X and z velocity for custom physics[HELP NEEDED]

[Kilpamations (Kilp)]

Hello! I am wondering how to make a curved trajectory for a ball while using custom physics because when I try to it does an upside-down V shape instead. I am trying to avoid bezier curves because they will make it difficult to account for gravity. This is what my code looks like right now:

function module.Stepped(ball)
	local prevpos
	local stepped
	local bouncing = false
	local canbounce = true
	local bouncefactor = 0.5
	local i = 0
	
	local justbounced = false
	local hitpeak = false
	local peak = 20
	local maxbounce = 3
	local bounces = 0
	stepped = run.RenderStepped:Connect(function(dt)
		if not bouncing then
			i +=dt 
		elseif bouncing then
			i-= dt
		end
		if ball.Parent.Parent == nil then stepped:Disconnect() end
		if prevpos and ball:GetAttribute("LerpID") == nil and not bouncing then -- checks if the ball hasn't been hit yet
		
			ball:SetAttribute("Velocity", Vector3.new(0,  -workspace.Gravity/500 ,0) )
			ball.Position += ball:GetAttribute("Velocity") * i
		elseif not prevpos then
		
			ball:SetAttribute("Velocity", Vector3.new(0,  -workspace.Gravity/500 ,0) )
			ball.Position += ball:GetAttribute("Velocity") * i
		end
		local rayparams = RaycastParams.new()
		rayparams.CollisionGroup = "ServerBall"
		rayparams.IgnoreWater = true
		local groundray = workspace:Raycast(ball.Position, Vector3.yAxis * -1, rayparams)
		
		if groundray then
			if groundray.Instance and (groundray.Instance.Name == "Court" or groundray.Instance.Name == "Baseplate") and justbounced == false and canbounce == true and bounces < maxbounce then
				canbounce = false
					bouncing  = true
					justbounced = true
					bounces += 1
					ball.Anchored = true
					print("bounce")
					ball:SetAttribute("Velocity", ball:GetAttribute("Velocity") * Vector3.new(1,-1,1) * bouncefactor)
			
					justbounced = false
					task.spawn(function()
					task.wait(0.3)
					canbounce = true
					end)
				
			elseif bounces >= maxbounce then
				bouncing = false
				
			end
		end
		if bouncing == true and justbounced == false then
			if math.abs(ball.Position.Y - peak) < 2 and ball:GetAttribute("Velocity").Y > 0 then
				
				hitpeak = true
				ball:SetAttribute("Velocity", Vector3.new(0, -workspace.Gravity/500,0))
				bouncing = false
				peak = peak/1.7
				i=0
				task.wait(0.2)
				hitpeak = false
			else
				
			local gravity = Vector3.new(0, workspace.Gravity, 0)
			
				print(ball:GetAttribute("Velocity"))
			ball.Position += (ball:GetAttribute("Velocity") ) * i 
			end
		end
		 prevpos = ball.Position
	end)
end

There is no x and z axis implementation yet. Help is appreciated; thank you!

[Kilpamations (Kilp)]

bump bump bu,mp bump bump bump

[Kilpamations (Kilp)]

I forgot to mention but it is only for the bounce of the ball when it hits the ground

[Den_vers]

Are you using a gravity simulation? Give the ball a velocity, ballVelocity (Vector3) and a gravity constant gravity (number).

local RS = game:GetService("RunService")

local ball = path.to.ball

local gravity = 10
local ballVelocity = Vector3.zero

RS.RenderStepped:Connect(function(dt)
    ballVelocity = Vector3.new(ballVelocity.X, ballVelocity.Y - (gravity * dt), ballVelocity.Z)
    ball.Position += ballVelocity * dt
end)

Are you using a system like this?

[Kilpamations (Kilp)]

yes I’m using a similar system; here is what I referenced :homework and exercises - Simple mathematical model for a bouncing ball - Physics Stack Exchange

[Kilpamations (Kilp)]

also I am already using a gravity constant, which is workspace.Gravity/500. The vertical bouncing works good, but I am worried about horizontal bouncing

[Kilpamations (Kilp)]

bump bump bump bump bump need help

[Kilpamations (Kilp)]

bump again… if nobodys gonna help i guess ill have to use bezier curves

[happya_x (Happya)]

height = vt + 1/2at^2 where v is initial velocity, t is time, and a is gravity

assuming no air resistance, the position of the ball is a function of time given by

Vector3.new(
  xVelocity * time, 
  upwardInitialVelocity * time + gravity * (time^2) / 2,
  zVelocity * time
)

then when you bounce just reset time and decrease the initial upward velocity

[Kilpamations (Kilp)]

How would I calculate the upwards initial velocity?

[happya_x (Happya)]

you dont calculate it

its just how much you push the ball upwards at first

after each bounce you should divide it by like 1.3 or something

[Kilpamations (Kilp)]

so would it be (nextpos-startpos)/time?
Like how would you know how much you push the ball upwards at first?

[happya_x (Happya)]

the first one is a random number like 10

then when you bounce you divide by how much energy you want to lose

in the real world its all different for different surfaces/materials so its whatever you want to choose to make it look realistic

[Kilpamations (Kilp)]

So it isnt realy initial velocity then? Just a bouncefactor?

[Kilpamations (Kilp)]

also when it search it up it says the equation for initial velocity is u = v-at

[Kilpamations (Kilp)]

Alright I figured out the solution. Reference this sprite sheet for projectile motion:Horizontal and Vertical Velocity of a Projectile
as you can see, the x and z velocities never change, but the Y velocity accelerates due to gravity. So just accelerate the y axis velocity and keep the x and z axis velocities constant. Tweak the speed to your liking, but it works.