Nasty Bubbling Death Goo

Let's talk a bit about how some of the new visuals in T-SOL work. The new fire area features a nasty hazard in the form of a deep pool of boiling goo which rapidly sucks away Saul's HP. It took some effort to get a reasonable look. It still needs work but further visual polish is something that is going to wait until later. Here it is!

Originally the deadly goo was simply a translucent layer. Boring. Really really boring.

At first I considered animated tiles but decided against it. I don't like needing to both make something that animates well and tiles well too. That's difficult and time consuming. Also if we decide to change the goo's look later on I'd need do the animation work all over again. So, instead, I made bubbles using particle effects. The effect itself started out simple. It emits particles out of a box and makes them accelerate upward. But this presented a problem.

Yeah. Bubbles floating into space looks rather silly. My first fix was to use Sprite Masks which will prevent the particles from drawing outside of the area of the goo.

No more silly floating bubbles. But the result looks really unnatural. After some research (reading the manual) I found that it's possible to have a particle in an effect spawn an additional effect. This is done with some simple settings on the particle effect and a tiny bit of code

The Triggers section, in the top image, is what fires the code in GooBubblePop. The goo's space is contained in a collider. When any particle leaves the collider the code in GooBubblePop runs. That happens because the Triggers section is set to Callback on particles Outside the collider. The code then tells the particle to activate a Sub Emitter which fires the effect GooBubblesPop. The code also kills the bubble to prevent it from floating into space and looking weird.

This, along with a second particle emitter which produces wavy clouds gives the goo its final look. Eventually I'd like to add a bit more depth to the goo. It still looks like a flat block on top of the map to me. I'm also considering some way of making the top of the liquid undulate a bit to emphasize the bubbles. But for now, it is done! Yay!