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SvennoJ on 06 August 2015
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Shinobi-san said:
SvennoJ said:

It can't look as amazing because rendering resources are still limited. The physics calculations only off-load the CPU, all the extra persistent rubble and falling pieces still need to be rendered with their own lighting, texturing and shadowing.  More pieces, more memory demands, more geometry to handle, more smoke effects, fire effects.

Targeting 2-4 mbps sounds low, it's not though when you share your internet connection with your household. Plus how far will it spike during big collapses. A lot of new geometry gets created that needs to be send to the clients. (unless things breaking up is scripted and only the falling and collision physics are computed in the cloud) It takes a lot more bandwidth to send geometry than a simple lossless compressed video stream.
For example in their early build they had over 40,000 chunks being tracked by the server. Just updating the position and orientation of those chunks at 30fps is close to 220 mbps. In the new build it looks like there are far less pieces and after stuff hits the ground it stops moving. Yet buildings collapsing into eachother, creating new geometry and everything flying through the air colliding into eachother will make a big spike.

Those bandwidth requirements are why we still don't see any of the various lighting and other rendering enhancements that can be done in the cloud. It simply takes too much bandwidth to do anything that looks substantially better. Physics is the least expensive in bandwidth yet I'm curious how far they can push it and how much will still have to be done by the client. (For example tracking the pieces locally according to simple gravity rules while the server only updates collisions and provides new speed vectors next to introducing new pieces)

People reply to crappy posts all the time, but nobody replies to this :(

Nice post Sven! I didnt realise it required that much bandwidth to make a significant difference on the experience.

Thanks. I've been thinking about it some more (would be an awesome project to work on) and you can smooth out the spikes considerably with forward prediction. You don't have to wait until the rocket hits the building or for one building to hit the other building, the server can predict what's going to happen as long as the player doesn't interfere. That way it can spoon feed the new data beforehand. The tricky part is all the revision (or patches) you need to do when a player does interfere with already computed data which can cascade on.

For example if building A is going to hit building B or building C explodes on rocket impact it might generate a big spike of data to be send within just a few frames. To recieve all that in just 3 frames you might need internet capable of 40 mbps, even though you only need it for 0.1 sec. Since ther server can already predict what's going to happen as soon as you press fire, same with predicting where a building is going when it starts to collapse. The server can start to transmit future data with that 2-4 mbps limit several seconds before the actual impact happens. Basically buffering future data, same way streaming movies keeps running smooth.  (4 mbps is only 17 kilobyte per frame after all)

The hard part is multiple players interfering, and what happens when everyone starts firing rockets into everything at once without any pauses to catch up. A big smoke screen could solve that :)

I also wonder how much overhead this generates by using general distributed computing. It wouldn't surprise me if a single modern physx chip can easily do the same. The difference is that those are now only used to add tons of particles, more realistic water or hair, pure visual enhancements. Nobody wants to make it a requirement so it can't effect gameplay in any way. By sticking it in the cloud, the same experience is available to everyone.

Anyway by what the new demo shows it wouldn't surprise me the least if a high end pc can easily breeze through that without the cloud. The impressive part is that it works with general distributed computing, which means it can run on a virtualized server on any hardware. Of course that's a lot more impressive as a programmer, a gamer doesn't care where it comes from. Well maybe some do judging by the comments.

So I'll take a stab at that flame bait article :) Did MAG turn the ps3 into the most powerful console ever? 256 players together all firing projectiles, never seen before, imagine the possibilities. Yeah, that went far. People complained it looked basic, and that it did for good reason, all those players need to be rendered. Same way all the destruction in Crackdown 3 will still need to be rendered.