DirectX 11 Getting Started

Your comprehensive guide to the fundamentals of DirectX 11 graphics programming.

Introduction to DirectX 11

Welcome to the DirectX 11 Getting Started tutorial. This series will guide you through the fundamental concepts and steps required to begin developing graphics applications using DirectX 11 on Windows. DirectX is a collection of APIs for handling tasks related to multimedia, especially game programming and video, on Microsoft platforms.

DirectX 11 introduces significant improvements and new features over its predecessors, including the Unified Shading Core, hardware tessellation, DirectCompute for general-purpose GPU computing, and improved multithreading support. This tutorial will focus on the graphics pipeline and getting your first triangle rendered on the screen.

Note: While DirectX 12 is now available and offers lower-level hardware access, understanding DirectX 11 provides a strong foundation and is still widely used in many applications and games.

Prerequisites

Before you begin, ensure you have the following:

  • A solid understanding of C++ programming.
  • Familiarity with basic linear algebra (vectors and matrices).
  • A Windows development environment set up (Visual Studio is highly recommended).
  • A DirectX 11 compatible graphics card.

Setting Up Your Environment

To start, you'll need to create a new C++ project in Visual Studio. We'll be using a standard Win32 application template.

  1. Open Visual Studio.
  2. Create a new project: File > New > Project.
  3. Under Templates, select "Visual C++" > "Windows Desktop" > "Windows Desktop Application".
  4. Name your project (e.g., "DX11Starter") and choose a location. Click OK.
  5. In the Application Settings dialog, select "Empty Project" and click OK.

Next, you need to include the necessary DirectX SDK headers and link against the DirectX libraries. For modern Windows SDKs, these are usually included by default. If not, you may need to configure your project properties:

  • Right-click on your project in Solution Explorer and select Properties.
  • Navigate to Configuration Properties > C/C++ > General. Ensure "Additional Include Directories" includes the path to your Windows SDK's `Include` folder.
  • Navigate to Configuration Properties > Linker > Input. Add `d3d11.lib`, `d3d10_1.lib`, `d3d10.lib`, `dxgi.lib`, and `d3dcompiler.lib` to "Additional Dependencies".
Tip: For a simple Win32 application, you'll also need to set up a window procedure and message loop. This tutorial assumes you have a basic understanding of Windows programming.

Core DirectX 11 Concepts

DirectX 11 operates on several key objects that manage the graphics pipeline. Understanding these is crucial for effective programming.

1. Device and Device Context

The ID3D11Device object represents your graphics adapter (GPU) and is used to create all DirectX resources such as textures, buffers, and shaders. The ID3D11DeviceContext is used to issue commands to the GPU, such as drawing primitives, setting pipeline states, and updating resources.

You typically obtain a device and context using D3D11CreateDevice or D3D11CreateDeviceAndSwapChain.

2. Swap Chain

The IDXGISwapChain interface manages the presentation of rendered frames to the screen. It essentially holds a chain of buffers. When you finish rendering a frame to one buffer, you tell the swap chain to present it. This buffer then becomes the front buffer (visible on screen), and the next buffer in the chain becomes the back buffer, ready for you to render the next frame.

3. Render Target View

An ID3D11RenderTargetView is a pointer to the resource (usually a texture) that you will render to. This is often the back buffer provided by the swap chain. It defines how the GPU accesses the resource as a render target.

4. Depth-Stencil View

The ID3D11DepthStencilView is a pointer to a depth/stencil buffer. This buffer is used for depth testing (to determine which objects are in front of others) and stencil operations. It's essential for creating 3D scenes with correct occlusion.

Warning: The depth/stencil buffer must have the same dimensions and format as your render target.

Rendering Your First Frame

The process of rendering your first frame involves several steps:

  1. Create the Swap Chain and Device: Use D3D11CreateDeviceAndSwapChain to initialize DirectX, create the device, device context, and swap chain. 
    
HRESULT hr = D3D11CreateDeviceAndSwapChain(
    nullptr,                    // Default adapter
    D3D_DRIVER_TYPE_HARDWARE,   // Hardware driver
    nullptr,                    // No software rasterizer module
    creationFlags,              // Flags for device creation
    &featureLevel,              // Feature level array
    &featureLevels,             // Number of feature levels
    D3D11_SDK_VERSION,          // SDK version
    &sdp,                       // Swap chain description
    &m_pSwapChain,              // Pointer to the swap chain
    &m_pDevice,                 // Pointer to the device
    &m_pFeatureLevel,           // Actual feature level used
    &m_pImmediateContext        // Pointer to the device context
);
  2. Get the Back Buffer: Obtain the back buffer from the swap chain. 
    
ID3D11Texture2D* pBackBuffer;
hr = m_pSwapChain->GetBuffer(0, __uuidof(ID3D11Texture2D), (LPVOID*)&pBackBuffer);
  3. Create Render Target View: Create an RTV for the back buffer. 
    
hr = m_pDevice->CreateRenderTargetView(pBackBuffer, nullptr, &m_pRenderTargetView);
pBackBuffer->Release(); // Release the temporary texture pointer
  4. Create Depth-Stencil Buffer and View: If needed, create a depth/stencil buffer and its view.
  5. Set the Render Target: Bind the RTV (and DSV if applicable) to the output merger stage of the pipeline. 
    
m_pImmediateContext->OMSetRenderTargets(1, &m_pRenderTargetView, m_pDepthStencilView);
  6. Set the Viewport: Define the viewport, which is the rectangular region of the render target where the geometry will be rendered. 
    
D3D11_VIEWPORT vp;
vp.Width = (FLOAT)screenWidth;
vp.Height = (FLOAT)screenHeight;
vp.MinDepth = 0.0f;
vp.MaxDepth = 1.0f;
vp.TopLeftX = 0;
vp.TopLeftY = 0;
m_pImmediateContext->RSSetViewports(1, &vp);
  7. Clear the Render Target: Clear the render target to a specific color before drawing. 
    
FLOAT clearColor[4] = { 0.1f, 0.1f, 0.1f, 1.0f }; // Dark grey
m_pImmediateContext->ClearRenderTargetView(m_pRenderTargetView, clearColor);
if (m_pDepthStencilView)
    m_pImmediateContext->ClearDepthStencilView(m_pDepthStencilView, D3D11_CLEAR_DEPTH | D3D11_CLEAR_STENCIL, 1.0f, 0);
  8. Draw Primitives: This step involves binding vertex buffers, index buffers, shaders, and then calling a draw command. (Covered in next sections).
  9. Present the Frame: Present the back buffer to the screen. 
    
m_pSwapChain->Present(0, 0); // 0, 0 for no vsync and no flags

Understanding Shaders

Shaders are small programs that run on the GPU. DirectX 11 uses different types of shaders, including Vertex Shaders, Pixel Shaders, and Hull, Domain, Geometry, and Compute Shaders. For basic rendering, Vertex and Pixel Shaders are essential.

  • Vertex Shader: Processes individual vertices, transforming them from model space to clip space.
  • Pixel Shader (Fragment Shader): Processes individual pixels (fragments), determining their final color.

Shaders are typically written in High-Level Shading Language (HLSL) and compiled into bytecode that the GPU can execute.

Important: You will need to compile your HLSL shaders using d3dcompiler.dll.

Example of a simple Vertex Shader (HLSL):


struct VertexInput
{
    float4 pos : POSITION;
};

struct VertexOutput
{
    float4 pos : SV_POSITION;
};

VertexOutput VSMain(VertexInput input)
{
    VertexOutput output;
    output.pos = input.pos; // Pass through in this simple example
    return output;
}

Example of a simple Pixel Shader (HLSL):


float4 PSMain() : SV_TARGET
{
    return float4(1.0f, 0.0f, 0.0f, 1.0f); // Solid red color
}

Next Steps

Congratulations on getting this far! You've laid the groundwork for DirectX 11 graphics programming.

From here, you can explore:

  • Drawing more complex geometry (meshes, models).
  • Implementing lighting and materials.
  • Using textures to add detail.
  • Exploring advanced shader techniques.
  • Understanding the Input Assembler and Rasterizer stages.
  • Delving into DirectCompute for GPU-accelerated tasks.

Continue to the next tutorials in the MSDN documentation to build upon these fundamentals and create increasingly sophisticated graphics applications.