DirectX 9 vs DirectX 11

[SylvanElf]

Originally Posted by SylvanElf
Hey folks,

If you have the option to enable it in your WoW options, does that mean your video card can handle it?


Nope, i was able to select it on my GTS250 aswell as on my GTX460. However the GTS250 is a DX10 card.

well... is there any reason or benefit in the slightest to set your game client to it? Will it just use whatever your card is capable of? Will there be any detriment?

[vesseblah]

well... is there any reason or benefit in the slightest to set your game client to it? Will it just use whatever your card is capable of? Will there be any detriment?

The way DirectX work is something like this simplified:

1) Game tells DirectX to draw something on screen
2) DirectX tries to make best guess if the current graphics card can draw something faster, or if the CPU would do it faster
3) Something is drawn into either graphics memory or main system memory, and copied over to screen memory for display

What the "something" that can be drawn on screen actually is, depends on the DirectX version. Again doing gross simplifying:

DX9 can draw dots
-> to make a circle, game sends hundred dots to DX9 and calculates in CPU where those dots should be, working both CPU and GPU

DX10 can draw lines
-> to make a circle, game first calculates in CPU ten lines that make up the circle, and then tells DX10 to draw bunch of lines. Part of the work is again done in CPU and part in GPU.

DX11 can draw circles
-> game tells DX11 the center point and radius, and gets a line with single command bypassing CPU completely.

When it comes to WoW, the selection between DX9 and DX11 works something like this, again simplified:

DX9 card in DX9 mode
-> game needs to draw a circle, therefore it calculates all points in CPU and sends a list of dots to GPU

DX10 card in DX9 mode
-> game needs to draw a circle, therefore it calculates all points in CPU and sends a list of dots to GPU

DX9 card in DX11 mode
-> game needs to draw a circle, therefore it sends center point and radius to DX11 driver which calculates all points in CPU and sends a list of dots to DX9 GPU because it can not understand circles or lines. Sending and counting dots takes a long time.

DX10 card in DX11 mode
-> game needs to draw a circle, therefore it sends center point and radius to DX11 driver which calculates bunch of lines in CPU and sends a list of lines to DX10 GPU. Because it can not understand circles but it does understand slightly more complex lines that are faster to draw than simple dots, lines are produced by CPU instead of dots.

DX11 card in DX11 mode
-> game needs to draw a circle, therefore it sends center point and radius to DX11 driver which sends the raw circle command to GPU bypassing CPU completely.


Now the reason why some DX10 card works well in DX11 mode is because it supports some of the more advanced drawing tools that DX9 does not, and can do part of the work GPU accelerated. In case of DX9 card it just would ignore all commands to draw DX10 features because those would take too long time done in CPU only causing much lower framerate.

And finally the answer to the question:

Fortunately for the end users, games are designed so that the most basic and always required things like the user interface elements can be drawn with any version of DirectX, as can 3D models. Where the differences start coming up is the processing of light and shadows.

For example DX7 was the first with some shadows and light sources, and with DX7 supporting card a 3D object standing next to light source would have one side lighter color (where the light shines) and one side darker color (on the shade), but with cards not supporting DX7 the object would have same color on all sides totally ignoring the effect of light. Things like these will affect the visual quality of the game to a certain point, especially physics modeling and realism, but the game will still run correctly.

Still in WoW the difference between DX9 and DX11 is mostly cosmetic, but it is there if you know where to look. One of the biggest advances in DirectX from 9 to 10 was in particle effects, in things like smoke and fire. How this affects WoW is that DX9 mode will draw simple and crude particle effects while DX10 and DX11 cards in DX11 mode will show more realistic smoke and fire. Whole another thing is that how many people will stop admiring the better fire while standing in one...

[Deleted]

I personally think that the DX9 water looks better than the 11 :s

[SylvanElf]

I bow to your munificence Vesseblah!!! In short, thanks! Hit that answer out of the ballpark! So generally, it will do what it *can* better in DX11 mode, while not actually hindering frame rates, only *possibly* improving them.

Edit: Well, my card is a DX10 card, and setting WoW to DX11 seems to only drop the framerate slightly (flying through Dalaran was my test)

[SylvanElf]

Hrm, well I'm not sure if this is the right thread... but when WoW runs 64 bit, will it have any impact on the graphics, and will DX factor into it any?

[Deleted]

Hrm, well I'm not sure if this is the right thread... but when WoW runs 64 bit, will it have any impact on the graphics, and will DX factor into it any?

No.
By the way, to run 64 bit WoW you need a 64 bit cpu and os, which for the end user is merely required if they want over about 3,5GB ram.
The 64 bit version of WoW will only allow it to address more than 2GB of ram, but the usage of a normal user (1920x1080 @ Ultra) only sits at about 1GB so it won't make a difference

[pdude]

It kind of sucks the graphical improvements made in Cataclysm (i.e. Water and Sunshafts) aren't implemented in the OpenGL renderer.
I don't want to start a war, but Windows 7 doesn't run at a stable enough level to reliably play WoW for any length of time (I get random blue screens), so I primarily run it on Linux with the OpenGL renderer.

[Deleted]

It kind of sucks the graphical improvements made in Cataclysm (i.e. Water and Sunshafts) aren't implemented in the OpenGL renderer.
I don't want to start a war, but Windows 7 doesn't run at a stable enough level to reliably play WoW for any length of time (I get random blue screens), so I primarily run it on Linux with the OpenGL renderer.

Must be something with your system, mine only bluesceens on heavy unstable overclocks, and a couple of times when one of my ram modules was faulty

[Asmekiel]

It kind of sucks the graphical improvements made in Cataclysm (i.e. Water and Sunshafts) aren't implemented in the OpenGL renderer.
I don't want to start a war, but Windows 7 doesn't run at a stable enough level to reliably play WoW for any length of time (I get random blue screens), so I primarily run it on Linux with the OpenGL renderer.

Lolwut, Windows 7 not stable enough. In the 2 years I'm using it now it crashed only due to unstable overclocking and 1 time due to bad drivers... You are doing something very wrong.

[pdude]

Lolwut, Windows 7 not stable enough. In the 2 years I'm using it now it crashed only due to unstable overclocking and 1 time due to bad drivers... You are doing something very wrong.

I'm pretty sure it's a driver issue, but the only 3rd party driver I've installed is the Nvidia driver which is currently the latest version.
I had the same problem when I had a Radeon 4850 running the latest AMD driver.

All the other drivers are the Windows defaults.
But I didn't have this problem until I upgraded to 8gb of RAM (yes I use 64-bit Windows), but there isn't anything wrong with the RAM. I ran Memtest, and Linux doesn't ever crash using the same RAM.

I don't overclock by the way.