// Crest Water System
// Copyright © 2024 Wave Harmonic. All rights reserved.

// Draw cached world-space heights into current frame data. If heights are coming
// from an ODC, then they are in object-space and are converted to world-space as
// the LOD data stores world-space height.

#pragma kernel CrestExecute

#pragma multi_compile_local __ d_CrestSDF

#include "HLSLSupport.cginc"

#include "Packages/com.waveharmonic.crest/Runtime/Shaders/Library/Macros.hlsl"
#include "Packages/com.waveharmonic.crest/Runtime/Shaders/Library/Constants.hlsl"
#include "Packages/com.waveharmonic.crest/Runtime/Shaders/Library/Globals.hlsl"
#include "Packages/com.waveharmonic.crest/Runtime/Shaders/Library/Helpers.hlsl"
#include "Packages/com.waveharmonic.crest/Runtime/Shaders/Library/InputsDriven.hlsl"
#include "Packages/com.waveharmonic.crest/Runtime/Shaders/Library/Cascade.hlsl"

#define m_CrestType float

#if d_CrestSDF
#undef m_CrestType
#define m_CrestType float2
#endif

Texture2D<m_CrestType> _Crest_Texture;
RWTexture2DArray<m_CrestType> _Crest_Target;

CBUFFER_START(CrestInputTexture)
float2 _Crest_Multiplier;
float2 _Crest_TextureSize;
float2 _Crest_TexturePosition;
float2 _Crest_TextureRotation;
float _Crest_HeightOffset;
bool _Crest_SDF;
CBUFFER_END

m_CrestNameSpace

void Execute(uint3 id)
{
    const Cascade cascade = Cascade::MakeDepth(id.z);
    const float2 uv = DataIDToInputUV(id.xy, cascade, _Crest_TexturePosition, _Crest_TextureRotation, _Crest_TextureSize);

    // Check we are within bounds.
    if (!WithinUV(uv))
    {
        return;
    }

    m_CrestType current = _Crest_Target[id];
    m_CrestType result = _Crest_Texture.SampleLevel(LODData_linear_clamp_sampler, uv, 0) * _Crest_Multiplier;
    result.x += _Crest_HeightOffset;

    // Take highest terrain height.
    result.x = max(current.x, result.x);

#if d_CrestSDF
    // Take shortest distance.
    result.y = _Crest_SDF ? min(current.y, result.y) : current.y;
#endif

    _Crest_Target[id] = result;
}

m_CrestNameSpaceEnd

m_CrestInputKernelDefault(Execute)