function init_event()
    local crate_texture = ag.loadTexture("checker.jpg")
    local ground = ag.createPlaneStatic(0, 0, 1, 0)
    ground:setColor(0.2, 1.0, 0.2)
    ground:setTexture(crate_texture)
    ag.setCamera(10, -10, 10, 0, 0, 0)

    if (ag.import("rot_camera") ~= true) then
        ag.println("error importing rot_camera")
        ag.exit()
    end
end

function init_obj(obj)
    obj:setColor(math.random(), math.random(), math.random())
    obj:setPosition((math.random() - 0.5) * 10, (math.random() - 0.5) * 10, 10)
end

-- function update_event()
--     rot_camera()
-- end

function key_down_event(key)
    if     (key == "b") then
        local box = ag.createBox(1, 1, 1)
        init_obj(box)
    elseif (key == "c") then
        -- cylinders are buggy in ODE
        local cyl = ag.createCylinder(0.5, 1)
        init_obj(cyl)
    elseif (key == "a") then
        local ccyl = ag.createCapsule(0.5, 1)
        init_obj(ccyl)
    elseif (key == "s") then
        local sphere = ag.createSphere(0.8)
        init_obj(sphere)
    elseif (key == "q") then
        ag.exit()
    end
end