[1.8] [SOLVED] Spawning Particle Trail Along a Vector

[Himself12794]

I'm making a flamethrower spell, of sorts, and want it to generate a line of flames.

What I've done is create a projectile that leaves a trail of flames behind it. This works just as I'd like to. I have the entity set to die after a certain distance traveled.

My problem is that when the projectile is thrown, it is able to generate just a few particles before disappearing. If I drop the velocity, I get the fire trail I desire, but the fire is not traveling at the speed expected of a flamethrower.

 

I've tried to get the previous position, the current position, and take the velocity into account to spawn particles in the space between these two vectors, but it's just not working like I want it to, and they are spawning in a line, but not where I want them to.

 

Here's my flawed code:

	
    public void onUpdate(EntitySpell spell) {
	World world = spell.worldObj;
	float distTraveled = getSpellVelocity() * spell.getTicksInAir();

	for (float i = 0.0F; i < getSpellSpeed(); i += getSpellSpeed() * 0.1)
		world.spawnParticle(EnumParticleTypes.FLAME, spell.posX - spell.motionX + i, spell.posY - spell.motionY + i, spell.posZ - spell.motionZ + i, 0.0D, 0.0D, 0.0D, new int[0]);		
	//world.spawnParticle(EnumParticleTypes.FLAME, spell.posX, spell.posY, spell.posZ, 0.0D, 0.0D, 0.0D, new int[0]);

	if (distTraveled > 3) spell.setDead();
	if (spell.getTicksInGround() > 0) spell.setDead();


}

If you  need more context, the whole of my code can be found here: https://github.com/Himself12794/usefulthings/blob/master/src/main/java/com/himself12794/usefulthings/spell/Flames.java

This is the first time I've really messed with vector locations and movement, so I'm a bit new.

[coolAlias]

If you haven't already, it is very helpful to look through the vanilla examples e.g. the critical particles trailing arrows.

 

Gaussian values are also very nice for certain types of particles, but in this case I'd stick with rand.nextFloat() as an addition to each position value.

 

For example:

for (int i = 0; i < 4; ++i) {
world.spawnParticle(EnumParticleTypes.FLAME,
	x + 0.5F - world.rand.nextFloat(),
	y + 0.5F - world.rand.nextFloat(),
	z + 0.5F - world.rand.nextFloat(),
	0, 0, 0));
}

You can place whatever you want in the motion values; the more random, the better (usually). In the example above, I get x, y, and z by iterating along the player's look vector, so that whole section of code is actually in a loop that iterates as far along that vector as I want to go.

 

Each type of particle also has its own motion behavior, so an algorithm that works well for one particle type may not produce the same results with another.

[Izzy Axel]

Sounds like you want to get the player's look vec, and multiply it by i to get various points along it?  I did a similar fire jet effect with my mod's Blaze Staff, but I had it do a for loop that added (rand.nextInt(3) - 1) * rand.nextFloat() to each coordinate, which of course generated a new random number each loop through, making a more organic looking, less perfect stream of fire particles.  I also threw in random rotations, just for good measure.

[Himself12794]

Sounds like you want to get the player's look vec, and multiply it by i to get various points along it?  I did a similar fire jet effect with my mod's Blaze Staff, but I had it do a for loop that added (rand.nextInt(3) - 1) * rand.nextFloat() to each coordinate, which of course generated a new random number each loop through, making a more organic looking, less perfect stream of fire particles.  I also threw in random rotations, just for good measure.

I already have the vector, that is taken from the EntitySpell. That's similar to what I want to do, I'm just unsure how exactly to implement it. Trigonometry was not my strong suit.

[Himself12794]

If you haven't already, it is very helpful to look through the vanilla examples e.g. the critical particles trailing arrows.

 

Gaussian values are also very nice for certain types of particles, but in this case I'd stick with rand.nextFloat() as an addition to each position value.

 

For example:

for (int i = 0; i < 4; ++i) {
world.spawnParticle(EnumParticleTypes.FLAME,
	x + 0.5F - world.rand.nextFloat(),
	y + 0.5F - world.rand.nextFloat(),
	z + 0.5F - world.rand.nextFloat(),
	0, 0, 0));
}

You can place whatever you want in the motion values; the more random, the better (usually). In the example above, I get x, y, and z by iterating along the player's look vector, so that whole section of code is actually in a loop that iterates as far along that vector as I want to go.

 

Each type of particle also has its own motion behavior, so an algorithm that works well for one particle type may not produce the same results with another.

That does work similar to what I'm looking for, however I'd like the spread to be much tighter, and just a little less random. It doesn't seem to be generating a trail, just a bunch of particles where the EntitySpell is at that moment. That formula will be useful though once I figure out the best way to use it on about every 0.2 blocks. Perhaps I get a vector from the caster to the Spell, and maybe I can do something with that?

[Izzy Axel]

That's what I was saying, while the spell is in use, get the player's lookvec, multiply it by a finely stepped number that's above 1, and you have near infinite control over how small the spacing between the particles is, that's how you extend a normalized vector's magnitude.  The more decimal places, the smaller the individual step will be.

 

Edit: didn't see the last bit, you would do something like: (pseudocode)

Vec3 lookVec = player.getLookVec();
for(float i = blahblahblah)
{
    world.spawnParticles(EnumParticleTypes.FLAME, player.posX + (lookVec.xCoord * i),  player.posY + (lookVec.yCoord * i), player.posZ + (lookVec.zCoord * i), 0, 0, 0);
}

[coolAlias]

If you haven't already, it is very helpful to look through the vanilla examples e.g. the critical particles trailing arrows.

 

Gaussian values are also very nice for certain types of particles, but in this case I'd stick with rand.nextFloat() as an addition to each position value.

 

For example:

for (int i = 0; i < 4; ++i) {
world.spawnParticle(EnumParticleTypes.FLAME,
	x + 0.5F - world.rand.nextFloat(),
	y + 0.5F - world.rand.nextFloat(),
	z + 0.5F - world.rand.nextFloat(),
	0, 0, 0));
}

You can place whatever you want in the motion values; the more random, the better (usually). In the example above, I get x, y, and z by iterating along the player's look vector, so that whole section of code is actually in a loop that iterates as far along that vector as I want to go.

 

Each type of particle also has its own motion behavior, so an algorithm that works well for one particle type may not produce the same results with another.

That does work similar to what I'm looking for, however I'd like the spread to be much tighter, and just a little less random. It doesn't seem to be generating a trail, just a bunch of particles where the EntitySpell is at that moment. That formula will be useful though once I figure out the best way to use it on about every 0.2 blocks. Perhaps I get a vector from the caster to the Spell, and maybe I can do something with that?

Please read more carefully - I already said I use the player's look vector to determine the x/y/z and iterate along that, I just left that out of the code example. Of course if you just copy/paste the above without changing anything all of the particles spawn roughly in one location.

 

To get a tighter pattern, reduce the randomness:

coordinate + 0.25F - (rand.nextFloat() * 0.5F) // now the random value can only be +/- 0.25F in either direction

Whereas in my previous example, it was +/- 0.5F in either direction. Random#nextFloat() returns a value between -1.0F and 1.0F, inclusive.

[Himself12794]

 

Please read more carefully - I already said I use the player's look vector to determine the x/y/z and iterate along that, I just left that out of the code example. Of course if you just copy/paste the above without changing anything all of the particles spawn roughly in one location.

 

To get a tighter pattern, reduce the randomness:

coordinate + 0.25F - (rand.nextFloat() * 0.5F) // now the random value can only be +/- 0.25F in either direction

Whereas in my previous example, it was +/- 0.5F in either direction. Random#nextFloat() returns a value between -1.0F and 1.0F, inclusive.

Ah yes, I apologize. I was able to tighten the spread by doing what you did. I was also able to spawn along the line and achieve my desired effect using this code:

			for(float j = 0.0F; j < 1.0F; j += 0.05F) {
			for (int i = 0; i < 10; ++i) {
				world.spawnParticle(EnumParticleTypes.FLAME,
					spell.prevPosX + (spell.motionX * j) - world.rand.nextFloat() * 0.5F,
					spell.prevPosY + (spell.motionY * j) - world.rand.nextFloat() * 0.5F,
					spell.prevPosZ + (spell.motionZ * j) - world.rand.nextFloat() * 0.5F,
					0, 0, 0);
			}
		}

[Himself12794]

That's what I was saying, while the spell is in use, get the player's lookvec, multiply it by a finely stepped number that's above 1, and you have near infinite control over how small the spacing between the particles is, that's how you extend a normalized vector's magnitude.  The more decimal places, the smaller the individual step will be.

 

Edit: didn't see the last bit, you would do something like: (pseudocode)

Vec3 lookVec = player.getLookVec();
for(float i = blahblahblah)
{
    world.spawnParticles(EnumParticleTypes.FLAME, player.posX + (lookVec.xCoord * i),  player.posY + (lookVec.yCoord * i), player.posZ + (lookVec.zCoord * i), 0, 0, 0);
}

That would work, but I've been trying to keep the code tied to the entity spell, and not to the player, so perhaps I could fire the spells without there necessarily being a caster. I found a code that works for me, taking into account your and coolAlias'scode. I posted it at the end, if you're interested.