Acceleration

Value Type: Vector3

Description:

The Acceleration property determines how particles ParticleEmitter/Speed changes over the particle’s lifetime. It is defined using a DataType/Vector3 to determine the acceleration on the global X/Y/Z axes. It is measured in studs per second squared. When changed, this property affects all particles emit by the emitter, both current and future particles.

Pictured below are two default ParticleEmitters. The foreground (right) emitter has an Acceleration on the positive-X axis, causing the path of the particles to bend in that direction.
An image of two default ParticleEmitters, wherein the foreground emitter has a +X Acceleration

Acceleration will slow particles down if the vector points in the opposite ParticleEmitter/EmissionDirection in which particles are emitted. Otherwise, it will speed them up. You can use ParticleEmitter/Drag to slow particles down no matter what direction they travel.

Acceleration is most often used to apply a gravity effect to particles (try a value of (0, -3, 0) for this). You can also use small values on the X/Z axes to make it look like particles are being blown away by wind. If you emit a bubble particle downwards, you could use an acceleration of (0, 5, 0) to cause the bubbles to decelerate and then float back upwards.

Code Samples

Creating a Particle Emitter from Scratch

This rather lengthy code sample shows how every property of a ParticleEmitter can be set, including DataType/NumberRange, DataType/NumberSequence and DataType/ColorSequence properties. Below is how the ParticleEmitter should after every property is set. Try playing around with the different properties to customize how the effect looks!

The final product

			
				CODE SAMPLE
			
			
				EXPECTED OUTPUT
			
			
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			local emitter = Instance.new("ParticleEmitter")
-- Number of particles = Rate * Lifetime
emitter.Rate = 5 -- Particles per second
emitter.Lifetime = NumberRange.new(1,1) -- How long the particles should be alive (min, max)
emitter.Enabled = true 

-- Visual properties
emitter.Texture = "rbxassetid://1266170131" -- A transparent image of a white ring
-- For Color, build a ColorSequence using ColorSequenceKeypoint
local colorKeypoints = {
	-- API: ColorSequenceKeypoint.new(time, color)
	ColorSequenceKeypoint.new( 0, Color3.new(1, 1, 1)),  -- At t=0, White
	ColorSequenceKeypoint.new(.5, Color3.new(1, .5, 0)), -- At t=.5, Orange
	ColorSequenceKeypoint.new( 1, Color3.new(1, 0, 0))   -- At t=1, Red
}
emitter.Color = ColorSequence.new(colorKeypoints)
local numberKeypoints = {
	-- API: NumberSequenceKeypoint.new(time, size, envelop)
	NumberSequenceKeypoint.new( 0, 1);    -- At t=0, fully transparent
	NumberSequenceKeypoint.new(.1, 0);    -- At t=.1, fully opaque
	NumberSequenceKeypoint.new(.5, .25);  -- At t=.5, mostly opaque
	NumberSequenceKeypoint.new( 1, 1);    -- At t=1, fully transparent
}
emitter.Transparency = NumberSequence.new(numberKeypoints)
emitter.LightEmission = 1 -- When particles overlap, multiply their color to be brighter
emitter.LightInfluence = 0 -- Don't be affected by world lighting

-- Speed properties
emitter.EmissionDirection = Enum.NormalId.Front -- Emit forwards
emitter.Speed = NumberRange.new(0, 0) -- Speed of zero
emitter.Drag = 0 -- Apply no drag to particle motion
emitter.VelocitySpread = NumberRange.new(0, 0)
emitter.VelocityInheritance = 0 -- Don't inherit parent velocity
emitter.Acceleration = Vector3.new(0, 0, 0)
emitter.LockedToPart = false -- Don't lock the particles to the parent 
emitter.SpreadAngle = Vector2.new(0,0) -- No spread angle on either axis

-- Simulation properties
local numberKeypoints2 = {
	NumberSequenceKeypoint.new(0, 0);  -- At t=0, size of 0
	NumberSequenceKeypoint.new(1, 10); -- At t=1, size of 10
}
emitter.Size = NumberSequence.new(numberKeypoints2)
emitter.ZOffset = -1 -- Render slightly behind the actual position
emitter.Rotation = NumberRange.new(0, 360) -- Start at random rotation
emitter.RotSpeed = NumberRange.new(0) -- Do not rotate during simulation

-- Create an attachment so particles emit from the exact same spot (concentric rings)
local attachment = Instance.new("Attachment", script.Parent)
attachment.Position = Vector3.new(0, 5, 0) -- Move the attachment upwards a little
emitter.Parent = attachment
		

			When you run the code sample, you should see particles that look like the provided animation.
		

			
				
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