54 lines
2.3 KiB
Markdown
54 lines
2.3 KiB
Markdown
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# Gradient Noise Node
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## Description
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Generates a gradient, or [Perlin](https://en.wikipedia.org/wiki/Perlin_noise), noise based on input **UV**. The scale of the generated noise is controlled by input **Scale**. In terms of performance cost, Gradient Noise node can be slightly more computationally intensive than sampling a texture map.
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You can also choose to use two different hashing methods for calculating the noise. As of Unity version 2021.2, the Gradient Noise node defaults to the **Deterministic** hash, to ensure consistent results for noise generation across platforms. Because the **UV** value is used as the seed for the noise generation, you can offset, scale, or distort the **UV** value to generate different noise patterns.
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## Ports
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| Name | Direction | Type | Binding | Description |
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|:------|:----------|:---------|:--------|:---------------|
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| UV | Input | Vector 2 | UV | Input UV value |
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| Scale | Input | Float | None | Noise scale |
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| Out | Output | Float | None | Output value in the range 0.0 to 1.0 |
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## Controls
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| Name | Type | Options | Description |
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|:----------|:---------|:-------------------------|:------------|
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| Hash Type | Dropdown | Deterministic, LegacyMod | Selects the hash function used to generate random numbers for noise generation. |
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## Generated Code Example
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The following example code represents one possible outcome of this node.
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```
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float2 unity_gradientNoise_dir(float2 p)
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{
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p = p % 289;
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float x = (34 * p.x + 1) * p.x % 289 + p.y;
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x = (34 * x + 1) * x % 289;
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x = frac(x / 41) * 2 - 1;
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return normalize(float2(x - floor(x + 0.5), abs(x) - 0.5));
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}
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float unity_gradientNoise(float2 p)
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{
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float2 ip = floor(p);
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float2 fp = frac(p);
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float d00 = dot(unity_gradientNoise_dir(ip), fp);
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float d01 = dot(unity_gradientNoise_dir(ip + float2(0, 1)), fp - float2(0, 1));
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float d10 = dot(unity_gradientNoise_dir(ip + float2(1, 0)), fp - float2(1, 0));
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float d11 = dot(unity_gradientNoise_dir(ip + float2(1, 1)), fp - float2(1, 1));
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fp = fp * fp * fp * (fp * (fp * 6 - 15) + 10);
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return lerp(lerp(d00, d01, fp.y), lerp(d10, d11, fp.y), fp.x);
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}
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void Unity_GradientNoise_float(float2 UV, float Scale, out float Out)
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{
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Out = unity_gradientNoise(UV * Scale) + 0.5;
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}
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```
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