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An abstract class that all parts based on solid modeling inherit from.



Properties inherited from TriangleMeshPartProperties inherited from BasePartProperties inherited from PVInstance


Methods inherited from BasePartMethods inherited from PVInstance


Events inherited from BasePart



read parallel

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 Enum.RenderFidelity enum.

By default, solid modeled parts will always be shown in precise fidelity, no matter how far they are from the camera. This improves their appearance when viewed from any distance, but if a place has a large number of detailed solid modeled parts, it may reduce overall performance.

Distance From CameraRender Fidelity
Less than 250 studsHighest
250-500 studsMedium
500 or more studsLowest


read parallel

This property represents an angle in degrees for a threshold value between face normals on a solid modeled 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
SmoothingAngle = 0
Solid modeled part with SmoothingAngle of 50
SmoothingAngle = 50


read only
not replicated
read parallel

The number of polygons in this solid model.


read parallel

Sets whether the PartOperation can be recolored using the BasePart.Color or BasePart.BrickColor properties. When true, the entire union will be colored as per Color or BrickColor. When false, the parts in the union will maintain their original colors from before the onion operation was performed.




Substitutes the geometry of this PartOperation with the geometry of another PartOperation. This makes it easier to utilize the geometry of a solid modeling operation like UnionAsync(), SubtractAsync(), or IntersectAsync() but maintain properties, attributes, tags, and children of the main part such as Attachments, Constraints, ParticleEmitters, light objects, decals, and more. This approach also circumvents the potential "flicker" of completely replacing the original PartOperation with another.

Note that if you're calling this method on a PartOperation with child Attachments or Constraints, you should calculate the affected instances with CalculateConstraintsToPreserve(), then drop those whose recommended parent is nil.


source: Instance

The PartOperation whose geometry will substitute the geometry of this PartOperation.



Code Samples

Substitute Geometry and Drop Constraints

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)
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
-- 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
if item.AttachmentParent == nil then
item.Attachment.Parent = nil
elseif item.WeldConstraint then
if item.Parent == nil then
item.WeldConstraint.Parent = nil
-- Destroy other parts
for _, otherPart in pairs(otherParts) do
otherPart.Parent = nil