Rendering a model

This lesson loads and draws models in 3D.

Setup

First create a new project using the instructions from the first two lessons: The basic game loop and Adding the DirectX Tool Kit which we will use for this lesson.

Creating a model

Source assets for models are often stored in Autodesk FBX, Wavefront OBJ, or similar formats. A build process is used to convert them to a more run-time friendly format that is easier to load and render.

For this tutorial, we will make of use of the DirectXMesh meshconvert command-line tool. Start by saving cup._obj, cup.mtl, and cup.jpg into your new project's directory, and then from the top menu select Project / Add Existing Item.... Select "cup.jpg" and click "OK".

1. Download the Meshconvert.exe from the DirectXMesh site save the EXE into your project's folder.
2. Open a command-prompt and then change to your project's folder.

Run the following command-line

meshconvert cup._obj -sdkmesh -nodds -y -flipu

Then from the top menu in Visual Studio select Project / Add Existing Item.... Select cup.sdkmesh and click "OK".

Technical notes

• The switch -sdkmesh selects the output type. The meshconvert command-line tool also supports -cmo and -vbo. See Geometry formats for more information.
• The switch -nods causes any texture file name references in the material information of the source file to stay in their original file format (such as .png or .jpg). Otherwise, it assumes you will be converting all the needed texture files to a .dds instead.
• The -flipu flips the direction of the texture coordinates. Since SimpleMath and these tutorials assume we are using right-handed viewing coordinates and the model was created using left-handed viewing coordinates we have to flip them to get the text in the texture to appear correctly.
• The switch -y indicates that it is ok to overwrite the output file in case you run it multiple times.

DirectX Tool Kit for DirectX 12 does not support .cmo models.

Drawing a model

In the Game.h file, add the following variables to the bottom of the Game class's private declarations (right after where you added m_graphicsMemory as part of setup):

DirectX::SimpleMath::Matrix m_world;
DirectX::SimpleMath::Matrix m_view;
DirectX::SimpleMath::Matrix m_proj;

std::unique_ptr<DirectX::CommonStates> m_states;
std::unique_ptr<DirectX::EffectFactory> m_fxFactory;
std::unique_ptr<DirectX::EffectTextureFactory> m_modelResources; 
std::unique_ptr<DirectX::Model> m_model;
std::vector<std::shared_ptr<DirectX::IEffect>> m_modelNormal;

In Game.cpp, add to the TODO of CreateDevice right after you create m_graphicsMemory:

m_states = std::make_unique<CommonStates>(m_d3dDevice.Get());

m_model = Model::CreateFromSDKMESH(L"cup.sdkmesh");

ResourceUploadBatch resourceUpload(m_d3dDevice.Get());

resourceUpload.Begin();

m_modelResources = m_model->LoadTextures(m_d3dDevice.Get(), resourceUpload);

m_fxFactory = std::make_unique<EffectFactory>(m_modelResources->Heap(), m_states->Heap());

auto uploadResourcesFinished = resourceUpload.End(m_commandQueue.Get());

WaitForGpu();

uploadResourcesFinished.wait();

RenderTargetState rtState(DXGI_FORMAT_B8G8R8A8_UNORM, DXGI_FORMAT_D32_FLOAT);

EffectPipelineStateDescription pd(
    nullptr,
    CommonStates::Opaque,
    CommonStates::DepthDefault,
    CommonStates::CullClockwise,
    rtState);

EffectPipelineStateDescription pdAlpha(
    nullptr,
    CommonStates::AlphaBlend,
    CommonStates::DepthDefault,
    CommonStates::CullClockwise,
    rtState);

m_modelNormal = m_model->CreateEffects(*m_fxFactory, pd, pdAlpha);

m_world = Matrix::Identity;

In Game.cpp, add to the TODO of CreateResources:

m_view = Matrix::CreateLookAt(Vector3(2.f, 2.f, 2.f),
    Vector3::Zero, Vector3::UnitY);
m_proj = Matrix::CreatePerspectiveFieldOfView(XM_PI / 4.f,
    float(backBufferWidth) / float(backBufferHeight), 0.1f, 10.f);

In Game.cpp, add to the TODO of OnDeviceLost:

m_states.reset();
m_fxFactory.reset();
m_modelResources.reset();
m_model.reset();
m_modelNormal.clear();

In Game.cpp, add to the TODO of Render:

ID3D12DescriptorHeap* heaps[] = { m_modelResources->Heap(), m_states->Heap() };
m_commandList->SetDescriptorHeaps(_countof(heaps), heaps);

Model::UpdateEffectMatrices(m_modelNormal, m_world, m_view, m_proj);

m_model->Draw(m_commandList.Get(), m_modelNormal.cbegin());

In Game.cpp, add to the TODO of Update:

float time = float(timer.GetTotalSeconds());

m_world = Matrix::CreateRotationZ(cosf(time) * 2.f);

Build and run and you will see our cup model rendered with default lighting:

Troubleshooting: If you get a runtime exception, then you may have the "cup.jpg" or "cup.sdkmesh" in the wrong folder, have modified the "Working Directory" in the "Debugging" configuration settings, or otherwise changed the expected paths at runtime of the application. You should set a break-point on Model::CreateFromSDKMESH and step into the code to find the exact problem.

Further reading

DirectX Tool Kit docs EffectFactory, EffectTextureFactory, Effects, Model