// Evaluates the shader flow functions for a buffer of positions and gradients, so that
// Aetheria.EditorTools.FlowFieldParityVerify can compare them with FlowField (ServerShared). Reads the same global
// _Flow* uniforms the nebula and stardust read, set by VolumeSampling.LowerFlow.
#pragma kernel Evaluate
// A compute shader declares the global keywords itself (as Stardust.compute does); the flow() it calls is keyword-gated.
#pragma multi_compile __ FLOW_GLOBAL
#pragma multi_compile __ FLOW_SLOPE

#include "Assets/Shaders/Volumetric.cginc"

StructuredBuffer<float3> positions;
StructuredBuffer<float2> gradients;
RWStructuredBuffer<float3> globalOut;
RWStructuredBuffer<float3> slopeOut;
RWStructuredBuffer<float3> gatedOut; // flow(): the keyword-gated function the nebula and stardust call
RWStructuredBuffer<float> noiseOut; // triNoise3d: the nebula noise the flow advects
uint count;

[numthreads(64, 1, 1)]
void Evaluate(uint3 id : SV_DispatchThreadID)
{
    if (id.x >= count) return;
    globalOut[id.x] = globalFlow(positions[id.x]);
    slopeOut[id.x] = slopeFlow(gradients[id.x]);
    gatedOut[id.x] = flow(positions[id.x]);
    noiseOut[id.x] = triNoise3d(positions[id.x] / 512);
}