Hello, Per pixel lighting is simple and popular technique. Unfortunately I'm no lucky. I have done many test and even more shaders. Results always were other than I expect. There are any 'standard' approach do deal with? I always had problems with generating tangent space matrix for vertices. Actually, I don't know this correct or not. I can check that one vector is prependicular to second but results still do not satisfy me. I think, the mesh has some 'internal' bugs, because is looks absoluely different in 3D Studio and in my viewer. I have tried write 3DS file reader to avoid whole model system but I'm stuck in tangent space generation again! So I have a few questions: 1) How to propertly calculate tangent space form simple mesh (ie. triangles)? 2) From where can I know that results are correct? 3) Is it depdendent of RH camera? 4) Effect depends form hadrware (aka. results are this same on nVIDIA and ATI)? 5) Where is the difference between D3D and OpenGL? I hear about different UV mappings, but there is something more? Lighting depends form tangent stuff, so it cannot be correct until problem is not solved. I think, my shaders are correct. Thanks for are replies. TheDmD

Actually I need tangent space exacly for normal maps. :)

Thanks for source. I will use it to compare results. After that I will post some more informations.