wehub-resource-sync
68 lines
2.6 KiB
C#
68 lines
2.6 KiB
C#
namespace Lib.numbers.@float.random;
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[Guid("f2b80aaa-b353-45cc-9504-48c86e69ce99")]
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internal sealed class FloatHash : Instance<FloatHash>
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{
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[Output(Guid = "4BBBD40F-3D03-4AB7-B7CE-664578EFED94")]
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public readonly Slot<int> Result = new();
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public FloatHash()
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{
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Result.UpdateAction += Update;
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}
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private void Update(EvaluationContext context)
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{
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var floatSeed = Seed.GetValue(context);
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var intSeed = HashRawBitsToInt32(floatSeed);
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var makeUniqueForChild = UniqueForChild.GetValue(context);
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var childId = SymbolChildId;
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var bigInteger= new BigInteger(childId.ToByteArray());
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var childSeed = makeUniqueForChild
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? (uint)(bigInteger & 0xFFFFFFFF)
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: 0;
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var randomValue = PcgHash((uint)(childSeed + intSeed));
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Result.Value = (int)randomValue;
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}
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// PCG output function variant (Output XSL RR) - as provided before
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// This remains the core integer hashing logic.
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private static uint PcgHash(uint input)
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{
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uint state = input * 747796405u + 2891336453u; // LCG step
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uint word = ((state >> (int)((state >> 28) + 4u)) ^ state) * 277803737u; // Permutation
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return (word >> 22) ^ word; // Output transformation
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}
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/// <summary>
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/// Computes a 32-bit signed hash for a float value by directly hashing its raw bits.
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/// WARNING: Directly uses the float's binary representation. This means:
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/// - +0.0f and -0.0f will produce DIFFERENT hashes.
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/// - Different NaN representations might produce DIFFERENT hashes.
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/// - Infinity values will be hashed based on their specific bit patterns.
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/// This method is fast but ignores standard float equality rules.
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/// </summary>
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/// <param name="input">The float value to hash.</param>
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/// <returns>An int32 hash value based on the float's raw bit pattern.</returns>
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[MethodImpl(MethodImplOptions.AggressiveInlining)] // Suggest inlining for performance
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public static int HashRawBitsToInt32(float input)
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{
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// 1. Reinterpret the float bits directly as a uint using Unsafe.As
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uint bits = Unsafe.As<float, uint>(ref input);
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// 2. Apply the PCG hash function to the raw bits and cast to int
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return (int)PcgHash(bits);
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}
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[Input(Guid = "9427B1CB-DA57-431F-B182-DE16B7E11002")]
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public readonly InputSlot<float> Seed = new();
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[Input(Guid = "dbeffbd5-92b0-4a63-9d28-5592c6b42b69")]
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public readonly InputSlot<bool> UniqueForChild = new();
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} |