Geometry Shaders for Irrlicht(development closed till later)

devsh · Post by **devsh** » Mon Jan 04, 2010 9:45 am

this one is entirely made from scratch by me

FuzzYspo0N · Post by **FuzzYspo0N** » Mon Jan 04, 2010 3:25 pm

we are unable to see any code, and the devs cant see if its possible to include without code.

devsh · Post by **devsh** » Mon Jan 04, 2010 7:50 pm

first of all i need to make the shader

that runs at reasonable speeds

geometry shaders run serial, so i need to unroll every loop by hand

devsh · Post by **devsh** » Tue Jan 05, 2010 6:55 pm

final result... I would say very close to dx11 (dx11 can make a lot more triangles

, but i did this on dx10 hardware so no tesselation there ), lets hope the story repeats and openGL gets tessellation just like geometry shaders.

right now i'm writing the CPP

Nadro · Post by **Nadro** » Tue Jan 05, 2010 8:37 pm

Nice work, but You have to remember about performance. On DX11 tessellation in much faster than via Geometry Shader. Only problem are GeForce cards, because Tessellation is also avaiable on Radeon HD2xxx and up, so on DX10 hardware.

devsh · Post by **devsh** » Tue Jan 05, 2010 9:25 pm

how much faster??? (I hope openGL gets it soon, and i will get a fermi card and will implement it in irrlicht)

Halifax · Post by **Halifax** » Tue Jan 05, 2010 9:46 pm

It should be orders of magnitude faster because it is a fixed-function part of the pipeline that is meant to do it. Geometry shaders really were never meant to do tessellation which is why I'm curious how fast your demonstration there runs and on what hardware?

And OpenGL will only receive hardware tessellation into its core specification sometime after both AMD and nVidia support it. Right now AMD is the only manufacturer to have it and they haven't released any recent extensions related to the new hardware tessellation unit for their GPUs.

devsh · Post by **devsh** » Wed Jan 06, 2010 11:58 am

i love and hate triangle strip output type.

love:
because on tesselation level 1 i output 4 verts instead of 6
on level 2 i have 8 instead of 12

hate:
because on tesselation level 2 i output 2 useless triangles

but with some luck i can add another tesselation level.

that would make 64 triangles per big triangle

aaand i need to optimise texture reads

96 reads for 36 vertices

some are double reads... (same tcoord)

UPDATE:

Im super happy now.

I fixed my level 2 code. 4 triangles and 8 vertices

Even Better level 3 (8 triangles, originally 24 verts) 13 vertices

devsh · Post by **devsh** » Wed Jan 06, 2010 9:10 pm

now i understand why the ATI/dx11 tesselation is honey comb shaped..

as my tesselation level 5 got (32 triangles) closer to 2n vertices per N triangles
their triangle strip must be a loop cut and therefore very efficient and must be close to the optimal n+2

devsh · Post by **devsh** » Thu Jan 07, 2010 12:58 pm

HELP I NEED SOMEONE WITH "GLU" or something that is able to make triangle strips out of triangles.

basically i need this converted to triangle strips (can be more than one), but using less than 86 vertices.

this image shows what i want to have less than 86 verts

devsh · Post by **devsh** » Thu Jan 07, 2010 4:50 pm

and we are almost done....

Ladies and Gentlemen, I am proud to present....

IrRLiChT ExAmPLe O24.GeOMeTrYsHaDeRs (really openGL tesselation)

devsh · Post by **devsh** » Fri Jan 08, 2010 12:09 pm

ladies and gentlemen i am officially finished (at least for this realease)

http://project-ninja-star.googlecode.co ... rsGLSL.zip

Ulf · Post by **Ulf** » Fri Jan 08, 2010 12:33 pm

devsh wrote:you people amaze me, I make anext gen addition to the engine and no one is interested?

"You people". haha. Tickle me pink.

Virion · Post by **Virion** » Fri Jan 08, 2010 3:16 pm

what's the real advantage of this?

Dan911 · Post by **Dan911** » Fri Mar 05, 2010 1:15 am

I think its kick-ass.. don't stop (BELIEVING!!!!!)

sorry..

had to do it..