#pragma kernel FindVerticalDisplacements

#pragma only_renderers d3d11 playstation xboxone xboxseries vulkan metal switch

// #pragma enable_d3d11_debug_symbols

// Required for finding the vertical displacements
#pragma multi_compile WATER_ONE_BAND WATER_TWO_BANDS WATER_THREE_BANDS
#pragma multi_compile _ WATER_LOCAL_CURRENT

// Required to be defined for some includes
#define WATER_SIMULATION

// Small optimization to reduce deformation reads
#define IGNORE_WATER_DEFORMATION
#define WATER_POST_INCLUDE_DEFORMATION

// SRP generic includes
#include "Packages/com.unity.render-pipelines.core/ShaderLibrary/Common.hlsl"
#include "Packages/com.unity.render-pipelines.high-definition/Runtime/ShaderLibrary/ShaderVariables.hlsl"
#include "Packages/com.unity.render-pipelines.high-definition/Runtime/Water/Shaders/SampleWaterSurface.hlsl"

// The set of input position we need to process
RWStructuredBuffer<float> _WaterCameraHeightBufferRW;

// We allow up to 10 steps to figure out the height of the point
#define SEARCH_ITERATION_COUNT 8

// We consider that we found the point if we were able to
#define SEARCH_DISTANCE_THRESHOLD 0.001

[numthreads(1, 1, 1)]
void FindVerticalDisplacements(uint3 currentThread : SV_DispatchThreadID)
{
    UNITY_XR_ASSIGN_VIEW_INDEX(currentThread.z);

    int stepCount;
    float currentError;
    float height = FindVerticalDisplacement(_WorldSpaceCameraPos.xyz, SEARCH_ITERATION_COUNT, SEARCH_DISTANCE_THRESHOLD, stepCount, currentError);

    _WaterCameraHeightBufferRW[4 * unity_StereoEyeIndex + 0] = height;
    _WaterCameraHeightBufferRW[4 * unity_StereoEyeIndex + 1] = currentError;
    _WaterCameraHeightBufferRW[4 * unity_StereoEyeIndex + 2] = stepCount;
    _WaterCameraHeightBufferRW[4 * unity_StereoEyeIndex + 3] = 0.0;
}