What do MRT actually do???

devsh · Post by **devsh** » Sun Apr 12, 2009 6:58 pm

hey i have done a couple of effects and they really do take up rendering time, first is depth of field which really requires to draw everything again using a shadow material. This takes as much time as rendring everything again, even thought it is from the same angle.

What do MRT actually do??

can i render simultaneously into two RTTs using different materials???

Does instancing work under OpenGL???

how could i use it ???

Or least speed enchancing method, is there any function which would render a whole scene using one material???

so i do not have to store all materials in an array and assign the depth material, render the node and assign back all the materials from the array.

Is the irr::Array slowing me down???

devsh · Post by **devsh** » Mon Apr 13, 2009 12:21 pm

anyone this is really important!!!

psychophoniac · Post by **psychophoniac** » Mon Apr 13, 2009 1:30 pm

http://en.lmgtfy.com/?q=multiple+render+target

and be patient, you did not even wait a day for an answer.

Nadro · Post by **Nadro** » Mon Apr 13, 2009 2:26 pm

With MRTs, You can write different color informations to other RTT in one render pass, eg: COLOR0, COLOR1, COLOR2 in Cg/HLSL sementics.

Acki · Post by **Acki** » Mon Apr 13, 2009 2:27 pm

are you sure your IQ is 159 !?!?!

I mean with such an high IQ you should be able to use a search engine !!!

devsh · Post by **devsh** » Mon Apr 13, 2009 2:58 pm

ok but how would i go on applying it to the depth pass???

do i have to make a shader or something??

FuzzYspo0N · Post by **FuzzYspo0N** » Mon Apr 13, 2009 3:36 pm

in order to access the depth pass you have to download the internet.

www.google.com

PLEASE.

devsh · Post by **devsh** » Mon Apr 13, 2009 8:45 pm

no i mean to order to render to mutliple targets with different outputs (colors and stuff) do i have to use a shader???

so lets say i set up 2 RTs

in GLSL does the built in variable gl_Color determine the color of the pixel on the RT and does the i symbolise the RT.

so in standard shader i write gl_Color[0] = x;

so if i had two RTTs, could i use

gl_Color[0] = normal render
gl_Color[1] = depth pass

???

Nadro · Post by **Nadro** » Tue Apr 14, 2009 9:31 am

You can check my Deferred Shading example (Cg shaders):
http://irrlicht.sourceforge.net/phpBB2/ ... hp?t=28965
This demo use MRTs.

devsh · Post by **devsh** » Fri Apr 17, 2009 9:49 pm

MRT in OpenGL and GLSL posssible????

hey and btw on the array gl_FragCoord???

could i invert or translate them along some axis and get a "mirrored" vertex transormed image render and render that into a let's say third RTT. So i wouldn't have to render the whole scene again from a translated camera angle for my water node...

I think obviously some object could get occluded by frustrum culling.

hybrid · Post by **hybrid** » Sat Apr 18, 2009 10:18 am

This is fragment shader, you cannot combine multiple vertex shaders within one MRT call.

devsh · Post by **devsh** » Sat Apr 18, 2009 9:24 pm

i'm giving a try to nadro's update for FPT and MRT so far so good.

9YkKsvXM · Post by **9YkKsvXM** » Sat Apr 18, 2009 11:59 pm

devsh · Post by **devsh** » Sun Apr 19, 2009 11:48 am

i seem to have a problem

COpenGLDriver.cpp

error: ‘class irr::video::COpenGLTexture’ has no member named ‘unbindFrameBufferObject’
COpenGLDriver.cpp

error: ‘class irr::video::COpenGLTexture’ has no member named ‘bindFrameBufferObject’

Nadro · Post by **Nadro** » Sun Apr 19, 2009 1:29 pm

My patch for FP textures is very old and first You have to update it to compatible with the latest Irrlicht version.