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How to Program an RTS Game with Direct3D

Real-time strategy (RTS) games are a genre of video games that require the player to control and manage multiple units and resources in a dynamic environment. RTS games often feature complex graphics, animations, and effects that require a powerful rendering engine. One of the most popular and widely used rendering engines for RTS games is Direct3D, a part of the DirectX API that provides low-level access to the graphics hardware.

In this article, we will explore some of the basic concepts and techniques involved in programming an RTS game with Direct3D. We will cover topics such as:

• Setting up a Direct3D device and rendering context

• Loading and displaying 3D models and textures

• Implementing a camera system and user input

• Creating a terrain system and height map

• Applying lighting and shadows

• Optimizing performance and memory usage

By the end of this article, you should have a solid understanding of how to program an RTS game with Direct3D and be able to apply these skills to your own projects.

Setting up a Direct3D device and rendering context

The first step in programming an RTS game with Direct3D is to set up a Direct3D device and rendering context. A Direct3D device is an object that represents the connection between your application and the graphics hardware. A rendering context is a set of states and resources that define how the device will render the scene.

To create a Direct3D device, you need to use the IDirect3D9 interface, which can be obtained by calling the Direct3DCreate9 function. This interface provides methods for enumerating the available display adapters, modes, and capabilities, as well as creating a device object. To create a device object, you need to specify parameters such as the adapter index, the device type (hardware or software), the window handle, the behavior flags (such as windowed or fullscreen mode), and the presentation parameters (such as back buffer format, multisampling, depth stencil format, etc.). For example:

```cpp

// Create a Direct3D9 interface

IDirect3D9* pD3D = Direct3DCreate9(D3D_SDK_VERSION);

// Check for valid pointer

if (!pD3D)

// Handle error

// Create a device object

IDirect3DDevice9* pDevice = NULL;

// Set up the device parameters

D3DPRESENT_PARAMETERS d3dpp;

ZeroMemory(&d3dpp, sizeof(d3dpp));

d3dpp.Windowed = TRUE; // Windowed mode

d3dpp.SwapEffect = D3DSWAPEFFECT_DISCARD; // Discard old frames

d3dpp.BackBufferFormat = D3DFMT_UNKNOWN; // Use current display format

d3dpp.EnableAutoDepthStencil = TRUE; // Enable depth buffer

d3dpp.AutoDepthStencilFormat = D3DFMT_D16; // 16-bit depth buffer

// Create the device object

HRESULT hr = pD3D->CreateDevice(

D3DADAPTER_DEFAULT, // Use default adapter

D3DDEVTYPE_HAL, // Use hardware device

hWnd, // Handle to window

D3DCREATE_SOFTWARE_VERTEXPROCESSING, // Use software vertex processing

&d3dpp, // Pointer to presentation parameters

&pDevice // Pointer to device object

);

// Check for success

if (FAILED(hr))

// Handle error

```

Once you have created a device object, you can use it to render the scene. To do so, you need to follow these steps:

• Clear the back buffer and depth buffer using the Clear method.

• Call the BeginScene method to indicate the start of rendering.

• Set up the render states, shaders, textures, matrices, etc. using various methods of the device object.

• Draw the primitives (such as triangles) using methods such as DrawPrimitive, DrawIndexedPrimitive, or DrawPrimitiveUP.

• Call the EndScene 51082c0ec5