Bouncing Brick Bug

Bug Reports Engine Bugs
#1

The Part is inside a Model. It’s anchored. No velocity. No RotVelocity. So why does the Humanoid bounce up and down on it?

Here’s the raw XML of the model and the part it contains:

<roblox xmlns:xmime="http://www.w3.org/2005/05/xmlmime" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="http://www.roblox.com/roblox.xsd" version="4">
	<External>null</External>
	<External>nil</External>
	<Item class="Model" referent="RBX81BB895BF7B94417B1C1DE1DDFFEC9A2">
		<Properties>
			<CoordinateFrame name="ModelInPrimary">
				<X>0</X>
				<Y>0</Y>
				<Z>0</Z>
				<R00>1</R00>
				<R01>0</R01>
				<R02>0</R02>
				<R10>0</R10>
				<R11>1</R11>
				<R12>0</R12>
				<R20>0</R20>
				<R21>0</R21>
				<R22>1</R22>
			</CoordinateFrame>
			<string name="Name">MapModel</string>
			<Ref name="PrimaryPart">null</Ref>
		</Properties>
		<Item class="Part" referent="RBX0A2D361788974B3C95D8A65421EA49C8">
			<Properties>
				<bool name="Anchored">true</bool>
				<float name="BackParamA">-0.5</float>
				<float name="BackParamB">0.5</float>
				<token name="BackSurface">0</token>
				<token name="BackSurfaceInput">0</token>
				<float name="BottomParamA">-0.5</float>
				<float name="BottomParamB">0.5</float>
				<token name="BottomSurface">4</token>
				<token name="BottomSurfaceInput">0</token>
				<int name="BrickColor">194</int>
				<CoordinateFrame name="CFrame">
					<X>131</X>
					<Y>-4.5</Y>
					<Z>29</Z>
					<R00>1</R00>
					<R01>0</R01>
					<R02>0</R02>
					<R10>0</R10>
					<R11>1</R11>
					<R12>0</R12>
					<R20>0</R20>
					<R21>0</R21>
					<R22>1</R22>
				</CoordinateFrame>
				<bool name="CanCollide">true</bool>
				<float name="Elasticity">0.5</float>
				<float name="Friction">0.300000012</float>
				<float name="FrontParamA">-0.5</float>
				<float name="FrontParamB">0.5</float>
				<token name="FrontSurface">0</token>
				<token name="FrontSurfaceInput">0</token>
				<float name="LeftParamA">-0.5</float>
				<float name="LeftParamB">0.5</float>
				<token name="LeftSurface">0</token>
				<token name="LeftSurfaceInput">0</token>
				<bool name="Locked">false</bool>
				<token name="Material">256</token>
				<string name="Name">Part</string>
				<float name="Reflectance">0</float>
				<float name="RightParamA">-0.5</float>
				<float name="RightParamB">0.5</float>
				<token name="RightSurface">0</token>
				<token name="RightSurfaceInput">0</token>
				<Vector3 name="RotVelocity">
					<X>0</X>
					<Y>0</Y>
					<Z>0</Z>
				</Vector3>
				<float name="TopParamA">-0.5</float>
				<float name="TopParamB">0.5</float>
				<token name="TopSurface">3</token>
				<token name="TopSurfaceInput">0</token>
				<float name="Transparency">0</float>
				<Vector3 name="Velocity">
					<X>0</X>
					<Y>0</Y>
					<Z>0</Z>
				</Vector3>
				<token name="formFactorRaw">0</token>
				<token name="shape">1</token>
				<Vector3 name="size">
					<X>28</X>
					<Y>3</Y>
					<Z>6</Z>
				</Vector3>
			</Properties>
		</Item>
	</Item>
</roblox>
1 Like
#2

I can repro this behavior. It clicked when you said the y position of the brick was -4.5. I experienced a similar anomaly in a place involving purple pool noodles.

Anyone can do this to see it:
3-high sized brick, placed at -4.5 y.

In my place a week ago it happened but the baseplate was 1 high, so it must be where the top surface is located.

I guess that this bug came from the “falling-through”-prevention update that humanoids got so they don’t clip through baseplates from a high height.

Edit: A 1-high sized brick, placed at -3.5 y will do this as well. That’s what I did a week ago by accident. The HumanoidRootPart’s position is coincidentally at exactly 0 y during both experiments.

Edit2: I mean when the RootPart’s Y hits 0, it triggers the legs to go limp, making you fall to -2 y.

#3

So is the temporary solution to this is to move all parts in workspace to a higher Vector3 Y value?

#4

Nah, just move the parts whose topsurface, when standing on, puts your torso/root’s Y-Position to exactly 0.

#5

Hmm, problem still occurring in exactly the same way. :frowning: