o3de/Gems/AtomTressFX/Assets/Shaders/HairRenderingSrgs.azsli

/*
 * Modifications 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
 *
 */
 
//------------------------------------------------------------------------------
// Shader code related to lighting and shadowing for TressFX
//------------------------------------------------------------------------------
//
// Copyright (c) 2019 Advanced Micro Devices, Inc. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//
// originated from: TressFXRendering.hlsl

#pragma once

#include <viewsrg.srgi>

//------------------------------------------------------------------------------
#define g_mVP               ViewSrg::m_viewProjectionMatrix
#define g_vEye              ViewSrg::m_worldPosition.xyz
#define g_vViewport         ViewSrg::m_unprojectionConstants    // xy = normaliz scale, zw = offset in 0..1 scale
#define cInvViewProjMatrix  ViewSrg::m_viewProjectionInverseMatrix
//------------------------------------------------------------------------------

#define AMD_PI 3.1415926
#define AMD_e 2.71828183
#define AMD_TRESSFX_KERNEL_SIZE 5
#define KBUFFER_SIZE 8
#define MAX_FRAGMENTS 512
// Using value 0 as indicator will skip the first hair fragment to allow 
// for clear screen value (0). 
// If Atom will allow other value (0xffffffff) this can be avoided.
#define FRAGMENT_LIST_NULL 0    
//!=============================================================================
//!
//!                             Render Pass only
//! 
//!=============================================================================
// If you change this, you MUST also change TressFXRenderParams in TressFXConstantBuffers.h
// originally: cbuffer TressFXParameters : register(b3, space0)
struct TressFXRenderParameters
{
    // General information
    float       m_hairFiberRadius;

    // For deep approximated shadow lookup
    float       m_shadowAlpha;
    float       m_fiberSpacing;

    // Original TressFX Kajiya lighting model parameters
    float       m_hairKs2;
    float       m_hairEx2;
    float3      m_fPadding0;           
    float4      m_matKValue;

    int         m_maxShadowFibers;

    // Marschner lighting model parameters 
    float       m_roughness;
    float       m_cuticleTilt;

    float       m_fPadding1;
};

// Separate strand params from pixel render params (so we can index for PPLL)
// If you change this, you MUST change TressFXStrandParams in TressFXConstantBuffers.h
// originally: cbuffer TressFXStrandParameters : register(b4, space0)
struct TressFXStrandParameters
{
    float4      m_matBaseColor;
    float4      m_matTipColor;

    float       m_tipPercentage;
    float       m_strandUVTilingFactor;
    float       m_fiberRatio;
    float       m_fiberRadius;

    int         m_numVerticesPerStrand;
    int         m_enableThinTip;
    int         m_nodePoolSize;
    int         m_renderParamsIndex;    // Material index in the hair material array

    // Other params
    int         m_enableStrandUV;
    int         m_enableStrandTangent;
    int2        m_iPadding1;
};

//!------------------------------ SRG Structure --------------------------------
//! Used by the rendering raster pass only - might be possible to harness 
//! the material pipeline / tooling.  
//! This is the per draw Srg containing the specific per hair object parameters 
//! for the physics simulation and material rendering.
//! Originally at space0 in TressFXRendering.hlsl 
//!-----------------------------------------------------------------------------
ShaderResourceGroup HairRenderingMaterialSrg : SRG_PerMaterial
{
    // Generated 
    Buffer<float>     m_hairThicknessCoeffs;  // Does not seem to be used!
    Buffer<float2>    m_hairStrandTexCd;

    //! The hair textures defining the color of the hair at its base
    Texture2D<float4>           m_baseAlbedoTexture;
    Texture2D<float4>           m_strandAlbedoTexture;

    //! The hair render material properties (combined with the above textures)
    TressFXRenderParameters     m_tressFXRenderParameters;

    //! The hair object physical material properties.
    TressFXStrandParameters     m_tressFXStrandParameters;

    Sampler LinearWrapSampler
    {
        MinFilter = Linear;
        MagFilter = Linear;
        MipFilter = Linear;
        AddressU = Wrap;
        AddressV = Wrap;
        AddressW = Wrap;
    };
};
//------------------------------------------------------------------------------
#define g_HairThicknessCoeffs   HairRenderingMaterialSrg::m_hairThicknessCoeffs
#define g_HairStrandTexCd       HairRenderingMaterialSrg::m_hairStrandTexCd
#define BaseAlbedoTexture       HairRenderingMaterialSrg::m_baseAlbedoTexture
#define StrandAlbedoTexture     HairRenderingMaterialSrg::m_strandAlbedoTexture
#define LinearWrapSampler       HairRenderingMaterialSrg::LinearWrapSampler

#define HairFiberRadius         HairRenderingMaterialSrg::m_tressFXRenderParameters.m_hairFiberRadius
#define ShadowAlpha             HairRenderingMaterialSrg::m_tressFXRenderParameters.m_shadowAlpha
#define FiberSpacing            HairRenderingMaterialSrg::m_tressFXRenderParameters.m_fiberSpacing
#define HairKs2                 HairRenderingMaterialSrg::m_tressFXRenderParameters.m_hairKs2
#define HairEx2                 HairRenderingMaterialSrg::m_tressFXRenderParameters.m_hairEx2
#define MatKValue               HairRenderingMaterialSrg::m_tressFXRenderParameters.m_matKValue
#define MaxShadowFibers         HairRenderingMaterialSrg::m_tressFXRenderParameters.m_maxShadowFibers

#define MatBaseColor            HairRenderingMaterialSrg::m_tressFXStrandParameters.m_matBaseColor
#define MatTipColor             HairRenderingMaterialSrg::m_tressFXStrandParameters.m_matTipColor
#define TipPercentage           HairRenderingMaterialSrg::m_tressFXStrandParameters.m_tipPercentage
#define StrandUVTilingFactor    HairRenderingMaterialSrg::m_tressFXStrandParameters.m_strandUVTilingFactor
#define FiberRatio              HairRenderingMaterialSrg::m_tressFXStrandParameters.m_fiberRatio
#define FiberRadius             HairRenderingMaterialSrg::m_tressFXStrandParameters.m_fiberRadius
#define NumVerticesPerStrand    HairRenderingMaterialSrg::m_tressFXStrandParameters.m_numVerticesPerStrand
#define EnableThinTip           HairRenderingMaterialSrg::m_tressFXStrandParameters.m_enableThinTip
#define NodePoolSize            HairRenderingMaterialSrg::m_tressFXStrandParameters.m_nodePoolSize
#define RenderParamsIndex       HairRenderingMaterialSrg::m_tressFXStrandParameters.m_renderParamsIndex
#define EnableStrandUV          HairRenderingMaterialSrg::m_tressFXStrandParameters.m_enableStrandUV
#define EnableStrandTangent     HairRenderingMaterialSrg::m_tressFXStrandParameters.m_enableStrandTangent
//------------------------------------------------------------------------------

//------------------------------------------------------------------------------
//! If you change this, you MUST also change TressFXShadeParams in TressFXConstantBuffers.h 
//!  and ShadeParams in TressFXShortcut.hlsl
struct HairObjectShadeParams
{
    // General information
    float       m_fiberRadius;
    // For deep approximated shadow lookup
    float       m_shadowAlpha;
    float       m_fiberSpacing;

    // Original TressFX Kajiya lighting model parameters
    float       m_hairEx2;
    float4      m_matKValue;   // KAmbient, KDiffuse, KSpec1, Exp1
    float       m_hairKs2;

    // Marschner lighting model parameters 
    float       m_roughness;
    float       m_cuticleTilt;

    float       fPadding0;
};

//------------------------------------------------------------------------------
struct PPLL_STRUCT
{
    uint    depth;
    uint    data;
    uint    color;
    uint    uNext;
};
//------------------------------------------------------------------------------