Look at

Setup

This example shows how to rotate a game object to look at the mouse cursor. It reads the mouse position in on_input and uses the mathematical function math.atan2(x, y) to calculate the angle between the ray to the point to look at and the positive x-axis. This angle is used to set the rotation of the game object to always look at the mouse position.

The example is suitable for the movement in two dimensions, for platformers or top-down games. For 3D objects, check out the next example.

Scripts

look_at.script

function init(self)
    -- make sure the script will receive user input
    msg.post(".", "acquire_input_focus")
end

local function look_at(target_position)
    -- own positon
    local my_position = go.get_position()

    -- calculate the angle that this object has to rotate to look at the given point
    local angle = math.atan2(my_position.x - target_position.x, target_position.y - my_position.y)
    -- set rotation as a quaternion
    go.set_rotation(vmath.quat_rotation_z(angle))
end

function on_input(self, action_id, action)
    -- mouse/finger movement has action_id set to nil
    if not action_id then
        -- the position to look at (mouse/finger)
        local target_position = vmath.vector3(action.x, action.y, 0)
        -- rotate this object to look at the target position
        look_at(target_position)
    end
end

If you want to play with these examples, you can get the project on Github.

Do you want to see more examples? Why not write a few yourself and submit a pull request? We love contributions.

GITHUB