OGRE版本1.7.1的Sample裡包含了地形的示例，且用到了PSSM+LiSPSM。

今天嘗試把Character的Sinbad模型擺到地形上，不過模型的材質本身不支援PSSM。

看了下地形示例的實現，發現它在給Shader傳PSSM分界點資料時，用了把模板材質clone一份，再設定diffusemap和pssm分界點的方法，相當讓人無語....

1. MaterialPtr ret = MaterialManager::getSingleton().getByName(matName);   
2. MaterialPtr baseMat = MaterialManager::getSingleton().getByName(
   "Ogre/shadow/depth/integrated/pssm");   
3. ret = baseMat->clone(matName);   
4. Pass* p = ret->getTechnique(0)->getPass(0);   
5. p->getTextureUnitState("diffuse")->setTextureName(textureName);   
6. Vector4 splitPoints;   
7. const PSSMShadowCameraSetup::SplitPointList& splitPointList =    
8. static_cast<PSSMShadowCameraSetup*>(mPSSMSetup.get())->getSplitPoints();   
9. for (int i = 0; i < 3; ++i)   
10. {   
11.     splitPoints[i] = splitPointList[i];   
12. }   
13. p->getFragmentProgramParameters()->setNamedConstant("pssmSplitPoints", splitPoints);  

1. MaterialPtr ret = MaterialManager::getSingleton().getByName(matName);  
2. MaterialPtr baseMat = MaterialManager::getSingleton().getByName("Ogre/shadow/depth/integrated/pssm"
   );  
3. ret = baseMat->clone(matName);  
4. Pass* p = ret->getTechnique(0)->getPass(0);  
5. p->getTextureUnitState("diffuse")->setTextureName(textureName);  
6. Vector4 splitPoints;  
7. const PSSMShadowCameraSetup::SplitPointList& splitPointList =   
8.     static_cast<PSSMShadowCameraSetup*>(mPSSMSetup.get())->getSplitPoints();  
9. for (int i = 0; i < 3; ++i)  
10. {  
11.     splitPoints[i] = splitPointList[i];  
12. }  
13. p->getFragmentProgramParameters()->setNamedConstant("pssmSplitPoints", splitPoints);  

如果有幾百種不同貼圖的物件，就得在程式碼裡手動為每一個物件設定diffusemap和pssm分界點，前者其實在材質指令碼中可以用繼承來覆蓋，後者其實整個場景用到的資料都是一樣的。好在OGRE增加了shared_params，可以多個shader共享相同的引數，在程式碼裡只設置一遍就可以了。

修改後的fp:

1. shared_params pssm_params   
2. {   
3.     shared_param_named pssmSplitPoints float4   
4. }   
5. fragment_program Ogre/shadow/receiver/depth/pssm3/fp cg   
6. {   
7.     source depthshadowobject.cg   
8.     profiles ps_2_x arbfp1   
9.     entry_point main_fp   
10.     compile_arguments -DSHADOWCASTER=0 -DDEPTH_SHADOWCASTER=0 -DDEPTH_SHADOWRECEIVER=1    
11.     default_params   
12.     {   
13.         param_named_auto materialAmbient derived_ambient_light_colour   
14. // shadow samplers are indexes 1/2/3
15.         param_named_auto inverseShadowmapSize0 inverse_texture_size 1   
16.         param_named_auto inverseShadowmapSize1 inverse_texture_size 2   
17.         param_named_auto inverseShadowmapSize2 inverse_texture_size 3   
18. //SET THIS MANUALLY!
19. //param_named pssmSplitPoints 0 0 0 0
20.         shared_params_ref pssm_params   
21.     }   
22. }  

1. shared_params pssm_params  
2. {  
3.     shared_param_named pssmSplitPoints float4  
4. }  
5. fragment_program Ogre/shadow/receiver/depth/pssm3/fp cg  
6. {  
7.     source depthshadowobject.cg  
8.     profiles ps_2_x arbfp1  
9.     entry_point main_fp  
10.     compile_arguments -DSHADOWCASTER=0 -DDEPTH_SHADOWCASTER=0 -DDEPTH_SHADOWRECEIVER=1   
11.     default_params  
12.     {  
13.         param_named_auto materialAmbient derived_ambient_light_colour  
14.         // shadow samplers are indexes 1/2/3
15.         param_named_auto inverseShadowmapSize0 inverse_texture_size 1  
16.         param_named_auto inverseShadowmapSize1 inverse_texture_size 2  
17.         param_named_auto inverseShadowmapSize2 inverse_texture_size 3  
18.         //SET THIS MANUALLY!
19.         //param_named pssmSplitPoints 0 0 0 0
20.         shared_params_ref pssm_params  
21.     }  
22. }  

c++:

1. Vector4 splitPoints;   
2. const PSSMShadowCameraSetup::SplitPointList& splitPointList =    
3. static_cast<PSSMShadowCameraSetup*>(mPSSMSetup.get())->getSplitPoints();   
4. for (int i = 0; i < 3; ++i)   
5. {   
6.     splitPoints[i] = splitPointList[i];   
7. }   
8. GpuSharedParametersPtr p = GpuProgramManager::getSingleton().getSharedParameters("pssm_params");   
9. p->setNamedConstant("pssmSplitPoints", splitPoints);  

1. Vector4 splitPoints;  
2. const PSSMShadowCameraSetup::SplitPointList& splitPointList =   
3. static_cast<PSSMShadowCameraSetup*>(mPSSMSetup.get())->getSplitPoints();  
4. for (int i = 0; i < 3; ++i)  
5. {  
6.     splitPoints[i] = splitPointList[i];  
7. }  
8. GpuSharedParametersPtr p = GpuProgramManager::getSingleton().getSharedParameters("pssm_params");  
9. p->setNamedConstant("pssmSplitPoints", splitPoints);