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Chuck Walbourn edited this page Apr 26, 2022 · 22 revisions
Getting Started for DX11 Getting Started for DX12

This lesson will show how to read user input from game controllers, and use it to control a simple 3D camera.

Setup

First create a new project using the instructions from the earlier lessons: Using DeviceResources and Adding the DirectX Tool Kit which we will use for this lesson.

If using DirectX Tool Kit for DX12, use Using DeviceResources and Adding the DirectX Tool Kit.

Adding use of a gamepad

In the Game.h file, add the following variable to the bottom of the Game class's private declarations:

std::unique_ptr<DirectX::GamePad> m_gamePad;

In Game.cpp, add to the end of Initialize:

m_gamePad = std::make_unique<GamePad>();

In Game.cpp, add to the TODO of OnSuspending and OnDeactivated:

m_gamePad->Suspend();

In Game.cpp, add to the TODO of OnResuming and OnActivated:

m_gamePad->Resume();

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

auto pad = m_gamePad->GetState(0);

if (pad.IsConnected())
{
    if (pad.IsViewPressed())
    {
        ExitGame();
    }
}

Build and run. The application does not display anything other than our cornflower blue screen, but you can use the View button on the Xbox One controller or Back on the Xbox 360 Controller to exit.

Adding a a simple scene

Start by saving roomtexture.dds into your new project's directory, and then from the top menu select Project / Add Existing Item.... Select "roomtexture.dds" and click "OK".

In the Game.h file, add the following variables to the bottom of the Game class's private declarations:

std::unique_ptr<DirectX::GeometricPrimitive> m_room;

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

float m_pitch;
float m_yaw;
DirectX::SimpleMath::Vector3 m_cameraPos;

DirectX::SimpleMath::Color m_roomColor;

At the top of Game.cpp after the using statements, add:

namespace
{
   const XMVECTORF32 START_POSITION = { 0.f, -1.5f, 0.f, 0.f };
   const XMVECTORF32 ROOM_BOUNDS = { 8.f, 6.f, 12.f, 0.f };
   constexpr float ROTATION_GAIN = 0.1f;
}

In Game.cpp file, modify the Game constructor to initialize our variables:

Game::Game() noexcept(false) :
    m_pitch(0),
    m_yaw(0),
    m_cameraPos(START_POSITION),
    m_roomColor(Colors::White)
{
    m_deviceResources = std::make_unique<DX::DeviceResources>();
    m_deviceResources->RegisterDeviceNotify(this);
}

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

auto size = m_deviceResources->GetOutputSize();
m_proj = Matrix::CreatePerspectiveFieldOfView(
    XMConvertToRadians(70.f),
    float(size.right) / float(size.bottom), 0.01f, 100.f);

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

// limit pitch to straight up or straight down
constexpr float limit = XM_PIDIV2 - 0.01f;
m_pitch = std::max(-limit, m_pitch);
m_pitch = std::min(+limit, m_pitch);

// keep longitude in sane range by wrapping
if (m_yaw > XM_PI)
{
    m_yaw -= XM_2PI;
}
else if (m_yaw < -XM_PI)
{
    m_yaw += XM_2PI;
}

float y = sinf(m_pitch);
float r = cosf(m_pitch);
float z = r * cosf(m_yaw);
float x = r * sinf(m_yaw);

XMVECTOR lookAt = m_cameraPos + Vector3(x, y, z);

m_view = XMMatrixLookAtRH(m_cameraPos, lookAt, Vector3::Up);

Continue below depending on which version of DirectX Tool Kit you are using.

DirectX 11

In the Game.h file, add the following variables to the bottom of the Game class's private declarations:

Microsoft::WRL::ComPtr<ID3D11ShaderResourceView> m_roomTex;

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

auto context = m_deviceResources->GetD3DDeviceContext();
m_room = GeometricPrimitive::CreateBox(context,
    XMFLOAT3(ROOM_BOUNDS[0], ROOM_BOUNDS[1], ROOM_BOUNDS[2]),
    false, true);

DX::ThrowIfFailed(
    CreateDDSTextureFromFile(device, L"roomtexture.dds",
        nullptr, m_roomTex.ReleaseAndGetAddressOf()));

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

m_room.reset();
m_roomTex.Reset();

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

m_room->Draw(Matrix::Identity, m_view, m_proj,
    m_roomColor, m_roomTex.Get());

DirectX 12

This assumes you've already added DirectX Tool Kit for 12 support including GraphicsMemory to your project.

In the Game.h file, add the following variables to the bottom of the Game class's private declarations:

Microsoft::WRL::ComPtr<ID3D12Resource> m_roomTex;
std::unique_ptr<DirectX::DescriptorHeap> m_resourceDescriptors;
std::unique_ptr<DirectX::CommonStates> m_states;
std::unique_ptr<DirectX::BasicEffect> m_roomEffect;

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

m_resourceDescriptors = std::make_unique<DescriptorHeap>(device, 1);

m_states = std::make_unique<CommonStates>(device);

m_room = GeometricPrimitive::CreateBox(
    XMFLOAT3(ROOM_BOUNDS[0], ROOM_BOUNDS[1], ROOM_BOUNDS[2]),
    false, true);

RenderTargetState rtState(m_deviceResources->GetBackBufferFormat(),
    m_deviceResources->GetDepthBufferFormat());

{
    EffectPipelineStateDescription pd(
        &GeometricPrimitive::VertexType::InputLayout,
        CommonStates::Opaque,
        CommonStates::DepthDefault,
        CommonStates::CullCounterClockwise,
        rtState);

    m_roomEffect = std::make_unique<BasicEffect>(device,
        EffectFlags::Lighting | EffectFlags::Texture, pd);
    m_roomEffect->EnableDefaultLighting();
}

ResourceUploadBatch resourceUpload(device);

resourceUpload.Begin();

DX::ThrowIfFailed(CreateDDSTextureFromFile(device, resourceUpload,
    L"roomtexture.dds",
    m_roomTex.ReleaseAndGetAddressOf()));

CreateShaderResourceView(device, m_roomTex.Get(),
    m_resourceDescriptors->GetFirstCpuHandle());

m_roomEffect->SetTexture(m_resourceDescriptors->GetFirstGpuHandle(),
    m_states->LinearClamp());

auto uploadResourcesFinished = resourceUpload.End(
    m_deviceResources->GetCommandQueue());
uploadResourcesFinished.wait();

m_deviceResources->WaitForGpu();

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

m_room.reset();
m_roomTex.Reset();
m_resourceDescriptors.reset();
m_states.reset();
m_roomEffect.reset();

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

ID3D12DescriptorHeap* heaps[] = {
    m_resourceDescriptors->Heap(), m_states->Heap()
};
commandList->SetDescriptorHeaps(static_cast<UINT>(std::size(heaps)),
    heaps);

m_roomEffect->SetMatrices(Matrix::Identity, m_view, m_proj);
m_roomEffect->SetDiffuseColor(m_roomColor);
m_roomEffect->Apply(commandList);
m_room->Draw(commandList);

Build and run

Build and run, and you should get the following screen:

Screenshot of room

Click here for troubleshooting advice

If you get a runtime exception, then you may have the "roomtexture.dds" 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 CreateDDSTextureFromFile and step into the code to find the exact problem.

Adding gamepad controls

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

auto pad = m_gamePad->GetState(0);
if (pad.IsConnected())
{
    if (pad.IsViewPressed())
    {
        ExitGame();
    }

    if (pad.IsLeftStickPressed())
    {
        m_yaw = m_pitch = 0.f;
    }
    else
    {
        m_yaw += -pad.thumbSticks.leftX * ROTATION_GAIN;
        m_pitch += pad.thumbSticks.leftY * ROTATION_GAIN;
    }
}

// limit pitch to straight up or straight down
...

Build and run. The left thumb stick on the gamepad can be used to adjust the view. If you click the left-stick, it resets the view.

Technical notes

  • The view can never be exactly straight up or straight down to avoid a problem known as gimbal lock which can cause the camera view to flip unexpectedly or tumble uncontrollably.

  • This control implementation is very simple, and really only works on a system with fast frame-rate. For a more robust implementation, the Update code should make use of elapsedTime to scale the keyboard movement rate values and ROTATION_GAIN adjusted accordingly.

Using vibration

In Game.cpp, modify the TODO section of Update:

auto pad = m_gamePad->GetState(0);

if (pad.IsConnected())
{
    if (pad.IsViewPressed())
    {
        ExitGame();
    }
...

    {
        float left = (pad.IsAPressed()) ? 1.f : 0;
        float right = (pad.IsBPressed()) ? 1.f : 0;

        m_gamePad->SetVibration(0, left, right);
    }
}

Build and run. If you press and hold A or B, you get vibration motors of the controller to activate.

Scaling vibration

In Game.cpp, modify the TODO section of Update to replace the use of SetVibration above with:

m_gamePad->SetVibration( 0, pad.triggers.left, pad.triggers.right);

Build and run. Slowly depress the left and right triggers to feel the vibration motor change intensity.

Detecting button transitions

The use of gamepad above is all written using 'instantaneous state' where we only care about the position or state at the time we read the gamepad. For many controls, you want to trigger an event at the moment a button is pressed or released.

In the Game.h file, add the following variables to the bottom of the Game class's private declarations:

DirectX::GamePad::ButtonStateTracker m_buttons;

In Game.cpp, add to the TODO of OnResuming and OnActivated:

m_buttons.Reset();

In Game.cpp, modify the TODO section of Update:

auto pad = m_gamePad->GetState(0);
if (pad.IsConnected())
{
    m_buttons.Update(pad);

    if (pad.IsViewPressed())
    {
        ExitGame();
    }

...
}
else
{
    m_buttons.Reset();
}
...

if (m_buttons.a == GamePad::ButtonStateTracker::PRESSED)
{
    if (m_roomColor == Colors::Red.v)
        m_roomColor = Colors::Green;
    else if (m_roomColor == Colors::Green.v)
        m_roomColor = Colors::Blue;
   else if (m_roomColor == Colors::Blue.v)
        m_roomColor = Colors::White;
   else
        m_roomColor = Colors::Red;
}

Build and run. Pressing the A button will cycle the color of the room through Red, Green, Blue, and White. Holding down the A button does not flash though the colors with the framerate.

Orbit vs. FPS Style Camera

The code above implements an "First-Person Shooter" (FPS) style look camera. This has the viewpoint at a specific location, and then rotates to look around from there. Another common style of camera is an 'orbit' camera that moves around a point-of-focus, often used for viewing objects. To modify our FPS-style to an Orbit style, follow these instructions.

In the Game.h file, add the following variables to the bottom of the Game class's private declarations:

float m_theta;
float m_phi;
float m_radius;

You should delete or comment out the m_pitch, m_yaw, and m_cameraPos declarations.

At the top of Game.cpp after the using statements, modify the anonymous namespace:

namespace
{
  const XMVECTORF32 ROOM_BOUNDS = { 8.f, 6.f, 12.f, 0.f };
  constexpr float ROTATION_GAIN = 0.1f;

  constexpr float c_defaultPhi = XM_2PI / 6.0f;
  constexpr float c_defaultRadius = 3.3f;
  constexpr float c_minRadius = 0.1f;
  constexpr float c_maxRadius = 5.f;
}

In Game.cpp file, modify the Game constructor to initialize our new variables:

Game::Game() noexcept(false) :
    m_theta(0.f),
    m_phi(c_defaultPhi),
    m_radius(c_defaultRadius),
    m_roomColor(Colors::White)
{
    m_deviceResources = std::make_unique<DX::DeviceResources>();
    m_deviceResources->RegisterDeviceNotify(this);
}

In Game.cpp, modify the TODO of Update:

auto pad = m_gamePad->GetState(0);
if (pad.IsConnected())
{
    m_buttons.Update(pad);

    if (pad.IsViewPressed())
    {
        ExitGame();
    }

    if (pad.IsLeftStickPressed())
    {
        m_theta = 0.f;
        m_phi = c_defaultPhi;
        m_radius = c_defaultRadius;
    }
    else
    {
        m_theta += pad.thumbSticks.rightX * XM_PI * ROTATION_GAIN;
        m_phi -= pad.thumbSticks.rightY * XM_PI * ROTATION_GAIN;
        m_radius -= pad.thumbSticks.leftY * 5.f * ROTATION_GAIN;
    }

    m_gamePad->SetVibration(0, pad.triggers.left, pad.triggers.right);
}
else
{
    m_buttons.Reset();
}

// Limit to avoid looking directly up or down
constexpr float limit = XM_PIDIV2 - 0.01f;
m_phi = std::max(1e-2f, std::min(limit, m_phi));
m_radius = std::max(c_minRadius, std::min(c_maxRadius, m_radius));

if (m_theta > XM_PI)
{
    m_theta -= XM_2PI;
}
else if (m_theta < -XM_PI)
{
    m_theta += XM_2PI;
}

XMVECTOR lookFrom = XMVectorSet(
    m_radius * sinf(m_phi) * cosf(m_theta),
    m_radius * cosf(m_phi),
    m_radius * sinf(m_phi) * sinf(m_theta),
    0);

m_view = XMMatrixLookAtRH(lookFrom, g_XMZero, Vector3::Up);

if (m_buttons.a == GamePad::ButtonStateTracker::PRESSED)
{
    if (m_roomColor == Colors::Red.v)
        m_roomColor = Colors::Green;
    else if (m_roomColor == Colors::Green.v)
        m_roomColor = Colors::Blue;
    else if (m_roomColor == Colors::Blue.v)
        m_roomColor = Colors::White;
    else
        m_roomColor = Colors::Red;
}

Build and run. The same controls are present, but now move the camera in an 'orbital' path around the origin with the left stick moving closer/further away to the center.

Next lessons: Mouse and keyboard input

Further reading

DirectX Tool Kit docs GamePad
DirectX Tool Kit: Now with GamePads
XInput and Windows 8

All content and source code for this package are subject to the terms of the MIT License.

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact [email protected] with any additional questions or comments.

For Use

  • Universal Windows Platform apps
  • Windows desktop apps
  • Windows 11
  • Windows 10
  • Windows 8.1
  • Xbox One

Architecture

  • x86
  • x64
  • ARM64

For Development

  • Visual Studio 2022
  • Visual Studio 2019 (16.11)
  • clang/LLVM v12 - v18
  • MinGW 12.2, 13.2
  • CMake 3.20

Related Projects

DirectX Tool Kit for DirectX 12

DirectXMesh

DirectXTex

DirectXMath

Win2D

Tools

Test Suite

Model Viewer

Content Exporter

DxCapsViewer

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