Introduction

Texture mapping is a technique used in computer graphics to apply images (textures) to 3D models. This process enhances the visual detail of 3D objects without increasing their geometric complexity. In this section, we will cover the basics of texture mapping in DirectX, including how to load textures, apply them to 3D models, and manage texture coordinates.

Key Concepts

Textures: Images applied to the surface of 3D models.
Texture Coordinates (UV Mapping): Coordinates that map the texture to the 3D model.
Sampler States: Settings that control how textures are sampled and applied.

Steps to Implement Texture Mapping

Loading Textures

To load a texture in DirectX, you typically use the DirectX Tool Kit (DirectXTK) or DirectXTex library. Here’s an example of how to load a texture using DirectXTK:

#include <d3d11.h>
#include <DDSTextureLoader.h>

// Assume device is a valid ID3D11Device pointer
ID3D11ShaderResourceView* textureView = nullptr;
HRESULT hr = DirectX::CreateDDSTextureFromFile(device, L"texture.dds", nullptr, &textureView);

if (FAILED(hr)) {
    // Handle error
}

Applying Textures to 3D Models

To apply a texture to a 3D model, you need to set the texture as a shader resource and configure the pixel shader to use it. Here’s an example:

// Assume context is a valid ID3D11DeviceContext pointer
context->PSSetShaderResources(0, 1, &textureView);

Managing Texture Coordinates

Texture coordinates (UV coordinates) are used to map the texture to the vertices of the 3D model. Here’s an example of a vertex structure with texture coordinates:

struct Vertex {
    DirectX::XMFLOAT3 position;
    DirectX::XMFLOAT2 texCoord;
};

// Example vertex data
Vertex vertices[] = {
    { DirectX::XMFLOAT3(-1.0f, -1.0f, 0.0f), DirectX::XMFLOAT2(0.0f, 1.0f) },
    { DirectX::XMFLOAT3(1.0f, -1.0f, 0.0f), DirectX::XMFLOAT2(1.0f, 1.0f) },
    { DirectX::XMFLOAT3(0.0f, 1.0f, 0.0f), DirectX::XMFLOAT2(0.5f, 0.0f) }
};

Configuring Sampler States

Sampler states control how textures are sampled and applied. Here’s an example of creating a sampler state:

D3D11_SAMPLER_DESC samplerDesc = {};
samplerDesc.Filter = D3D11_FILTER_MIN_MAG_MIP_LINEAR;
samplerDesc.AddressU = D3D11_TEXTURE_ADDRESS_WRAP;
samplerDesc.AddressV = D3D11_TEXTURE_ADDRESS_WRAP;
samplerDesc.AddressW = D3D11_TEXTURE_ADDRESS_WRAP;
samplerDesc.ComparisonFunc = D3D11_COMPARISON_NEVER;
samplerDesc.MinLOD = 0;
samplerDesc.MaxLOD = D3D11_FLOAT32_MAX;

ID3D11SamplerState* samplerState = nullptr;
hr = device->CreateSamplerState(&samplerDesc, &samplerState);

if (FAILED(hr)) {
    // Handle error
}

// Set the sampler state
context->PSSetSamplers(0, 1, &samplerState);

Practical Exercise

Exercise: Apply a Texture to a Triangle

Objective: Apply a texture to a simple triangle.
Steps:
- Load a texture from a file.
- Create a vertex buffer with texture coordinates.
- Set the texture and sampler state in the pixel shader.
- Render the triangle with the applied texture.

Solution

// Vertex structure with texture coordinates
struct Vertex {
    DirectX::XMFLOAT3 position;
    DirectX::XMFLOAT2 texCoord;
};

// Vertex data
Vertex vertices[] = {
    { DirectX::XMFLOAT3(-1.0f, -1.0f, 0.0f), DirectX::XMFLOAT2(0.0f, 1.0f) },
    { DirectX::XMFLOAT3(1.0f, -1.0f, 0.0f), DirectX::XMFLOAT2(1.0f, 1.0f) },
    { DirectX::XMFLOAT3(0.0f, 1.0f, 0.0f), DirectX::XMFLOAT2(0.5f, 0.0f) }
};

// Load texture
ID3D11ShaderResourceView* textureView = nullptr;
HRESULT hr = DirectX::CreateDDSTextureFromFile(device, L"texture.dds", nullptr, &textureView);

// Create sampler state
D3D11_SAMPLER_DESC samplerDesc = {};
samplerDesc.Filter = D3D11_FILTER_MIN_MAG_MIP_LINEAR;
samplerDesc.AddressU = D3D11_TEXTURE_ADDRESS_WRAP;
samplerDesc.AddressV = D3D11_TEXTURE_ADDRESS_WRAP;
samplerDesc.AddressW = D3D11_TEXTURE_ADDRESS_WRAP;
samplerDesc.ComparisonFunc = D3D11_COMPARISON_NEVER;
samplerDesc.MinLOD = 0;
samplerDesc.MaxLOD = D3D11_FLOAT32_MAX;

ID3D11SamplerState* samplerState = nullptr;
hr = device->CreateSamplerState(&samplerDesc, &samplerState);

// Set texture and sampler state
context->PSSetShaderResources(0, 1, &textureView);
context->PSSetSamplers(0, 1, &samplerState);

// Render the triangle (assuming vertex buffer and other setup is done)
context->Draw(3, 0);

Common Mistakes and Tips

Incorrect Texture Coordinates: Ensure that the texture coordinates are correctly mapped to the vertices.
Sampler State Configuration: Incorrect sampler state settings can lead to unexpected texture behavior. Double-check the sampler state configuration.
Resource Management: Remember to release resources (textures, sampler states) to avoid memory leaks.

Conclusion

In this section, we covered the basics of texture mapping in DirectX, including loading textures, applying them to 3D models, managing texture coordinates, and configuring sampler states. By understanding these concepts, you can enhance the visual detail of your 3D applications. In the next section, we will delve into lighting and materials to further improve the realism of your 3D scenes.

Texture Mapping

Introduction

Key Concepts

Steps to Implement Texture Mapping

Loading Textures

Applying Textures to 3D Models

Managing Texture Coordinates

Configuring Sampler States

Practical Exercise

Exercise: Apply a Texture to a Triangle

Solution

Common Mistakes and Tips

Conclusion

DirectX Programming Course

Module 1: Introduction to DirectX

Module 2: Direct3D Basics

Module 3: Working with Shaders

Module 4: Advanced Rendering Techniques

Module 5: 3D Models and Animation

Module 6: Performance Optimization

Module 7: Advanced Topics

Module 8: DirectX in Practice