Ogre2.1 分析笔记(八) 实现天空盒

1.      新建一个空工程添加如下代码，完成Ogre的初始化。

int WinMain(HINSTANCE
hInst, HINSTANCE
hPrevInstance, LPSTR
strCmdLine, INT
nCmdShow) {
Ogre::Root *root =
new Ogre::Root;
string renderSystemName =
"OpenGL 3+ Rendering Subsystem";
//在Root的构造函数中会直接启动OGL3+和DX11两种渲染系统，一下代码只是去获取渲染系统的指针
Ogre::RenderSystem *renderSystem =root->getRenderSystemByName(renderSystemName);
renderSystem->setConfigOption("Full Screen",
"No");
renderSystem->setConfigOption("Video Mode",
"800x600 @32-bit colour");
root->setRenderSystem(renderSystem);
Ogre::RenderWindow *renderWindow = root->initialise(true);
    while (true) {
     root->renderOneFrame();
}
}

2.      创建相机

 

    Ogre::SceneManager *sceneManager =root->createSceneManager(Ogre::ST_GENERIC, 1, Ogre::INSTANCING_CULLING_SINGLETHREAD);
    Ogre::Camera *camera =sceneManager->createCamera("MainCamera",
true, true);
    camera->setPosition(0,5, 15);
    camera->setNearClipDistance(0.2f);
    camera->setFarClipDistance(1000.0f);
camera->setAutoAspectRatio(true);

3.      定义合成器。在SkyBox.compositor中添加以下定义。

compositor_node SkyBoxNode
{
in 0 renderWindow
target renderWindow
{
     pass clear
     {
         colour_value0.5 1 1 1
     }
 
     passrender_quad
     {
         quad_normals    camera_direction
         m
4000
aterialSkyBox
     }
 
}
}
 
workspace SkyBox
{
connect_outputSkyBoxNode 0
}

4.      添加材质文件。在SkyBox.material中添加以下代码

vertex_program SkyBox_vs glsl
{
sourceSkyBox_vs.glsl
    default_params
{
     param_named_autoworldViewProj worldviewproj_matrix
}
}
 
fragment_program SkyBox_ps glsl
{
sourceSkyBox_ps.glsl
default_params
{
     param_namedskyCubemap int 0
}
}
 
material SkyBox
{
technique
{
     pass
     {
         vertex_program_refSkyBox_vs
         {
         }
         fragment_program_refSkyBox_ps
            {
         }
         texture_unit
         {
             textureSaintPetersBasilica.dds cubic gamma
             filtering           trilinear
             tex_address_mode    clamp
         }
     }
}
}

5. 添加对应的顶点shader和像素shader。在SkyBox_vs.glsl中添加以下代码。

#version 330

 

in vec4 vertex;

in vec3 normal;

uniform mat4 worldViewProj;

 

out gl_PerVertex

{

   vec4 gl_Position;

};

 

out block

{

   vec3 cameraDir;

} outVs;

 

void main()

{

   gl_Position = (worldViewProj * vertex).xyww;

   outVs.cameraDir.xyz = normal.xyz;

}

在在SkyBox_ps.glsl中添加以下代码。

#version 330

 

uniform samplerCube skyCubemap;

 

in block

{

   vec3 cameraDir;

} inPs;

 

out vec3 fragColour;

 

void main()

{

    //Cubemapsare left-handed

    fragColour= texture( skyCubemap, vec3( inPs.cameraDir.xy, -inPs.cameraDir.z ) ).xyz;

}

6. 在程序中添加资源

    Ogre::ResourceGroupManager::getSingleton().addResourceLocation("C:/Users/aa/Documents/Visual Studio2015/Projects/ORGE/OgreSkyBox",
"FileSystem");
Ogre::ResourceGroupManager::getSingleton().addResourceLocation("C:/Users/aa/Documents/ogre/Samples/Media/materials/textures/Cubemaps",
"FileSystem");
    Ogre::ResourceGroupManager::getSingleton().initialiseAllResourceGroups();

7. 在程序中添加工作空间

    Ogre::CompositorManager2 *compositorManager = root->getCompositorManager2();
    compositorManager->addWorkspace(sceneManager,renderWindow, camera,
"SkyBox", true);

8. 渲染循环

    while (true) {
        root->renderOneFrame();
    }