/*
 * 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 <viewsrg.srgi>
#include <Atom/Features/Pipeline/Forward/ForwardPassSrg.azsli>
#include <Atom/Features/PBR/DefaultObjectSrg.azsli>
#include <Atom/RPI/ShaderResourceGroups/DefaultDrawSrg.azsli>

option bool o_wavyLines = false;

ShaderResourceGroup MaterialSrg : SRG_PerMaterial
{
    float4 m_colorA;
    float4 m_colorB;
}

struct VertexInput
{
    float3 m_position : POSITION;
};

struct VertexOutput
{
    float4 m_position : SV_Position;
    float3 m_worldPosition : TexCoord;
};

VertexOutput MainVS(VertexInput input)
{
    const float4x4 objectToWorldMatrix = ObjectSrg::GetWorldMatrix();

    VertexOutput output;
    float3 worldPosition = mul(objectToWorldMatrix, float4(input.m_position, 1)).xyz;
    output.m_worldPosition = worldPosition;
    output.m_position = mul(ViewSrg::m_viewProjectionMatrix, float4(worldPosition, 1.0));

    return output;
}

struct PixelOutput
{
    float4 m_color : SV_Target0;
};

PixelOutput MainPS(VertexOutput input)
{
    PixelOutput output;

    float scale = 10;
    float stripeThickness = 0.3;
    float stripeShift = 0.66;

    float position = input.m_worldPosition.z;
    if(o_wavyLines)
    {
        position += sin(input.m_worldPosition.x * 10) * 0.05;
    }

    float t = step(frac(position * scale + stripeShift), stripeThickness);

    output.m_color = lerp(MaterialSrg::m_colorA, MaterialSrg::m_colorB, t);
    output.m_color.a = 0.5;
        
    return output;
}