Ian – Page 9 – MagicalTimeBean

Switched to Integer Math

I was planning for the refactoring of the coordinates system to take two full days, and I am already done with it. I needed to move from floats and Vector2’s to my own fixed-point based structs for position and velocity. I’m a huge fan of integers, and now the Soulcaster engine uses them just like Escape Goat.

World coordinates are now independent from pixels, so I can boost the resolution to HD, and even try a few different tile sizes. I still haven’t figured out what the best visible room size is yet. I might have a bit of zoom like EG2, but there should be a max size that fits the whole screen.

Off The Grid: Research Complete

After a quick rewrite of the collision detection system, and a couple extra AI systems that aid in pathfinding (more on that in a future post), I’ve got the monsters working just how I need them to. Even with a super fast spawn rate, they don’t overlap, and if they get deadlocked trying to get into a doorway from opposite directions, they will back off after a moment and retry.

With omniscient pathing turned on, the rats are completely unstoppable.

This is with pathfinding disabled, and AI set to move Gauntlet style (always towards the player).

Collision Purgatory

Pixel accurate movement has taken a bit longer than I thought it would. I was expecting about one week to get things operational–I think I got 75% of the way there in a week, but now it’s the final 20% that could take up 80% of the time.

Pathfinding and general movement works, but needs hacks to work properly. I created a system to help the monsters file through doorways without getting stuck, but it still relies on a system that temporarily disables clipping for monsters that get stuck together for too long. That system works great for declogging the doorways, but when the monsters get close to the player and start phasing through one another, they just stack in a jumbled, writhing mess. I really want it to look like Gauntlet, with mobs flowing gracefully around corners and stacking into nice grids.

I think my collision detection will also have to move from floating point to fixed point, because accumulation errors are probably one of the causes of clipping bugs among monsters. That change will take at least two days, if not more.

I’m pretty confident it will have been worth the trouble once everything is together. For now, it’s in that purgatorial state where the code is broken and ugly… not a place I like to leave things.

Pathfinding Test With 30 Rats

Pathfinding is operational. The rats intelligently pick new routes to flank the player and avoid congestion in the long term. What they don’t do very well yet is avoid clogging up the doorways when they’re already bunched up. They also unnecessarily zigzag a bit, slowing them down and making them look just a bit more insane.

I have an idea I’m going to try tomorrow that might fix the clogging around doorways. The monsters will have access to a traffic map that tags each tile with a movement vector. They all start out neutral, and when a monster moves into a tile, that tile’s vector is set to match the same direction as the monster’s movement. When inside a tile, a monster has to move along with the current, or vacate the tile. Currents get reset with a timer, so if a monster hasn’t walked on the tile for a few frames, it gets neutralized.

It’s an unusual system, so I don’t know if it’ll work yet, but it’s worth trying.

To fix the zigzagging, I can set the monsters to keep a course for longer. Once they are in sight range of a hero, though, the zigzagging will stop because they stop pathing altogether at that point.