Shader based Skin

Mel · Post by **Mel** » Sat Nov 14, 2009 12:20 pm

Finally, the current trunk of the Irrlicht has support for Multi Render Target. They are great news indeed, so, my question/request for the next development steps for the engine would be that it also included support to use skin shaders, or even, that the skin system of irrlicht used the hardware to make all the operations.

Currently it is the weakest point of irrlicht, and it could enhance totally not only the eficiency of the engine, but also, the looks of the animated skin based models it can display. I think it should be must. Even if the target hardware didn't have support for hardware skinned meshes, it could still fallback to the current software based skin system.

BlindSide · Post by **BlindSide** » Sun Nov 15, 2009 7:44 am

This has been on the backburner for a while if you wanna take a look at what I got done a few years ago here it is:

http://irrlichtirc.g0dsoft.com/BlindSide/HWSkin.zip

PS: There is a memory leak in the provided source code, you should change it so that it deletes the float arrays in the loop.

Personally I will integrate shadow maps first, this may come after.

shadowslair · Post by **shadowslair** » Sun Nov 15, 2009 10:44 am

@BlindSide:

I tried it, but it doesn`t give some spottable performance boost- 390 with, 406 without. What calculations are passed to the GPU and what are left for Irrlicht? In what circumstances it has its benefits? Or should I put more models in it?

Woah. A memory leak of 2mb/second. How exactly can I delete those float arrays, since I tried it, but it either doesn`t affect the leak, or causes a crash?

PS: What are the differences between this and to sio2`s HW skinning demo for Dx9? You know I`m not a "shader guy". Except the released source of course.

Thanks.

BlindSide · Post by **BlindSide** » Sun Nov 15, 2009 11:03 am

It should give about 2X performance with more models like 20 dwarves but you have to set EHM_STATIC hardware mapping hint on the models otherwise it won't help that much (Doesn't look like I did that in that sample).

Here is a cleaned up version with the memory leaks fixed but I didn't test it: http://pastebin.com/m45dfa28f

The difference from sio2's is that sio2 copied that demo from a D3D example and also it's only available in D3D9, other than that I can't tell you much because the source was never released.

shadowslair · Post by **shadowslair** » Sun Nov 15, 2009 3:17 pm

Thanks for the memory leak bug.

When I set the EHM_STATIC hw mapping hint there still has no difference- 390 with, 406 without. Here`s the last version for 1.6 with status text showing the fps and having the hw mapping set.: http://pastebin.com/d3a3a3746
I want to use this in my app, since it`s really easy to use and compact, but I cannot see some results. What am I doing wrong? Or my video card (Radeon 9550) doesn`t support this somehow?

Mel · Post by **Mel** » Sun Nov 15, 2009 10:55 pm

Great work BlindSide!, though i think is more important to integrate the Hardware Skin support, because the shadows are a secondary matter in graphics representation, on the other hand, the extra time saved by processing the skin calculations using hardware support could be used for other tasks, e.g. just as you said, perhaps, for shadow mapping calculations of animated meshes.

shadowslair · Post by **shadowslair** » Mon Nov 16, 2009 2:09 pm

Mel, does your app run a little bit faster with this skinning? Because it`s not working for me for some reason, probably doing sth wrong...

PS: In my opinion hw skinning is more important than shadow mapping too.

hybrid · Post by **hybrid** » Mon Nov 16, 2009 9:58 pm

No, it's not. Because we don't have a proper shadowing at all for now, but we have skinning already. Even if it's slow.

BlindSide · Post by **BlindSide** » Tue Nov 17, 2009 2:03 am

shadowslair wrote:Mel, does your app run a little bit faster with this skinning? Because it`s not working for me for some reason, probably doing sth wrong...

PS: In my opinion hw skinning is more important than shadow mapping too.

It's most likely because of the video card, same results in OpenGL and D3D?

Shadow mapping is a little more straightforward to integrate whilst hardware skinning requires us to intrude on all the original material types and replace their vertex shader with a hardware skinning one whilst keeping all the fixed function functionality, so it's a little more complex. I also found that it's near-impossible to use my method on AMD cards in OpenGL but I haven't tested it on newer ones, only SM 2.0 capable cards.