/*
 * Copyright (c) Contributors to the Open 3D Engine Project.
 * For complete copyright and license terms please see the LICENSE at the root of this distribution.
 *
 * SPDX-License-Identifier: Apache-2.0 OR MIT
 *
 */

#include <Atom/Features/SrgSemantics.azsli>
#include <Atom/Features/ColorManagement/TransformColor.azsli>

ShaderResourceGroup ImageSrg : SRG_PerDraw
{
    Texture3D m_texture3D;
    uint m_sliceCount;
    float2 m_position;
    float2 m_size;
    uint2 m_resolution;
}

struct VSInput
{
    uint m_vertexIndex :SV_VertexID;
    uint m_instanceIndex :SV_InstanceID;
};

struct VSOutput
{
    float4 m_position : SV_Position;
    float2 m_uv : UV0;
    uint slice : SLICE;
};

struct PSOutput
{
    float4 m_color : SV_Target0;
};

VSOutput MainVS(VSInput vsInput)
{
    VSOutput OUT;
    float2 uvs[4] = { {0.0, 0.0}, {1.0, 0.0}, {0.0, 1.0}, {1.0, 1.0} };
    uint index = vsInput.m_vertexIndex%4;
    uint sliceIndex = vsInput.m_instanceIndex;
    float seam = 0.01;

    float2 startPosition = ImageSrg::m_position + float2((ImageSrg::m_size.x + seam) * sliceIndex, 0.0);
    OUT.m_position = float4(startPosition + uvs[index] * ImageSrg::m_size, 0, 1.0);
    OUT.m_uv = uvs[index];
    OUT.slice = sliceIndex;
    return OUT;
}

PSOutput MainPS(VSOutput psInput)
{
    PSOutput OUT;

    // Get the image dimensions
    uint width;
    uint height;
    uint depth;
    uint numberOfLevels;
    ImageSrg::m_texture3D.GetDimensions(0, width, height, depth, numberOfLevels);

    float3 texColor = ImageSrg::m_texture3D.Load(int4(width * psInput.m_uv.x, height * psInput.m_uv.y, psInput.slice, 0)).xyz;
    OUT.m_color = float4(TransformColor(texColor, ColorSpaceId::LinearSRGB, ColorSpaceId::SRGB), 1.0);
    
    return OUT;
}