Direct3D轮回：游戏特效之全屏泛光(Bloom)

Bloom，又称“全屏泛光”，是大名鼎鼎的虚幻3游戏引擎中最通用的后期特效技术~

Bloom特效的实现主要依赖于PostProcess框架，即实时绘制当前场景到一后台渲染表面，而后针对其对应贴图进行像素级渲染~

大家还记得我们之前实现的水面效果中的反射和折射贴图吗？此即为PostProcess的典型应用，与Bloom特效有异曲同工之妙。

下面，我们就来揭秘这个Bloom特效的实现流程~

本节我们实现的Bloom特效，在流程上总共分为4步：

1.提取原场景贴图中的亮色；

2.针对提取贴图进行横向模糊；

3.在横向模糊基础上进行纵向模糊；

4.所得贴图与原场景贴图叠加得最终效果图。

所用到的Shader主要有三个，分别对应如上4个步骤中的第1步、第2、3步和第4步。我们来看源代码：

D3DGame.cpp

/*-------------------------------------

代码清单：D3DGame.cpp
来自：http://www.cnblogs.com/kenkao

-------------------------------------*/

#include "StdAfx.h"
#include "D3DGame.h"
#include "D3DCamera.h"
#include "D3DEffect.h"
#include "CoordCross.h"
#include "SimpleXMesh.h"
#include "Texture2D.h"
#include "Skybox.h"
#include "SpriteBatch.h"
#include "BaseTerrain.h"
#include "Water.h"
#include "PlantCollect.h"
#include "LensFlare.h"
#include "D3DFog.h"
#include "BloomEffect.h"
#include <stdio.h>
#include <time.h>

//---通用全局变量

HINSTANCE g_hInst;
HWND g_hWnd;
D3DXMATRIX g_matWorld;
D3DXMATRIX g_matProjection;
D3DPRESENT_PARAMETERS g_D3DPP;

//---D3D全局变量

IDirect3D9 *g_pD3D = NULL;
IDirect3DDevice9 *g_pD3DDevice = NULL;
CMouseInput *g_pMouseInput = NULL;
CKeyboardInput *g_pKeyboardInput = NULL;
CD3DCamera *g_pD3DCamera = NULL;
CSpriteBatch *g_pSpriteBatch = NULL;
CSkybox *g_pSkybox = NULL;
CBaseTerrain *g_pBaseTerrain = NULL;
CWater *g_pWater = NULL;
CPlantCollect *g_pPlant = NULL;
CSimpleXMesh *g_pMesh = NULL;
CLensFlare *g_pFlare = NULL;
CBloomEffect *g_pBloom = NULL;

// Bloom参数体数组及全局索引
int g_bloomParamIndex = 0;
BloomParam g_BloomParams[6]={
BloomParam("Default", 0.25f, 4, 1.25f, 1, 1, 1),
BloomParam("Soft", 0, 3, 1, 1, 1, 1),
BloomParam("Desaturated", 0.5f, 8, 2, 1, 0, 1),
BloomParam("Saturated", 0.25f, 4, 2, 1, 2, 0),
BloomParam("Blurry", 0, 2, 1, 0.1f, 1, 1),
BloomParam("Subtle", 0.5f, 2, 1, 1, 1, 1)
};

// 场景绘制
void DrawScene(bool isReflect,bool isRefract);

void Initialize(HINSTANCE hInst, HWND hWnd)
{
g_hInst = hInst;
g_hWnd = hWnd;
InitD3D(&g_pD3D, &g_pD3DDevice, g_D3DPP, g_matProjection, hWnd);
g_pMouseInput = new CMouseInput;
g_pMouseInput->Initialize(hInst,hWnd);
g_pKeyboardInput = new CKeyboardInput;
g_pKeyboardInput->Initialize(hInst,hWnd);
g_pD3DCamera = new CD3DCamera;
g_pSpriteBatch = new CSpriteBatch(g_pD3DDevice);
srand(time(0));
}

CTexture2D* debugTexture = NULL;

void LoadContent()
{
g_pD3DCamera->SetCameraPos(D3DXVECTOR3(600.0f,0.0f,600.0f));

g_pSkybox = new CSkybox;
g_pSkybox->Create("Skybox_0.JPG","Skybox_1.JPG","Skybox_2.JPG"
,"Skybox_3.JPG","Skybox_4.JPG","Skybox_5.JPG");

g_pBaseTerrain = new CBaseTerrain;
g_pBaseTerrain->Create(128,128,10,"HeightData_128x128.raw","Grass.dds");

g_pWater = new CWater;
g_pWater->Create(1280,1280,0.0f,0.0f,40.0f);

g_pPlant = new CPlantCollect;
g_pPlant->Create(60,90,15);

g_pMesh = new CSimpleXMesh;
g_pMesh->LoadXMesh("WindMill.x");

g_pFlare = new CLensFlare;
g_pFlare->Create(D3DXVECTOR3(-1600,700,600),D3DXVECTOR2(800,600));

//ResetFog(D3DFOGTYPE_PIXEL,D3DFOG_EXP2,D3DXCOLOR_WHITE,0.001f);

// 创建并初始化Bloom特效
g_pBloom = new CBloomEffect;
g_pBloom->Create();
}

void Update(float gameTick)
{
g_pMouseInput->GetState();
g_pKeyboardInput->GetState();

// 更新摄影机高度
D3DXVECTOR3 CameraPos = g_pD3DCamera->GetCameraPos();
float roleHeight = 25.0f;
float Ty = g_pBaseTerrain->GetExactHeightAt(CameraPos.x,CameraPos.z) + roleHeight;
g_pD3DCamera->SetCameraPos(D3DXVECTOR3(
CameraPos.x,
Ty,
CameraPos.z));

g_pD3DCamera->Update();

if(g_pKeyboardInput->IsJustKeyDown(DIK_SPACE))
{
g_bloomParamIndex++;
if(g_bloomParamIndex>=6)
g_bloomParamIndex = 0;
}
g_pBloom->SetParam(&g_BloomParams[g_bloomParamIndex]);

}

void Draw(float gameTick)
{
g_pD3DDevice->GetTransform(D3DTS_WORLD, &g_matWorld);
g_pD3DDevice->SetTransform(D3DTS_VIEW, &g_pD3DCamera->GetViewMatrix());
g_pD3DDevice->Clear(0, NULL, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, D3DCOLOR_RGBA(100,149,237,255), 1.0f, 0);
if(SUCCEEDED(g_pD3DDevice->BeginScene()))
{
//BeginFog(g_pD3DDevice);

g_pWater->BeginReflect();
DrawScene(true,false);
g_pWater->EndReflect();

g_pWater->BeginRefract();
DrawScene(false,true);
g_pWater->EndRefract();

// 开启Bloom
g_pBloom->Begin();

// 绘制实时场景到Bloom原始后台表面
DrawScene(false,false);
g_pWater->Draw(gameTick);
g_pPlant->Draw(gameTick);

// 结束Bloom，并触发Bloom前三个步骤
g_pBloom->End();

// 触发Bloom第四个步骤，而后进行Bloom渲染
g_pBloom->DrawScene();

g_pFlare->Draw();

//EndFog(g_pD3DDevice);

g_pD3DDevice->EndScene();
}
g_pD3DDevice->Present(NULL, NULL, NULL, NULL);
}

void DrawScene(bool isReflect,bool isRefract)
{
g_pSkybox->Draw(isReflect,isRefract);
g_pBaseTerrain->Draw();

D3DXMATRIX scalTrans;
D3DXMatrixScaling(&scalTrans,5.0f,5.0f,5.0f);
D3DXMATRIX movTrans;
D3DXMatrixTranslation(&movTrans,366,g_pBaseTerrain->GetExactHeightAt(366,190)-5.0f,190);
g_pMesh->DrawXMesh(scalTrans * movTrans);
}

void UnloadContent()
{
ReleaseCOM(g_pBloom);
ReleaseCOM(g_pMesh);
ReleaseCOM(g_pFlare);
ReleaseCOM(g_pPlant);
ReleaseCOM(g_pWater);
ReleaseCOM(g_pBaseTerrain);
ReleaseCOM(g_pSkybox);
}

void Dispose()
{
ReleaseCOM(g_pSpriteBatch);
ReleaseCOM(g_pD3DCamera);
ReleaseCOM(g_pKeyboardInput);
ReleaseCOM(g_pMouseInput);
ReleaseCOM(g_pD3DDevice);
ReleaseCOM(g_pD3D);
}

对Bloom参数体各个成员变量数值进行交叉组合，则我们可以得到一系列不同的Bloom效果：









还在羡慕那些专业游戏中美轮美奂的后期特效吗？现在我们也有能力实现了~ 大家赶快动手尝试一下吧 ^ ^

以上，谢谢~