用Ogre生成天龙八部的lightmap和minimap的简单方法

自从在一家创业小公司当了客户端主程以后，就忙的没有时间写博客了，整个公司没有一个人有完整的项目经验，所有一切都在摸索中前进，但初生牛犊不怕虎，项目还算进展顺利。但我始终认为，安静下来总结整理一下工作心得是必要的，可惜这个愿望恐怕得等到这个项目忙完以后。

周末有点时间，还是可以抽空随便写点东西。

lightmap的重要性不用多说，没必要所有阴影都动态去渲染，那些一辈子也不会动的静态物体，贴一张lightmap就行了，可惜Ogre只提供动态阴影给我们，帮人也不帮到底。

如何生成天龙八部一样lightmap，如果你去百度一下，他们会告诉你各种方法，什么光线追踪，shader，之类

以上都是告诉你，自己去产生一个阴影。但是Ogre已经帮我们产生了动态阴影，我们就没必要再自己去生成阴影，

只要用动态阴影的渲染一张静态阴影图，保存下来不就行了么。

那么如何用Ogre的动态阴影去产生一张静态的阴影图呢？

1）先学会渲染一张minimap的缩略图，缩略图大家都应该会吧，创建一个垂直俯瞰的摄像机，平行投影拍一张就是

2）改进minimap，让垂直俯瞰的摄像机的视口只渲染地形队列。不渲染其他队列

这样拍出来的minimap就只有阴影和地形纹理混合后效果了

Ogre::RenderQueueInvocationSequence* rqis =
Ogre::Root::getSingleton().createRenderQueueInvocationSequence("Lightmap maker");
Ogre::RenderQueueInvocation* rqi =
rqis->add(Ogre::RENDER_QUEUE_WORLD_GEOMETRY_1, "World Geometry");
viewport->setRenderQueueInvocationSequenceName("Lightmap maker");

3）再改进一下，把地形材质设置为BaseWhite，全白，那么minimap就变成了lightmap了。

4）Ogre的阴影并不好用，所以你需要优化，怎么优化，或者用shader实现，以后再写。

//////////这是动态阴影的图片、、、、、、、、、、、、、、、、、、、、、、、、、、





//////////////////////////

//////////////////////////这是贴上lightmap的图片



.



.//////////////////////////这是阴影图、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、



附上代码，看看思路就好！

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/*
@filename WXLightMapMaker.h
@creator LuoYinan
@data 2010.6.14
@remarks 创建场景光照图
*/
#ifndef __WX_LIGHTMAP_MAKER_H__
#define __WX_LIGHTMAP_MAKER_H__

#include "SceneManipulator.h"

namespace WX
{
class LightMapMaker
{
public:
LightMapMaker(SceneManipulator* manipulator);
~LightMapMaker(void);

// 初始化，包括创建render texture，camera等
void initial(void);
// 销毁render texture
void destroy(void);

// 保存光照图到文件
// 格式 "emei.lightmap.png",也支持全路径,比如../../Data/Scene/emei.lightmap.png"
void outputTexture(const Ogre::String& fileName);

protected:

SceneManipulator* mSceneManipulator;
Ogre::RenderTexture* mRenderTexture;

};
}
#endif
/*
@filename WXLightMapMaker.h
@creator LuoYinan
@data 2010.6.14
@remarks 创建场景光照图
*/
#ifndef __WX_LIGHTMAP_MAKER_H__
#define __WX_LIGHTMAP_MAKER_H__

#include "SceneManipulator.h"

namespace WX
{
class LightMapMaker
{
public:
LightMapMaker(SceneManipulator* manipulator);
~LightMapMaker(void);

// 初始化，包括创建render texture，camera等
void initial(void);
// 销毁render texture
void destroy(void);

// 保存光照图到文件
// 格式 "emei.lightmap.png",也支持全路径,比如../../Data/Scene/emei.lightmap.png"
void outputTexture(const Ogre::String& fileName);

protected:

SceneManipulator* mSceneManipulator;
Ogre::RenderTexture* mRenderTexture;

};
}
#endif view plaincopy to clipboardprint?
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#include "WXLightMapMaker.h"

#include "GameScene/TerrainData.h"
#include "GameScene/WXScene.h"
#include "GameScene/WXSceneInfo.h"
#include "GameScene/WXStaticEntityObject.h"
#include "GameScene/WXModelObject.h"
namespace WX
{
//----------------------------------------------------------------------------------
LightMapMaker::LightMapMaker(SceneManipulator* manipulator)
: mSceneManipulator(manipulator)
, mRenderTexture(0)
{

}

//--------------------------------------------------------------------------------
LightMapMaker::~LightMapMaker(void)
{

}

//--------------------------------------------------------------------------------
void LightMapMaker::initial(void)
{
// 确保地形已经载入
TerrainData* data = mSceneManipulator->getTerrainData();
assert(data && "TerrainData* == NULL");

// 创建lightmap摄像机,垂直俯瞰整个地图
Ogre::SceneManager* mSceneManager = mSceneManipulator->getSceneManager();
//if (mSceneManipulator->getTerrainData()->mLightmapImage == NULL)
{
static const String msLightmapMaker("Lightmap maker");
Ogre::Camera* camera = 0;
try
{
camera = mSceneManager->getCamera(msLightmapMaker);
}
catch (const Ogre::Exception& e)
{
// 只提示异常,而不退出程序
if (e.getNumber() == e.ERR_ITEM_NOT_FOUND)
{
//MessageBox(NULL, e.what(), "An exception has occured!", MB_OK | MB_ICONERROR | MB_TASKMODAL);
}
else
{
throw;
}

}
if (!camera)
{
camera = mSceneManager->createCamera(msLightmapMaker);
camera->setAutoAspectRatio(true);
camera->setProjectionType(Ogre::PT_ORTHOGRAPHIC); // 平行投影
// 在Ogre1.6版本中,平行投影的大小改为setOrthoWindowWidth和setOrthoWindowHeight来决定,
// 而不是以前版本用的FOV和近截面,so...
camera->setFOVy(Ogre::Degree(90));
camera->setOrthoWindowWidth(mSceneManipulator->getTerrainData()->getXSize()*mSceneManipulator->getBaseScale());
camera->setOrthoWindowHeight(mSceneManipulator->getTerrainData()->getZSize()*mSceneManipulator->getBaseScale());

Ogre::Quaternion orientation;
orientation.FromAxes(Ogre::Vector3::UNIT_X, Ogre::Vector3::NEGATIVE_UNIT_Z, Ogre::Vector3::UNIT_Y);
camera->setOrientation(orientation);
}

// 计算所有对象包围盒,以此来决定摄像机的参数
Ogre::AxisAlignedBox aabb;
Ogre::SceneManager::MovableObjectIterator itm =
mSceneManager->getMovableObjectIterator(Ogre::EntityFactory::FACTORY_TYPE_NAME);
while (itm.hasMoreElements())
{
Ogre::MovableObject* movable = itm.getNext();
aabb.merge(movable->getWorldBoundingBox(true));
}
camera->setNearClipDistance(32 * mSceneManipulator->getBaseScale() / 2);
camera->setFarClipDistance(camera->getNearClipDistance() + aabb.getMaximum().y - aabb.getMinimum().y);
camera->setPosition(0, camera->getNearClipDistance() + aabb.getMaximum().y, 0);

// 调整阴影参数
Ogre::Real distance = camera->getNearClipDistance() * Ogre::Math::Sqrt(1 + Ogre::Math::Sqr(camera->getAspectRatio()));
mSceneManager->setShadowFarDistance(distance);
Ogre::Real camHeight = camera->getPosition().y;
mSceneManager->setShadowDirLightTextureOffset(camHeight / distance);


// 创建lightmap的Rtt纹理,和天龙一样,设为地形大小的8倍
Ogre::TexturePtr pTexture = (Ogre::TexturePtr)Ogre::TextureManager::getSingleton().getByName("LightmapRttTex");
if (pTexture.isNull())
{
size_t width = data->getXSize() * 8;
size_t height = data->getZSize() * 8;
pTexture = Ogre::TextureManager::getSingleton().createManual(
"LightmapRttTex", Ogre::ResourceGroupManager::DEFAULT_RESOURCE_GROUP_NAME,
Ogre::TEX_TYPE_2D,
width, height, 1, 0, Ogre::PF_BYTE_RGB,
Ogre::TU_RENDERTARGET, 0);
}
Ogre::HardwarePixelBufferSharedPtr pBuffer = pTexture->getBuffer(0, 0);
mRenderTexture = pBuffer->getRenderTarget(0);

// 创建lightmap的视口
Ogre::Viewport* viewport = mRenderTexture->addViewport(mSceneManipulator->getSceneManager()->getCamera("Lightmap maker"));
viewport->setOverlaysEnabled(false);
viewport->setSkiesEnabled(false);
viewport->setShadowsEnabled(true);
// 自定义一个渲染队列调用组,只渲染地形队列,这是关键,我们只要阴影,不要其他的.
// 如果你全部都渲染了,那就变成了minimap,缩略图了.
Ogre::RenderQueueInvocationSequence* rqis =
Ogre::Root::getSingleton().createRenderQueueInvocationSequence("Lightmap maker");
Ogre::RenderQueueInvocation* rqi =
rqis->add(Ogre::RENDER_QUEUE_WORLD_GEOMETRY_1, "World Geometry");
viewport->setRenderQueueInvocationSequenceName("Lightmap maker");
}

}
//--------------------------------------------------------------------------------
void LightMapMaker::destroy(void)
{
if (mRenderTexture)
{
mSceneManipulator->getSceneManager()->destroyCamera("Lightmap maker");

mRenderTexture->removeAllViewports();

Ogre::TextureManager::getSingleton().remove("LightmapRttTex");

mRenderTexture = NULL;
}
}

//--------------------------------------------------------------------------------
void LightMapMaker::outputTexture(const Ogre::String& fileName)
{
// 如果已经有lightmap了,跳过
if (mSceneManipulator->getTerrainData()->mLightmapImage)
{
// 需要提示么?
return;
}

// 让所有静态物体都可以投射阴影,来***lightmap
Scene::ObjectsByTypeRange objests = mSceneManipulator->getSceneInfo()->findObjectsByType(StaticEntityObject::msType);
for (Scene::ObjectsByTypeIterator it = objests.first; it != objests.second; ++ it)
{
ObjectPtr object = (*it);
object->setPropertyAsString("cast shadows", "true");
//object->setPropertyAsString("receive shadows", "true");
}
objests = mSceneManipulator->getSceneInfo()->findObjectsByType(ModelObject::msType);
for (Scene::ObjectsByTypeIterator it = objests.first; it != objests.second; ++ it)
{
ObjectPtr object = (*it);
object->setPropertyAsString("cast shadows", "true");
//object->setPropertyAsString("receive shadows", "true");
}

// 用BaseWhite代替原来的地形材质,并重构地形
TerrainData::MaterialTemplates& materials = mSceneManipulator->getTerrainData()->mMaterialTemplates;
TerrainData::MaterialTemplates materialsCopy(materials);
materials["OneLayer"] = "BaseWhite";
materials["OneLayerLightmap"] = "BaseWhite";
materials["TwoLayer"] = "BaseWhite";
materials["TwoLayerLightmap"] = "BaseWhite";
mSceneManipulator->getTerrain()->buildGeometry(mSceneManipulator->getBaseSceneNode(), true);

// 更新
//mSceneManipulator->getSceneManager()->_updateSceneGraph(mSceneManipulator->getSceneManager()->getCamera("Lightmap maker"));
mRenderTexture->update();

// 保存lightmap到文件
Ogre::String LightmapFileName(fileName);
String baseName, path, outExtention;
if (fileName.empty())
{
WX::TerrainData* data = mSceneManipulator->getTerrainData();
Ogre::StringUtil::splitBaseFilename(data->mHeightmapFilename, baseName, outExtention);
LightmapFileName = baseName + ".lightmap.png";
}
mRenderTexture->writeContentsToFile(LightmapFileName);

// 载入lightmap
static const String TEMP_GROUP_NAME = "#TEMP#"; // 临时资源组
Ogre::StringUtil::splitFilename(LightmapFileName, baseName, path);
mSceneManipulator->getTerrainData()->mLightmapFilename = baseName;
Ogre::ResourceGroupManager& rgm = Ogre::ResourceGroupManager::getSingleton();
rgm.addResourceLocation(path, "FileSystem", TEMP_GROUP_NAME, false);
// 这个函数本来是protected,以后最好还是重新载入整个地形,而不是单独载入lightmap
mSceneManipulator->getTerrainData()->_loadLightmap(baseName, "image", TEMP_GROUP_NAME);

// 换回原来的地形材质,并重构地形
std::swap(materials, materialsCopy);
mSceneManipulator->getTerrain()->buildGeometry(mSceneManipulator->getBaseSceneNode(), true);

// 所有静态物体不再需要投射阴影了,因为我们有lightmap
objests = mSceneManipulator->getSceneInfo()->findObjectsByType(StaticEntityObject::msType);
for (Scene::ObjectsByTypeIterator it = objests.first; it != objests.second; ++ it)
{
ObjectPtr object = (*it);
object->setPropertyAsString("cast shadows", "false");
//object->setPropertyAsString("receive shadows", "true");
}
objests = mSceneManipulator->getSceneInfo()->findObjectsByType(ModelObject::msType);
for (Scene::ObjectsByTypeIterator it = objests.first; it != objests.second; ++ it)
{
ObjectPtr object = (*it);
object->setPropertyAsString("cast shadows", "false");
//object->setPropertyAsString("receive shadows", "true");
}

// 销毁临时资源组
rgm.destroyResourceGroup(TEMP_GROUP_NAME);
}


}

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本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/qq18052887/archive/2010/08/15/5812611.aspx