Y offset issues with interpolate

imjustmike

Apologies for the wall of text, hopefully this makes sense. Hopefully.

I'm currently running into some issues trying to dynamically shift an actor's Y position.

I have a game where actor A and actor B move horizontally to the hero character. When actor A collides with the hero a point is scored and actor A is destroyed. The hero has to jump of actor B. I wanted to have an interp effect on the hero to make it constantly grow and shrink a little bit, whilst sitting on a platform, giving the illusion of getting taller and shorter. Unfortunately this interp effect causes the collision rules to go wrong - they don't fire when the hero's size is being interpolated.

Easy enough I thought, I'll have another (invisible) actor behind the hero, without all of the interp effects. The collision rules will trigger with this invisible actor, and I'll constrain the Y to the hero actor, so that when one jumps the other does.

Unfortunately, I now have a hero actor with a height that grows and shrinks repeatedly, with a fixed Y position, not sitting on top of a platform. Which means that instead of sitting flat on a platform and getting taller, it grows from a fixed point in the middle.

What I want to happen is create an offset to the Y position, to give the illusion that it's getting taller, not growing from the middle.

I've tried what seems to make sense in my head: constrain self.position.y to game.hero_y+(self.size.height/2) but for some reason this prevents the interp rules from kicking in at all.

So back to the drawing board - anyone have any suggestions of where to look?

gyroscope

Hi @imjustmike here's a different approach you might want to try:

Interpolate the height to what you want, and over the same time, Interpolate to the actual final y position.

Here's a sample of what i mean:

imjustmike

@gyroscope‌ that's a great shout. Annoyingly it won't work quite perfectly due to the timings of interps not quite lining up but it smooths it out a lot! Thanks

RThurman

@imjustmike‌ -- your first way should work. Just use
(self.size.height/2) + (whatever Y position should be the bottom)

I think its the "game.hero_y" that is throwing things off. Are you sure you want that for the bottom Y position?

imjustmike

@RThurman‌ Well I actually have an offset in there too to find the bottom Y. My issue is that using this rule actually prevents the interp rules from kicking in. Which is strange.

RThurman

Take a look at the attached file. Is it what you are looking for?

imjustmike

@RThurman‌ that's exactly right. Bizarrely it's almost exactly what I was using, but in a different order. Didn't think that would make a difference, but apparently it does. THANK YOU!