顶点着色器例子——Diffuse Lighting(《龙书》)

 

#include "d3dUtility.h"

//
// Globals
//

IDirect3DDevice9* Device = 0; 

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

IDirect3DVertexShader9* DiffuseShader = 0;			//顶点着色器
ID3DXConstantTable* DiffuseConstTable = 0;			//shader的常量表

ID3DXMesh* Teapot            = 0;

//常量表中shader变量句柄，用于设置shader中对应变量的值
D3DXHANDLE ViewMatrixHandle     = 0;
D3DXHANDLE ViewProjMatrixHandle = 0;
D3DXHANDLE AmbientMtrlHandle    = 0;
D3DXHANDLE DiffuseMtrlHandle    = 0;
D3DXHANDLE LightDirHandle       = 0;

D3DXMATRIX Proj;

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

	//
	// Create geometry:
	//

	D3DXCreateTeapot(Device, &Teapot, 0);

	//
	// 编译着色器
	//

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

	hr = D3DXCompileShaderFromFile(
		"diffuse.txt",//shader文件名
		0,
		0,
		"Main", // entry point function name
		"vs_1_1",
		D3DXSHADER_DEBUG | D3DXSHADER_ENABLE_BACKWARDS_COMPATIBILITY, 
		&shader,//编译后的着色器代码
		&errorBuffer,//存储错误代码
		&DiffuseConstTable);//获取常量表

	// 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;
	}

	//
	// 创建着色器
	//

	hr = Device->CreateVertexShader(
		(DWORD*)shader->GetBufferPointer(),//前面得到的编译后的着色器代码
		&DiffuseShader);//创建的着色器

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

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


	// 
	// Get Handles，根据shader变量名获取句柄（关联变量，以便于外部设置shader变量的值）
	//

	ViewMatrixHandle    = DiffuseConstTable->GetConstantByName(0, "ViewMatrix");
	ViewProjMatrixHandle= DiffuseConstTable->GetConstantByName(0, "ViewProjMatrix");
	AmbientMtrlHandle   = DiffuseConstTable->GetConstantByName(0, "AmbientMtrl");
	DiffuseMtrlHandle   = DiffuseConstTable->GetConstantByName(0, "DiffuseMtrl");
	LightDirHandle      = DiffuseConstTable->GetConstantByName(0, "LightDirection");

	//
	// Set shader constants:（设置shader变量的值，有些shader变量需要在C++代码中初始化，即外部初始化）
	//

	// Light direction:
	D3DXVECTOR4 directionToLight(-0.57f, 0.57f, -0.57f, 0.0f);
	DiffuseConstTable->SetVector(Device, LightDirHandle, &directionToLight);

	// Materials:
	D3DXVECTOR4 ambientMtrl(0.0f, 0.0f, 1.0f, 1.0f);
	D3DXVECTOR4 diffuseMtrl(0.0f, 0.0f, 1.0f, 1.0f);

	DiffuseConstTable->SetVector(Device,AmbientMtrlHandle,&ambientMtrl);
	DiffuseConstTable->SetVector(Device,DiffuseMtrlHandle,&diffuseMtrl);
	DiffuseConstTable->SetDefaults(Device);				//此方法在应用程序的设置用应调用一次，设置常量的默认值

	// Compute projection matrix.计算投影矩阵
	D3DXMatrixPerspectiveFovLH(
		&Proj,	D3DX_PI * 0.25f, 
		(float)Width / (float)Height, 1.0f, 1000.0f);
	//固定管线：Device->SetTransform(D3DTS_PROJECTION, &Proj);


	return true;
}

void Cleanup()
{
	d3d::Release<ID3DXMesh*>(Teapot);
	d3d::Release<IDirect3DVertexShader9*>(DiffuseShader);
	d3d::Release<ID3DXConstantTable*>(DiffuseConstTable);
}

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 height = 3.0f;
	
		if( ::GetAsyncKeyState(VK_LEFT) & 0x8000f )
			angle -= 0.5f * timeDelta;

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

		if( ::GetAsyncKeyState(VK_UP) & 0x8000f )
			height += 5.0f * timeDelta;

		if( ::GetAsyncKeyState(VK_DOWN) & 0x8000f )
			height -= 5.0f * timeDelta;

		D3DXVECTOR3 position( cosf(angle) * 7.0f, height, sinf(angle) * 7.0f );
		D3DXVECTOR3 target(0.0f, 0.0f, 0.0f);
		D3DXVECTOR3 up(0.0f, 1.0f, 0.0f);
		D3DXMATRIX V;
		D3DXMatrixLookAtLH(&V, &position, &target, &up);
		//固定管线：Device->SetTransform(D3DTS_VIEW, &V);//设置照相机的位置

		DiffuseConstTable->SetMatrix(Device, ViewMatrixHandle, &V);

		D3DXMATRIX ViewProj = V * Proj;
		DiffuseConstTable->SetMatrix(Device, ViewProjMatrixHandle, &ViewProj);

		//
		// Render
		//

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

		//启用定点着色器
		//Device->SetVertexShader(DiffuseShader);

		Teapot->DrawSubset(0);
		
		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;
}

// File: diffuse.txt
matrix ViewMatrix;

matrix ViewProjMatrix;

vector AmbientMtrl;

vector DiffuseMtrl

vector LightDirection;

vector DiffuseLightIntensity = {0.0f, 0.0f, 1.0f, 1.0f};

vector AmbientLightIntensity = {0.0f, 0.0f, 0.2f, 1.0f};

struct VS_INPUT

{   

 　　vector position : POSITION;   

 　　vector normal   : NORMAL;

};
struct VS_OUTPUT

{    

　　vector position : POSITION;  

　　vector diffuse  : COLOR;

};

VS_OUTPUT Main(VS_INPUT input)

{   

　　 VS_OUTPUT output = (VS_OUTPUT)0;

　　// Transform position to homogeneous clip space(齐次裁剪空间)   

　　// and store in the output.position member.     

　　output.position = mul(input.position, ViewProjMatrix);

　　// Transform lights and normals to view space（视口空间）.  Set w    

　　// componentes to zero since we're transforming vectors     

　　// here and not points.        

　　LightDirection.w = 0.0f;   

　　input.normal.w   = 0.0f;    

　　LightDirection   = mul(LightDirection, ViewMatrix);    

　　input.normal     = mul(input.normal,   ViewMatrix);

 

　　// Compute cosine of the angle between light and normal.     

　　float s = dot(LightDirection, input.normal);

　　if( s < 0.0f )        

　　　　s = 0.0f;

　　
    output.diffuse = (AmbientMtrl * AmbientLightIntensity) + (s * (DiffuseLightIntensity * DiffuseMtrl)); 

　　return output;

}