Roblox - Rotating a Model

Question

I am working on a game which allows some buildings to be placed and procedurally rotated.

I found the following rotation code which I am trying to incorporate:

function TransformModel(objects, center, new, recurse)
    for _,object in pairs(objects) do
        if object:IsA("BasePart") then
            object.CFrame =     new:toWorldSpace(center:toObjectSpace(object.CFrame))
        end
        if recurse then
            TransformModel(object:GetChildren(), center, new, true)
        end
    end
end

which is invoked as follows in my building placement script:

local center = model:GetModelCFrame()
TransformModel( model:GetChildren(), center, center * CFrame.Angles(0,math.rad(45),0), true )

So the code works, somewhat... The model does sort of rotate but only after it jumps into the air and lands haphazardly before finally settling down in the rotated position, although its far from an exact 45 degree rotation after the physics effect of jumping in the air and settling back down.

I am not quite sure but I suspect there is a better way to accomplish this where the model smoothly rotates. Any help would be greatly appreciated.

Thanks, Andy

UristMcSparks UristMcSparks · Accepted Answer · 2016-03-25T18:24:34

GetModelCFrame is a deprecated method. It is instead recommended to utilize the PrimaryPart, GetPrimaryPartCFrame, and SetPrimaryPartCFrame. Setting the primary part designates a specific part in the model to serve as a base that you can move around via its CFrame. What's nice about this approach is that if you transform the PrimaryPart of a Model with these methods, all of the other parts in the Model will also transform to maintain their offset from the PrimaryPart.

For placing buildings and props, it is usually desired to have this part be a flat part at the bottom that represents the footprint of the building.

For example, consider the following model:

In this case the best part to make the primary part would be the one on the bottom. If your model doesn't have a part incorporated in the geometry then you can make an invisible and cancollide false part to serve as the base. In the following example, there is a tree model that doesn't have a wide base, but we want to make sure the footprint is large enough that it wouldn't overlap with other nearby objects:

In this case the yellow part should be made fully transparent at runtime.

So in terms of the code to actually orient a model in the way you want, all you have to do is call SetPrimaryPartCFrame with the new CFrame. The TransformModel function simply becomes:

local function TransformModel(model, newCFrame)
    model:SetPrimaryPartCFrame(newCFrame)
end

When you want to call this function to say rotate a model 45 degrees:

local model = game.Workspace.Model
model.PrimaryPart = model.Base
local rotatedCFrame = model:GetPrimaryPartCFrame() * CFrame.Angles(0, math.rad(45), 0)

TransformModel(model, rotatedCFrame)

Roblox - Rotating a Model

2 Answers