THE GLORIOUS ROBOT ARMY HAS BEEN CREATED

Working on these guys made me pull in all of the knowledge of unreal and blender I’ve learned over the years. I’ll break it down into hurdles that I had to overcome.

1.) Retargeting skeletons

All of these models have their own skeletons, and each animation that you import has its own skeleton assignment. For the life of me I had no idea how to swap animations that I imported from version 1 of a model to version 2 (i.e. all of the skeleton bones had the same names). I went down a dark path of ik rigging just to realize I should’ve just right clicked a single animation.

…nuts…I had to re-import the assault rifle because I removed the stock for the bot and I made a new animation for the bot:

2.) Making the bots reload.

Again so the goal was to make the bots throw a physical object into the air so that the player would have the opportunity to shoot it. This is a crazy concept that requires a lot of tweaking to get right. The idea here is that I mark a point on the back of the bot as a “throw point” where I spawn a mag.

Then Unreal has a system called “Animation Notifies” which lets me communicate from an animation asset through an animation blueprint back to the controlled pawn.

You can see there are two here: “release Mag” which is the bot dropping a mag and “Spawn Mag” which creates and throws the new mag.

These are then tied to triggers within the animation blueprint to call back to the pawn.

Honestly not a great system but its apparently how unreal wants us to handle these things. Ideally you would have a nicer hierarchy of ownership but making what I would consider “Good” software left the room once I decided to go with blueprints.

3.) Unreal’s AI is helpful and horrible at the same time.

The tree I showed yesterday was very simplistic relative to this. When looking at this the first reaction is “oh yeah that makes sense” then “wait why would you do it this way” then finally “I don’t understand what this picture is”. So quick explanation: start at the root node, go down to the sequence node which triggers the nodes below it from left to right. The green box uptop is called a “service” and essentially is a while(true) loop that triggers while the sequence is executing. The blue boxes are if checks that happen before executing each node, for example “doIHaveAmmo” is used twice here and checks if the bot has ammo before executing. In the event that these blueboxes return false the entire sequence is canceled and you go back to the first node in the sequence(which in this case is the reload node).

4.) Niagra confuses me and I might get back into HLSL to avoid it

I made the muzzle flashes but I still kinda hate how they look. I started trying to make some 2d stuff but that ended up not really working:

The idea there was to try to make a ribbon that had a sinewave of width that would be lower frequency and a radial sinewave that would give bumps on the side. That didn’t really work however.

Then I got creative with making a mesh in blender and importing it in as the firecloud that comes out the front of the gun.

I stuck with that 2nd iteration and it seems like its better than the ribbon but I still want some more cloud-ness to it.

When firing (as seen above) it kinda looks like an orb just kinda spawned in front of your barrel. Most other games try to do this with 2d sprites however I’m a big fan of 3d sprite muzzle flashes like those from the tf2 announcement trailer:

Image taken from : https://gamebanana.com/mods/198837

I might just add some more spikes onto the current model and call it quits on that front.

Now next up for work is probably the environment, I have a bunch of reference images of place I thought were cool in boston and the surrounding area I’m going to try to generate some textures using them as inspiration. I then eventually have to do audio but I’m really dreading looking back into unreal’s dsp system. It’s very intense (and I literally do hardware based DSP in my day job).

Woo! Got some animations in game, I made the mistake of thinking that Unreal engine control rigs were actually something useful for what I’m doing. Once I found that out I just gritted my teeth and did the whole animation process in blender and transferred it over into unreal.

These animations will definitely need to be remade at some point but I’ll punt on that until I think I have a level of robot shooting going on.

I tried being clever and pretty much wasted 6 hours….

I spent a bunch of time rigging up this model, a large portion of the time was spent undoing the dumb modifiers I put on the legs. Specifically I used array modifiers and mirror modifiers to generate the legs after making the first one.

Using this technique ensures that when you finally go to export you need to manually re-assign origins somewhere on the model which is something you really need to keep track of when rigging properly.

This all went good but I decided to put the bones 90 degrees offset because I thought it would make it nicer to manipulate. Which I would say is true if I was going to manually manipulate the bones. However, I tried getting smart and moving into unreal engine control rigs: https://dev.epicgames.com/documentation/en-us/unreal-engine/control-rig-in-unreal-engine

Which in theory should let me animate in unreal, which would save me an export/debug step which I normally have to do from blender. However I kept hitting weird issues with setting up controls and having unreal auto-recognize things… Then I noticed the issue once I tried testing the physics asset:

So that isn’t good. Essentially unreal makes a set of simple geometric shapes that it glues onto your model when you import to try to get a good collision box setup. In this case me twisting the bones make the system give up and just surrounded the body with a capsule and legs with one big box:

So I attempted to fix this (which looked good)

…But then I hit the next problem…

What’s going on here is that there’s a parenting loop going on. Looking back at the original model I put the bones 90 degrees offset from the mesh (again because I think I’m smarter than how everyone does stuff).

With the bones offset from the mesh I had to apply the physics geometries to the mesh itself rather than the bone. So then unreal was trying to modify the position of the mesh, but the bone had no constraints to the physics so it tried putting the mesh back, then the physics manipulated the mesh, then the bone manipulated the mesh, then the physics manipulated the mesh, then the bone manipulated the mesh….So that comes out with the result you see above which is everything kind of giving up. The fix here is to re-orient the bones so I can attach the physics geometries to the bone….I basically wasted my morning setting myself up for failure. However this is the first complex mechanical mesh I’ve ever done so it’s still a learning experience in my head.