Fireball Spell giving inconsistent results because of the look vector

[xKaihatsu]

So I have this fireball spell, and it works, however the direction of the body velocities are inconsistent and change based on a players rotation. Sometimes as shown in the video a fireball doesn’t even move.

CODE

local maxForce = Vector3.new(1e6, 1e6, 1e6)
local lookVector = character.HumanoidRootPart.CFrame.LookVector
	
local bv1 = Instance.new("BodyVelocity")
bv1.MaxForce = maxForce
bv1.Velocity = (lookVector) * force

local bv2 = Instance.new("BodyVelocity")
bv2.MaxForce = maxForce
bv2.Velocity = (lookVector - Vector3.new(0, 0, 1)) * force
	
local bv3 = Instance.new("BodyVelocity")
bv3.MaxForce = maxForce
bv3.Velocity = (lookVector + Vector3.new(0, 0, 1)) * force
	
local bv4 = Instance.new("BodyVelocity")
bv4.MaxForce = maxForce
bv4.Velocity = (lookVector + Vector3.new(0, 0, 1.5)) * force
	
local bv5 = Instance.new("BodyVelocity")
bv5.MaxForce = maxForce
bv5.Velocity = (lookVector - Vector3.new(0, 0, 1.5)) * force

If the full code is needed, then I’ll post it.

[dthecoolest]

Seems like this is a problem caused by the direction vector not being relative to the humanoid root part. Personally I recommend manipulating rotating the humanoid root part along the UpVector to get the new direction:

Consequently, because we are rotating the look vector along the UpVector even if the character gets knocked down it will still cast the spell in front of the chest.

--Angle in degrees cuz degrees are easier to work with
local angle = 25
local upDirection = character.HumanoidRootPart.CFrame.UpVector

local rotateCFrameAlongHumanoidAxis = CFrame.fromAxisAngle(upDirection,math.rad(angle))

local newCFrame2 =  character.HumanoidRootPart.CFrame * rotateCFrameAlongYAxis
local fireBallDirection2 = newCFrame2.LookVector

bv2.Velocity = fireBallDirection2 * force

This is the operation of the CFrame look vector illustrated from the top of the character always(Via the UpVector).

As seen the angle spread will always stay the same as it’s being rotated the same amount from the look vector.

---

Here is what you were doing before for bv3:

bv3.Velocity = (lookVector + Vector3.new(0, 0, 1)) * force

The red arrow in the diagram is the look vector and the black arrow is Vector3.new(0, 0, 1)

When the player is facing along the x axis then:

(lookVector + Vector3.new(0, 0, 1))

Would work but then when you start rotating it player towards the z axis the vector triangle would change and the angle of the spread would be change relative to the red look vector.

[xKaihatsu]

Very interesting solution, but kinda hard for me to understand, so I just rotated the particles part.

CODE

fireburst2.CFrame = character.HumanoidRootPart.CFrame * CFrame.new(3, 0, -6) * CFrame.Angles(0, math.rad(-30), 0)

-- when the time comes to apply the force

local bv2 = Instance.new("BodyVelocity")
bv2.MaxForce = maxForce
bv2.Velocity = (fireburst2.CFrame.LookVector) * force

-- set the parents

bv2.Parent = fireburst2
fireburst2.Parent = workspace

-- optional debris (you'll probably use this though.)
Debris:AddItem(fireburst2, 6)

Thanks for the insight on Vectors though, I’ll refer to this whenever I need to refresh my mind on Vectors and how they work.