader
SkPerlinNoiseShader 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
*/
namespace SkShaders {
/**
* 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) and must be non-negative.
*
* The number of octaves provided should be fairly small, with a limit of 255 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.
*/
SK_API sk_sp<SkShader> MakeFractalNoise(SkScalar baseFrequencyX, SkScalar baseFrequencyY,
int numOctaves, SkScalar seed,
const SkISize* tileSize = nullptr);
SK_API sk_sp<SkShader> MakeTurbulence(SkScalar baseFrequencyX, SkScalar baseFrequencyY,
int numOctaves, SkScalar seed,
const SkISize* tileSize = nullptr);
} // namespace SkShaders
#endif
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