Roblox塔防游戏碰撞组脚本报错：该API仅支持服务器端调用

报错原因 #

你遇到的this api can only be used on server错误，核心原因是：PhysicsService:RegisterCollisionGroup和PhysicsService:CollisionGroupSetCollidable属于服务器专属API，只能在ServerScript中调用，你现在把这些逻辑放在了客户端的LocalScript里，触发了权限限制。

解决方案思路 #

1. 提前在服务器端注册好所有需要的碰撞组并设置碰撞规则，客户端不碰碰撞组注册逻辑
2. 客户端仅负责塔的位置预览，实际塔的生成和碰撞组设置交给服务器处理
3. 通过RemoteEvent实现客户端与服务器的通信，请求服务器生成正式塔

步骤1：服务器端注册碰撞组 #

在ServerScriptService新建一个ServerScript，提前注册碰撞组并配置规则：

local PhysicsService = game:GetService("PhysicsService")

-- 注册所需碰撞组（仅在未注册时执行）
local collisionGroups = {"Tower", "Player", "Monster"}
for _, groupName in ipairs(collisionGroups) do
    if not PhysicsService:IsCollisionGroupRegistered(groupName) then
        PhysicsService:RegisterCollisionGroup(groupName)
    end
end

-- 设置碰撞规则：塔不与玩家、怪物、其他塔碰撞
PhysicsService:CollisionGroupSetCollidable("Tower", "Player", false)
PhysicsService:CollisionGroupSetCollidable("Tower", "Monster", false)
PhysicsService:CollisionGroupSetCollidable("Tower", "Tower", false)

步骤2：修改客户端LocalScript（仅做预览） #

移除客户端中所有PhysicsService相关调用，专注于塔的位置预览和放置请求：

local UserInputService = game:GetService("UserInputService")
local RunService = game:GetService("RunService")
local camera = workspace.CurrentCamera
local towerToSpawn = nil
local gui = script.Parent
local replicatedstorage = game:GetService("ReplicatedStorage")
local towers = replicatedstorage:WaitForChild("Towers")
-- 获取用于通信的RemoteEvent（需提前在ReplicatedStorage创建）
local placeTowerEvent = replicatedstorage:WaitForChild("PlaceTowerEvent")

local function MouseRaycast(blacklist)
    local mousePosition = UserInputService:GetMouseLocation()
    local mouseRay = camera:ViewportPointToRay(mousePosition.X,mousePosition.Y)
    local raycastParams = RaycastParams.new()
    
    raycastParams.FilterType = Enum.RaycastFilterType.Blacklist
    raycastParams.FilterDescendantsInstances = blacklist
    
    local raycastResult = workspace:Raycast(mouseRay.Origin, mouseRay.Direction * 1000, raycastParams)
    return raycastResult
end

local function AddPlaceHolderTower(name)
    local towerExists = towers:FindFirstChild(name)
    if towerExists then
        towerToSpawn = towerExists:Clone()
        -- 创建客户端专属预览容器（仅当前玩家可见）
        local clientPreview = workspace:FindFirstChild("ClientPreview") or Instance.new("Folder")
        clientPreview.Name = "ClientPreview"
        clientPreview.Parent = workspace
        -- 标记预览塔的视觉样式
        for _, object in ipairs(towerToSpawn:GetDescendants()) do
            if object:IsA("BasePart") then
                object.Material = Enum.Material.ForceField
                object.Transparency = 0.5
            end
        end
        towerToSpawn.Parent = clientPreview
    end
end

gui.Gunslinger.Activated:Connect(function()
    AddPlaceHolderTower("Gunslinger")
end)

UserInputService.InputBegan:Connect(function(input, processed)
    if processed or not towerToSpawn then return end
    if input.UserInputType == Enum.UserInputType.MouseButton1 then
        local result = MouseRaycast({towerToSpawn})
        if result and result.Instance then
            -- 计算正确的生成位置
            local spawnPos = result.Position + Vector3.new(0, towerToSpawn.Humanoid.HipHeight + towerToSpawn.PrimaryPart.Size.Y/2, 0)
            -- 请求服务器生成正式塔
            placeTowerEvent:FireServer("Gunslinger", spawnPos)
            -- 销毁预览塔
            towerToSpawn:Destroy()
            towerToSpawn = nil
        end
    end
end)

RunService.RenderStepped:Connect(function()
    if towerToSpawn then
        local result = MouseRaycast({towerToSpawn})
        if result and result.Instance then
            local spawnPos = result.Position + Vector3.new(0, towerToSpawn.Humanoid.HipHeight + towerToSpawn.PrimaryPart.Size.Y/2, 0)
            towerToSpawn:SetPrimaryPartCFrame(CFrame.new(spawnPos))
        end
    end 
end)

步骤3：服务器处理塔生成请求 #

1. 在ReplicatedStorage中创建RemoteEvent，命名为PlaceTowerEvent
2. 在ServerScriptService新建ServerScript，处理客户端的放置请求：

local replicatedstorage = game:GetService("ReplicatedStorage")
local PhysicsService = game:GetService("PhysicsService")
local towers = replicatedstorage:WaitForChild("Towers")
local placeTowerEvent = replicatedstorage:WaitForChild("PlaceTowerEvent")

placeTowerEvent.OnServerEvent:Connect(function(player, towerName, spawnPosition)
    local towerTemplate = towers:FindFirstChild(towerName)
    if not towerTemplate then return end
    
    -- 生成正式塔并设置位置
    local newTower = towerTemplate:Clone()
    newTower.Parent = workspace.Towers
    newTower:SetPrimaryPartCFrame(CFrame.new(spawnPosition))
    
    -- 为塔的所有零件设置碰撞组
    for _, part in ipairs(newTower:GetDescendants()) do
        if part:IsA("BasePart") then
            part.CollisionGroup = "Tower"
        end
    end
end)

内容的提问来源于stack exchange，提问作者Twebs Playz