| /* |
| * 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/SkShader.h" |
| |
| /** \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 |
| */ |
| class SK_API SkPerlinNoiseShader { |
| public: |
| /** |
| * 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. |
| */ |
| static sk_sp<SkShader> MakeFractalNoise(SkScalar baseFrequencyX, SkScalar baseFrequencyY, |
| int numOctaves, SkScalar seed, |
| const SkISize* tileSize = nullptr); |
| static sk_sp<SkShader> MakeTurbulence(SkScalar baseFrequencyX, SkScalar baseFrequencyY, |
| int numOctaves, SkScalar seed, |
| const SkISize* tileSize = nullptr); |
| |
| static void RegisterFlattenables(); |
| |
| private: |
| SkPerlinNoiseShader() = delete; |
| }; |
| |
| #endif |