I don't know that anyone would have done a dedicated engine for that since it's not something you can really just apply to everything. I've done some pretty detailed ones before but there's no way I could pull an engine out of them.
It's kind of hard to help with something that's so simple and so variable. Exactly how you implement it differs depending on the game and what you want it to look like. If you can tell us the specific problem you're having with it we can help with that, but 'blood particle effect engine' is pretty general.
Well, I'm making a platformer hack'n'slash, it's sidescrolling and fairly realistic. So I need just a general blood (and decapitation, WOOT) engine, just a bit of particles.
Here's the trouble: I make particles, but they all disappear at the same distance, and the sprites are bad, and they don't go up in the air and then arch down, they just fly straight, and overall it just looks terrible.
but they all disappear at the same distance
--add random(2)+1 to alterable value A(bloodparticle)
alterable value A(bloodparticle) > 50
bloodparticle collides with the backdrop
--bloodparticle: paste into background
Adjust the values as needed.
and the sprites are bad
Can't help you with that. Well, I could, but I'm not going to.
and they don't go up in the air and then arch down, they just fly straight
Well the easiest way to do that is to make them bouncing ball objects and use the direction calculator to rotate them towards direction 24.
A better way would be to give them the same gravity coding that you would for a custom platform movement, and give them all a random initial 'up velocity' value.
And horizontal randomness of some sort would be a good idea too, but that would require some fine-tuning. The easiest way to do that would just be to make them a bouncing ball object (but with custom gravity), but ONLY set them to either left(16) or right(0) initially (preferably the opposite direction to where the player is standing for realism), and give them random speeds. Maybe.
I haven't tried MMF2 since that horrible beta, but I assume the built-in fastloop should work fine. Direction calculator, if it hasn't got a built-in equivalent by now, might not be ported yet. Like I said direction calculator is a cheap way to do it though.
I forgot how I did blood/sparks, but I think all I did was use the particle spray thing, then adjusted the wind/grav stuff according to direction of shot. And for blood sticking to things, just paste to background.
Not sure about flying parts, but maybe you can stick a particle spray when moving a part out. I'm wondering how to get a sprite to walk around with a severed body part though without drawing multiple sprites.
I could probably make an example if you really insist, but I don't have my comp right now and university's making me sleep at > 12 AM and waking up at 6 AM . Maybe next week at best, as seeing 350 ml of blood coming from my arm 2 hours ago put me out of the mood for gore. But as it is, making a 360 deg bullet engine & a blood engine in MMF2's kinda high on my list this month.
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