--- name: PartOperation last_updated: 2026-06-11T17:05:16Z inherits: - TriangleMeshPart - BasePart - PVInstance - Instance - Object type: class memory_category: Instances summary: "An abstract class that all parts based on solid modeling inherit from." --- # Class: PartOperation > An abstract class that all parts based on solid modeling inherit from. ## Description An abstract class that all parts based on [solid modeling](/docs/en-us/parts/solid-modeling.md) inherit from. ## Properties ### Property: PartOperation.RenderFidelity ```json { "type": "RenderFidelity", "access": "ReadOnly", "security": { "read": "None", "write": "PluginSecurity" }, "serialization": { "can_load": true, "can_save": true }, "thread_safety": "ReadSafe", "category": "Appearance", "capabilities": [ "Basic", "CSG" ] } ``` This property determines the level of detail that the solid modeled part will be shown in. It can be set to the possible values of the [RenderFidelity](/docs/reference/engine/enums/RenderFidelity.md) enum except for [Performance](/docs/reference/engine/enums/RenderFidelity.md). The default value is [Automatic](/docs/reference/engine/enums/RenderFidelity.md), meaning the part's detail is based on its distance from the camera as outlined in the following table. | Distance From Camera | Render Fidelity | | --- | --- | | Less than 250 studs | Highest | | 250-500 studs | Medium | | 500 or more studs | Lowest | ### Property: PartOperation.SmoothingAngle ```json { "type": "float", "access": "ReadOnly", "security": { "read": "None", "write": "PluginSecurity" }, "serialization": { "can_load": true, "can_save": true }, "thread_safety": "ReadSafe", "category": "Appearance", "capabilities": [ "Basic", "CSG" ] } ``` This property represents an angle in degrees for a threshold value between face normals on a [solid modeled](/docs/en-us/parts/solid-modeling.md) part. If the normal difference is less than the value, normals will be adjusted to smooth the difference. While a value between 30 and 70 degrees usually produces a good result, values between 90 and 180 are not recommended as they may cause a "shadowing" effect on unions with sharp edges. Note that smoothing does not affect the normals between different materials or different colors. ![Solid modeled part with SmoothingAngle of 0](../../../assets/modeling/solid-modeling/CSG-SmoothingAngle-0.jpg)_[SmoothingAngle](/docs/reference/engine/classes/PartOperation.md) = 0_ ![Solid modeled part with SmoothingAngle of 50](../../../assets/modeling/solid-modeling/CSG-SmoothingAngle-50.jpg)_[SmoothingAngle](/docs/reference/engine/classes/PartOperation.md) = 50_ ### Property: PartOperation.TriangleCount ```json { "type": "int", "access": "ReadOnly", "security": { "read": "None", "write": "RobloxEngineSecurity" }, "serialization": { "can_load": true, "can_save": true }, "thread_safety": "ReadSafe", "category": "Data", "capabilities": [ "Basic", "CSG" ] } ``` The number of polygons in this solid model. ### Property: PartOperation.UsePartColor ```json { "type": "boolean", "access": "ReadWrite", "security": { "read": "None", "write": "None" }, "serialization": { "can_load": true, "can_save": true }, "thread_safety": "ReadSafe", "category": "Data", "capabilities": [ "Basic", "CSG" ] } ``` Sets whether the [PartOperation](/docs/reference/engine/classes/PartOperation.md) can be recolored using the [BasePart.Color](/docs/reference/engine/classes/BasePart.md) or [BasePart.BrickColor](/docs/reference/engine/classes/BasePart.md) properties. When true, the entire union will be colored as per [Color](/docs/reference/engine/classes/BasePart.md) or [BrickColor](/docs/reference/engine/classes/BasePart.md). When false, the parts in the union will maintain their original colors from before the onion operation was performed. ## Methods ### Method: PartOperation:SubstituteGeometry **Signature:** `PartOperation:SubstituteGeometry(source: Instance): ()` Substitutes the geometry of this [PartOperation](/docs/reference/engine/classes/PartOperation.md) with the geometry of another [PartOperation](/docs/reference/engine/classes/PartOperation.md). This makes it easier to utilize the geometry of a solid modeling operation like [UnionAsync()](/docs/reference/engine/classes/GeometryService.md), [SubtractAsync()](/docs/reference/engine/classes/GeometryService.md), or [IntersectAsync()](/docs/reference/engine/classes/GeometryService.md) but maintain properties, attributes, tags, and children of the main part such as [Attachments](/docs/reference/engine/classes/Attachment.md), [Constraints](/docs/reference/engine/classes/Constraint.md), [ParticleEmitters](/docs/reference/engine/classes/ParticleEmitter.md), light objects, decals, and more. This approach also circumvents the potential "flicker" of completely replacing the original [PartOperation](/docs/reference/engine/classes/PartOperation.md) with another. Note that if you're calling this method on a [PartOperation](/docs/reference/engine/classes/PartOperation.md) with child [Attachments](/docs/reference/engine/classes/Attachment.md) or [Constraints](/docs/reference/engine/classes/Constraint.md), you should calculate the affected instances with [CalculateConstraintsToPreserve()](/docs/reference/engine/classes/GeometryService.md), then drop those whose recommended parent is `nil`. *Security: None · Thread Safety: Unsafe · Capabilities: Basic, CSG* **Parameters:** | Name | Type | Default | Description | |------|------|---------|-------------| | `source` | `Instance` | | The [PartOperation](/docs/reference/engine/classes/PartOperation.md) whose geometry will substitute the geometry of this [PartOperation](/docs/reference/engine/classes/PartOperation.md). | **Returns:** `()` **Substitute Geometry and Drop Constraints** The following example substitutes the geometry of one [PartOperation](/docs/reference/engine/classes/PartOperation.md) with the geometry of another [PartOperation](/docs/reference/engine/classes/PartOperation.md), then drops constraints/attachments that should not be preserved after substitution. ```lua local GeometryService = game:GetService("GeometryService") local mainPart = workspace.PurpleBlock local otherParts = { workspace.BlueBlock } local options = { CollisionFidelity = Enum.CollisionFidelity.Default, RenderFidelity = Enum.RenderFidelity.Automatic, SplitApart = false, } local constraintOptions = { tolerance = 0.1, weldConstraintPreserve = Enum.WeldConstraintPreserve.All, } -- Perform union operation in pcall() since it's asyncronous local success, newParts = pcall(function() return GeometryService:UnionAsync(mainPart, otherParts, options) end) if success and #newParts > 0 and mainPart:IsA("PartOperation") then -- Set first part in resulting operation as part to use for substitution -- First part is simply an option; this can be any PartOperation local substitutePart = newParts[1] -- Reposition part to the position of main part substitutePart.CFrame = mainPart.CFrame -- Calculate constraints/attachments to either preserve or drop local recommendedTable = GeometryService:CalculateConstraintsToPreserve(mainPart, newParts, constraintOptions) -- Substitute main part's geometry with substitution geometry mainPart:SubstituteGeometry(substitutePart) -- Drop constraints/attachments that are not automatically preserved with substitution for _, item in pairs(recommendedTable) do if item.Attachment then if item.ConstraintParent == nil then item.Constraint.Parent = nil end if item.AttachmentParent == nil then item.Attachment.Parent = nil end elseif item.WeldConstraint then if item.Parent == nil then item.WeldConstraint.Parent = nil end end end -- Destroy other parts for _, otherPart in pairs(otherParts) do otherPart.Parent = nil otherPart:Destroy() end end ``` ## Inherited Members ### From [TriangleMeshPart](/docs/reference/engine/classes/TriangleMeshPart.md) - **Property `CollisionFidelity`** (`CollisionFidelity`): Determines the level of detail the part's physics will adhere to its mesh. - **Property `FluidFidelity`** (`FluidFidelity`): Determines the geometric representation used to compute aerodynamic forces - **Property `MeshSize`** (`Vector3`): ### From [BasePart](/docs/reference/engine/classes/BasePart.md) - **Property `Anchored`** (`boolean`): Determines whether a part is immovable by physics. - **Property `AssemblyAngularVelocity`** (`Vector3`): The angular velocity of the part's assembly. - **Property `AssemblyCenterOfMass`** (`Vector3`): The center of mass of the part's assembly in world space. - **Property `AssemblyLinearVelocity`** (`Vector3`): The linear velocity of the part's assembly. - **Property `AssemblyMass`** (`float`): The total mass of the part's assembly. - **Property `AssemblyRootPart`** (`BasePart`): A reference to the root part of the assembly. - **Property `AudioCanCollide`** (`boolean`): Determines whether the part will physically interact with audio - **Property `BackParamA`** (`float`): Determines the first parameter for the SurfaceType on the Back face of a *(deprecated, hidden)* - **Property `BackParamB`** (`float`): Determines the second parameter for the SurfaceType on the Back face of a *(deprecated, hidden)* - **Property `BackSurface`** (`SurfaceType`): Determines the type of surface for the back face of a part. - **Property `BackSurfaceInput`** (`InputType`): Determines the kind of input for the Back face of a part. *(deprecated, hidden)* - **Property `BottomParamA`** (`float`): Determines the first parameter for the SurfaceType on the Bottom face of a *(deprecated, hidden)* - **Property `BottomParamB`** (`float`): Determines the second parameter for the SurfaceType on the Bottom face of *(deprecated, hidden)* - **Property `BottomSurface`** (`SurfaceType`): Determines the type of surface for the bottom face of a part. - **Property `BottomSurfaceInput`** (`InputType`): Determines the kind of input for the Bottom face of a part. *(deprecated, hidden)* - **Property `BrickColor`** (`BrickColor`): Determines the color of a part. - **Property `brickColor`** (`BrickColor`): *(deprecated)* - **Property `CanCollide`** (`boolean`): Determines whether a part may collide with other parts. - **Property `CanQuery`** (`boolean`): Determines whether the part is considered during spatial query operations. - **Property `CanTouch`** (`boolean`): Determines if Touched and - **Property `CastShadow`** (`boolean`): Determines whether or not a part casts a shadow. - **Property `CenterOfMass`** (`Vector3`): Describes the world position in which a part's center of mass is located. - **Property `CFrame`** (`CFrame`): Determines the position and orientation of the BasePart in the - **Property `CollisionGroup`** (`string`): Describes the name of a part's collision group. - **Property `CollisionGroupId`** (`int`): Describes the automatically set ID number of a part's collision group. *(deprecated)* - **Property `Color`** (`Color3`): Determines the color of a part. - **Property `CurrentPhysicalProperties`** (`PhysicalProperties`): Indicates the current physical properties of the part. - **Property `CustomPhysicalProperties`** (`PhysicalProperties`): Determines several physical properties of a part. - **Property `Elasticity`** (`float`): Used to control the Elasticity of the part, but it no longer does *(deprecated, hidden)* - **Property `EnableFluidForces`** (`boolean`): Used to enable or disable aerodynamic forces on parts and assemblies. - **Property `ExtentsCFrame`** (`CFrame`): The CFrame of the physical extents of the BasePart. - **Property `ExtentsSize`** (`Vector3`): The actual physical size of the BasePart as regarded by the - **Property `Friction`** (`float`): Used to control the Friction of the part, but now it no longer does *(deprecated, hidden)* - **Property `FrontParamA`** (`float`): Determines the first parameter for the SurfaceType on the Front face of a *(deprecated, hidden)* - **Property `FrontParamB`** (`float`): Determines the second parameter for the SurfaceType on the Front face of a *(deprecated, hidden)* - **Property `FrontSurface`** (`SurfaceType`): Determines the type of surface for the front face of a part. - **Property `FrontSurfaceInput`** (`InputType`): Determines the kind of input for the Front face of a part (-Z direction). *(deprecated, hidden)* - **Property `LeftParamA`** (`float`): Determines the first parameter for the SurfaceType on the Left face of a *(deprecated, hidden)* - **Property `LeftParamB`** (`float`): Determines the second parameter for the SurfaceType on the Left face of a *(deprecated, hidden)* - **Property `LeftSurface`** (`SurfaceType`): Determines the type of surface for the left face of a part. - **Property `LeftSurfaceInput`** (`InputType`): Determines the kind of input for the Left face of a part. *(deprecated, hidden)* - **Property `LocalTransparencyModifier`** (`float`): Determines a multiplier for BasePart.Transparency that is only *(hidden)* - **Property `Locked`** (`boolean`): Determines whether a part is selectable in Studio. - **Property `Mass`** (`float`): Describes the mass of the part, the product of its density and volume. - **Property `Massless`** (`boolean`): Determines whether the part contributes to the total mass or inertia of - **Property `Material`** (`Material`): Determines the texture and default physical properties of a part. - **Property `MaterialVariant`** (`string`): The name of MaterialVariant. - **Property `Orientation`** (`Vector3`): Describes the rotation of the part in the world. *(hidden)* - **Property `PivotOffset`** (`CFrame`): Specifies the offset of the part's pivot from its CFrame. - **Property `Position`** (`Vector3`): Describes the position of the part in the world. *(hidden)* - **Property `ReceiveAge`** (`float`): Time since last recorded physics update. *(hidden)* - **Property `Reflectance`** (`float`): Determines how much a part reflects the skybox. - **Property `ResizeableFaces`** (`Faces`): Describes the faces on which a part may be resized. - **Property `ResizeIncrement`** (`int`): Describes the smallest change in size allowable by the - **Property `RightParamA`** (`float`): Determines the first parameter for the SurfaceType on the Right face of a *(deprecated, hidden)* - **Property `RightParamB`** (`float`): Determines the second parameter for the SurfaceType on the Right face of a *(deprecated, hidden)* - **Property `RightSurface`** (`SurfaceType`): Determines the type of surface for the right face of a part. - **Property `RightSurfaceInput`** (`InputType`): Determines the kind of input for the Right face of a part (-X direction). *(deprecated, hidden)* - **Property `RootPriority`** (`int`): The main rule in determining the root part of an assembly. - **Property `Rotation`** (`Vector3`): The rotation of the part in degrees for the three axes. - **Property `RotVelocity`** (`Vector3`): Determines a part's change in orientation over time. *(deprecated, hidden)* - **Property `Size`** (`Vector3`): Determines the dimensions of a part (length, width, height). - **Property `SpecificGravity`** (`float`): The ratio of the part's density to the density of water determined by the *(deprecated)* - **Property `TopParamA`** (`float`): Determines the first parameter for the SurfaceType on the Top face of a *(deprecated, hidden)* - **Property `TopParamB`** (`float`): Determines the second parameter for the SurfaceType on the Top face of a *(deprecated, hidden)* - **Property `TopSurface`** (`SurfaceType`): Determines the type of surface for the top face of a part. - **Property `TopSurfaceInput`** (`InputType`): Determines the kind of input for the Top face of a part (+Y direction). *(deprecated, hidden)* - **Property `Transparency`** (`float`): Determines how much a part can be seen through (the inverse of part - **Property `Velocity`** (`Vector3`): Determines a part's change in position over time. *(deprecated, hidden)* - **Method `AngularAccelerationToTorque(angAcceleration: Vector3, angVelocity?: Vector3): Vector3`**: Returns the torque needed to achieve a given angular acceleration on this - **Method `ApplyAngularImpulse(impulse: Vector3): ()`**: Apply an angular impulse to the assembly. - **Method `ApplyImpulse(impulse: Vector3): ()`**: Apply an impulse to the assembly at the assembly's - **Method `ApplyImpulseAtPosition(impulse: Vector3, position: Vector3): ()`**: Apply an impulse to the assembly at specified position. - **Method `BreakJoints(): ()`**: Breaks any surface connection with any adjacent part, including *(deprecated)* - **Method `breakJoints(): ()`**: *(deprecated)* - **Method `CanCollideWith(part: BasePart): boolean`**: Returns whether the parts can collide with each other. - **Method `CanSetNetworkOwnership(): Tuple`**: Checks whether you can set a part's network ownership. - **Method `GetClosestPointOnSurface(position: Vector3): Vector3`**: Returns the closest point on the part's surface to the given point. - **Method `GetConnectedParts(recursive?: boolean): List`**: Returns a table of parts connected to the object by any kind of rigid - **Method `GetJoints(): Instances`**: Return all Joints or Constraints that is connected to this Part. - **Method `GetMass(): float`**: Returns the value of the Mass property. - **Method `getMass(): float`**: *(deprecated)* - **Method `GetNetworkOwner(): Instance`**: Returns the current player who is the network owner of this part, or `nil` - **Method `GetNetworkOwnershipAuto(): boolean`**: Returns true if the game engine automatically decides the network owner - **Method `GetNoCollisionConstraints(): Instances`**: - **Method `GetRenderCFrame(): CFrame`**: OBSOLETE. Returns a CFrame describing where the part is being rendered at. *(deprecated)* - **Method `GetRootPart(): Instance`**: Returns the base part of an assembly of parts. *(deprecated)* - **Method `GetTouchingParts(): Instances`**: Returns a table of all BasePart.CanCollide true parts that - **Method `GetVelocityAtPosition(position: Vector3): Vector3`**: Returns the linear velocity of the part's assembly at the given position - **Method `IntersectAsync(parts: Instances, collisionfidelity?: CollisionFidelity, renderFidelity?: RenderFidelity): Instance`**: Note: It is highly recommended to use the newer - **Method `IsGrounded(): boolean`**: Returns true if the object is connected to a part that will hold it in - **Method `MakeJoints(): ()`**: Creates a joint on any side of the object that has a surface ID that can *(deprecated)* - **Method `makeJoints(): ()`**: *(deprecated)* - **Method `Resize(normalId: NormalId, deltaAmount: int): boolean`**: Changes the size of an object just like using the Studio resize tool. - **Method `resize(normalId: NormalId, deltaAmount: int): boolean`**: *(deprecated)* - **Method `SetNetworkOwner(playerInstance?: Player): ()`**: Sets the given player as network owner for this and all connected parts. - **Method `SetNetworkOwnershipAuto(): ()`**: Lets the game engine dynamically decide who will handle the part's physics - **Method `SubtractAsync(parts: Instances, collisionfidelity?: CollisionFidelity, renderFidelity?: RenderFidelity): Instance`**: Note: It is highly recommended to use the newer - **Method `TorqueToAngularAcceleration(torque: Vector3, angVelocity?: Vector3): Vector3`**: Returns the angular acceleration that would result from applying a given - **Method `UnionAsync(parts: Instances, collisionfidelity?: CollisionFidelity, renderFidelity?: RenderFidelity): Instance`**: Note: It is highly recommended to use the newer - **Event `LocalSimulationTouched`**: *(deprecated)* - **Event `OutfitChanged`**: *(deprecated)* - **Event `StoppedTouching`**: *(deprecated)* - **Event `Touched`**: Fires when a part touches another part as a result of physical movement. - **Event `TouchEnded`**: Fires when a part stops touching another part as a result of physical ### From [PVInstance](/docs/reference/engine/classes/PVInstance.md) - **Property `Origin`** (`CFrame`): - **Property `Pivot Offset`** (`CFrame`): - **Method `GetPivot(): CFrame`**: Gets the pivot of a PVInstance. - **Method `PivotTo(targetCFrame: CFrame): ()`**: Transforms the PVInstance along with all of its descendant ### From [Instance](/docs/reference/engine/classes/Instance.md) - **Property `Archivable`** (`boolean`): Determines if an Instance and its descendants can be cloned using - **Property `archivable`** (`boolean`): *(deprecated, hidden)* - **Property `Capabilities`** (`SecurityCapabilities`): The set of capabilities allowed to be used for scripts inside this - **Property `Name`** (`string`): A non-unique identifier of the Instance. - **Property `Parent`** (`Instance`): Determines the hierarchical parent of the Instance. - **Property `PredictionMode`** (`PredictionMode`): - **Property `RobloxLocked`** (`boolean`): A deprecated property that used to protect CoreGui objects. *(hidden)* - **Property `Sandboxed`** (`boolean`): When enabled, the instance can only access abilities in its `Capabilities` - **Property `UniqueId`** (`UniqueId`): A unique identifier for the instance. - **Method `AddTag(tag: string): ()`**: Applies a tag to the instance. - **Method `children(): Instances`**: Returns an array of the object's children. *(deprecated)* - **Method `ClearAllChildren(): ()`**: This method destroys all of an instance's children. - **Method `Clone(): Instance`**: Create a copy of an instance and all its descendants, ignoring instances - **Method `clone(): Instance`**: *(deprecated)* - **Method `Destroy(): ()`**: Sets the Instance.Parent property to `nil`, locks the - **Method `destroy(): ()`**: *(deprecated)* - **Method `FindFirstAncestor(name: string): Instance?`**: Returns the first ancestor of the Instance whose - **Method `FindFirstAncestorOfClass(className: string): Instance?`**: Returns the first ancestor of the Instance whose - **Method `FindFirstAncestorWhichIsA(className: string): Instance?`**: Returns the first ancestor of the Instance for whom - **Method `FindFirstChild(name: string, recursive?: boolean): Instance?`**: Returns the first child of the Instance found with the given name. - **Method `findFirstChild(name: string, recursive?: boolean): Instance`**: *(deprecated)* - **Method `FindFirstChildOfClass(className: string): Instance?`**: Returns the first child of the Instance whose - **Method `FindFirstChildWhichIsA(className: string, recursive?: boolean): Instance?`**: Returns the first child of the Instance for whom - **Method `FindFirstDescendant(name: string): Instance?`**: Returns the first descendant found with the given Instance.Name. - **Method `GetActor(): Actor?`**: Returns the Actor associated with the Instance, if any. - **Method `GetAttribute(attribute: string): Variant`**: Returns the value which has been assigned to the given attribute name. - **Method `GetAttributeChangedSignal(attribute: string): RBXScriptSignal`**: Returns an event that fires when the given attribute changes. - **Method `GetAttributes(): Dictionary`**: Returns a dictionary of the instance's attributes. - **Method `GetChildren(): Instances`**: Returns an array containing all of the instance's children. - **Method `getChildren(): Instances`**: *(deprecated)* - **Method `GetDebugId(scopeLength?: int): string`**: Returns a coded string of the debug ID used internally by Roblox. - **Method `GetDescendants(): Instances`**: Returns an array containing all of the descendants of the instance. - **Method `GetFullName(): string`**: Returns a string describing the instance's ancestry. - **Method `GetStyled(name: string, selector: string?): Variant`**: Returns the styled or explicitly modified value of the specified property, - **Method `GetStyledPropertyChangedSignal(property: string): RBXScriptSignal`**: - **Method `GetTags(): Array`**: Gets an array of all tags applied to the instance. - **Method `HasTag(tag: string): boolean`**: Check whether the instance has a given tag. - **Method `IsAncestorOf(descendant: Instance): boolean`**: Returns true if an Instance is an ancestor of the given - **Method `IsDescendantOf(ancestor: Instance): boolean`**: Returns `true` if an Instance is a descendant of the given - **Method `isDescendantOf(ancestor: Instance): boolean`**: *(deprecated)* - **Method `IsPropertyModified(property: string): boolean`**: Returns `true` if the value stored in the specified property is not equal - **Method `QueryDescendants(selector: string): Instances`**: - **Method `Remove(): ()`**: Sets the object's `Parent` to `nil`, and does the same for all its *(deprecated)* - **Method `remove(): ()`**: *(deprecated)* - **Method `RemoveTag(tag: string): ()`**: Removes a tag from the instance. - **Method `ResetPropertyToDefault(property: string): ()`**: Resets a property to its default value. - **Method `SetAttribute(attribute: string, value: Variant): ()`**: Sets the attribute with the given name to the given value. - **Method `WaitForChild(childName: string, timeOut: double): Instance`**: Returns the child of the Instance with the given name. If the - **Event `AncestryChanged`**: Fires when the Instance.Parent property of this object or one of - **Event `AttributeChanged`**: Fires whenever an attribute is changed on the Instance. - **Event `ChildAdded`**: Fires after an object is parented to this Instance. - **Event `childAdded`**: *(deprecated)* - **Event `ChildRemoved`**: Fires after a child is removed from this Instance. - **Event `DescendantAdded`**: Fires after a descendant is added to the Instance. - **Event `DescendantRemoving`**: Fires immediately before a descendant of the Instance is removed. - **Event `Destroying`**: Fires immediately before (or is deferred until after) the instance is - **Event `StyledPropertiesChanged`**: Fires whenever any style property is changed on the instance, including ### From [Object](/docs/reference/engine/classes/Object.md) - **Property `ClassName`** (`string`): A read-only string representing the class this Object belongs to. - **Property `className`** (`string`): *(deprecated)* - **Method `GetPropertyChangedSignal(property: string): RBXScriptSignal`**: Get an event that fires when a given property of the object changes. - **Method `IsA(className: string): boolean`**: Returns true if an object's class matches or inherits from a given class. - **Method `isA(className: string): boolean`**: *(deprecated)* - **Event `Changed`**: Fires immediately after a property of the object changes, with some