urho3d/bin/Data/LuaScripts/28_Urho2DPhysicsRope.lua

-- Urho2D physics rope sample.
-- This sample demonstrates:
--     - Create revolute constraint
--     - Create roop constraint
--     - Displaying physics debug geometry

require "LuaScripts/Utilities/Sample"

function Start()
    -- Execute the common startup for samples
    SampleStart()

    -- Create the scene content
    CreateScene()

    -- Create the UI content
    CreateInstructions()

    -- Setup the viewport for displaying the scene
    SetupViewport()

    -- Hook up to the frame update events
    SubscribeToEvents()
end

function CreateScene()
    scene_ = Scene()

    -- Create the Octree component to the scene. This is required before adding any drawable components, or else nothing will
    -- show up. The default octree volume will be from (-1000, -1000, -1000) to (1000, 1000, 1000) in world coordinates it
    -- is also legal to place objects outside the volume but their visibility can then not be checked in a hierarchically
    -- optimizing manner
    scene_:CreateComponent("Octree")
    scene_:CreateComponent("DebugRenderer")

    -- Create a scene node for the camera, which we will move around
    -- The camera will use default settings (1000 far clip distance, 45 degrees FOV, set aspect ratio automatically)
    cameraNode = scene_:CreateChild("Camera")
    -- Set an initial position for the camera scene node above the plane
    cameraNode.position = Vector3(0.0, 5.0, -10.0)
    local camera = cameraNode:CreateComponent("Camera")
    camera.orthographic = true
    camera.orthoSize = graphics.height * 0.05
    camera.zoom = 1.5 * Min(graphics.width / 1280, graphics.height / 800) -- Set zoom according to user's resolution to ensure full visibility (initial zoom (1.5) is set for full visibility at 1280x800 resolution)

    -- Create 2D physics world component
    local physicsWorld = scene_:CreateComponent("PhysicsWorld2D")
    physicsWorld.drawJoint = true

    -- Create ground.
    local groundNode = scene_:CreateChild("Ground")
    -- Create 2D rigid body for gound
    local groundBody = groundNode:CreateComponent("RigidBody2D")
    -- Create edge collider for ground
    local groundShape = groundNode:CreateComponent("CollisionEdge2D")
    groundShape:SetVertices(Vector2(-40.0, 0.0), Vector2(40.0, 0.0))

    local y = 15.0
    local prevBody = groundBody

    local NUM_OBJECTS = 10
    for i = 0, NUM_OBJECTS - 1 do
        local node  = scene_:CreateChild("RigidBody")
        -- Create rigid body
        local body = node:CreateComponent("RigidBody2D")
        body.bodyType = BT_DYNAMIC

        -- Create box
        local box = node:CreateComponent("CollisionBox2D")
        -- Set friction
        box.friction = 0.2
        -- Set mask bits.
        box.maskBits = 0xFFFF - 0x0002

        if i == NUM_OBJECTS - 1 then
            node.position  = Vector3(1.0 * i, y, 0.0)
            body.angularDamping = 0.4
            box:SetSize(3.0, 3.0)
            box.density = 100.0
            box.categoryBits = 0x0002
        else
            node.position = Vector3(0.5 + 1.0 * i, y, 0.0)
            box:SetSize(1.0, 0.25)
            box.density = 20.0
            box.categoryBits = 0x0001
        end

        local joint = node:CreateComponent("ConstraintRevolute2D")
        joint.otherBody = prevBody
        joint.anchor = Vector2(i, y)
        joint.collideConnected = false

        prevBody = body
    end

    local constraintRope = groundNode:CreateComponent("ConstraintRope2D")
    constraintRope.otherBody = prevBody
    constraintRope.ownerBodyAnchor = Vector2(0.0, y)
    constraintRope.maxLength = NUM_OBJECTS - 1.0 + 0.01
end

function CreateInstructions()
    -- Construct new Text object, set string to display and font to use
    local instructionText = ui.root:CreateChild("Text")
    instructionText:SetText("Use WASD keys and mouse to move, Use PageUp PageDown to zoom.")
    instructionText:SetFont(cache:GetResource("Font", "Fonts/Anonymous Pro.ttf"), 15)

    -- Position the text relative to the screen center
    instructionText.horizontalAlignment = HA_CENTER
    instructionText.verticalAlignment = VA_CENTER
    instructionText:SetPosition(0, ui.root.height / 4)
end

function SetupViewport()
    -- Set up a viewport to the Renderer subsystem so that the 3D scene can be seen. We need to define the scene and the camera
    -- at minimum. Additionally we could configure the viewport screen size and the rendering path (eg. forward / deferred) to
    -- use, but now we just use full screen and default render path configured in the engine command line options
    local viewport = Viewport:new(scene_, cameraNode:GetComponent("Camera"))
    renderer:SetViewport(0, viewport)
end

function MoveCamera(timeStep)
    -- Do not move if the UI has a focused element (the console)
    if ui.focusElement ~= nil then
        return
    end

    -- Movement speed as world units per second
    local MOVE_SPEED = 4.0

    -- Read WASD keys and move the camera scene node to the corresponding direction if they are pressed
    if input:GetKeyDown(KEY_W) then
        cameraNode:Translate(Vector3(0.0, 1.0, 0.0) * MOVE_SPEED * timeStep)
    end
    if input:GetKeyDown(KEY_S) then
        cameraNode:Translate(Vector3(0.0, -1.0, 0.0) * MOVE_SPEED * timeStep)
    end
    if input:GetKeyDown(KEY_A) then
        cameraNode:Translate(Vector3(-1.0, 0.0, 0.0) * MOVE_SPEED * timeStep)
    end
    if input:GetKeyDown(KEY_D) then
        cameraNode:Translate(Vector3(1.0, 0.0, 0.0) * MOVE_SPEED * timeStep)
    end

    if input:GetKeyDown(KEY_PAGEUP) then
        local camera = cameraNode:GetComponent("Camera")
        camera.zoom = camera.zoom * 1.01
    end

    if input:GetKeyDown(KEY_PAGEDOWN) then
        local camera = cameraNode:GetComponent("Camera")
        camera.zoom = camera.zoom * 0.99
    end
end

function SubscribeToEvents()
    -- Subscribe HandleUpdate() function for processing update events
    SubscribeToEvent("Update", "HandleUpdate")

    -- Unsubscribe the SceneUpdate event from base class to prevent camera pitch and yaw in 2D sample
    UnsubscribeFromEvent("SceneUpdate")
end

function HandleUpdate(eventType, eventData)
    -- Take the frame time step, which is stored as a float
    local timeStep = eventData["TimeStep"]:GetFloat()

    -- Move the camera, scale movement with time step
    MoveCamera(timeStep)

    local physicsWorld = scene_:GetComponent("PhysicsWorld2D")
    physicsWorld:DrawDebugGeometry()

end

-- Create XML patch instructions for screen joystick layout specific to this sample app
function GetScreenJoystickPatchString()
    return
        "<patch>" ..
        "    <remove sel=\"/element/element[./attribute[@name='Name' and @value='Button0']]/attribute[@name='Is Visible']\" />" ..
        "    <replace sel=\"/element/element[./attribute[@name='Name' and @value='Button0']]/element[./attribute[@name='Name' and @value='Label']]/attribute[@name='Text']/@value\">Zoom In</replace>" ..
        "    <add sel=\"/element/element[./attribute[@name='Name' and @value='Button0']]\">" ..
        "        <element type=\"Text\">" ..
        "            <attribute name=\"Name\" value=\"KeyBinding\" />" ..
        "            <attribute name=\"Text\" value=\"PAGEUP\" />" ..
        "        </element>" ..
        "    </add>" ..
        "    <remove sel=\"/element/element[./attribute[@name='Name' and @value='Button1']]/attribute[@name='Is Visible']\" />" ..
        "    <replace sel=\"/element/element[./attribute[@name='Name' and @value='Button1']]/element[./attribute[@name='Name' and @value='Label']]/attribute[@name='Text']/@value\">Zoom Out</replace>" ..
        "    <add sel=\"/element/element[./attribute[@name='Name' and @value='Button1']]\">" ..
        "        <element type=\"Text\">" ..
        "            <attribute name=\"Name\" value=\"KeyBinding\" />" ..
        "            <attribute name=\"Text\" value=\"PAGEDOWN\" />" ..
        "        </element>" ..
        "    </add>" ..
        "</patch>"
end