BasePart

The Anchored property determines whether the part will be immovable by physics. When enabled, a part will never change position due to gravity, other parts collisions, overlapping other parts, or any other physics-related causes. A part that is not anchored is called unanchored. As a result, two anchored parts will never fire the BasePart.Touched event on each other. An anchored part may still be moved by changing its BasePart.CFrame or BasePart.Position, and it still may have a nonzero BasePart.AssemblyLinearVelocity and BasePart.AssemblyAngularVelocity. Finally, if an unanchored part is joined with an anchored part through an object like a Weld, it too will act anchored. If such a joint breaks the part may be affected by physics again. See Understanding Assemblies for more on this.

Network ownership cannot be set on anchored parts. If a part's anchored status changes on the server, the network ownership of that part will be affected.

The angular velocity vector of this part's assembly. It's the rate of change of orientation in radians per second.

Angular velocity is the same at every point of the assembly.

Setting the velocity directly may lead to unrealistic motion. Using Torque or AngularVelocity constraint is preferred, or use BasePart:ApplyAngularImpulse() if you want instantaneous change in velocity.

A position calculated via the mass and position of all the parts in the assembly.

If the assembly has an anchored part, that part's center of mass will be the assembly's center of mass, and the assembly will have infinite mass.

Knowing the center of mass can help the assembly maintain stability. A force applied to the center of mass will not cause angular acceleration, only linear. An assembly with a low center of mass will have a better time staying upright under the effect of gravity.

The linear velocity vector of this part's assembly. It's the rate of change in position of the assembly's center of mass in studs per second.

If you want to know the velocity at a point other than the assembly's center of mass, use BasePart:GetVelocityAtPosition().

Setting the velocity directly may lead to unrealistic motion. Using a VectorForce constraint is preferred, or use BasePart:ApplyImpulse() if you want instantaneous change in velocity.

The sum of the mass of all the parts in this part's assembly. Parts that are Massless and are not the assembly's root part will not contribute to the AssemblyMass.

If the assembly has an anchored part, the assembly's mass is considered infinite. Constraints and other physical interactions between unanchored assemblies with a large difference in mass may cause instabilities.

This property indicates the BasePart automatically chosen to represent the Assembly|assembly's root part. It is the same part that's returned when developers call GetRootPart().

The root part can be changed by changing the RootPriority of the parts in the assembly.

Parts that all share the same AssemblyRootPart are in the same assembly.

For more information on root parts, see Understanding Assemblies.

The BackSurface property determines the type of surface used for the +Z direction of a part. When two parts' faces are placed next to each other, they may create a joint between them. If set to Motor, the BasePart.BackSurfaceInput determines how a motor joint should behave.

Most SurfaceTypes render a texture on the part face if the BasePart.Material is set to Plastic. Some SurfaceTypes - Hinge, Motor and SteppingMotor - will render a 3D adornment instead. If this property is selected in the Properties window, it will be highlighted in the game world similar to that of a SurfaceSelection.

The BottomSurface property determines the type of surface used for the -Y direction of a part. When two parts' faces are placed next to each other, they may create a joint between them. If set to Motor, the BasePart.BottomSurfaceInput determines how a motor joint should behave.

Most SurfaceTypes render a texture on the part face if the BasePart.Material is set to Plastic. Some SurfaceTypes - Hinge, Motor and SteppingMotor - will render a 3D adornment instead. If this property is selected in the Properties window, it will be highlighted in the game world similar to that of a SurfaceSelection.

The BrickColor property determines the color of a part. If the part has a BasePart.Material, this also determines the color used when rendering the material texture. For more control over the color, the BasePart.Color property can be used (it is a Color3 variant of this property). If Color set, this property will use the closest BrickColor.

Other visual properties of a part are determined by BasePart.Transparency and BasePart.Reflectance.

The CFrame property determines both the position and orientation of the BasePart in the world. The part is rendered such that CFrame is the center of the rendered 3D model.

When setting CFrame on a part, other joined parts are also moved relative to the part, but it is recommended that you use PVInstance:PivotTo() to move an entire model, such as when teleporting a player's character.

Unlike setting BasePart.Position, setting CFrame will always move the part to the exact given CFrame; in other words: no overlap checking is done and the physics solver will attempt to resolve any overlap unless both parts are Anchored.

For keeping track of positions relative to a part's CFrame, an Attachment is useful, as its position is always relative to the part's center.

CanCollide determines whether a part will physically interact with other parts. When disabled, other parts can pass through the brick uninterrupted. Parts used for decoration usually have CanCollide disabled, as they need not be considered by the physics engine.

If a part is not BasePart.Anchored and has CanCollide disabled, it may fall out of the world to be eventually destroyed by Workspace.FallenPartsDestroyHeight.

When CanCollide is disabled, parts may still fire the BasePart.Touched event (as well the other parts touching them). You can disable this with BasePart.CanTouch.

More information on collisions, see Detecting Collisions and Collision Filtering.

CanQuery determines whether the part is considered during spatial query operations, such as GetPartBoundsInBox or Raycast. CanCollide must also be disabled when disabling CanQuery. These functions will never include parts whose CanQuery and CanCollide is false.

Beyond this property, it is also possible to blacklist parts which are descendants of a given list of parts using an OverlapParams or RaycastParams object when calling the spatial query functions.

This property determines if Touched and TouchEnded events fire on the part. If true, other touching parts must also have CanTouch set to true for touch events to fire. If false, touch events cannot be set up for the part and attempting to do so will throw an error. Similarly, if the property is set to false after a touch event is connected, the event will be disconnected and the TouchTransmitter removed.

The two images below demonstrate how the property behaves using a non-colliding part with a script telling it to turn green when touched. In the first image, both the large block and falling parts have CanTouch set to true. In the second image, the falling parts have CanTouch set to false.

Note that this collision logic can be set to respect collision groups through the Workspace.TouchesUseCollisionGroups property. If true, parts in non-colliding groups will ignore both collisions and touch events, thereby making this property irrelevant.

Performance

There is a small performance gain on parts that have both CanTouch and CanCollide set to false, as these parts will never need to compute any kind of part to part collisions. However, they can still be hit by Raycasts and OverlapParams queries.

Determines whether or not a part casts a shadow.

Note that this feature is not designed for performance enhancement. It should only be disabled on parts where you want to hide the shadows the part casts. Disabling this property for a given part may cause visual artifacts on the shadows cast upon that part.

The CenterOfMass property describes the local position of a part's center of mass. If this is a single part assembly, this is the AssemblyCenterOfMass converted from world space to local. On simple Parts, the center of mass is always (0,0,0). It can vary for WedgePart or MeshPart however.

The CollisionGroup property describes the name of the part's collision group. Parts start off in the default group whose name is "Default". This value cannot be empty.

The BasePart.CollisionGroupId property describes the ID number of the part's collision group. Parts start off in the "Default" group whose ID is 0. If a part is unregistered, the value becomes -1. This value cannot be less than -1 and it cannot exceed PhysicsService:GetMaxCollisionGroups(). Invalid IDs are clamped.

Although this property can be directly changed, it's recommended that you specify the collision group by setting BasePart.CollisionGroup to the collision group's name.

The Color property determines the color of a part. If the part has a BasePart.Material, this also determines the color used when rendering the material texture. If this property is set, BasePart.BrickColor will use the closest BrickColor to the Color3 value.

Other visual properties of a part are determined by BasePart.Transparency and BasePart.Reflectance.

CurrentPhysicalProperties indicates the current physical properties of the part. You can set custom values for the physical properties per part, custom material, and material override. The Engine prioritizes more granular definitions when determining the effective physical properties of a part. The values in the following list are in order from highest to lowest priority:

• Custom physical properties of the part
• Custom physical properties of the part's custom material
• Custom physical properties of the material override of the part's material
• Default physical properties of the part's material

CustomPhysicalProperties lets you customize various physical aspects of a Part, such as its density, friction, and elasticity.

If enabled, this property let's you configure these physical properties. If disabled, these physical properties are determined by the BasePart.Material of the part. The page for Material contains list of the various part materials.

The CFrame of the physical extents of the BasePart, representing its physcial center.

The actual physical size of the BasePart as regarded by the physics engine, for example in collision detection.

The FrontSurface property determines the type of surface used for the -Z direction of a part. When two parts' faces are placed next to each other, they may create a joint between them. If set to Motor, the BasePart.FrontSurfaceInput determines how a motor joint should behave.

Most SurfaceTypes render a texture on the part face if the BasePart.Material is set to Plastic. Some SurfaceTypes including Hinge, Motor, and SteppingMotor render a 3D adornment instead. If this property is selected in the Properties window, it will be highlighted in the game world similar to that of a SurfaceSelection.

The LeftSurface property determines the type of surface used for the -X direction of a part. When two parts' faces are placed next to each other, they may create a joint between them. If set to Motor, the BasePart.LeftSurfaceInput determines how a motor joint should behave.

Most SurfaceTypes render a texture on the part face if the BasePart.Material is set to Plastic. Some SurfaceTypes including Hinge, Motor, and SteppingMotor render a 3D adornment instead. If this property is selected in the Properties window, it will be highlighted in the game world similar to that of a SurfaceSelection.

The LocalTransparencyModifier property is a multiplier to BasePart.Transparency that is only visible to the local client. It does not replicate from client to server. It is useful for when a part should not render for a specific client, such as how the player does not see their character's body parts when they zoom into first person mode.

The property modifies the local part's transparency increases a part's transparency on a scale from 0 to 1 using the following formula:

-- Calculate the part's client-side transparency. Values greater than 1
	round down to 1. local clientTransparency = part.Transparency + (1 *
	part.localTransparencyModifier)

Take a look at the table below for an example of how this property affect's a part's client-side transparency:

The Locked property determines whether a part (or a model it is contained within) may be selected in Roblox Studio by clicking on it. This property is most often enabled on parts within environment models that aren't being edited at the moment. Roblox Studio has a Lock/Unlock All tool that can toggle the Locked state of every part descendant in a model at once.

Mass is a read-only property that describes the product of a part's volume and density. It is returned by the GetMass function.

• The volume of a part is determined by its Size and its Shape, which varies depending on the kind of BasePart used, such as WedgePart.
• The density of a part is determined by its Material or CustomPhysicalProperties, if specified.

If this property is enabled, the BasePart will not contribute to the total mass or inertia of its assembly as long as it is welded to another part that has mass.

If the part is its own root part according to AssemblyRootPart, this will be ignored for that part, and it will still contribute mass and inertia to its assembly like a normal part. Parts that are massless should never become an assembly root part unless all other parts in the assembly are also massless.

This might be useful for things like optional accessories on vehicles that you don't want to affect the handling of the car or a massless render mesh welded to a simpler collision mesh.

See also Understanding Assemblies, an article documenting what root parts are and how to use them.

The Material property allows a builder to set a part's texture and default physical properties (in the case that BasePart.CustomPhysicalProperties is unset). The default Plastic material has a very light texture, and the SmoothPlastic material has no texture at all. Some material textures like DiamondPlate and Granite have very visible textures. Each material's texture reflects sunlight differently, especially Foil.

Setting this property then enabling BasePart.CustomPhysicalProperties will use the default physical properties of a material. For instance, DiamondPlate is a very dense material while Wood is very light. A part's density determines whether it will float in terrain water.

The Glass material changes rendering behavior on moderate graphics settings. It applies a bit of reflectiveness (similar to BasePart.Reflectance) and perspective distortion. The effect is especially pronounced on sphere-shaped parts (set BasePart.Shape to Ball). Semitransparent objects and Glass parts behind Glass are not visible.

The system searches the MaterialVariant instance with specified MaterialVariant name and BasePart.Material type. If it successfully finds a matching MaterialVariant instance, it uses this MaterialVariant instance to replace the default material. Default material can be the built-in material or an override MaterialVariant specified in MaterialService.

The Orientation property describes the part's rotation in degrees around the X, Y and Z axes using a Vector3. The rotations are applied in Y → X → Z order. This differs from proper Euler angles, and is instead Tait–Bryan angles which describe yaw, pitch and roll. It is also worth noting how this property differs from the CFrame.Angles() constructor, which applies rotations in a different order (Z → Y → X). For better control over the rotation of a part, it is recommended that BasePart.CFrame is set instead.

When setting this property any Welds or Motor6Ds connected to this part will have the matching C0 or C1 property updated and to allow the part to move relative to any other parts it is joined to.

WeldConstraints will also be temporarily disabled and re-enabled during the move.

This property specifies the offset of the part's pivot from its CFrame, that is part:GetPivot() is the same as part.CFrame * part.PivotOffset.

This is convenient for setting the pivot to a location in local space, but setting a part's pivot to a location in world space can be done as follows:

local part = workspace.BluePart
local desiredPivotCFrameInWorldSpace = CFrame.new(0, 10, 0)
part.PivotOffset = part.CFrame:ToObjectSpace(desiredPivotCFrameInWorldSpace)

The Position property describes the coordinates of a part using a Vector3. It reflects the position of the part's BasePart.CFrame, however it can also be set.

When setting this property any Welds or Motor6Ds connected to this part will have the matching C0 or C1 property updated and to allow the part to move relative to any other parts it is joined to.

WeldConstraints will also be temporarily disabled and re-enabled during the move.

This returns the time in seconds since the part's physics got last updated on the local client (or the server). Returns 0 when the part has no physics (Anchored)

The Reflectance property determines how much a part reflects the skybox. A value of 0 indicates the part is not reflective at all, and a value of 1 indicates the part should fully reflect.

Reflectance is not affected by BasePart.Transparency, unless the part is fully transparent, in which case reflectance will not render at all. Reflectance may or may not be ignored depending on the BasePart.Material of the part.

The ResizeIncrement property is a read-only property that describes the smallest change in size allowable by the BasePart:Resize() method. It differs between implementations of the BasePart abstract class. For instance, Part has this set to 1 and TrussPart has this set to 2 (since individual truss sections are 2x2x2 in size).

The ResizeableFaces property (with an e, not ResizableFaces) describes using a Faces object the different faces on which a part may be resized. For most implementations of BasePart, such as Part and WedgePart, this property includes all faces. However, TrussPart will set its ResizeableFaces set to only two faces since those kinds of parts must have two BasePart.Size dimensions of length 2. This property is most commonly used with tools used for building and manipulating parts and has little use outside of that context. The Handles class, which has the Handles.Faces property, can be used in conjunction with this property to display only the handles on faces that can be resized on a part.

The RightSurface property determines the type of surface used for the +X direction of a part. When two parts' faces are placed next to each other, they may create a joint between them. If set to Motor, the BasePart.RightSurfaceInput determines how a motor joint should behave.

Most SurfaceTypes render a texture on the part face if the BasePart.Material is set to Plastic. Some SurfaceTypes including Hinge, Motor, and SteppingMotor will render a 3D adornment instead. If this property is selected in the Properties window, it will be highlighted in the game world similar to that of a SurfaceSelection.

This property is an integer between -127 and 127 that takes precedence over all other rules for root part sort. When considering multiple parts that are not Anchored and which share the same Massless value, a part with a higher RootPriority will take priority over those with lower RootPriority.

You can use this property to control which part of an assembly is the root part and keep the root part stable if size changes.

See also Understanding Assemblies, an article documenting what root parts are and how to use them.

The rotation of the part in degrees for the three axes.

When setting this property any Welds or Motor6Ds connected to this part will have the matching C0 or C1 property updated and to allow the part to move relative to any other parts it is joined to.

WeldConstraints will also be temporarily disabled and re-enabled during the move.

A part's Size property determines its visual dimensions, while ExtentsSize represents the actual size used by the physics engine, for example in collision detection. The individual dimensions (length, width, height) can be as low as 0.001 and as high as 2048. Size dimensions below 0.05 will be visually represented as if the part's dimensions are 0.05.

The size of the part determines its mass which is given by BasePart:GetMass(). The BasePart.Shape of a part can apply some restrictions on size; namely, a shape of PartType.Ball must have the same three dimensions.

A part's Size is also used by a variety of other objects:

• ParticleEmitter to determine the area from which particles are spawned.
• BlockMesh to partially determine the rendered rectangular prism.
• SpecialMesh for certain MeshTypes, to determine the size of the rendered mesh.
• SurfaceLight to determine the space to illuminate.

The TopSurface property determines the type of surface used for the +Y direction of a part. When two parts' faces are placed next to each other, they may create a joint between them. If set to Motor, the BasePart.TopSurfaceInput determines how a motor joint should behave.

Most SurfaceTypes render a texture on the part face if the BasePart.Material is set to Plastic. Some SurfaceTypes - Hinge, Motor and SteppingMotor - will render a 3D adornment instead. If this property is selected in the Properties window, it will be highlighted in the game world similar to that of a SurfaceSelection.

The Transparency property controls the visibility of a part on a scale of 0 to 1, where 0 is completely visible (opaque), and a value of 1 is completely invisible (not rendered at all).

BasePart.Reflectance can reduce the overall transparency of a brick if set to a value close to 1.

While fully transparent parts are not rendered at all, partially transparent objects have some significant rendering costs. Having many translucent parts may slow down the game's performance.

When transparent parts overlap, render order can act unpredictable - try to keep semi-transparent parts from overlapping to avoid this.

The BasePart.LocalTransparencyModifier is a multiplier to Transparency that is only visible to the local client.

Applies an instant angular force impulse to this part's assembly, causing the assembly to spin.

The resulting angular velocity from the impulse relies on the assembly's mass. So a higher impulse is required to move more massive assemblies. Impulses are useful for cases where you want a force applied instantly, such as an explosion or collision.

If the part is owned by the server, this function must be called on a server Script. If the part is owned by a client, this function can be called on a LocalScript or server Script.

This function applies an instant force impulse to this part's assembly.

The force is applied at the assembly's center of mass, so the resulting movement will only be linear.

The resulting velocity from the impulse relies on the assembly's mass. So a higher impulse is required to move more massive assemblies. Impulses are useful for cases where you want a force applied instantly, such as an explosion or collision.

If the part is owned by the server, this function must be called on a server Script. If the part is owned by a client, this function can be called on a LocalScript or server Script.

This function applies an instant force impulse to this part's assembly, at the specified position in world space.

If the position is not at the assembly's center of mass, the impulse will cause a positional and rotational movement.

The resulting velocity from the impulse relies on the assembly's mass. So a higher impulse is required to move more massive assemblies. Impulses are useful for cases where developers want a force applied instantly, such as an explosion or collision.

If the part is owned by the server, this function must be called on a server Script. If the part is owned by a client, this function can be called on a LocalScript or server Script.

Breaks any surface connection with any adjacent part, including Weld and other JointInstance.

Returns whether the parts can collide with each other or not. This function takes into account the collision groups of the two parts. This function will error if the specified part is not a BasePart.

The CanSetNetworkOwnership function checks whether you can set a part's network ownership.

The function's return value verifies whether or not you can call BasePart:SetNetworkOwner() or BasePart:SetNetworkOwnershipAuto() without encountering an error. It returns true if you can modify/read the network ownership, or returns false and the reason you can't, as a string.

Returns a table of parts connected to the object by any kind of rigid joint.

If recursive is true this function will return all of the parts in the assembly rigidly connected to the BasePart.

Rigid Joints

When a joint connects two parts together (Part0 → Part1), a joint is rigid if the physics of Part1 are completely locked down by Part0. This only applies to the following joint types:

• Weld
• Snap
• ManualWeld
• Motor
• Motor6D
• WeldConstraint

Return all Joints or Constraints that is connected to this Part.

GetMass returns the value of the read-only Mass property.

This function predates the Mass property. It remains supported for backward-compatibility; you should use the Mass property directly.

Returns the current player who is the network owner of this part, or nil in case of the server.

Returns true if the game engine automatically decides the network owner for this part.

Returns the base part of an assembly. When moving an assembly of parts using a CFrame. it is important to move this base part (this will move all other parts connected to it accordingly).

More information is available in the Understanding Assemblies article.

This function predates the AssemblyRootPart property. It remains supported for backward-compatibility; you should use the AssemblyRootPart property directly.

Returns a table of all parts that are physically interacting with this part. If the part itself has CanCollide set to false, then this function returns an empty table unless the part has a TouchInterest object parented to it (meaning something is connected to its Touched event). Parts that are adjacent but not intersecting are not considered touching. This function predates the WorldRoot:GetPartsInPart() function, which provides more flexibility and avoids the special TouchInterest rules described above. Use WorldRoot:GetPartsInPart() instead.

Returns the linear velocity of the part's assembly at the given position relative to this part. It can be used to identify the linear velocity of parts in an assembly other than the root part. If the assembly has no angular velocity, than the linear velocity will always be the same for every position.