Introduction to 3D Game …ogramming with DirectX 12/Introduction-to-3D-Game-Programming-with-DirectX-12.ISO/Code.Textures/Chapter 12 The Geometry Shader/TreeBillboards/TreeBillboardsApp.cpp

C/C++ Source or Header | 2016-03-02 | 45KB | 1,243 lines

//***************************************************************************************
// TreeBillboardsApp.cpp by Frank Luna (C) 2015 All Rights Reserved.
//***************************************************************************************

#include "../../Common/d3dApp.h"
#include "../../Common/MathHelper.h"
#include "../../Common/UploadBuffer.h"
#include "../../Common/GeometryGenerator.h"
#include "FrameResource.h"
#include "Waves.h"

using Microsoft::WRL::ComPtr;
using namespace DirectX;
using namespace DirectX::PackedVector;

#pragma comment(lib, "d3dcompiler.lib")
#pragma comment(lib, "D3D12.lib")

const int gNumFrameResources = 3;

// Lightweight structure stores parameters to draw a shape.  This will
// vary from app-to-app.
struct RenderItem
{
    RenderItem() = default;

    // World matrix of the shape that describes the object's local space
    // relative to the world space, which defines the position, orientation,
    // and scale of the object in the world.
    XMFLOAT4X4 World = MathHelper::Identity4x4();

    XMFLOAT4X4 TexTransform = MathHelper::Identity4x4();

    // Dirty flag indicating the object data has changed and we need to update the constant buffer.
    // Because we have an object cbuffer for each FrameResource, we have to apply the
    // update to each FrameResource.  Thus, when we modify obect data we should set
    // NumFramesDirty = gNumFrameResources so that each frame resource gets the update.
    int NumFramesDirty = gNumFrameResources;

    // Index into GPU constant buffer corresponding to the ObjectCB for this render item.
    UINT ObjCBIndex = -1;

    Material* Mat = nullptr;
    MeshGeometry* Geo = nullptr;

    // Primitive topology.
    D3D12_PRIMITIVE_TOPOLOGY PrimitiveType = D3D11_PRIMITIVE_TOPOLOGY_TRIANGLELIST;

    // DrawIndexedInstanced parameters.
    UINT IndexCount = 0;
    UINT StartIndexLocation = 0;
    int BaseVertexLocation = 0;
};

enum class RenderLayer : int
{
    Opaque = 0,
    Transparent,
    AlphaTested,
    AlphaTestedTreeSprites,
    Count
};

class TreeBillboardsApp : public D3DApp
{
public:
    TreeBillboardsApp(HINSTANCE hInstance);
    TreeBillboardsApp(const TreeBillboardsApp& rhs) = delete;
    TreeBillboardsApp& operator=(const TreeBillboardsApp& rhs) = delete;
    ~TreeBillboardsApp();

    virtual bool Initialize()override;

private:
    virtual void OnResize()override;
    virtual void Update(const GameTimer& gt)override;
    virtual void Draw(const GameTimer& gt)override;

    virtual void OnMouseDown(WPARAM btnState, int x, int y)override;
    virtual void OnMouseUp(WPARAM btnState, int x, int y)override;
    virtual void OnMouseMove(WPARAM btnState, int x, int y)override;

    void OnKeyboardInput(const GameTimer& gt);
    void UpdateCamera(const GameTimer& gt);
    void AnimateMaterials(const GameTimer& gt);
    void UpdateObjectCBs(const GameTimer& gt);
    void UpdateMaterialCBs(const GameTimer& gt);
    void UpdateMainPassCB(const GameTimer& gt);
    void UpdateWaves(const GameTimer& gt);

    void LoadTextures();
    void BuildRootSignature();
    void BuildDescriptorHeaps();
    void BuildShadersAndInputLayouts();
    void BuildLandGeometry();
    void BuildWavesGeometry();
    void BuildBoxGeometry();
    void BuildTreeSpritesGeometry();
    void BuildPSOs();
    void BuildFrameResources();
    void BuildMaterials();
    void BuildRenderItems();
    void DrawRenderItems(ID3D12GraphicsCommandList* cmdList, const std::vector<RenderItem*>& ritems);

    std::array<const CD3DX12_STATIC_SAMPLER_DESC, 6> GetStaticSamplers();

    float GetHillsHeight(float x, float z)const;
    XMFLOAT3 GetHillsNormal(float x, float z)const;

private:

    std::vector<std::unique_ptr<FrameResource>> mFrameResources;
    FrameResource* mCurrFrameResource = nullptr;
    int mCurrFrameResourceIndex = 0;

    UINT mCbvSrvDescriptorSize = 0;

    ComPtr<ID3D12RootSignature> mRootSignature = nullptr;

    ComPtr<ID3D12DescriptorHeap> mSrvDescriptorHeap = nullptr;

    std::unordered_map<std::string, std::unique_ptr<MeshGeometry>> mGeometries;
    std::unordered_map<std::string, std::unique_ptr<Material>> mMaterials;
    std::unordered_map<std::string, std::unique_ptr<Texture>> mTextures;
    std::unordered_map<std::string, ComPtr<ID3DBlob>> mShaders;
    std::unordered_map<std::string, ComPtr<ID3D12PipelineState>> mPSOs;

    std::vector<D3D12_INPUT_ELEMENT_DESC> mStdInputLayout;
    std::vector<D3D12_INPUT_ELEMENT_DESC> mTreeSpriteInputLayout;

    RenderItem* mWavesRitem = nullptr;

    // List of all the render items.
    std::vector<std::unique_ptr<RenderItem>> mAllRitems;

    // Render items divided by PSO.
    std::vector<RenderItem*> mRitemLayer[(int)RenderLayer::Count];

    std::unique_ptr<Waves> mWaves;

    PassConstants mMainPassCB;

    XMFLOAT3 mEyePos = { 0.0f, 0.0f, 0.0f };
    XMFLOAT4X4 mView = MathHelper::Identity4x4();
    XMFLOAT4X4 mProj = MathHelper::Identity4x4();

    float mTheta = 1.5f*XM_PI;
    float mPhi = XM_PIDIV2 - 0.1f;
    float mRadius = 50.0f;

    POINT mLastMousePos;
};

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE prevInstance,
    PSTR cmdLine, int showCmd)
{
    // Enable run-time memory check for debug builds.
#if defined(DEBUG) | defined(_DEBUG)
    _CrtSetDbgFlag(_CRTDBG_ALLOC_MEM_DF | _CRTDBG_LEAK_CHECK_DF);
#endif

    try
    {
        TreeBillboardsApp theApp(hInstance);
        if(!theApp.Initialize())
            return 0;

        return theApp.Run();
    }
    catch(DxException& e)
    {
        MessageBox(nullptr, e.ToString().c_str(), L"HR Failed", MB_OK);
        return 0;
    }
}

TreeBillboardsApp::TreeBillboardsApp(HINSTANCE hInstance)
    : D3DApp(hInstance)
{
}

TreeBillboardsApp::~TreeBillboardsApp()
{
    if(md3dDevice != nullptr)
        FlushCommandQueue();
}

bool TreeBillboardsApp::Initialize()
{
    if(!D3DApp::Initialize())
        return false;

    // Reset the command list to prep for initialization commands.
    ThrowIfFailed(mCommandList->Reset(mDirectCmdListAlloc.Get(), nullptr));

    // Get the increment size of a descriptor in this heap type.  This is hardware specific,
    // so we have to query this information.
    mCbvSrvDescriptorSize = md3dDevice->GetDescriptorHandleIncrementSize(D3D12_DESCRIPTOR_HEAP_TYPE_CBV_SRV_UAV);

    mWaves = std::make_unique<Waves>(128, 128, 1.0f, 0.03f, 4.0f, 0.2f);

    LoadTextures();
    BuildRootSignature();
    BuildDescriptorHeaps();
    BuildShadersAndInputLayouts();
    BuildLandGeometry();
    BuildWavesGeometry();
    BuildBoxGeometry();
    BuildTreeSpritesGeometry();
    BuildMaterials();
    BuildRenderItems();
    BuildFrameResources();
    BuildPSOs();

    // Execute the initialization commands.
    ThrowIfFailed(mCommandList->Close());
    ID3D12CommandList* cmdsLists[] = { mCommandList.Get() };
    mCommandQueue->ExecuteCommandLists(_countof(cmdsLists), cmdsLists);

    // Wait until initialization is complete.
    FlushCommandQueue();

    return true;
}

void TreeBillboardsApp::OnResize()
{
    D3DApp::OnResize();

    // The window resized, so update the aspect ratio and recompute the projection matrix.
    XMMATRIX P = XMMatrixPerspectiveFovLH(0.25f*MathHelper::Pi, AspectRatio(), 1.0f, 1000.0f);
    XMStoreFloat4x4(&mProj, P);
}

void TreeBillboardsApp::Update(const GameTimer& gt)
{
    OnKeyboardInput(gt);
    UpdateCamera(gt);

    // Cycle through the circular frame resource array.
    mCurrFrameResourceIndex = (mCurrFrameResourceIndex + 1) % gNumFrameResources;
    mCurrFrameResource = mFrameResources[mCurrFrameResourceIndex].get();

    // Has the GPU finished processing the commands of the current frame resource?
    // If not, wait until the GPU has completed commands up to this fence point.
    if(mCurrFrameResource->Fence != 0 && mFence->GetCompletedValue() < mCurrFrameResource->Fence)
    {
        HANDLE eventHandle = CreateEventEx(nullptr, false, false, EVENT_ALL_ACCESS);
        ThrowIfFailed(mFence->SetEventOnCompletion(mCurrFrameResource->Fence, eventHandle));
        WaitForSingleObject(eventHandle, INFINITE);
        CloseHandle(eventHandle);
    }

    AnimateMaterials(gt);
    UpdateObjectCBs(gt);
    UpdateMaterialCBs(gt);
    UpdateMainPassCB(gt);
    UpdateWaves(gt);
}

void TreeBillboardsApp::Draw(const GameTimer& gt)
{
    auto cmdListAlloc = mCurrFrameResource->CmdListAlloc;

    // Reuse the memory associated with command recording.
    // We can only reset when the associated command lists have finished execution on the GPU.
    ThrowIfFailed(cmdListAlloc->Reset());

    // A command list can be reset after it has been added to the command queue via ExecuteCommandList.
    // Reusing the command list reuses memory.
    ThrowIfFailed(mCommandList->Reset(cmdListAlloc.Get(), mPSOs["opaque"].Get()));

    mCommandList->RSSetViewports(1, &mScreenViewport);
    mCommandList->RSSetScissorRects(1, &mScissorRect);

    // Indicate a state transition on the resource usage.
    mCommandList->ResourceBarrier(1, &CD3DX12_RESOURCE_BARRIER::Transition(CurrentBackBuffer(),
        D3D12_RESOURCE_STATE_PRESENT, D3D12_RESOURCE_STATE_RENDER_TARGET));

    // Clear the back buffer and depth buffer.
    mCommandList->ClearRenderTargetView(CurrentBackBufferView(), (float*)&mMainPassCB.FogColor, 0, nullptr);
    mCommandList->ClearDepthStencilView(DepthStencilView(), D3D12_CLEAR_FLAG_DEPTH | D3D12_CLEAR_FLAG_STENCIL, 1.0f, 0, 0, nullptr);

    // Specify the buffers we are going to render to.
    mCommandList->OMSetRenderTargets(1, &CurrentBackBufferView(), true, &DepthStencilView());

    ID3D12DescriptorHeap* descriptorHeaps[] = { mSrvDescriptorHeap.Get() };
    mCommandList->SetDescriptorHeaps(_countof(descriptorHeaps), descriptorHeaps);

    mCommandList->SetGraphicsRootSignature(mRootSignature.Get());

    auto passCB = mCurrFrameResource->PassCB->Resource();
    mCommandList->SetGraphicsRootConstantBufferView(2, passCB->GetGPUVirtualAddress());

    DrawRenderItems(mCommandList.Get(), mRitemLayer[(int)RenderLayer::Opaque]);

    mCommandList->SetPipelineState(mPSOs["alphaTested"].Get());
    DrawRenderItems(mCommandList.Get(), mRitemLayer[(int)RenderLayer::AlphaTested]);

    mCommandList->SetPipelineState(mPSOs["treeSprites"].Get());
    DrawRenderItems(mCommandList.Get(), mRitemLayer[(int)RenderLayer::AlphaTestedTreeSprites]);

    mCommandList->SetPipelineState(mPSOs["transparent"].Get());
    DrawRenderItems(mCommandList.Get(), mRitemLayer[(int)RenderLayer::Transparent]);

    // Indicate a state transition on the resource usage.
    mCommandList->ResourceBarrier(1, &CD3DX12_RESOURCE_BARRIER::Transition(CurrentBackBuffer(),
        D3D12_RESOURCE_STATE_RENDER_TARGET, D3D12_RESOURCE_STATE_PRESENT));

    // Done recording commands.
    ThrowIfFailed(mCommandList->Close());

    // Add the command list to the queue for execution.
    ID3D12CommandList* cmdsLists[] = { mCommandList.Get() };
    mCommandQueue->ExecuteCommandLists(_countof(cmdsLists), cmdsLists);

    // Swap the back and front buffers
    ThrowIfFailed(mSwapChain->Present(0, 0));
    mCurrBackBuffer = (mCurrBackBuffer + 1) % SwapChainBufferCount;

    // Advance the fence value to mark commands up to this fence point.
    mCurrFrameResource->Fence = ++mCurrentFence;

    // Add an instruction to the command queue to set a new fence point.
    // Because we are on the GPU timeline, the new fence point won't be
    // set until the GPU finishes processing all the commands prior to this Signal().
    mCommandQueue->Signal(mFence.Get(), mCurrentFence);
}

void TreeBillboardsApp::OnMouseDown(WPARAM btnState, int x, int y)
{
    mLastMousePos.x = x;
    mLastMousePos.y = y;

    SetCapture(mhMainWnd);
}

void TreeBillboardsApp::OnMouseUp(WPARAM btnState, int x, int y)
{
    ReleaseCapture();
}

void TreeBillboardsApp::OnMouseMove(WPARAM btnState, int x, int y)
{
    if((btnState & MK_LBUTTON) != 0)
    {
        // Make each pixel correspond to a quarter of a degree.
        float dx = XMConvertToRadians(0.25f*static_cast<float>(x - mLastMousePos.x));
        float dy = XMConvertToRadians(0.25f*static_cast<float>(y - mLastMousePos.y));

        // Update angles based on input to orbit camera around box.
        mTheta += dx;
        mPhi += dy;

        // Restrict the angle mPhi.
        mPhi = MathHelper::Clamp(mPhi, 0.1f, MathHelper::Pi - 0.1f);
    }
    else if((btnState & MK_RBUTTON) != 0)
    {
        // Make each pixel correspond to 0.2 unit in the scene.
        float dx = 0.2f*static_cast<float>(x - mLastMousePos.x);
        float dy = 0.2f*static_cast<float>(y - mLastMousePos.y);

        // Update the camera radius based on input.
        mRadius += dx - dy;

        // Restrict the radius.
        mRadius = MathHelper::Clamp(mRadius, 5.0f, 150.0f);
    }

    mLastMousePos.x = x;
    mLastMousePos.y = y;
}

void TreeBillboardsApp::OnKeyboardInput(const GameTimer& gt)
{
}

void TreeBillboardsApp::UpdateCamera(const GameTimer& gt)
{
    // Convert Spherical to Cartesian coordinates.
    mEyePos.x = mRadius*sinf(mPhi)*cosf(mTheta);
    mEyePos.z = mRadius*sinf(mPhi)*sinf(mTheta);
    mEyePos.y = mRadius*cosf(mPhi);

    // Build the view matrix.
    XMVECTOR pos = XMVectorSet(mEyePos.x, mEyePos.y, mEyePos.z, 1.0f);
    XMVECTOR target = XMVectorZero();
    XMVECTOR up = XMVectorSet(0.0f, 1.0f, 0.0f, 0.0f);

    XMMATRIX view = XMMatrixLookAtLH(pos, target, up);
    XMStoreFloat4x4(&mView, view);
}

void TreeBillboardsApp::AnimateMaterials(const GameTimer& gt)
{
    // Scroll the water material texture coordinates.
    auto waterMat = mMaterials["water"].get();

    float& tu = waterMat->MatTransform(3, 0);
    float& tv = waterMat->MatTransform(3, 1);

    tu += 0.1f * gt.DeltaTime();
    tv += 0.02f * gt.DeltaTime();

    if(tu >= 1.0f)
        tu -= 1.0f;

    if(tv >= 1.0f)
        tv -= 1.0f;

    waterMat->MatTransform(3, 0) = tu;
    waterMat->MatTransform(3, 1) = tv;

    // Material has changed, so need to update cbuffer.
    waterMat->NumFramesDirty = gNumFrameResources;
}

void TreeBillboardsApp::UpdateObjectCBs(const GameTimer& gt)
{
    auto currObjectCB = mCurrFrameResource->ObjectCB.get();
    for(auto& e : mAllRitems)
    {
        // Only update the cbuffer data if the constants have changed.
        // This needs to be tracked per frame resource.
        if(e->NumFramesDirty > 0)
        {
            XMMATRIX world = XMLoadFloat4x4(&e->World);
            XMMATRIX texTransform = XMLoadFloat4x4(&e->TexTransform);

            ObjectConstants objConstants;
            XMStoreFloat4x4(&objConstants.World, XMMatrixTranspose(world));
            XMStoreFloat4x4(&objConstants.TexTransform, XMMatrixTranspose(texTransform));

            currObjectCB->CopyData(e->ObjCBIndex, objConstants);

            // Next FrameResource need to be updated too.
            e->NumFramesDirty--;
        }
    }
}

void TreeBillboardsApp::UpdateMaterialCBs(const GameTimer& gt)
{
    auto currMaterialCB = mCurrFrameResource->MaterialCB.get();
    for(auto& e : mMaterials)
    {
        // Only update the cbuffer data if the constants have changed.  If the cbuffer
        // data changes, it needs to be updated for each FrameResource.
        Material* mat = e.second.get();
        if(mat->NumFramesDirty > 0)
        {
            XMMATRIX matTransform = XMLoadFloat4x4(&mat->MatTransform);

            MaterialConstants matConstants;
            matConstants.DiffuseAlbedo = mat->DiffuseAlbedo;
            matConstants.FresnelR0 = mat->FresnelR0;
            matConstants.Roughness = mat->Roughness;
            XMStoreFloat4x4(&matConstants.MatTransform, XMMatrixTranspose(matTransform));

            currMaterialCB->CopyData(mat->MatCBIndex, matConstants);

            // Next FrameResource need to be updated too.
            mat->NumFramesDirty--;
        }
    }
}

void TreeBillboardsApp::UpdateMainPassCB(const GameTimer& gt)
{
    XMMATRIX view = XMLoadFloat4x4(&mView);
    XMMATRIX proj = XMLoadFloat4x4(&mProj);

    XMMATRIX viewProj = XMMatrixMultiply(view, proj);
    XMMATRIX invView = XMMatrixInverse(&XMMatrixDeterminant(view), view);
    XMMATRIX invProj = XMMatrixInverse(&XMMatrixDeterminant(proj), proj);
    XMMATRIX invViewProj = XMMatrixInverse(&XMMatrixDeterminant(viewProj), viewProj);

    XMStoreFloat4x4(&mMainPassCB.View, XMMatrixTranspose(view));
    XMStoreFloat4x4(&mMainPassCB.InvView, XMMatrixTranspose(invView));
    XMStoreFloat4x4(&mMainPassCB.Proj, XMMatrixTranspose(proj));
    XMStoreFloat4x4(&mMainPassCB.InvProj, XMMatrixTranspose(invProj));
    XMStoreFloat4x4(&mMainPassCB.ViewProj, XMMatrixTranspose(viewProj));
    XMStoreFloat4x4(&mMainPassCB.InvViewProj, XMMatrixTranspose(invViewProj));
    mMainPassCB.EyePosW = mEyePos;
    mMainPassCB.RenderTargetSize = XMFLOAT2((float)mClientWidth, (float)mClientHeight);
    mMainPassCB.InvRenderTargetSize = XMFLOAT2(1.0f / mClientWidth, 1.0f / mClientHeight);
    mMainPassCB.NearZ = 1.0f;
    mMainPassCB.FarZ = 1000.0f;
    mMainPassCB.TotalTime = gt.TotalTime();
    mMainPassCB.DeltaTime = gt.DeltaTime();
    mMainPassCB.AmbientLight = { 0.25f, 0.25f, 0.35f, 1.0f };
    mMainPassCB.Lights[0].Direction = { 0.57735f, -0.57735f, 0.57735f };
    mMainPassCB.Lights[0].Strength = { 0.6f, 0.6f, 0.6f };
    mMainPassCB.Lights[1].Direction = { -0.57735f, -0.57735f, 0.57735f };
    mMainPassCB.Lights[1].Strength = { 0.3f, 0.3f, 0.3f };
    mMainPassCB.Lights[2].Direction = { 0.0f, -0.707f, -0.707f };
    mMainPassCB.Lights[2].Strength = { 0.15f, 0.15f, 0.15f };

    auto currPassCB = mCurrFrameResource->PassCB.get();
    currPassCB->CopyData(0, mMainPassCB);
}

void TreeBillboardsApp::UpdateWaves(const GameTimer& gt)
{
    // Every quarter second, generate a random wave.
    static float t_base = 0.0f;
    if((mTimer.TotalTime() - t_base) >= 0.25f)
    {
        t_base += 0.25f;

        int i = MathHelper::Rand(4, mWaves->RowCount() - 5);
        int j = MathHelper::Rand(4, mWaves->ColumnCount() - 5);

        float r = MathHelper::RandF(0.2f, 0.5f);

        mWaves->Disturb(i, j, r);
    }

    // Update the wave simulation.
    mWaves->Update(gt.DeltaTime());

    // Update the wave vertex buffer with the new solution.
    auto currWavesVB = mCurrFrameResource->WavesVB.get();
    for(int i = 0; i < mWaves->VertexCount(); ++i)
    {
        Vertex v;

        v.Pos = mWaves->Position(i);
        v.Normal = mWaves->Normal(i);

        // Derive tex-coords from position by
        // mapping [-w/2,w/2] --> [0,1]
        v.TexC.x = 0.5f + v.Pos.x / mWaves->Width();
        v.TexC.y = 0.5f - v.Pos.z / mWaves->Depth();

        currWavesVB->CopyData(i, v);
    }

    // Set the dynamic VB of the wave renderitem to the current frame VB.
    mWavesRitem->Geo->VertexBufferGPU = currWavesVB->Resource();
}

void TreeBillboardsApp::LoadTextures()
{
    auto grassTex = std::make_unique<Texture>();
    grassTex->Name = "grassTex";
    grassTex->Filename = L"../../Textures/grass.dds";
    ThrowIfFailed(DirectX::CreateDDSTextureFromFile12(md3dDevice.Get(),
        mCommandList.Get(), grassTex->Filename.c_str(),
        grassTex->Resource, grassTex->UploadHeap));

    auto waterTex = std::make_unique<Texture>();
    waterTex->Name = "waterTex";
    waterTex->Filename = L"../../Textures/water1.dds";
    ThrowIfFailed(DirectX::CreateDDSTextureFromFile12(md3dDevice.Get(),
        mCommandList.Get(), waterTex->Filename.c_str(),
        waterTex->Resource, waterTex->UploadHeap));

    auto fenceTex = std::make_unique<Texture>();
    fenceTex->Name = "fenceTex";
    fenceTex->Filename = L"../../Textures/WireFence.dds";
    ThrowIfFailed(DirectX::CreateDDSTextureFromFile12(md3dDevice.Get(),
        mCommandList.Get(), fenceTex->Filename.c_str(),
        fenceTex->Resource, fenceTex->UploadHeap));

    auto treeArrayTex = std::make_unique<Texture>();
    treeArrayTex->Name = "treeArrayTex";
    treeArrayTex->Filename = L"../../Textures/treeArray2.dds";
    ThrowIfFailed(DirectX::CreateDDSTextureFromFile12(md3dDevice.Get(),
        mCommandList.Get(), treeArrayTex->Filename.c_str(),
        treeArrayTex->Resource, treeArrayTex->UploadHeap));

    mTextures[grassTex->Name] = std::move(grassTex);
    mTextures[waterTex->Name] = std::move(waterTex);
    mTextures[fenceTex->Name] = std::move(fenceTex);
    mTextures[treeArrayTex->Name] = std::move(treeArrayTex);
}

void TreeBillboardsApp::BuildRootSignature()
{
    CD3DX12_DESCRIPTOR_RANGE texTable;
    texTable.Init(D3D12_DESCRIPTOR_RANGE_TYPE_SRV, 1, 0);

    // Root parameter can be a table, root descriptor or root constants.
    CD3DX12_ROOT_PARAMETER slotRootParameter[4];

    // Perfomance TIP: Order from most frequent to least frequent.
    slotRootParameter[0].InitAsDescriptorTable(1, &texTable, D3D12_SHADER_VISIBILITY_PIXEL);
    slotRootParameter[1].InitAsConstantBufferView(0);
    slotRootParameter[2].InitAsConstantBufferView(1);
    slotRootParameter[3].InitAsConstantBufferView(2);

    auto staticSamplers = GetStaticSamplers();

    // A root signature is an array of root parameters.
    CD3DX12_ROOT_SIGNATURE_DESC rootSigDesc(4, slotRootParameter,
        (UINT)staticSamplers.size(), staticSamplers.data(),
        D3D12_ROOT_SIGNATURE_FLAG_ALLOW_INPUT_ASSEMBLER_INPUT_LAYOUT);

    // create a root signature with a single slot which points to a descriptor range consisting of a single constant buffer
    ComPtr<ID3DBlob> serializedRootSig = nullptr;
    ComPtr<ID3DBlob> errorBlob = nullptr;
    HRESULT hr = D3D12SerializeRootSignature(&rootSigDesc, D3D_ROOT_SIGNATURE_VERSION_1,
        serializedRootSig.GetAddressOf(), errorBlob.GetAddressOf());

    if(errorBlob != nullptr)
    {
        ::OutputDebugStringA((char*)errorBlob->GetBufferPointer());
    }
    ThrowIfFailed(hr);

    ThrowIfFailed(md3dDevice->CreateRootSignature(
        0,
        serializedRootSig->GetBufferPointer(),
        serializedRootSig->GetBufferSize(),
        IID_PPV_ARGS(mRootSignature.GetAddressOf())));
}

void TreeBillboardsApp::BuildDescriptorHeaps()
{
    //
    // Create the SRV heap.
    //
    D3D12_DESCRIPTOR_HEAP_DESC srvHeapDesc = {};
    srvHeapDesc.NumDescriptors = 4;
    srvHeapDesc.Type = D3D12_DESCRIPTOR_HEAP_TYPE_CBV_SRV_UAV;
    srvHeapDesc.Flags = D3D12_DESCRIPTOR_HEAP_FLAG_SHADER_VISIBLE;
    ThrowIfFailed(md3dDevice->CreateDescriptorHeap(&srvHeapDesc, IID_PPV_ARGS(&mSrvDescriptorHeap)));

    //
    // Fill out the heap with actual descriptors.
    //
    CD3DX12_CPU_DESCRIPTOR_HANDLE hDescriptor(mSrvDescriptorHeap->GetCPUDescriptorHandleForHeapStart());

    auto grassTex = mTextures["grassTex"]->Resource;
    auto waterTex = mTextures["waterTex"]->Resource;
    auto fenceTex = mTextures["fenceTex"]->Resource;
    auto treeArrayTex = mTextures["treeArrayTex"]->Resource;

    D3D12_SHADER_RESOURCE_VIEW_DESC srvDesc = {};
    srvDesc.Shader4ComponentMapping = D3D12_DEFAULT_SHADER_4_COMPONENT_MAPPING;
    srvDesc.Format = grassTex->GetDesc().Format;
    srvDesc.ViewDimension = D3D12_SRV_DIMENSION_TEXTURE2D;
    srvDesc.Texture2D.MostDetailedMip = 0;
    srvDesc.Texture2D.MipLevels = -1;
    md3dDevice->CreateShaderResourceView(grassTex.Get(), &srvDesc, hDescriptor);

    // next descriptor
    hDescriptor.Offset(1, mCbvSrvDescriptorSize);

    srvDesc.Format = waterTex->GetDesc().Format;
    md3dDevice->CreateShaderResourceView(waterTex.Get(), &srvDesc, hDescriptor);

    // next descriptor
    hDescriptor.Offset(1, mCbvSrvDescriptorSize);

    srvDesc.Format = fenceTex->GetDesc().Format;
    md3dDevice->CreateShaderResourceView(fenceTex.Get(), &srvDesc, hDescriptor);

    // next descriptor
    hDescriptor.Offset(1, mCbvSrvDescriptorSize);

    auto desc = treeArrayTex->GetDesc();
    srvDesc.ViewDimension = D3D12_SRV_DIMENSION_TEXTURE2DARRAY;
    srvDesc.Format = treeArrayTex->GetDesc().Format;
    srvDesc.Texture2DArray.MostDetailedMip = 0;
    srvDesc.Texture2DArray.MipLevels = -1;
    srvDesc.Texture2DArray.FirstArraySlice = 0;
    srvDesc.Texture2DArray.ArraySize = treeArrayTex->GetDesc().DepthOrArraySize;
    md3dDevice->CreateShaderResourceView(treeArrayTex.Get(), &srvDesc, hDescriptor);
}

void TreeBillboardsApp::BuildShadersAndInputLayouts()
{
    const D3D_SHADER_MACRO defines[] =
    {
        "FOG", "1",
        NULL, NULL
    };

    const D3D_SHADER_MACRO alphaTestDefines[] =
    {
        "FOG", "1",
        "ALPHA_TEST", "1",
        NULL, NULL
    };

    mShaders["standardVS"] = d3dUtil::CompileShader(L"Shaders\\Default.hlsl", nullptr, "VS", "vs_5_0");
    mShaders["opaquePS"] = d3dUtil::CompileShader(L"Shaders\\Default.hlsl", defines, "PS", "ps_5_0");
    mShaders["alphaTestedPS"] = d3dUtil::CompileShader(L"Shaders\\Default.hlsl", alphaTestDefines, "PS", "ps_5_0");

    mShaders["treeSpriteVS"] = d3dUtil::CompileShader(L"Shaders\\TreeSprite.hlsl", nullptr, "VS", "vs_5_0");
    mShaders["treeSpriteGS"] = d3dUtil::CompileShader(L"Shaders\\TreeSprite.hlsl", nullptr, "GS", "gs_5_0");
    mShaders["treeSpritePS"] = d3dUtil::CompileShader(L"Shaders\\TreeSprite.hlsl", alphaTestDefines, "PS", "ps_5_0");

    mStdInputLayout =
    {
        { "POSITION", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, 0, D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0 },
        { "NORMAL", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, 12, D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0 },
        { "TEXCOORD", 0, DXGI_FORMAT_R32G32_FLOAT, 0, 24, D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0 },
    };

    mTreeSpriteInputLayout =
    {
        { "POSITION", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, 0, D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0 },
        { "SIZE", 0, DXGI_FORMAT_R32G32_FLOAT, 0, 12, D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0 },
    };
}

void TreeBillboardsApp::BuildLandGeometry()
{
    GeometryGenerator geoGen;
    GeometryGenerator::MeshData grid = geoGen.CreateGrid(160.0f, 160.0f, 50, 50);

    //
    // Extract the vertex elements we are interested and apply the height function to
    // each vertex.  In addition, color the vertices based on their height so we have
    // sandy looking beaches, grassy low hills, and snow mountain peaks.
    //

    std::vector<Vertex> vertices(grid.Vertices.size());
    for(size_t i = 0; i < grid.Vertices.size(); ++i)
    {
        auto& p = grid.Vertices[i].Position;
        vertices[i].Pos = p;
        vertices[i].Pos.y = GetHillsHeight(p.x, p.z);
        vertices[i].Normal = GetHillsNormal(p.x, p.z);
        vertices[i].TexC = grid.Vertices[i].TexC;
    }

    const UINT vbByteSize = (UINT)vertices.size() * sizeof(Vertex);

    std::vector<std::uint16_t> indices = grid.GetIndices16();
    const UINT ibByteSize = (UINT)indices.size() * sizeof(std::uint16_t);

    auto geo = std::make_unique<MeshGeometry>();
    geo->Name = "landGeo";

    ThrowIfFailed(D3DCreateBlob(vbByteSize, &geo->VertexBufferCPU));
    CopyMemory(geo->VertexBufferCPU->GetBufferPointer(), vertices.data(), vbByteSize);

    ThrowIfFailed(D3DCreateBlob(ibByteSize, &geo->IndexBufferCPU));
    CopyMemory(geo->IndexBufferCPU->GetBufferPointer(), indices.data(), ibByteSize);

    geo->VertexBufferGPU = d3dUtil::CreateDefaultBuffer(md3dDevice.Get(),
        mCommandList.Get(), vertices.data(), vbByteSize, geo->VertexBufferUploader);

    geo->IndexBufferGPU = d3dUtil::CreateDefaultBuffer(md3dDevice.Get(),
        mCommandList.Get(), indices.data(), ibByteSize, geo->IndexBufferUploader);

    geo->VertexByteStride = sizeof(Vertex);
    geo->VertexBufferByteSize = vbByteSize;
    geo->IndexFormat = DXGI_FORMAT_R16_UINT;
    geo->IndexBufferByteSize = ibByteSize;

    SubmeshGeometry submesh;
    submesh.IndexCount = (UINT)indices.size();
    submesh.StartIndexLocation = 0;
    submesh.BaseVertexLocation = 0;

    geo->DrawArgs["grid"] = submesh;

    mGeometries["landGeo"] = std::move(geo);
}

void TreeBillboardsApp::BuildWavesGeometry()
{
    std::vector<std::uint16_t> indices(3 * mWaves->TriangleCount()); // 3 indices per face
    assert(mWaves->VertexCount() < 0x0000ffff);

    // Iterate over each quad.
    int m = mWaves->RowCount();
    int n = mWaves->ColumnCount();
    int k = 0;
    for(int i = 0; i < m - 1; ++i)
    {
        for(int j = 0; j < n - 1; ++j)
        {
            indices[k] = i*n + j;
            indices[k + 1] = i*n + j + 1;
            indices[k + 2] = (i + 1)*n + j;

            indices[k + 3] = (i + 1)*n + j;
            indices[k + 4] = i*n + j + 1;
            indices[k + 5] = (i + 1)*n + j + 1;

            k += 6; // next quad
        }
    }

    UINT vbByteSize = mWaves->VertexCount()*sizeof(Vertex);
    UINT ibByteSize = (UINT)indices.size()*sizeof(std::uint16_t);

    auto geo = std::make_unique<MeshGeometry>();
    geo->Name = "waterGeo";

    // Set dynamically.
    geo->VertexBufferCPU = nullptr;
    geo->VertexBufferGPU = nullptr;

    ThrowIfFailed(D3DCreateBlob(ibByteSize, &geo->IndexBufferCPU));
    CopyMemory(geo->IndexBufferCPU->GetBufferPointer(), indices.data(), ibByteSize);

    geo->IndexBufferGPU = d3dUtil::CreateDefaultBuffer(md3dDevice.Get(),
        mCommandList.Get(), indices.data(), ibByteSize, geo->IndexBufferUploader);

    geo->VertexByteStride = sizeof(Vertex);
    geo->VertexBufferByteSize = vbByteSize;
    geo->IndexFormat = DXGI_FORMAT_R16_UINT;
    geo->IndexBufferByteSize = ibByteSize;

    SubmeshGeometry submesh;
    submesh.IndexCount = (UINT)indices.size();
    submesh.StartIndexLocation = 0;
    submesh.BaseVertexLocation = 0;

    geo->DrawArgs["grid"] = submesh;

    mGeometries["waterGeo"] = std::move(geo);
}

void TreeBillboardsApp::BuildBoxGeometry()
{
    GeometryGenerator geoGen;
    GeometryGenerator::MeshData box = geoGen.CreateBox(8.0f, 8.0f, 8.0f, 3);

    std::vector<Vertex> vertices(box.Vertices.size());
    for (size_t i = 0; i < box.Vertices.size(); ++i)
    {
        auto& p = box.Vertices[i].Position;
        vertices[i].Pos = p;
        vertices[i].Normal = box.Vertices[i].Normal;
        vertices[i].TexC = box.Vertices[i].TexC;
    }

    const UINT vbByteSize = (UINT)vertices.size() * sizeof(Vertex);

    std::vector<std::uint16_t> indices = box.GetIndices16();
    const UINT ibByteSize = (UINT)indices.size() * sizeof(std::uint16_t);

    auto geo = std::make_unique<MeshGeometry>();
    geo->Name = "boxGeo";

    ThrowIfFailed(D3DCreateBlob(vbByteSize, &geo->VertexBufferCPU));
    CopyMemory(geo->VertexBufferCPU->GetBufferPointer(), vertices.data(), vbByteSize);

    ThrowIfFailed(D3DCreateBlob(ibByteSize, &geo->IndexBufferCPU));
    CopyMemory(geo->IndexBufferCPU->GetBufferPointer(), indices.data(), ibByteSize);

    geo->VertexBufferGPU = d3dUtil::CreateDefaultBuffer(md3dDevice.Get(),
        mCommandList.Get(), vertices.data(), vbByteSize, geo->VertexBufferUploader);

    geo->IndexBufferGPU = d3dUtil::CreateDefaultBuffer(md3dDevice.Get(),
        mCommandList.Get(), indices.data(), ibByteSize, geo->IndexBufferUploader);

    geo->VertexByteStride = sizeof(Vertex);
    geo->VertexBufferByteSize = vbByteSize;
    geo->IndexFormat = DXGI_FORMAT_R16_UINT;
    geo->IndexBufferByteSize = ibByteSize;

    SubmeshGeometry submesh;
    submesh.IndexCount = (UINT)indices.size();
    submesh.StartIndexLocation = 0;
    submesh.BaseVertexLocation = 0;

    geo->DrawArgs["box"] = submesh;

    mGeometries["boxGeo"] = std::move(geo);
}

void TreeBillboardsApp::BuildTreeSpritesGeometry()
{
    struct TreeSpriteVertex
    {
        XMFLOAT3 Pos;
        XMFLOAT2 Size;
    };

    static const int treeCount = 16;
    std::array<TreeSpriteVertex, 16> vertices;
    for(UINT i = 0; i < treeCount; ++i)
    {
        float x = MathHelper::RandF(-45.0f, 45.0f);
        float z = MathHelper::RandF(-45.0f, 45.0f);
        float y = GetHillsHeight(x, z);

        // Move tree slightly above land height.
        y += 8.0f;

        vertices[i].Pos = XMFLOAT3(x, y, z);
        vertices[i].Size = XMFLOAT2(20.0f, 20.0f);
    }

    std::array<std::uint16_t, 16> indices =
    {
        0, 1, 2, 3, 4, 5, 6, 7,
        8, 9, 10, 11, 12, 13, 14, 15
    };

    const UINT vbByteSize = (UINT)vertices.size() * sizeof(TreeSpriteVertex);
    const UINT ibByteSize = (UINT)indices.size() * sizeof(std::uint16_t);

    auto geo = std::make_unique<MeshGeometry>();
    geo->Name = "treeSpritesGeo";

    ThrowIfFailed(D3DCreateBlob(vbByteSize, &geo->VertexBufferCPU));
    CopyMemory(geo->VertexBufferCPU->GetBufferPointer(), vertices.data(), vbByteSize);

    ThrowIfFailed(D3DCreateBlob(ibByteSize, &geo->IndexBufferCPU));
    CopyMemory(geo->IndexBufferCPU->GetBufferPointer(), indices.data(), ibByteSize);

    geo->VertexBufferGPU = d3dUtil::CreateDefaultBuffer(md3dDevice.Get(),
        mCommandList.Get(), vertices.data(), vbByteSize, geo->VertexBufferUploader);

    geo->IndexBufferGPU = d3dUtil::CreateDefaultBuffer(md3dDevice.Get(),
        mCommandList.Get(), indices.data(), ibByteSize, geo->IndexBufferUploader);

    geo->VertexByteStride = sizeof(TreeSpriteVertex);
    geo->VertexBufferByteSize = vbByteSize;
    geo->IndexFormat = DXGI_FORMAT_R16_UINT;
    geo->IndexBufferByteSize = ibByteSize;

    SubmeshGeometry submesh;
    submesh.IndexCount = (UINT)indices.size();
    submesh.StartIndexLocation = 0;
    submesh.BaseVertexLocation = 0;

    geo->DrawArgs["points"] = submesh;

    mGeometries["treeSpritesGeo"] = std::move(geo);
}

void TreeBillboardsApp::BuildPSOs()
{
    D3D12_GRAPHICS_PIPELINE_STATE_DESC opaquePsoDesc;

    //
    // PSO for opaque objects.
    //
    ZeroMemory(&opaquePsoDesc, sizeof(D3D12_GRAPHICS_PIPELINE_STATE_DESC));
    opaquePsoDesc.InputLayout = { mStdInputLayout.data(), (UINT)mStdInputLayout.size() };
    opaquePsoDesc.pRootSignature = mRootSignature.Get();
    opaquePsoDesc.VS =
    {
        reinterpret_cast<BYTE*>(mShaders["standardVS"]->GetBufferPointer()),
        mShaders["standardVS"]->GetBufferSize()
    };
    opaquePsoDesc.PS =
    {
        reinterpret_cast<BYTE*>(mShaders["opaquePS"]->GetBufferPointer()),
        mShaders["opaquePS"]->GetBufferSize()
    };
    opaquePsoDesc.RasterizerState = CD3DX12_RASTERIZER_DESC(D3D12_DEFAULT);
    opaquePsoDesc.BlendState = CD3DX12_BLEND_DESC(D3D12_DEFAULT);
    opaquePsoDesc.DepthStencilState = CD3DX12_DEPTH_STENCIL_DESC(D3D12_DEFAULT);
    opaquePsoDesc.SampleMask = UINT_MAX;
    opaquePsoDesc.PrimitiveTopologyType = D3D12_PRIMITIVE_TOPOLOGY_TYPE_TRIANGLE;
    opaquePsoDesc.NumRenderTargets = 1;
    opaquePsoDesc.RTVFormats[0] = mBackBufferFormat;
    opaquePsoDesc.SampleDesc.Count = m4xMsaaState ? 4 : 1;
    opaquePsoDesc.SampleDesc.Quality = m4xMsaaState ? (m4xMsaaQuality - 1) : 0;
    opaquePsoDesc.DSVFormat = mDepthStencilFormat;
    ThrowIfFailed(md3dDevice->CreateGraphicsPipelineState(&opaquePsoDesc, IID_PPV_ARGS(&mPSOs["opaque"])));

    //
    // PSO for transparent objects
    //

    D3D12_GRAPHICS_PIPELINE_STATE_DESC transparentPsoDesc = opaquePsoDesc;

    D3D12_RENDER_TARGET_BLEND_DESC transparencyBlendDesc;
    transparencyBlendDesc.BlendEnable = true;
    transparencyBlendDesc.LogicOpEnable = false;
    transparencyBlendDesc.SrcBlend = D3D12_BLEND_SRC_ALPHA;
    transparencyBlendDesc.DestBlend = D3D12_BLEND_INV_SRC_ALPHA;
    transparencyBlendDesc.BlendOp = D3D12_BLEND_OP_ADD;
    transparencyBlendDesc.SrcBlendAlpha = D3D12_BLEND_ONE;
    transparencyBlendDesc.DestBlendAlpha = D3D12_BLEND_ZERO;
    transparencyBlendDesc.BlendOpAlpha = D3D12_BLEND_OP_ADD;
    transparencyBlendDesc.LogicOp = D3D12_LOGIC_OP_NOOP;
    transparencyBlendDesc.RenderTargetWriteMask = D3D12_COLOR_WRITE_ENABLE_ALL;

    transparentPsoDesc.BlendState.RenderTarget[0] = transparencyBlendDesc;
    ThrowIfFailed(md3dDevice->CreateGraphicsPipelineState(&transparentPsoDesc, IID_PPV_ARGS(&mPSOs["transparent"])));

    //
    // PSO for alpha tested objects
    //

    D3D12_GRAPHICS_PIPELINE_STATE_DESC alphaTestedPsoDesc = opaquePsoDesc;
    alphaTestedPsoDesc.PS =
    {
        reinterpret_cast<BYTE*>(mShaders["alphaTestedPS"]->GetBufferPointer()),
        mShaders["alphaTestedPS"]->GetBufferSize()
    };
    alphaTestedPsoDesc.RasterizerState.CullMode = D3D12_CULL_MODE_NONE;
    ThrowIfFailed(md3dDevice->CreateGraphicsPipelineState(&alphaTestedPsoDesc, IID_PPV_ARGS(&mPSOs["alphaTested"])));

    //
    // PSO for tree sprites
    //
    D3D12_GRAPHICS_PIPELINE_STATE_DESC treeSpritePsoDesc = opaquePsoDesc;
    treeSpritePsoDesc.VS =
    {
        reinterpret_cast<BYTE*>(mShaders["treeSpriteVS"]->GetBufferPointer()),
        mShaders["treeSpriteVS"]->GetBufferSize()
    };
    treeSpritePsoDesc.GS =
    {
        reinterpret_cast<BYTE*>(mShaders["treeSpriteGS"]->GetBufferPointer()),
        mShaders["treeSpriteGS"]->GetBufferSize()
    };
    treeSpritePsoDesc.PS =
    {
        reinterpret_cast<BYTE*>(mShaders["treeSpritePS"]->GetBufferPointer()),
        mShaders["treeSpritePS"]->GetBufferSize()
    };
    treeSpritePsoDesc.PrimitiveTopologyType = D3D12_PRIMITIVE_TOPOLOGY_TYPE_POINT;
    treeSpritePsoDesc.InputLayout = { mTreeSpriteInputLayout.data(), (UINT)mTreeSpriteInputLayout.size() };
    treeSpritePsoDesc.RasterizerState.CullMode = D3D12_CULL_MODE_NONE;

    ThrowIfFailed(md3dDevice->CreateGraphicsPipelineState(&treeSpritePsoDesc, IID_PPV_ARGS(&mPSOs["treeSprites"])));
}

void TreeBillboardsApp::BuildFrameResources()
{
    for(int i = 0; i < gNumFrameResources; ++i)
    {
        mFrameResources.push_back(std::make_unique<FrameResource>(md3dDevice.Get(),
            1, (UINT)mAllRitems.size(), (UINT)mMaterials.size(), mWaves->VertexCount()));
    }
}

void TreeBillboardsApp::BuildMaterials()
{
    auto grass = std::make_unique<Material>();
    grass->Name = "grass";
    grass->MatCBIndex = 0;
    grass->DiffuseSrvHeapIndex = 0;
    grass->DiffuseAlbedo = XMFLOAT4(1.0f, 1.0f, 1.0f, 1.0f);
    grass->FresnelR0 = XMFLOAT3(0.01f, 0.01f, 0.01f);
    grass->Roughness = 0.125f;

    // This is not a good water material definition, but we do not have all the rendering
    // tools we need (transparency, environment reflection), so we fake it for now.
    auto water = std::make_unique<Material>();
    water->Name = "water";
    water->MatCBIndex = 1;
    water->DiffuseSrvHeapIndex = 1;
    water->DiffuseAlbedo = XMFLOAT4(1.0f, 1.0f, 1.0f, 0.5f);
    water->FresnelR0 = XMFLOAT3(0.1f, 0.1f, 0.1f);
    water->Roughness = 0.0f;

    auto wirefence = std::make_unique<Material>();
    wirefence->Name = "wirefence";
    wirefence->MatCBIndex = 2;
    wirefence->DiffuseSrvHeapIndex = 2;
    wirefence->DiffuseAlbedo = XMFLOAT4(1.0f, 1.0f, 1.0f, 1.0f);
    wirefence->FresnelR0 = XMFLOAT3(0.02f, 0.02f, 0.02f);
    wirefence->Roughness = 0.25f;

    auto treeSprites = std::make_unique<Material>();
    treeSprites->Name = "treeSprites";
    treeSprites->MatCBIndex = 3;
    treeSprites->DiffuseSrvHeapIndex = 3;
    treeSprites->DiffuseAlbedo = XMFLOAT4(1.0f, 1.0f, 1.0f, 1.0f);
    treeSprites->FresnelR0 = XMFLOAT3(0.01f, 0.01f, 0.01f);
    treeSprites->Roughness = 0.125f;

    mMaterials["grass"] = std::move(grass);
    mMaterials["water"] = std::move(water);
    mMaterials["wirefence"] = std::move(wirefence);
    mMaterials["treeSprites"] = std::move(treeSprites);
}

void TreeBillboardsApp::BuildRenderItems()
{
    auto wavesRitem = std::make_unique<RenderItem>();
    wavesRitem->World = MathHelper::Identity4x4();
    XMStoreFloat4x4(&wavesRitem->TexTransform, XMMatrixScaling(5.0f, 5.0f, 1.0f));
    wavesRitem->ObjCBIndex = 0;
    wavesRitem->Mat = mMaterials["water"].get();
    wavesRitem->Geo = mGeometries["waterGeo"].get();
    wavesRitem->PrimitiveType = D3D11_PRIMITIVE_TOPOLOGY_TRIANGLELIST;
    wavesRitem->IndexCount = wavesRitem->Geo->DrawArgs["grid"].IndexCount;
    wavesRitem->StartIndexLocation = wavesRitem->Geo->DrawArgs["grid"].StartIndexLocation;
    wavesRitem->BaseVertexLocation = wavesRitem->Geo->DrawArgs["grid"].BaseVertexLocation;

    mWavesRitem = wavesRitem.get();

    mRitemLayer[(int)RenderLayer::Transparent].push_back(wavesRitem.get());

    auto gridRitem = std::make_unique<RenderItem>();
    gridRitem->World = MathHelper::Identity4x4();
    XMStoreFloat4x4(&gridRitem->TexTransform, XMMatrixScaling(5.0f, 5.0f, 1.0f));
    gridRitem->ObjCBIndex = 1;
    gridRitem->Mat = mMaterials["grass"].get();
    gridRitem->Geo = mGeometries["landGeo"].get();
    gridRitem->PrimitiveType = D3D11_PRIMITIVE_TOPOLOGY_TRIANGLELIST;
    gridRitem->IndexCount = gridRitem->Geo->DrawArgs["grid"].IndexCount;
    gridRitem->StartIndexLocation = gridRitem->Geo->DrawArgs["grid"].StartIndexLocation;
    gridRitem->BaseVertexLocation = gridRitem->Geo->DrawArgs["grid"].BaseVertexLocation;

    mRitemLayer[(int)RenderLayer::Opaque].push_back(gridRitem.get());

    auto boxRitem = std::make_unique<RenderItem>();
    XMStoreFloat4x4(&boxRitem->World, XMMatrixTranslation(3.0f, 2.0f, -9.0f));
    boxRitem->ObjCBIndex = 2;
    boxRitem->Mat = mMaterials["wirefence"].get();
    boxRitem->Geo = mGeometries["boxGeo"].get();
    boxRitem->PrimitiveType = D3D11_PRIMITIVE_TOPOLOGY_TRIANGLELIST;
    boxRitem->IndexCount = boxRitem->Geo->DrawArgs["box"].IndexCount;
    boxRitem->StartIndexLocation = boxRitem->Geo->DrawArgs["box"].StartIndexLocation;
    boxRitem->BaseVertexLocation = boxRitem->Geo->DrawArgs["box"].BaseVertexLocation;

    mRitemLayer[(int)RenderLayer::AlphaTested].push_back(boxRitem.get());

    auto treeSpritesRitem = std::make_unique<RenderItem>();
    treeSpritesRitem->World = MathHelper::Identity4x4();
    treeSpritesRitem->ObjCBIndex = 3;
    treeSpritesRitem->Mat = mMaterials["treeSprites"].get();
    treeSpritesRitem->Geo = mGeometries["treeSpritesGeo"].get();
    treeSpritesRitem->PrimitiveType = D3D11_PRIMITIVE_TOPOLOGY_POINTLIST;
    treeSpritesRitem->IndexCount = treeSpritesRitem->Geo->DrawArgs["points"].IndexCount;
    treeSpritesRitem->StartIndexLocation = treeSpritesRitem->Geo->DrawArgs["points"].StartIndexLocation;
    treeSpritesRitem->BaseVertexLocation = treeSpritesRitem->Geo->DrawArgs["points"].BaseVertexLocation;

    mRitemLayer[(int)RenderLayer::AlphaTestedTreeSprites].push_back(treeSpritesRitem.get());

    mAllRitems.push_back(std::move(wavesRitem));
    mAllRitems.push_back(std::move(gridRitem));
    mAllRitems.push_back(std::move(boxRitem));
    mAllRitems.push_back(std::move(treeSpritesRitem));
}

void TreeBillboardsApp::DrawRenderItems(ID3D12GraphicsCommandList* cmdList, const std::vector<RenderItem*>& ritems)
{
    UINT objCBByteSize = d3dUtil::CalcConstantBufferByteSize(sizeof(ObjectConstants));
    UINT matCBByteSize = d3dUtil::CalcConstantBufferByteSize(sizeof(MaterialConstants));

    auto objectCB = mCurrFrameResource->ObjectCB->Resource();
    auto matCB = mCurrFrameResource->MaterialCB->Resource();

    // For each render item...
    for(size_t i = 0; i < ritems.size(); ++i)
    {
        auto ri = ritems[i];

        cmdList->IASetVertexBuffers(0, 1, &ri->Geo->VertexBufferView());
        cmdList->IASetIndexBuffer(&ri->Geo->IndexBufferView());
        cmdList->IASetPrimitiveTopology(ri->PrimitiveType);

        CD3DX12_GPU_DESCRIPTOR_HANDLE tex(mSrvDescriptorHeap->GetGPUDescriptorHandleForHeapStart());
        tex.Offset(ri->Mat->DiffuseSrvHeapIndex, mCbvSrvDescriptorSize);

        D3D12_GPU_VIRTUAL_ADDRESS objCBAddress = objectCB->GetGPUVirtualAddress() + ri->ObjCBIndex*objCBByteSize;
        D3D12_GPU_VIRTUAL_ADDRESS matCBAddress = matCB->GetGPUVirtualAddress() + ri->Mat->MatCBIndex*matCBByteSize;

        cmdList->SetGraphicsRootDescriptorTable(0, tex);
        cmdList->SetGraphicsRootConstantBufferView(1, objCBAddress);
        cmdList->SetGraphicsRootConstantBufferView(3, matCBAddress);

        cmdList->DrawIndexedInstanced(ri->IndexCount, 1, ri->StartIndexLocation, ri->BaseVertexLocation, 0);
    }
}

std::array<const CD3DX12_STATIC_SAMPLER_DESC, 6> TreeBillboardsApp::GetStaticSamplers()
{
    // Applications usually only need a handful of samplers.  So just define them all up front
    // and keep them available as part of the root signature.

    const CD3DX12_STATIC_SAMPLER_DESC pointWrap(
        0, // shaderRegister
        D3D12_FILTER_MIN_MAG_MIP_POINT, // filter
        D3D12_TEXTURE_ADDRESS_MODE_WRAP,  // addressU
        D3D12_TEXTURE_ADDRESS_MODE_WRAP,  // addressV
        D3D12_TEXTURE_ADDRESS_MODE_WRAP); // addressW

    const CD3DX12_STATIC_SAMPLER_DESC pointClamp(
        1, // shaderRegister
        D3D12_FILTER_MIN_MAG_MIP_POINT, // filter
        D3D12_TEXTURE_ADDRESS_MODE_CLAMP,  // addressU
        D3D12_TEXTURE_ADDRESS_MODE_CLAMP,  // addressV
        D3D12_TEXTURE_ADDRESS_MODE_CLAMP); // addressW

    const CD3DX12_STATIC_SAMPLER_DESC linearWrap(
        2, // shaderRegister
        D3D12_FILTER_MIN_MAG_MIP_LINEAR, // filter
        D3D12_TEXTURE_ADDRESS_MODE_WRAP,  // addressU
        D3D12_TEXTURE_ADDRESS_MODE_WRAP,  // addressV
        D3D12_TEXTURE_ADDRESS_MODE_WRAP); // addressW

    const CD3DX12_STATIC_SAMPLER_DESC linearClamp(
        3, // shaderRegister
        D3D12_FILTER_MIN_MAG_MIP_LINEAR, // filter
        D3D12_TEXTURE_ADDRESS_MODE_CLAMP,  // addressU
        D3D12_TEXTURE_ADDRESS_MODE_CLAMP,  // addressV
        D3D12_TEXTURE_ADDRESS_MODE_CLAMP); // addressW

    const CD3DX12_STATIC_SAMPLER_DESC anisotropicWrap(
        4, // shaderRegister
        D3D12_FILTER_ANISOTROPIC, // filter
        D3D12_TEXTURE_ADDRESS_MODE_WRAP,  // addressU
        D3D12_TEXTURE_ADDRESS_MODE_WRAP,  // addressV
        D3D12_TEXTURE_ADDRESS_MODE_WRAP,  // addressW
        0.0f,                             // mipLODBias
        8);                               // maxAnisotropy

    const CD3DX12_STATIC_SAMPLER_DESC anisotropicClamp(
        5, // shaderRegister
        D3D12_FILTER_ANISOTROPIC, // filter
        D3D12_TEXTURE_ADDRESS_MODE_CLAMP,  // addressU
        D3D12_TEXTURE_ADDRESS_MODE_CLAMP,  // addressV
        D3D12_TEXTURE_ADDRESS_MODE_CLAMP,  // addressW
        0.0f,                              // mipLODBias
        8);                                // maxAnisotropy

    return {
        pointWrap, pointClamp,
        linearWrap, linearClamp,
        anisotropicWrap, anisotropicClamp };
}

float TreeBillboardsApp::GetHillsHeight(float x, float z)const
{
    return 0.3f*(z*sinf(0.1f*x) + x*cosf(0.1f*z));
}

XMFLOAT3 TreeBillboardsApp::GetHillsNormal(float x, float z)const
{
    // n = (-df/dx, 1, -df/dz)
    XMFLOAT3 n(
        -0.03f*z*cosf(0.1f*x) - 0.3f*cosf(0.1f*z),
        1.0f,
        -0.3f*sinf(0.1f*x) + 0.03f*x*sinf(0.1f*z));

    XMVECTOR unitNormal = XMVector3Normalize(XMLoadFloat3(&n));
    XMStoreFloat3(&n, unitNormal);

    return n;
}