/*
 * 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/PostProcessing/FullscreenPixelInfo.azsli>
#include <Atom/Features/PostProcessing/PostProcessUtil.azsli>
#include <Atom/Features/PostProcessing/FullscreenVertexInfo.azsli>
#include <Atom/Features/PostProcessing/FullscreenVertexUtil.azsli>

struct VSOutputSMAAEdgeDetection
{
    float4 m_position : SV_Position;
    float2 m_texCoord : TEXCOORD0;
    float4 m_offset[3] : TEXCOORD1;
};

ShaderResourceGroup PassSrg : SRG_PerPass_WithFallback
{
    Texture2D<float4> m_framebuffer;
    Texture2D<float4> m_depthTexture;
    
    // Information for render target.
    // x = 1.0 / width
    // y = 1.0 / height
    // z = width
    // w = height
    float4 m_renderTargetMetrics;
    // This is a threshold value for edge detection sensitivity. For details please check comment related to SMAA_THRESHOLD in SMAA.azsli.
    float m_chromaThreshold;
    // This is a threshold value for depth edge detection sensitivity. For details please check comment related to SMAA_DEPTH_THRESHOLD in SMAA.azsli.
    float m_depthThreshold;
    // This is a tweak value for the local contrast adaptation feature. For details please check comment related to SMAA_LOCAL_CONTRAST_ADAPTATION_FACTOR in SMAA.azsli.
    float m_localContrastAdaptationFactor;
    // This is a threshold value for predication feature. For details please check comment related to SMAA_PREDICATION_THRESHOLD in SMAA.azsli.
    float m_predicationThreshold;
    // This is a tweak value for predication feature. For details please check comment related to SMAA_PREDICATION_SCALE in SMAA.azsli.
    float m_predicationScale;
    // This is a tweak value for predication feature. For details please check comment related to SMAA_PREDICATION_STRENGTH in SMAA.azsli.
    float m_predicationStrength;

    Sampler LinearSampler
    {
        MinFilter = Linear;
        MagFilter = Linear;
        MipFilter = Linear;
        AddressU = Clamp;
        AddressV = Clamp;
        AddressW = Clamp;
    };
    Sampler PointSampler
    {
        MinFilter = Point;
        MagFilter = Point;
        MipFilter = Point;
        AddressU = Clamp;
        AddressV = Clamp;
        AddressW = Clamp;
    };
}

// Option shader variable to enable predication feature. This option value will be used instead of SMAA_PREDICATION define in SMAA.azsli.
option bool o_enablePredicationFeature = false;
// Option shader variable for the edge detection mode.
option enum class EdgeDetectionMode { Depth, Luma, Color } o_edgeDetectionMode = EdgeDetectionMode::Color;

// This macro being defined before being included in SMAA.azsli, we can control which function is enabled in SMAA.azsli
// This macro is intended to enable the edge detection functions only.
#define ATOM_SMAA_EDGE_DETECTION_PASS_IMPLEMENTATION_ENABLE

// Defining the elements below before including SMAA.azsli as they'll be used in it.
// - PassSrg SRG to be used for the edge detection implementation.
// - The option shader variables to be used for the edge detection implementation.
#include "SMAA.azsli"

VSOutputSMAAEdgeDetection MainVS(VSInput input)
{
    VSOutputSMAAEdgeDetection OUT;

    float4 posTex = GetVertexPositionAndTexCoords(input.m_vertexID);
    
    OUT.m_texCoord = float2(posTex.z, posTex.w);
    OUT.m_position = float4(posTex.x, posTex.y, 0.0, 1.0);
    
    SMAAEdgeDetectionVS(OUT.m_texCoord, OUT.m_offset);

    return OUT;
}

PSOutput MainPS(VSOutputSMAAEdgeDetection IN)
{
    PSOutput OUT = (PSOutput)0;
    switch (o_edgeDetectionMode)
    {
        case EdgeDetectionMode::Depth:
            OUT.m_color.xy = SMAADepthEdgeDetectionPS(IN.m_texCoord, IN.m_offset, PassSrg::m_depthTexture);
            break;
        case EdgeDetectionMode::Luma:
            OUT.m_color.xy = SMAALumaEdgeDetectionPS(IN.m_texCoord, IN.m_offset, PassSrg::m_framebuffer, PassSrg::m_depthTexture);
            break;
        case EdgeDetectionMode::Color:
            OUT.m_color.xy = SMAAColorEdgeDetectionPS(IN.m_texCoord, IN.m_offset, PassSrg::m_framebuffer, PassSrg::m_depthTexture);
            break;
    }
    
    return OUT;
}