Skip to main content

RTS pathfinding

I spent some time today looking at the possibility of adding A* path-finding to my game.

I've used it in the past and I actually got it running pretty fast, even though it's written in python. So I was optimistic about replacing my less than stellar dumb path-finding with A*.

However I ran in to some problems.

First is the fact that I'm working with quite a fine graph, each infantry man takes up one tile, and tanks and the like take up several (a big tank takes up something like a 12x12 chunk of tiles. When you're working with a graph which might be several hundred tiles square, you get slow performance.

When I've used it before I worked with either a pretty course grid, or with navigation nodes.

[a* with grid]

[a* with nodes]
Both these situations give you quite a limited grid and so, good performance.
Working outdoors with such a fine and almost unlimited grid makes the algorithm work too hard, especially when you have a lot of agents.

Looks like I'll have to think more about this. One option would be to use a course grid or node array alongside my fine grid path-finding. That way the agents are just finding their way from one node to another. The curse grid could take in to account such things as rivers and buildings while ignoring vehicles and infantry. If the way to the next node is blocked the agent would just wait for the blockage to clear using the right of way system I mentioned last time.

In fact this is something I prototyped around 2 years ago, using node based a_star path-finding and a path smoothing algorithm.

[node path and smoothing]
When I watch these old videos I'm tempted to go back to the solution I was working on then, which wasn't tile based at all, but free form using beziers. Unfortunately I could never get the problems with colliding agents solved and the result often ended up with troublesome traffic jams.

I think I'm going to leave this for now though, as this doesn't form a part of the basic agent movement actions, rather a part of agent behavior, which will be controlled by the agents finite state machine. The agent can continue to use the dumb pathfinding, and a* will be used to supply some intermediate waypoints when long distance movement is required (by breaking down the agent destination list in to reachable steps).
Labels:

Comments

Post a Comment

Popular posts from this blog

Automating Level imports from Blender to Godot

  Recently I've been making some levels in Blender an importing them into Godot. There are only about 7 or 8 shaders for each level, not counting dynamic objects which will be added later. But to improve rendering performance, it can be a good idea to split the meshes up into sections. At that point you might be faced with a list like this: Or it might be even more chaotic, if you didn't use simple names for the objects in your level. So it can take a long time to sort out all the meshes, make them unique and add textures and so on. Blender imports with simple Blender textures, or with placeholder materials. This is sometimes OK, but if your Godot shaders are very different to those used by Blender, it means applying new materials to every mesh object in the level when you import the scene. I found that during the design process, I was importing and readying a level several times before I was happy with the final layout. So at first I was wasting a lot of time. In Blender, I us
3 comments
Read more

Upstairs / Downstairs.

I've decided to make my prefabs multilevel. Later this should allow me to add pit traps and other great stuff. It also makes it easier to line up stairs so that you can exit them on the same co-ordinates where you entered them. The prefab editor is pretty much finished, it just needs some code for loading up prefabs from a saved dictionary, so that they can be checked or edited. The entries will need to be forwards compatible, so I'll be loading each tile and then translating the indexes to a new array, that way if I add extra indexes or extra info (like traps or puzzles) I'll be able to update existing prefabs to work with the new standard. Click for a video.
6 comments
Read more

Make your game models POP with fake rim lighting.

I was watching one of my son's cartoons today and I noticed they models were using serious amounts of simulated rim lighting . Even though it wasn't a dark scene where you'd usually see such an effect, the result was actually quite effective. The white edge highlighting and ambient occluded creases give a kind of high contrast that is similar to, but different from traditional comic book ink work. I'll be honest, I don't know if there's a specific term for this effect in 3d design, since my major at university was in traditional art. I learned it as part of photography. You can find plenty of tutorials on "what is rim lighting" for photography. It basically means putting your main sources of light behind your subject so that they are lit around the edges. It can produce very arresting photographs, either with an obvious effect when used on a dark subject ... ..,or as part of a fully lit scene to add some subtle highlights. See ho
Post a Comment
Read more