DirectX 10 教程25:纹理平移

原文地址:Tutorial 25: Texture Translation(http://www.rastertek.com/dx10tut25.html)。

源代码下载:dx10tut25.zip

纹理平移是指让纹理沿着多边形表面运动的一种技术。本教程的的代码基于上一个教程。

通过前面教程学习我们知道UV坐标用来将纹理映射到多边形上,UV坐标对应XY坐标,X坐标沿多边形的水平方向,Y坐标沿竖直方向。要实现纹理的平移,我们需要在像素着色器中修改纹理的X、Y坐标,方法很简单:只需在X或Y坐标上加上或减去一个0至1之间的值。

例如我们有下列一个具有纹理的三角形:

原始纹理

如果我们在像素着色器中将纹理坐标X加0.5,就会使纹理移动一半:

平移后的纹理

框架

框架新添了TranslateShaderClass。

框架

Translate.fx

////////////////////////////////////////////////////////////////////////////////
// Filename: translate.fx
////////////////////////////////////////////////////////////////////////////////


/////////////
// GLOBALS //
/////////////
matrix worldMatrix;
matrix viewMatrix;
matrix projectionMatrix;
Texture2D shaderTexture;

新添了一个新的float类型的变量textureTranslation,它会在graphicsclass.cpp中的Render方法中进行设置以更新纹理坐标,这个值位于0和1之间。

float textureTranslation;


///////////////////
// SAMPLE STATES //
///////////////////
SamplerState SampleType
{
    Filter = MIN_MAG_MIP_LINEAR;
    AddressU = Wrap;
    AddressV = Wrap;
};


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

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


////////////////////////////////////////////////////////////////////////////////
// Vertex Shader
////////////////////////////////////////////////////////////////////////////////
PixelInputType TranslateVertexShader(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;
}

在像素着色器中修改纹理坐标。我们读取纹理坐标,然后在X坐标上增加了translation的大小,这样就会让纹理在多边形上平移了。

////////////////////////////////////////////////////////////////////////////////
// Pixel Shader
////////////////////////////////////////////////////////////////////////////////
float4 TranslatePixelShader(PixelInputType input) : SV_Target
{
	// Translate the position where we sample the pixel from.
	input.tex.x += textureTranslation;

	return shaderTexture.Sample(SampleType, input.tex);
}


////////////////////////////////////////////////////////////////////////////////
// Technique
////////////////////////////////////////////////////////////////////////////////
technique10 TranslateTechnique
{
    pass pass0
    {
        SetVertexShader(CompileShader(vs_4_0, TranslateVertexShader()));
        SetPixelShader(CompileShader(ps_4_0, TranslatePixelShader()));
        SetGeometryShader(NULL);
    }
}

Translateshaderclass.h

TranslateShaderClass是TextureShaderClass的改编版本,只是多了纹理平移的额外功能。

////////////////////////////////////////////////////////////////////////////////
// Filename: translateshaderclass.h
////////////////////////////////////////////////////////////////////////////////
#ifndef _TRANSLATESHADERCLASS_H_
#define _TRANSLATESHADERCLASS_H_


//////////////
// INCLUDES //
//////////////
#include <d3d10.h>
#include <d3dx10.h>
#include <fstream>
using namespace std;


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

	bool Initialize(ID3D10Device*, HWND);
	void Shutdown();
	void Render(ID3D10Device*, int, D3DXMATRIX, D3DXMATRIX, D3DXMATRIX, ID3D10ShaderResourceView*, float);

private:
	bool InitializeShader(ID3D10Device*, HWND, WCHAR*);
	void ShutdownShader();
	void OutputShaderErrorMessage(ID3D10Blob*, HWND, WCHAR*);

	void SetShaderParameters(D3DXMATRIX, D3DXMATRIX, D3DXMATRIX, ID3D10ShaderResourceView*, float);
	void RenderShader(ID3D10Device*, int);

private:
	ID3D10Effect* m_effect;
	ID3D10EffectTechnique* m_technique;
	ID3D10InputLayout* m_layout;

	ID3D10EffectMatrixVariable* m_worldMatrixPtr;
	ID3D10EffectMatrixVariable* m_viewMatrixPtr;
	ID3D10EffectMatrixVariable* m_projectionMatrixPtr;
	ID3D10EffectShaderResourceVariable* m_texturePtr;

新添了指向shader中translation变量的指针。

	ID3D10EffectScalarVariable* m_textureTranslationPtr;
};

#endif

Translateshaderclass.cpp

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


TranslateShaderClass::TranslateShaderClass()
{
	m_effect = 0;
	m_technique = 0;
	m_layout = 0;

	m_worldMatrixPtr = 0;
	m_viewMatrixPtr = 0;
	m_projectionMatrixPtr = 0;
	m_texturePtr = 0;

在构造函数中将texture初始化为null。

	m_textureTranslationPtr = 0;
}


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


TranslateShaderClass::~TranslateShaderClass()
{
}


bool TranslateShaderClass::Initialize(ID3D10Device* device, HWND hwnd)
{
	bool result;

加载translate shader HLSL文件。

	// Initialize the shader that will be used to draw the triangles.
	result = InitializeShader(device, hwnd, L"../Engine/translate.fx");
	if(!result)
	{
		return false;
	}

	return true;
}


void TranslateShaderClass::Shutdown()
{
	// Shutdown the shader effect.
	ShutdownShader();

	return;
}

Render方法中的参数translation用来平移纹理,这个变量会被传递到SetShaderParameters方法,设置shader中对应的参数。

void TranslateShaderClass::Render(ID3D10Device* device, int indexCount, D3DXMATRIX worldMatrix, D3DXMATRIX viewMatrix,
								  D3DXMATRIX projectionMatrix, ID3D10ShaderResourceView* texture, float translation)
{
	// Set the shader parameters that it will use for rendering.
	SetShaderParameters(worldMatrix, viewMatrix, projectionMatrix, texture, translation);

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

	return;
}


bool TranslateShaderClass::InitializeShader(ID3D10Device* device, HWND hwnd, WCHAR* filename)
{
	HRESULT result;
	ID3D10Blob* errorMessage;
	D3D10_INPUT_ELEMENT_DESC polygonLayout[2];
	unsigned int numElements;
    D3D10_PASS_DESC passDesc;


	// Initialize the error message.
	errorMessage = 0;

	// Load the shader in from the file.
	result = D3DX10CreateEffectFromFile(filename, NULL, NULL, "fx_4_0", D3D10_SHADER_ENABLE_STRICTNESS, 0, 
										device, NULL, NULL, &m_effect, &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, filename);
		}
		// If there was  nothing in the error message then it simply could not find the shader file itself.
		else
		{
			MessageBox(hwnd, filename, L"Missing Shader File", MB_OK);
		}

		return false;
	}

Technique名称修改为TranslateTechnique。

	// Get a pointer to the technique inside the shader.
	m_technique = m_effect->GetTechniqueByName("TranslateTechnique");
	if(!m_technique)
	{
		return false;
	}

	// Now setup the layout of the data that goes into the shader.
	// 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 = D3D10_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 = D3D10_APPEND_ALIGNED_ELEMENT;
	polygonLayout[1].InputSlotClass = D3D10_INPUT_PER_VERTEX_DATA;
	polygonLayout[1].InstanceDataStepRate = 0;

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

	// Get the description of the first pass described in the shader technique.
    m_technique->GetPassByIndex(0)->GetDesc(&passDesc);

	// Create the input layout.
    result = device->CreateInputLayout(polygonLayout, numElements, passDesc.pIAInputSignature, passDesc.IAInputSignatureSize, 
									   &m_layout);
	if(FAILED(result))
	{
		return false;
	}

	// Get pointers to the three matrices inside the shader so we can update them from this class.
    m_worldMatrixPtr = m_effect->GetVariableByName("worldMatrix")->AsMatrix();
	m_viewMatrixPtr = m_effect->GetVariableByName("viewMatrix")->AsMatrix();
    m_projectionMatrixPtr = m_effect->GetVariableByName("projectionMatrix")->AsMatrix();

	// Get pointer to the texture resource inside the shader.
	m_texturePtr = m_effect->GetVariableByName("shaderTexture")->AsShaderResource();

获取shader中textureTranslation变量的指针。

	// Get a pointer to the texture translation variable inside the shader.
 	m_textureTranslationPtr = m_effect->GetVariableByName("textureTranslation")->AsScalar();

	return true;
}


void TranslateShaderClass::ShutdownShader()
{
	// Release the pointer to the translation variable inside the shader.
	m_textureTranslationPtr = 0;

	// Release the pointer to the texture in the shader file.
	m_texturePtr = 0;

	// Release the pointers to the matrices inside the shader.
	m_worldMatrixPtr = 0;
	m_viewMatrixPtr = 0;
	m_projectionMatrixPtr = 0;

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

	// Release the pointer to the shader technique.
	m_technique = 0;

	// Release the pointer to the shader.
	if(m_effect)
	{
		m_effect->Release();
		m_effect = 0;
	}

	return;
}


void TranslateShaderClass::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 << compileErrors[i];
	}

	// Close the file.
	fout.close();

	// Release the error message.
	errorMessage->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;
}


void TranslateShaderClass::SetShaderParameters(D3DXMATRIX worldMatrix, D3DXMATRIX viewMatrix, D3DXMATRIX projectionMatrix,
											   ID3D10ShaderResourceView* texture, float translation)
{
	// Set the world matrix variable inside the shader.
    m_worldMatrixPtr->SetMatrix((float*)&worldMatrix);

	// Set the view matrix variable inside the shader.
	m_viewMatrixPtr->SetMatrix((float*)&viewMatrix);

	// Set the projection matrix variable inside the shader.
    m_projectionMatrixPtr->SetMatrix((float*)&projectionMatrix);

使用SetFloat方法将translation值设置到shader中。

	// Bind the texture.
	m_texturePtr->SetResource(texture);

	// Set the texture translation variable inside the shader.
	m_textureTranslationPtr->SetFloat(translation);

	return;
}


void TranslateShaderClass::RenderShader(ID3D10Device* device, int indexCount)
{
    D3D10_TECHNIQUE_DESC techniqueDesc;
	unsigned int i;
	

	// Set the input layout.
	device->IASetInputLayout(m_layout);

	// Get the description structure of the technique from inside the shader so it can be used for rendering.
    m_technique->GetDesc(&techniqueDesc);

    // Go through each pass in the technique (should be just one currently) and render the triangles.
	for(i=0; i<techniqueDesc.Passes; ++i)
    {
        m_technique->GetPassByIndex(i)->Apply(0);
        device->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"
#include "translateshaderclass.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;

新添了TranslateShaderClass对象。

	TranslateShaderClass* m_TranslateShader;
};

#endif

Graphicsclass.cpp

下面的代码只包含与上一个教程不同的部分。

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


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

在构造函数中将TranslateShaderClass对象设置为null。

	m_TranslateShader = 0;
}


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


GraphicsClass::~GraphicsClass()
{
}


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

		
	// 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;
	}

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

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

创建并初始化TranslateShaderClass对象。

	// Create the translate shader object.
	m_TranslateShader = new TranslateShaderClass;
	if(!m_TranslateShader)
	{
		return false;
	}

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

	return true;
}


void GraphicsClass::Shutdown()
{
	// Release the translate shader object.
	if(m_TranslateShader)
	{
		m_TranslateShader->Shutdown();
		delete m_TranslateShader;
		m_TranslateShader = 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 Direct3D object.
	if(m_D3D)
	{
		m_D3D->Shutdown();
		delete m_D3D;
		m_D3D = 0;
	}

	return;
}


bool GraphicsClass::Frame()
{
	// Set the position of the camera.
	m_Camera->SetPosition(0.0f, 0.0f, -10.0f);

	return true;
}


bool GraphicsClass::Render()
{
	D3DXMATRIX worldMatrix, viewMatrix, projectionMatrix;
	static float textureTranslation = 0.0f;

将translation的值每帧增加0.01,如果超过1则重新设置为0。

	// Increment the texture translation position.
	textureTranslation += 0.01f;
	if(textureTranslation > 1.0f)
	{
		textureTranslation -= 1.0f;
	}

	// Clear the scene to the color of the fog.
	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, and projection matrices from the camera and d3d objects.
	m_D3D->GetWorldMatrix(worldMatrix);
	m_Camera->GetViewMatrix(viewMatrix);
	m_D3D->GetProjectionMatrix(projectionMatrix);

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

	// Render the model using the translate shader.
	m_TranslateShader->Render(m_D3D->GetDevice(), m_Model->GetIndexCount(), worldMatrix, viewMatrix, projectionMatrix,
							  m_Model->GetTexture(), textureTranslation);

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

	return true;
}

总结

使用一个简单的像素着色器就可以实现一个非常有用的效果,通过使用一些简单的数学知识我们就可以创建许多不同的效果,也可以在表面上对不同的纹理施加动画模拟运动的效果。

程序截图

练习

1.编译并运行程序,你会看到纹理会在多边形表面上移动。

2.在像素着色器中将沿X轴平移修改为沿Y轴平移。

3.在像素着色器中设置同时沿X和Y轴平移。

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发布时间:2012/8/12 21:53:13  阅读次数:6217

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