DirectX/10.0/Direct3D/光照贴图

DirectX 11 中的光照贴图是使用辅助纹理或数据文件来创建快速查找表的过程，以创建几乎不需要处理即可实现的独特照明效果。由于我们使用辅助来源作为我们照明的基础，我们可以从我们的应用程序中删除任何其他光照计算。这可以让我们获得惊人的速度。

正如我们在上一个教程中介绍的多重纹理映射一样，我们只需要稍微更改一下代码，就可以在本教程中实现光照贴图。

使用光照贴图，我们需要两种纹理。第一种纹理是基础颜色纹理。我们将在本教程中使用以下纹理：

我们需要的第二种纹理是光照贴图。通常，这只是一个黑白纹理，白色代表每个像素的光照强度。我创建了一个聚光灯风格的光照贴图，我们将在本教程中使用它。

一旦我们有了颜色纹理和光照贴图，我们就可以在像素着色器中将它们组合起来，生成光照贴图纹理。着色器非常简单，因为我们只是将两个像素相乘，这将产生以下输出。

Lightmap.vs

光照贴图顶点着色器与上一个教程中的多重纹理顶点着色器相同。唯一改变的是名称。

////////////////////////////////////////////////////////////////////////////////
// Filename: lightmap.vs
////////////////////////////////////////////////////////////////////////////////


/////////////
// GLOBALS //
/////////////
cbuffer MatrixBuffer
{
    matrix worldMatrix;
    matrix viewMatrix;
    matrix projectionMatrix;
};


//////////////
// TYPEDEFS //
//////////////
struct VertexInputType
{
    float4 position : POSITION;
    float2 tex : TEXCOORD0;
};

struct PixelInputType
{
    float4 position : SV_POSITION;
    float2 tex : TEXCOORD0;
};


////////////////////////////////////////////////////////////////////////////////
// Vertex Shader
////////////////////////////////////////////////////////////////////////////////
PixelInputType LightMapVertexShader(VertexInputType input)
{
    PixelInputType output;
    

    // Change the position vector to be 4 units for proper matrix calculations.
    input.position.w = 1.0f;

    // Calculate the position of the vertex against the world, view, and projection matrices.
    output.position = mul(input.position, worldMatrix);
    output.position = mul(output.position, viewMatrix);
    output.position = mul(output.position, projectionMatrix);
    
    // Store the texture coordinates for the pixel shader.
    output.tex = input.tex;
    
    return output;
}

Lightmap.ps

////////////////////////////////////////////////////////////////////////////////
// Filename: lightmap.ps
////////////////////////////////////////////////////////////////////////////////


/////////////
// GLOBALS //
/////////////
Texture2D shaderTextures[2];
SamplerState SampleType;


//////////////
// TYPEDEFS //
//////////////
struct PixelInputType
{
    float4 position : SV_POSITION;
    float2 tex : TEXCOORD0;
};

光照贴图像素着色器非常简单。它将颜色纹理像素和光照贴图纹理值相乘以获得所需的输出。这与普通的混合纹理没什么不同，只是不需要校正伽马。

////////////////////////////////////////////////////////////////////////////////
// Pixel Shader
////////////////////////////////////////////////////////////////////////////////
float4 LightMapPixelShader(PixelInputType input) : SV_TARGET
{
    float4 color;
    float4 lightColor;
    float4 finalColor;


    // Get the pixel color from the color texture.
    color = shaderTextures[0].Sample(SampleType, input.tex);

    // Get the pixel color from the light map.
    lightColor = shaderTextures[1].Sample(SampleType, input.tex);

    // Blend the two pixels together.
    finalColor = color * lightColor;

    return finalColor;
}

Lightmapshaderclass.h

LightMapShaderClass 只是上一个教程中的 MultiTextureShaderClass，现在已经更新为光照贴图。

////////////////////////////////////////////////////////////////////////////////
// Filename: lightmapshaderclass.h
////////////////////////////////////////////////////////////////////////////////
#ifndef _LIGHTMAPSHADERCLASS_H_
#define _LIGHTMAPSHADERCLASS_H_


//////////////
// INCLUDES //
//////////////
#include <d3d11.h>
#include <d3dx10math.h>
#include <d3dx11async.h>
#include <fstream>
using namespace std;


////////////////////////////////////////////////////////////////////////////////
// Class name: LightMapShaderClass
////////////////////////////////////////////////////////////////////////////////
class LightMapShaderClass
{
private:
	struct MatrixBufferType
	{
		D3DXMATRIX world;
		D3DXMATRIX view;
		D3DXMATRIX projection;
	};

public:
	LightMapShaderClass();
	LightMapShaderClass(const LightMapShaderClass&);
	~LightMapShaderClass();

	bool Initialize(ID3D11Device*, HWND);
	void Shutdown();
	bool Render(ID3D11DeviceContext*, int, D3DXMATRIX, D3DXMATRIX, D3DXMATRIX, ID3D11ShaderResourceView**);

private:
	bool InitializeShader(ID3D11Device*, HWND, WCHAR*, WCHAR*);
	void ShutdownShader();
	void OutputShaderErrorMessage(ID3D10Blob*, HWND, WCHAR*);

	bool SetShaderParameters(ID3D11DeviceContext*, D3DXMATRIX, D3DXMATRIX, D3DXMATRIX, ID3D11ShaderResourceView**);
	void RenderShader(ID3D11DeviceContext*, int);

private:
	ID3D11VertexShader* m_vertexShader;
	ID3D11PixelShader* m_pixelShader;
	ID3D11InputLayout* m_layout;
	ID3D11Buffer* m_matrixBuffer;
	ID3D11SamplerState* m_sampleState;
};

#endif

Lightmapshaderclass.cpp

我只介绍一下与上一个教程的不同之处。除了函数名之外，只有几个更改。

////////////////////////////////////////////////////////////////////////////////
// Filename: lightmapshaderclass.cpp
////////////////////////////////////////////////////////////////////////////////
#include "lightmapshaderclass.h"


LightMapShaderClass::LightMapShaderClass()
{
	m_vertexShader = 0;
	m_pixelShader = 0;
	m_layout = 0;
	m_matrixBuffer = 0;
	m_sampleState = 0;
}


LightMapShaderClass::LightMapShaderClass(const LightMapShaderClass& other)
{
}


LightMapShaderClass::~LightMapShaderClass()
{
}


bool LightMapShaderClass::Initialize(ID3D11Device* device, HWND hwnd)
{
	bool result;

我们现在加载 lightmap.vs 和 lightmap.ps HLSL 着色器文件。

	// Initialize the vertex and pixel shaders.
	result = InitializeShader(device, hwnd, L"../Engine/lightmap.vs", L"../Engine/lightmap.ps");
	if(!result)
	{
		return false;
	}

	return true;
}


void LightMapShaderClass::Shutdown()
{
	// Shutdown the vertex and pixel shaders as well as the related objects.
	ShutdownShader();

	return;
}


bool LightMapShaderClass::Render(ID3D11DeviceContext* deviceContext, int indexCount, D3DXMATRIX worldMatrix,
				 D3DXMATRIX viewMatrix, D3DXMATRIX projectionMatrix, ID3D11ShaderResourceView** textureArray)
{
	bool result;


	// Set the shader parameters that it will use for rendering.
	result = SetShaderParameters(deviceContext, worldMatrix, viewMatrix, projectionMatrix, textureArray);
	if(!result)
	{
		return false;
	}

	// Now render the prepared buffers with the shader.
	RenderShader(deviceContext, indexCount);

	return true;
}


bool LightMapShaderClass::InitializeShader(ID3D11Device* device, HWND hwnd, WCHAR* vsFilename, WCHAR* psFilename)
{
	HRESULT result;
	ID3D10Blob* errorMessage;
	ID3D10Blob* vertexShaderBuffer;
	ID3D10Blob* pixelShaderBuffer;
	D3D11_INPUT_ELEMENT_DESC polygonLayout[2];
	unsigned int numElements;
	D3D11_BUFFER_DESC matrixBufferDesc;
	D3D11_SAMPLER_DESC samplerDesc;


	// Initialize the pointers this function will use to null.
	errorMessage = 0;
	vertexShaderBuffer = 0;
	pixelShaderBuffer = 0;

光照贴图顶点着色器在这里加载。

	// Compile the vertex shader code.
	result = D3DX11CompileFromFile(vsFilename, NULL, NULL, "LightMapVertexShader", "vs_5_0", D3D10_SHADER_ENABLE_STRICTNESS, 
				       0, NULL, &vertexShaderBuffer, &errorMessage, NULL);
	if(FAILED(result))
	{
		// If the shader failed to compile it should have writen something to the error message.
		if(errorMessage)
		{
			OutputShaderErrorMessage(errorMessage, hwnd, vsFilename);
		}
		// If there was  nothing in the error message then it simply could not find the shader file itself.
		else
		{
			MessageBox(hwnd, vsFilename, L"Missing Shader File", MB_OK);
		}

		return false;
	}

光照贴图像素着色器在这里加载。

	// Compile the pixel shader code.
	result = D3DX11CompileFromFile(psFilename, NULL, NULL, "LightMapPixelShader", "ps_5_0", D3D10_SHADER_ENABLE_STRICTNESS, 
				       0, NULL, &pixelShaderBuffer, &errorMessage, NULL);
	if(FAILED(result))
	{
		// If the shader failed to compile it should have writen something to the error message.
		if(errorMessage)
		{
			OutputShaderErrorMessage(errorMessage, hwnd, psFilename);
		}
		// If there was  nothing in the error message then it simply could not find the file itself.
		else
		{
			MessageBox(hwnd, psFilename, L"Missing Shader File", MB_OK);
		}

		return false;
	}

	// Create the vertex shader from the buffer.
	result = device->CreateVertexShader(vertexShaderBuffer->GetBufferPointer(), vertexShaderBuffer->GetBufferSize(), NULL, 
					    &m_vertexShader);
	if(FAILED(result))
	{
		return false;
	}

	// Create the vertex shader from the buffer.
	result = device->CreatePixelShader(pixelShaderBuffer->GetBufferPointer(), pixelShaderBuffer->GetBufferSize(), NULL, 
					   &m_pixelShader);
	if(FAILED(result))
	{
		return false;
	}

	// Create the vertex input layout description.
	// This setup needs to match the VertexType stucture in the ModelClass and in the shader.
	polygonLayout[0].SemanticName = "POSITION";
	polygonLayout[0].SemanticIndex = 0;
	polygonLayout[0].Format = DXGI_FORMAT_R32G32B32_FLOAT;
	polygonLayout[0].InputSlot = 0;
	polygonLayout[0].AlignedByteOffset = 0;
	polygonLayout[0].InputSlotClass = D3D11_INPUT_PER_VERTEX_DATA;
	polygonLayout[0].InstanceDataStepRate = 0;

	polygonLayout[1].SemanticName = "TEXCOORD";
	polygonLayout[1].SemanticIndex = 0;
	polygonLayout[1].Format = DXGI_FORMAT_R32G32_FLOAT;
	polygonLayout[1].InputSlot = 0;
	polygonLayout[1].AlignedByteOffset = D3D11_APPEND_ALIGNED_ELEMENT;
	polygonLayout[1].InputSlotClass = D3D11_INPUT_PER_VERTEX_DATA;
	polygonLayout[1].InstanceDataStepRate = 0;

	// Get a count of the elements in the layout.
	numElements = sizeof(polygonLayout) / sizeof(polygonLayout[0]);

	// Create the vertex input layout.
	result = device->CreateInputLayout(polygonLayout, numElements, vertexShaderBuffer->GetBufferPointer(), 
					   vertexShaderBuffer->GetBufferSize(), &m_layout);
	if(FAILED(result))
	{
		return false;
	}

	// Release the vertex shader buffer and pixel shader buffer since they are no longer needed.
	vertexShaderBuffer->Release();
	vertexShaderBuffer = 0;

	pixelShaderBuffer->Release();
	pixelShaderBuffer = 0;

	// Setup the description of the matrix dynamic constant buffer that is in the vertex shader.
	matrixBufferDesc.Usage = D3D11_USAGE_DYNAMIC;
	matrixBufferDesc.ByteWidth = sizeof(MatrixBufferType);
	matrixBufferDesc.BindFlags = D3D11_BIND_CONSTANT_BUFFER;
	matrixBufferDesc.CPUAccessFlags = D3D11_CPU_ACCESS_WRITE;
	matrixBufferDesc.MiscFlags = 0;
	matrixBufferDesc.StructureByteStride = 0;

	// Create the matrix constant buffer pointer so we can access the vertex shader constant buffer from within this class.
	result = device->CreateBuffer(&matrixBufferDesc, NULL, &m_matrixBuffer);
	if(FAILED(result))
	{
		return false;
	}

	// Create a texture sampler state description.
	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.MipLODBias = 0.0f;
	samplerDesc.MaxAnisotropy = 1;
	samplerDesc.ComparisonFunc = D3D11_COMPARISON_ALWAYS;
	samplerDesc.BorderColor[0] = 0;
	samplerDesc.BorderColor[1] = 0;
	samplerDesc.BorderColor[2] = 0;
	samplerDesc.BorderColor[3] = 0;
	samplerDesc.MinLOD = 0;
	samplerDesc.MaxLOD = D3D11_FLOAT32_MAX;

	// Create the texture sampler state.
	result = device->CreateSamplerState(&samplerDesc, &m_sampleState);
	if(FAILED(result))
	{
		return false;
	}

	return true;
}


void LightMapShaderClass::ShutdownShader()
{
	// Release the sampler state.
	if(m_sampleState)
	{
		m_sampleState->Release();
		m_sampleState = 0;
	}

	// Release the matrix constant buffer.
	if(m_matrixBuffer)
	{
		m_matrixBuffer->Release();
		m_matrixBuffer = 0;
	}

	// Release the layout.
	if(m_layout)
	{
		m_layout->Release();
		m_layout = 0;
	}

	// Release the pixel shader.
	if(m_pixelShader)
	{
		m_pixelShader->Release();
		m_pixelShader = 0;
	}

	// Release the vertex shader.
	if(m_vertexShader)
	{
		m_vertexShader->Release();
		m_vertexShader = 0;
	}

	return;
}


void LightMapShaderClass::OutputShaderErrorMessage(ID3D10Blob* errorMessage, HWND hwnd, WCHAR* shaderFilename)
{
	char* compileErrors;
	unsigned long bufferSize, i;
	ofstream fout;


	// Get a pointer to the error message text buffer.
	compileErrors = (char*)(errorMessage->GetBufferPointer());

	// Get the length of the message.
	bufferSize = errorMessage->GetBufferSize();

	// Open a file to write the error message to.
	fout.open("shader-error.txt");

	// Write out the error message.
	for(i=0; i<bufferSize; i++)
	{
		fout Release();
	errorMessage = 0;

	// Pop a message up on the screen to notify the user to check the text file for compile errors.
	MessageBox(hwnd, L"Error compiling shader.  Check shader-error.txt for message.", shaderFilename, MB_OK);

	return;
}


bool LightMapShaderClass::SetShaderParameters(ID3D11DeviceContext* deviceContext, D3DXMATRIX worldMatrix,
					      D3DXMATRIX viewMatrix, D3DXMATRIX projectionMatrix, 
					      ID3D11ShaderResourceView** textureArray)
{
	HRESULT result;
	D3D11_MAPPED_SUBRESOURCE mappedResource;
	MatrixBufferType* dataPtr;
	unsigned int bufferNumber;


	// Transpose the matrices to prepare them for the shader.
	D3DXMatrixTranspose(&worldMatrix, &worldMatrix);
	D3DXMatrixTranspose(&viewMatrix, &viewMatrix);
	D3DXMatrixTranspose(&projectionMatrix, &projectionMatrix);

	// Lock the matrix constant buffer so it can be written to.
	result = deviceContext->Map(m_matrixBuffer, 0, D3D11_MAP_WRITE_DISCARD, 0, &mappedResource);
	if(FAILED(result))
	{
		return false;
	}

	// Get a pointer to the data in the constant buffer.
	dataPtr = (MatrixBufferType*)mappedResource.pData;

	// Copy the matrices into the constant buffer.
	dataPtr->world = worldMatrix;
	dataPtr->view = viewMatrix;
	dataPtr->projection = projectionMatrix;

	// Unlock the matrix constant buffer.
	deviceContext->Unmap(m_matrixBuffer, 0);

	// Set the position of the matrix constant buffer in the vertex shader.
	bufferNumber = 0;

	// Now set the matrix constant buffer in the vertex shader with the updated values.
	deviceContext->VSSetConstantBuffers(bufferNumber, 1, &m_matrixBuffer);

纹理数组与上一个教程相同。但是，纹理数组中不再是两个颜色纹理，而是一个颜色纹理，另一个纹理是光照贴图。

	// Set shader texture array resource in the pixel shader.
	deviceContext->PSSetShaderResources(0, 2, textureArray);

	return true;
}


void LightMapShaderClass::RenderShader(ID3D11DeviceContext* deviceContext, int indexCount)
{
	// Set the vertex input layout.
	deviceContext->IASetInputLayout(m_layout);

	// Set the vertex and pixel shaders that will be used to render this triangle.
	deviceContext->VSSetShader(m_vertexShader, NULL, 0);
	deviceContext->PSSetShader(m_pixelShader, NULL, 0);

	// Set the sampler state in the pixel shader.
	deviceContext->PSSetSamplers(0, 1, &m_sampleState);

	// Render the triangles.
	deviceContext->DrawIndexed(indexCount, 0, 0);

	return;
}

Graphicsclass.h

////////////////////////////////////////////////////////////////////////////////
// Filename: graphicsclass.h
////////////////////////////////////////////////////////////////////////////////
#ifndef _GRAPHICSCLASS_H_
#define _GRAPHICSCLASS_H_


/////////////
// GLOBALS //
/////////////
const bool FULL_SCREEN = true;
const bool VSYNC_ENABLED = true;
const float SCREEN_DEPTH = 1000.0f;
const float SCREEN_NEAR = 0.1f;


///////////////////////
// MY CLASS INCLUDES //
///////////////////////
#include "d3dclass.h"
#include "cameraclass.h"
#include "modelclass.h"

LightMapShaderClass 的头文件现在包含在 GraphicsClass 头文件中。

#include "lightmapshaderclass.h"


////////////////////////////////////////////////////////////////////////////////
// Class name: GraphicsClass
////////////////////////////////////////////////////////////////////////////////
class GraphicsClass
{
public:
	GraphicsClass();
	GraphicsClass(const GraphicsClass&);
	~GraphicsClass();

	bool Initialize(int, int, HWND);
	void Shutdown();
	bool Frame();
	bool Render();

private:
	D3DClass* m_D3D;
	CameraClass* m_Camera;
	ModelClass* m_Model;

我们有一个新的 LightMapShaderClass 对象变量。

	LightMapShaderClass* m_LightMapShader;
};

#endif

Graphicsclass.cpp

我只介绍一下与上一个教程的不同之处。

////////////////////////////////////////////////////////////////////////////////
// Filename: graphicsclass.cpp
////////////////////////////////////////////////////////////////////////////////
#include "graphicsclass.h"


GraphicsClass::GraphicsClass()
{
	m_D3D = 0;
	m_Camera = 0;
	m_Model = 0;

新的 LightMapShaderClass 对象在类构造函数中初始化。

	m_LightMapShader = 0;
}


bool GraphicsClass::Initialize(int screenWidth, int screenHeight, HWND hwnd)
{
	bool result;
	D3DXMATRIX baseViewMatrix;

		
	// Create the Direct3D object.
	m_D3D = new D3DClass;
	if(!m_D3D)
	{
		return false;
	}

	// Initialize the Direct3D object.
	result = m_D3D->Initialize(screenWidth, screenHeight, VSYNC_ENABLED, hwnd, FULL_SCREEN, SCREEN_DEPTH, SCREEN_NEAR);
	if(!result)
	{
		MessageBox(hwnd, L"Could not initialize Direct3D", L"Error", MB_OK);
		return false;
	}

	// Create the camera object.
	m_Camera = new CameraClass;
	if(!m_Camera)
	{
		return false;
	}

	// Initialize a base view matrix with the camera for 2D user interface rendering.
	m_Camera->SetPosition(0.0f, 0.0f, -1.0f);
	m_Camera->Render();
	m_Camera->GetViewMatrix(baseViewMatrix);

	// Create the model object.
	m_Model = new ModelClass;
	if(!m_Model)
	{
		return false;
	}

ModelClass 对象以新的 light01.dds 光照贴图纹理作为输入，用于此模型的光照贴图着色。

	// Initialize the model object.
	result = m_Model->Initialize(m_D3D->GetDevice(), "../Engine/data/square.txt", L"../Engine/data/stone01.dds", 
				     L"../Engine/data/light01.dds");
	if(!result)
	{
		MessageBox(hwnd, L"Could not initialize the model object.", L"Error", MB_OK);
		return false;
	}

新的 LightMapShaderClass 对象在这里创建和初始化。

	// Create the light map shader object.
	m_LightMapShader = new LightMapShaderClass;
	if(!m_LightMapShader)
	{
		return false;
	}

	// Initialize the light map shader object.
	result = m_LightMapShader->Initialize(m_D3D->GetDevice(), hwnd);
	if(!result)
	{
		MessageBox(hwnd, L"Could not initialize the light map shader object.", L"Error", MB_OK);
		return false;
	}

	return true;
}


void GraphicsClass::Shutdown()
{

LightMapShaderClass 对象在 Shutdown 函数中释放。

	// Release the light map shader object.
	if(m_LightMapShader)
	{
		m_LightMapShader->Shutdown();
		delete m_LightMapShader;
		m_LightMapShader = 0;
	}

	// Release the model object.
	if(m_Model)
	{
		m_Model->Shutdown();
		delete m_Model;
		m_Model = 0;
	}

	// Release the camera object.
	if(m_Camera)
	{
		delete m_Camera;
		m_Camera = 0;
	}

	// Release the D3D object.
	if(m_D3D)
	{
		m_D3D->Shutdown();
		delete m_D3D;
		m_D3D = 0;
	}

	return;
}


bool GraphicsClass::Render()
{
	D3DXMATRIX worldMatrix, viewMatrix, projectionMatrix, orthoMatrix;


	// Clear the buffers to begin the scene.
	m_D3D->BeginScene(0.0f, 0.0f, 0.0f, 1.0f);

	// Generate the view matrix based on the camera's position.
	m_Camera->Render();

	// Get the world, view, projection, and ortho matrices from the camera and D3D objects.
	m_D3D->GetWorldMatrix(worldMatrix);
	m_Camera->GetViewMatrix(viewMatrix);
	m_D3D->GetProjectionMatrix(projectionMatrix);
	m_D3D->GetOrthoMatrix(orthoMatrix);

	// Put the model vertex and index buffers on the graphics pipeline to prepare them for drawing.
	m_Model->Render(m_D3D->GetDeviceContext());

模型在这里使用光照贴图着色器渲染。

	// Render the model using the light map shader.
	m_LightMapShader->Render(m_D3D->GetDeviceContext(), m_Model->GetIndexCount(), worldMatrix, viewMatrix, projectionMatrix,
				 m_Model->GetTextureArray());

	// Present the rendered scene to the screen.
	m_D3D->EndScene();

	return true;
}

总结

本教程与上一个混合教程没有太大区别，但它产生了非常有用的效果，在处理速度方面非常高效。

待办事项练习

1. 重新编译代码，确保屏幕上显示光照贴图纹理。

2. 创建一些自己的光照贴图并尝试一下。

3. 将像素着色器中最终输出像素的值乘以 2.0。注意，通过这样做，你可以创建更强和更柔和的照明效果。