DO NOT USE SIN HASH

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Use fract hash - https://www.shadertoy.com/view/4djSRW

Read Hash Noise in GPU Shaders - there lots of screenshots

Notice on screenshots below - use sin(large_numbers) by itself is broken - not just in hash.

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Short:

Sin-hash is not stable on "any scale" and there no way to fix it.

• Nvidia OpenGL sin-hash
• will be different on Nvidia DX11/12 sin hash
• will be different(and broken) on Vulkan
• will be different(and broken) on AMD/Mac/smartphone/anything else
• When fract-hash will be stable and exact same everywhere (except rare cases but can be fixed - read below FIX_FRACT_HASH)

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• Use fract hash - https://www.shadertoy.com/view/4djSRW
• Or int hash - but int hash have exact same behavior as fract hash - because source of random is float.
• But - int and fract hash can still be "broken"

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FIX_FRACT_HASH

Fix (not always needed) to inconsistent fract hash: (look screenshots below)

• use it only when you actually see fract hash is broken for your case - in most cases like noise-use case fract hash is stable
• this "fix" hit performance of fract-hash and making performance equal to int-hash (without this fix)
• int hash with this fix will be slower than fract-hash with fix
• and when fract-hash is broken int hash will also be broken so require same "fix" - image
• read blog - Hash Noise stability in GPU Shaders

// not always needed, and not always fix
#define FIX_FRACT_HASH 1000.

float hash12(vec2 p)
{
#ifdef FIX_FRACT_HASH
    p = sign(p)*(floor(abs(p))+floor(fract(abs(p))*FIX_FRACT_HASH)/FIX_FRACT_HASH);
#endif
    vec3 p3  = fract(vec3(p.xyx) * .1031);
    p3 += dot(p3, p3.yzx + 33.33);
    return fract((p3.x + p3.y) * p3.z);
}

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Screenshot, click to open	Bug link
sin hash instability	read blog - Hash Noise stability in GPU Shaders
	BUG Vulkan Nvidia sin hash - sin hash broken in Vulkan on Nvidia, when in OpenGL everything fine.
	BUG sin not same on AMD/Nvidia - similar as "sin hash broken" above, but in not-noise shader, in fractal shader sin making different visual image.
	BUG mod2pi does not fix sin/cos AMD/Nvidia - same shader as above, uncomment first two lines with define, obvious idea to fix sin inconsistensy just mod(x,2*PI) but it not just "not fix" it change pattern on Nvidia where it was working, on Nvidia pattern on left side with define will be different compare to no define.
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fract hash instability	read blog - Hash Noise stability in GPU Shaders
	BUG TEST Rough Seas fract hash - Just test shader for this blog post Hash Noise stability in GPU Shaders, blog mirror.
	Related-example of fract-hash instability described in blog post Hash Noise stability in GPU Shaders, blog mirror. Shader link.
	One more real-life example of fract-hash instability Shader link.
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more bugs in

GPU-my-list-of-bugs