In an exclusive interview with two of WoW's programmers, we learned why players could only summon one pet at a time (until now).
Each pet summoned requires a tiny bit of computing by the server. A single pet following each player is manageable. But multiply that by 10, 20 or 100? You end up with major lag spikes that inevitably crash the server.
This actually happened back in 2008 due to a known bug. Under certain conditions, players could desync from the server and summon an army of pets, only to resync and bring down the server moments later. So WoW's programming team developed a new technology to address this issue.
Variable Model Rendering
The programming that makes this possible was dubbed "VMR" or variable model rendering. This technology works in the same way that players can turn down their video settings to improve the game's performance. Only this is done automatically by the server based on its changing load. Blizzard decided to give players the ability to summon multiple pets as the first way of utilizing this technology.
In the case of pets, if enough people summon too many pets at a time, the game will automatically adapt by reducing the polygons and lowering the resolution of all currently summoned pet models.
A Preview of VMR for Pets
Blizzard programmers were kind enough to share with us a few model captures of VMR at different stages.
A pet rendered with 100% VMR appears normal. But as more pets are summoned realm-wide by multiple players, the VMR automatically scales downward.
Grassland Hopper at 90% VMR
Perky Pug at 75% VMR
As a pet's VMR drops, the model becomes more geometric, with less refined textures. Even special effects are reduced.
Restless Shadeling at 60% VMR
Below 50% VMR, you can see how WoW's newest pet models (like the Swamp Croaker) begin to look more like WoW's earliest pet models.
Swamp Croaker at 45% VMR
Eventually polygon counts fall so low that only basic shapes are supported.
Ghostly Skull at 30% VMR
Below 30%, VMR adapts with video rendering techniques that even predate World of Warcraft.
Pengu at 20% VMR
The programmers we spoke to explained that these older rendering techniques have a long and proud history of video game stability.
Fox Kit at 10% VMR
Lost of Lordaeron at 1% VMR
VMR is certainly going to take some getting used to. But on the plus side, we'll all be able to show off thousands of 8-bit pets!
And how will this effect pet battles? Just think of them as retrogaming within WoW.