Technical Question

[Wobbo]

What is a rendering path? As in the 'ARB2 Rendering path'

[Zoost]

What is a rendering path?

A rendering path is the path that is used to render stuff. Because there are different hardware implementations (think: ATI/Nvidia/DX7/DX8/DX9) it is neccesary to write different "paths" to make optimal use of the hardware.

Te following* hardware paths can be disquisted for DOOM3

*ARB1-DX7 level hardware via standard OpenGL (ATI Radeon 7000+, Intel i830G+, SiS, whatever). Will not have specular lighting.
*nv1x-original GeForce through GeForce4MX. All rendering options, five passes, no vertex programs so your CPU does more work.
*nv2x-GeForce3/4Ti, All rendering options, two or three passes, vertex programs
*R2x0-Radeon 8500 through 9200. All rendering options, usually one pass, vertex programs
*nv3x-Dropped.
*ARB2-uses arb_fragment_shader for the Radeon 9500+, nv30+, S3 DeltaChrome, XGI Volari, etc. All rendering options, one pass, vertex programs.

ARB2 is a name that Carmack came up with to describe a rendering path in Doom 3. It's the path that uses the ARB_fragment_program and ARB_vertex_program extensions. The closest thing D3D has to these extensions is PS 2.0 and VS 2.0. ARB2 is supported on R300 and NV30. The ARB2 path is single pass per light. Carmack has also said the path for R200 is single pass. Then there is at least 2 more paths that support older nvidia or older generic cards. He has stated that his basic philosophy is to keep the rendering equivalent, but just require more passes on the older hardware.

*copy/pasted from beyond3d boards

[Wobbo]

Ok thats basically what i thought, thanks.

a more in depth explanation of what excactly it is could still be appreciated though.

I suppos you cant really be anymore specific then?

[Zoost]

What is it that you don't understand?
You can read thisfor an more indepth look.

[Wobbo]

"He has stated that his basic philosophy is to keep the rendering equivalent, but just require more passes on the older hardware. "

Basically this is what i was concerned with and a little confused about, im assuming the the peoitn of all this is so that doom3 *looks* exccactly the same on all cards, just at differetn resolutions and speeds

thats what i had thought before, but the "Will not have specular lighting. " threw me off

[kalamari22]

Zoost said:

A rendering path is the path that is used to render stuff.

Well said.

[etimmerAZ]

kalamari22 said:

Well said.

Noob.

Peace,

The Bruce

[AirRaid]

etimmerAZ said:

Noob.

Peace,

The Bruce

What a thoughtful and insightful post.