Inconsistent results using the new SphereCast for projectile hit detection

I am trying to use SphereCasting as a more efficient way to do hit detection for slow to fast moving projectiles. Previously, I was using GetPartsInPart, but it was too heavy for usage in my game.

When testing, there were inconsistent hit results. The projectiles did not always detect a hit.

^Behavior with SphereCasts

^Intended Behavior with GetPartsInPart


Here is the code that CFrames projectiles and SphereCasts.

--manages all active projectiles
	game:GetService("RunService").Heartbeat:Connect(function(step: number)
		if not Players.LocalPlayer.Character then return end
		params.FilterDescendantsInstances = {Players.LocalPlayer.Character.HumanoidRootPart}
		local currentTick = tick()
		for i = #projectiles,1,-1 do
			local projData = projectiles[i]
			if not projData then continue end--or projData.Removing then continue end
			local part = projData.part
			local direction = projData.direction
			local speed = projData.speed
			local despawnTime = projData.despawnTime
			local cache = projData.cache
			--despawning checker
			if despawnTime>0 and currentTick>=despawnTime then
			--move proj
			local increment = step*speed
			part.CFrame = part.CFrame+direction*increment
			--checks for HumanoidRootPart hits
			local sphere = workspace:Spherecast(projData.LastPosition,part.Size.X/2,part.Position-projData.LastPosition,params)
			if sphere then
				local hs = projData.hitSound:Clone()
				hs.Parent = Players.LocalPlayer.Character
			projData.LastPosition = part.Position

I am not sure why this is causing problems, but my current guess is the magnitude of the distance parameter in the SphereCast. It might also be limitations with Raycast detection, but I am not very knowledgeable with Raycast.

1 Like

I believe what may be causing the issue is that you are going through the spheres to quickly for it to detect whether or not you were in the ShapeCast.

That is my problem. I want it to be able to detect a hit even if a player is moving fast through a projectile.

Try placing the ShapeCast further back then the actual sphere itself then. I think that might work. also possibly space the Shapecast away from the other ones.

This only seems to work on certain speeds of projectiles. When I make a slower projectile, it has another set of inconsistent hitting.

Maybe this is the reason why :man_shrugging:


maybe, shapecasts are pretty new so my peanut brain needs to comprehend what is being set before me to learn.

Yeah. That was the issue. I’ll need to figure out some sort of workaround.


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