Thursday, 6 June 2013

Urban Galaxy 3D assets - part2:Smaller fillers

In the first part we talked about the main set of assets that define the level. We described the process that led as to the final form of the buildings used in the levels and how we finally came up with what we have now, that is building sets with the ability to fit perfectly with each other.

In the second part we will talk about the extras, smaller assets that add more variety and character to the levels. This is actually the spice, that extra 20% that makes the difference (http://en.wikipedia.org/wiki/Pareto_principle).

GIG company garage
A beauty shot of a garage filler placed on top of a building

Starting thoughts

Having ready the main buildings layout in the level it was time to start developing additional fillers, that was a no-brainer. At the beginning fillers started as small 3D assets that one could find in a city, some street lights, traffic lights, flora elements, some shops. The whole idea behind was to think of fillers that would add some motion to the unmoving scene, bringing more life to the city.
The principle behind developing those fillers was yet again reusability. This time the specs were forced due to the presence of buildings that most of the fillers are attached to as well as from the hard specifications of those buildings (since the actual building had 500-700 polys and a 512x512 map, no filler would get larger specs that those).
Again the fillers were produced in sets and been grouped that way in texture, so instead of having 5 or 6 smaller textures for a set of traffic fillers you had only one shared with various other city assets in a larger texture. That was a good decision as more assets good derive by reusing the same texture on a different mesh - actually we still are adding more assets even to the first filler texture we created -.

Hands on

Ok, so what exactly is a filler set right now and how it is broken? A filler set is defined by a basic texture of 512x512 dimensions and a set of 3D meshes that are mapped on this texture. The basic thought here is reusability and small size. Each mesh tri-count varies between 130 and 450 tris. We try to be proportionate tri-count to asset size (more tris->bigger asset). Each filler set has approximately 10 different meshes of various sizes but as we move on more assets are added to the filler set.
What's implied above is that the base of a filler set is its texture. If that is carefully designed it can accomodate a long list of different assets on it. Currently on Urban Galaxy the filler sets are organised thematic.

Some assets from city fillers set


Lets take for example the basic city fillers set containing lights, power stations, antennas, signs, traffic lights. When we started the game development this set contained only some city lights and signs with most of its texture space unused. As we moved on we started adding similar assets to the filler set and currently the texture is fully used.

The city filler set texture right now.
There are 12-14 different assets on the set and more can easily be added as we come up with more ideas. 
When you design a texture that is to be used by various 3D meshes as filler assets you must keep the texture as generic as possible to avoid repeatability on distinctive elements in a level. As you can see in the above texture the repeatable elements are the sign letters "CITY ALTITUDE LIMITS" and the model name on the vertical train.

Update/Upgrade  iteration

Playing around with all those fillers in level design we created a set of levels. The levels were great but...they were still not that different. Navigating those levels and watching the various neighbourhoods from a far distance revealed the problem. Reusability of buildings and fillers turned against us as repeatability. Having only big assets, buildings, and small assets, smaller fillers, left a gap in the middle asssets area. In order to address this problem we took two steps, actually building bigger assets using filler textures and introducing building add-on fillers using the actual building textures.

Current state


Urban Galaxy, animated vertical train with some traffic in the background

Having a rich set of asset variations to create fancy and distinctive levels we started building up the levels of the game. The evolution of the assets as well as the underline engine can go nowhere but up. This means that we always keep an eye for new ideas and things that will make Urban Galaxy levels more rich and alive. Currently where we stand we have animated fillers, introduced particles on fillers (aka smoke), created filler ships to simulate traffic inside the level. Some future thoughts include a working horizontal train that goes around the level, some more fancy ads, under-construction area assets....and more to come!


We would love to hear more thoughts and suggestions on assets directly from you or even get more technical on some matters.

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