像素着色器例子——多重纹理(《龙书》)

#include "d3dUtility.h"

//
// Globals
//

IDirect3DDevice9* Device = 0; 

const int Width  = 640;
const int Height = 480;

IDirect3DPixelShader9* MultiTexPS = 0;		//像素着色器
ID3DXConstantTable* MultiTexCT    = 0;		//常量表

IDirect3DVertexBuffer9* QuadVB = 0;			//四边形定点缓存

//3个纹理
IDirect3DTexture9* BaseTex      = 0;		
IDirect3DTexture9* SpotLightTex = 0;
IDirect3DTexture9* StringTex    = 0;

//常量句柄
D3DXHANDLE BaseTexHandle      = 0;
D3DXHANDLE SpotLightTexHandle = 0;
D3DXHANDLE StringTexHandle    = 0;

//常量描述
D3DXCONSTANT_DESC BaseTexDesc;
D3DXCONSTANT_DESC SpotLightTexDesc;
D3DXCONSTANT_DESC StringTexDesc;

//定点结构
struct MultiTexVertex
{
	MultiTexVertex(float x, float y, float z,
		float u0, float v0,
		float u1, float v1,
		float u2, float v2)
	{
		 _x =  x;  _y =  y; _z = z;
		_u0 = u0; _v0 = v0; 
		_u1 = u1; _v1 = v1;
		_u2 = u2, _v2 = v2;
	}

	float _x, _y, _z;
	float _u0, _v0;
	float _u1, _v1;
	float _u2, _v2;

	static const DWORD FVF;
};
const DWORD MultiTexVertex::FVF = D3DFVF_XYZ | D3DFVF_TEX3; 

//
// Framework functions
//
bool Setup()
{
	HRESULT hr = 0;

	//
	// Create geometry.，创建顶点缓存
	//
	Device->CreateVertexBuffer(
		6 * sizeof(MultiTexVertex), 
		D3DUSAGE_WRITEONLY,
		MultiTexVertex::FVF,
		D3DPOOL_MANAGED,
		&QuadVB,
		0);

	MultiTexVertex* v = 0;
	QuadVB->Lock(0, 0, (void**)&v, 0);

	v[0] = MultiTexVertex(-10.0f, -10.0f, 5.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f);
	v[1] = MultiTexVertex(-10.0f,  10.0f, 5.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f);
	v[2] = MultiTexVertex( 10.0f,  10.0f, 5.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f);

	v[3] = MultiTexVertex(-10.0f, -10.0f, 5.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f);
	v[4] = MultiTexVertex( 10.0f,  10.0f, 5.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f);
	v[5] = MultiTexVertex( 10.0f, -10.0f, 5.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f);

	QuadVB->Unlock();

	//
	//编辑着色器代码
	//

	ID3DXBuffer* shader      = 0;
	ID3DXBuffer* errorBuffer = 0;

	hr = D3DXCompileShaderFromFile(
		"ps_multitex.txt",	//像素着色器文件
		0,
		0,
		"Main", // entry point function name
		"ps_2_0",
		D3DXSHADER_DEBUG | D3DXSHADER_ENABLE_BACKWARDS_COMPATIBILITY, 
		&shader,//编译后的代码shader
		&errorBuffer,
		&MultiTexCT);

	// output any error messages
	if( errorBuffer )
	{
		::MessageBox(0, (char*)errorBuffer->GetBufferPointer(), 0, 0);
		d3d::Release<ID3DXBuffer*>(errorBuffer);
	}

	if(FAILED(hr))
	{
		::MessageBox(0, "D3DXCompileShaderFromFile() - FAILED", 0, 0);
		return false;
	}

	//
	//创建像素着色器
	//
	hr = Device->CreatePixelShader(
		(DWORD*)shader->GetBufferPointer(),
		&MultiTexPS);

	if(FAILED(hr))
	{
		::MessageBox(0, "CreateVertexShader - FAILED", 0, 0);
		return false;
	}

	d3d::Release<ID3DXBuffer*>(shader);

	//
	//载入纹理
	//

	D3DXCreateTextureFromFile(Device, "crate.bmp", &BaseTex);
	D3DXCreateTextureFromFile(Device, "spotlight.bmp", &SpotLightTex);
	D3DXCreateTextureFromFile(Device, "text.bmp", &StringTex);

	//
	//设置投影矩阵
	//

	D3DXMATRIX P;
	D3DXMatrixPerspectiveFovLH(
			&P,	D3DX_PI * 0.25f, 
			(float)Width / (float)Height, 1.0f, 1000.0f);

	Device->SetTransform(D3DTS_PROJECTION, &P);

	//
	// 禁用光照
	//

	Device->SetRenderState(D3DRS_LIGHTING, false);

	// 
	// 获取常量句柄
	//

	BaseTexHandle      = MultiTexCT->GetConstantByName(0, "BaseTex");
	SpotLightTexHandle = MultiTexCT->GetConstantByName(0, "SpotLightTex");
	StringTexHandle    = MultiTexCT->GetConstantByName(0, "StringTex");

	//
	// 设置常量描述
	//

	UINT count;
	
	MultiTexCT->GetConstantDesc(BaseTexHandle,      &BaseTexDesc, &count);
	MultiTexCT->GetConstantDesc(SpotLightTexHandle, &SpotLightTexDesc, &count);
	MultiTexCT->GetConstantDesc(StringTexHandle,    &StringTexDesc, &count);

	MultiTexCT->SetDefaults(Device);

	return true;
}

void Cleanup()
{
	d3d::Release<IDirect3DVertexBuffer9*>(QuadVB);

	d3d::Release<IDirect3DTexture9*>(BaseTex);
	d3d::Release<IDirect3DTexture9*>(SpotLightTex);
	d3d::Release<IDirect3DTexture9*>(StringTex);

	d3d::Release<IDirect3DPixelShader9*>(MultiTexPS);
	d3d::Release<ID3DXConstantTable*>(MultiTexCT);
}

bool Display(float timeDelta)
{
	if( Device )
	{
		// 
		// Update the scene: Allow user to rotate around scene.
		//
		
		static float angle  = (3.0f * D3DX_PI) / 2.0f;
		static float radius = 20.0f;
		
		if( ::GetAsyncKeyState(VK_LEFT) & 0x8000f )
			angle -= 0.5f * timeDelta;

		if( ::GetAsyncKeyState(VK_RIGHT) & 0x8000f )
			angle += 0.5f * timeDelta;

		if( ::GetAsyncKeyState(VK_UP) & 0x8000f )
			radius -= 2.0f * timeDelta;

		if( ::GetAsyncKeyState(VK_DOWN) & 0x8000f )
			radius += 2.0f * timeDelta;

		D3DXVECTOR3 position( cosf(angle) * radius, 0.0f, sinf(angle) * radius );
		D3DXVECTOR3 target(0.0f, 0.0f, 0.0f);
		D3DXVECTOR3 up(0.0f, 1.0f, 0.0f);
		D3DXMATRIX V;
		D3DXMatrixLookAtLH(&V, &position, &target, &up);

		Device->SetTransform(D3DTS_VIEW, &V);
		
		//
		// Render
		//

		Device->Clear(0, 0, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, 0xffffffff, 1.0f, 0);
		Device->BeginScene();

		//启用像素着色器
		Device->SetPixelShader(MultiTexPS);
		Device->SetFVF(MultiTexVertex::FVF);
		Device->SetStreamSource(0, QuadVB, 0, sizeof(MultiTexVertex));

		// base tex
		Device->SetTexture(     BaseTexDesc.RegisterIndex, BaseTex);
		Device->SetSamplerState(BaseTexDesc.RegisterIndex, D3DSAMP_MAGFILTER, D3DTEXF_LINEAR);
		Device->SetSamplerState(BaseTexDesc.RegisterIndex, D3DSAMP_MINFILTER, D3DTEXF_LINEAR);
		Device->SetSamplerState(BaseTexDesc.RegisterIndex, D3DSAMP_MIPFILTER, D3DTEXF_LINEAR);

		// spotlight tex
		Device->SetTexture(     SpotLightTexDesc.RegisterIndex, SpotLightTex);
		Device->SetSamplerState(SpotLightTexDesc.RegisterIndex, D3DSAMP_MAGFILTER, D3DTEXF_LINEAR);
		Device->SetSamplerState(SpotLightTexDesc.RegisterIndex, D3DSAMP_MINFILTER, D3DTEXF_LINEAR);
		Device->SetSamplerState(SpotLightTexDesc.RegisterIndex, D3DSAMP_MIPFILTER, D3DTEXF_LINEAR);

		// string tex
		Device->SetTexture(     StringTexDesc.RegisterIndex, StringTex);
		Device->SetSamplerState(StringTexDesc.RegisterIndex, D3DSAMP_MAGFILTER, D3DTEXF_LINEAR);
		Device->SetSamplerState(StringTexDesc.RegisterIndex, D3DSAMP_MINFILTER, D3DTEXF_LINEAR);
		Device->SetSamplerState(StringTexDesc.RegisterIndex, D3DSAMP_MIPFILTER, D3DTEXF_LINEAR);

		Device->DrawPrimitive(D3DPT_TRIANGLELIST, 0, 2);

		Device->EndScene();
		Device->Present(0, 0, 0, 0);
	}
	return true;
}

//
// WndProc
//
LRESULT CALLBACK d3d::WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
	switch( msg )
	{
	case WM_DESTROY:
		::PostQuitMessage(0);
		break;
		
	case WM_KEYDOWN:
		if( wParam == VK_ESCAPE )
			::DestroyWindow(hwnd);

		break;
	}
	return ::DefWindowProc(hwnd, msg, wParam, lParam);
}

//
// WinMain
//
int WINAPI WinMain(HINSTANCE hinstance,
				   HINSTANCE prevInstance, 
				   PSTR cmdLine,
				   int showCmd)
{
	if(!d3d::InitD3D(hinstance,
		Width, Height, true, D3DDEVTYPE_HAL, &Device))
	{
		::MessageBox(0, "InitD3D() - FAILED", 0, 0);
		return 0;
	}
		
	if(!Setup())
	{
		::MessageBox(0, "Setup() - FAILED", 0, 0);
		return 0;
	}

	d3d::EnterMsgLoop( Display );

	Cleanup();

	Device->Release();

	return 0;
}

sampler BaseTex;

sampler SpotLightTex;

sampler StringTex;
struct PS_INPUT

{   

　　float2 base      : TEXCOORD0;   

　　float2 spotlight : TEXCOORD1;    

　　float2 text      : TEXCOORD2;

};

struct PS_OUTPUT

{   

　　vector diffuse : COLOR0;

};

PS_OUTPUT Main(PS_INPUT input)

{   

　　PS_OUTPUT output = (PS_OUTPUT)0;
　　// sample appropriate textures    

　　vector b = tex2D(BaseTex,      input.base);    

　　vector s = tex2D(SpotLightTex, input.spotlight);    

　　vector t = tex2D(StringTex,    input.text);
　　// combine texel colors   

　　vector c = b * s + t;
　　// increase the intensity of the pixel slightly    

　　c += 0.1f;
　　// save the resulting pixel color   

　　output.diffuse = c;

　　return output;

}

像素着色器实质上是取代了固定功能流水线中的多重纹理(multitexturing)环节，而且赋予了我们直接操纵单个像素以及访问每个像素的纹理坐标的能力。

第i个采样级为第i层纹理指定了采样器状态。

像素着色器的输入包括每个像素颜色和纹理坐标，输出计算所得的每个像素的单个颜色值。