Question about Dx10 and vista or something....

[Xburn]

http://developer.valvesoftware.com/wiki/%24envmap

"$envmapoptional <choices>
Sets the oldest DirectX version that should draw the reflection. Choose from:
80 (DirectX
81 (DirectX 8.1)
90 (DirectX 9)
95 (DirectX 9 with Shader Model 3)
98 (DirectX 9 with DirectX 10 hardware)"

How come directx 9 use some features of the dx10?
Did not the microsoft or something said that it cannot be ported in to Win xp? So how can xp use dx10 features then? or they just don't want to port dx10 in to xp? sorry about my bad english too...

[xoqolatl]

Direct X is an API - a library of shortcucts, standard functions designed to simplify certain operations.
All imaginable graphic effects can be achieved without any API - you will just have to do it the hard, less portable way. DX10 graphic card means it can execute some DirectX 10 instructions in hardware, on machine language level. It seems Valve implemented a way to draw reflections that makes use of these hardware optimizations in DX10 cards, but they do not use DX10 API for that.

[coder0xff]

It seems Valve implemented a way to draw reflections that makes use of these hardware optimizations in DX10 cards, but they do not use DX10 API for that.

Poor guys. Just a thought, but DX10 cards have fewer limitations on shader programs. Perhaps DX9 doesn't intrinsically limit some aspects but just allow the card to indicate the limitations, like number of operations, etc. and DX10 cards are just expected to be more versatile - even when using DX9. Also, DX specifies that all DX cards must have a certain interface that allows DX to talk to it. Perhaps they access this lower level API?