Flow, now with ebbs

Flow has some improvements in speed and looks. One of the updates was moving flow to a separate data layer. This allows the flow to go over short cubes, flow through fortifications and so on. But you saw that last week in my #screenshotsaturday post.

This week I was on vacation in Hawaii, so admittedly I wasn’t working on AOG too much. However, with the long flights and half the trip being stormy-rainy weather, I was able to implement active flows and flow out. Active flows are the flows the player will use to power equipment and they are immune to evaporation. When a flow is active it means there is flow moving through that position to somewhere else on the map. Or somewhere off the map, which is where flow outs come in. When a flow finds the edge of a map, that’s a flow out point. The flow out points take their flow level from their source each cycle. The effect this has is to limit the wide spread of flow once it reaches the edge of a map. Combined with active flows, this forms streams on a flat surface. The series of screen shots below show water spreading out from a source cube. At first a wide spread, then when the edge of the map is reached. The number of active flows decreases because most of the water is flowing off map. The flows that are no longer active eventually dry up and leave only the active flows.

I start by placing a flow source.

The water flows and ebbs spreading out from the source.

It continues to do so, and nears an edge of the map.

When it reaches the edge, the water begins to flow out at those points. Eventually, other water dries up and all that remains is a “stream like” flow from the source to the map edge.

Here I’m showing off some of my debugging tools that shows me the path a flow takes. This one is one of the flow out paths.

I love the flooding video. Super nice work. The sad thing is that you will be hired by Blizzard before you'll finished this game ;-)

Thanks, I’m glad you like it. Luckily, I’m working towards a goal of financial independence, so the risk of being hired away is low. Plus I think Blizzard would frown on my “research” days, where I just play games the whole time :)

The latest on flow

Once again, I’ve rewritten flow. I think I’m actually honing in on some kind of optimal solution for my needs. So far in my iterations I’ve come up with two basic methods for moving flow around, push or pull. But first some definitions.

Flow: So far, this is just Water or Lava. 

Cycle: A step through the flow loop. Ideally touches all flowing cubes to update them.

Source cubes: Infinite sources of flow (springs, rivers, etc.). While they will never run out of flow, they have a limited supply of flow per cycle.

Flow cubes: Cubes that have flow in them.

And now the two flow moving methods.

Push:

In this method, I keep track of source cubes. Each cycle these cubes had a certain amount of flow they want to get rid of. So I loop through each source cube, and find somewhere logical to put their flow. This is done by stepping out from source cubes until we find somewhere the flow fits, and then filling in that space. I’d skip past cubes that had full flow, to save the trouble of propagating flow through cubes that are already full, and would be full after. Additionally there’s some smoothing involved that lets us look for places where there’s too much flow, and spread it evenly among it’s neighbors.

Pull:

In this method, I keep track of all the cubes that are not full yet, including empty cubes that are directly adjacent to cubes with water in them. I also keep track of what Y level the cubes are on, lower level cubes get priority. Each cycle I start at the lowest level, and work my way up. This kind of simulates gravity, it makes sure that things will flow down hill before spreading on top of the hill. At each level I select cubes randomly until I’ve gone through all the cubes on that level. When a cube is selected, it follows it’s parent flows back trying to find a source cube. If it finds a source it pulls flow from it. If the source cube is empty for that cycle, it will check it’s parent flow. If the parent flow has two or more flow than the current flow cube, the current flow cube takes 1 unit of flow away. This has kind of a leveling effect.

With both methods I keep track of parent flows. This is required to see if a flow still has a source. This is where I think the pull method works so much better. When there is no source the pull method, it can just seek the highest parent, and take flow from them. See the image below to see what the parent child connections can end up looking like. Here black is the parent and white is the child. Parents can have multiple children, but children can’t have multiple parents. Also, as you can see, flows are non-diagonal only. This simplifies things greatly, but does make for some unintuitive flow paths.

My latest rewrite implemented the pull method. It’s mostly working. There are still a few issues I’m working on, but I’m getting closer. Check out how it looks in the video below. Feel free to ask questions about specifics if you’re trying to implement something similar.