ShaderVec3.h

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// Jolt Physics Library (https://github.com/jrouwe/JoltPhysics)
// SPDX-FileCopyrightText: 2025 Jorrit Rouwe
// SPDX-License-Identifier: MIT
 
inline float3 JPH_Vec3DecompressUnit(uint inValue)
{
    const float cOneOverSqrt2 = 0.70710678f;
    const uint cNumBits = 14;
    const uint cMask = (1u << cNumBits) - 1;
    const uint cMaxValue = cMask - 1; // Need odd number of buckets to quantize to or else we can't encode 0
    const int cHalfMaxValue = int(cMaxValue >> 1);
    const float cScale = 2.0f * cOneOverSqrt2 / float(cMaxValue);
 
    // Restore two components
    float2 v2 = float2(float(int(inValue & cMask) - cHalfMaxValue), float(int((inValue >> cNumBits) & cMask) - cHalfMaxValue)) * cScale;
 
    // Restore the highest component
    float3 v = float3(v2, sqrt(max(1.0f - dot(v2, v2), 0.0f)));
 
    // Extract sign
    if ((inValue & 0x80000000u) != 0)
        v = -v;
 
    // Swizzle the components in place
    uint max_element = (inValue >> 29) & 3;
    v = max_element == 0? v.zxy : (max_element == 1? v.xzy : v);
 
    return v;
}