WoW Render Scale question

[Iannis]

Hey all,
So I'm messing around with the Render Scale slider in WoW. By default it was on 200%.
The only thing I notice between 100 and 200% is slightly more blur at lower settings on distant objects.

Guess I'm not totally sure what the slider does? My frame rate is fine at 200% most of the time. I run everything on Ultra, including
shadows. Huge battles in Ashran will drop be from 60 to the mid 40s. Someone suggested I tone the slider down to
around 100% for Ashran. Anyway I don't like the thought of turning anything down for WoW

So I just need a little more info about what exactly this setting does? Thanks!

If it's relevant, I play at 1080p with an Nvidia 980Ti (1500mhz core), i7 4770k @ 4.5ghz

[Alindra]

Render scale adjusts the resolution WoW renders at before it hits your screen. For example, if you're running a 1920x1080 monitor and set your render scale to 200%, WoW renders at 3840x2160, then it down-samples it to your monitors resolution (1920x1080 in this case). It's a very expensive form of anti-aliasing because it's drawing exponentially more pixels (8.2 million vs ~2 million, 4x more in this case).

If you're CPU limited, then increasing the render scale will give you a prettier picture "for free" by using up the GPU's idle time. If, on the other hand, you're GPU limited, increasing the render scale will negatively impact your performance.

[Karon]

Hey all,
So I'm messing around with the Render Scale slider in WoW. By default it was on 200%.
The only thing I notice between 100 and 200% is slightly more blur at lower settings on distant objects.

Guess I'm not totally sure what the slider does? My frame rate is fine at 200% most of the time. I run everything on Ultra, including
shadows. Huge battles in Ashran will drop be from 60 to the mid 40s. Someone suggested I tone the slider down to
around 100% for Ashran. Anyway I don't like the thought of turning anything down for WoW

So I just need a little more info about what exactly this setting does? Thanks!

If it's relevant, I play at 1080p with an Nvidia 980Ti (1500mhz core), i7 4770k @ 4.5ghz

I'm not sure if it will do you any good to lower the render scale, since it's probably your CPU that's limiting your performance in WoW.

Alindra already said the most important stuff about what the render scale is for.

[Iannis]

Thanks for the info. yea I've been running around playing with the slider. I don't notice a frame rate drop at any setting. So probably a CPU limited thing. Which I don't like thinking that my 4770k with a nice OC is limiting -_-

[Kagthul]

Its the nature of a client-server MMO. All the draw calls have to be created by the CPU, in order, and it often has to wait for a server response to start more draw calls (as it waits to get updated positions on particles, for instance).

Even massively liquid cooled rigs have the same issues.

[Alindra]

Its the nature of a client-server MMO. All the draw calls have to be created by the CPU, in order, and it often has to wait for a server response to start more draw calls (as it waits to get updated positions on particles, for instance).

You're correct that current graphics APIs (DX10 and lower, OpenGL) can only issue draw calls from the main thread (or any graphics call, like state changes), I highly doubt that draw calls are paused while waiting on the network. I'd assume it would be more along the lines of:

Top of Frame
1) Update pending state information
2) Draw entities
3) Draw UI
4) Repeat

The pending state information could be from the network (position updates), animation / physics on the client side (the server might say "start animation X at Y time," but the client would be the one playing it and figuring how how the character should be positioned. The client can even preemptively start animations before the server responds - it's why when you're lagging you might start a cast animation for seconds before you see any progress. It's even possible (whether WoW does this or not I don't know) for particle systems to be maintained fully on the GPU and updated with a computer shader.

The problem is with the sequential drawing of the entities and the UI and the vast number of state changes required. Each time an application tells a graphics API to do something, there is a fixed cost. So issuing a command to draw 50 polygons or 5,000 will have the same cost associated with it. So graphics cards are happiest when they're given large workloads with no state changes. Unlike many FPS games which can have lots of duplication, entities in MMOs like wow tend to have a lot of variation (different textures, particle effects, etc) which means the workloads will be smaller with more state changes.

With current graphics APIs, there is only so much that can be done to speed it up.