LoveExample-5..10 设置指针可见性、获取输入键等

接下来的几篇 demo 都很简单，一片一片的写没什么意义，说起来之前三篇其实也可以合起来，事已至此，先这样吧

[5] 获取鼠标按键，代码本身就已经做了很好地说明了：

function love.load()
   love.graphics.setFont(love.graphics.newFont(11))
end
function love.draw()
    -- Left mouse button.
    if love.mouse.isDown(1) then
        love.graphics.print("Left mouse button is down", 50, 50)
    end
    -- Right mouse button.
    if love.mouse.isDown(2) then
        love.graphics.print("Right mouse button is down", 50, 100)
    end
    -- Middle mouse button.
    if love.mouse.isDown(3) then
        love.graphics.print("Middle mouse button is down", 50, 75)
    end 
end
​

[6] 设置鼠标可见性，配合之前说的图片跟随鼠标，就可以设置自定义鼠标样式了：

function love.load()
    -- Hide mouse on startup.
    love.mouse.setVisible(false)
    love.graphics.setFont(love.graphics.newFont(11))
end
-- Toggle cursor visibility.
function love.keypressed(k)
    if k == "v" then
	if love.mouse.isVisible() then
	    love.mouse.setVisible(false)
	else
	    love.mouse.setVisible(true)
	end
    end
end
function love.draw()
    love.graphics.print("Press V to toggle visibility.", 50, 50)
end
​

需知道的是，这个 love.keypressed 方法，只需要声明，不需要调用，可以想象这个方法是一直在线的。

[7] 挂起，作用大概就是阻塞 update 方法吧（示例看不出个啥效果）

function love.update(dt)
    -- Sleeps 10ms after each udpate. By doing this,
    -- CPU time is made available for other processes,
    -- and your OS will love you for it.
    love.timer.sleep(0.01)
end
​

[8] 忘了咋翻译了，分别代表了一秒钟的帧数和两帧时间间隔

function love.load()
    love.graphics.setFont(love.graphics.newFont(11))
end
function love.draw()
    -- Draw the current FPS.
    love.graphics.print("FPS: " .. love.timer.getFPS(), 50, 50)
    -- Draw the current delta-time. (The same value
    -- is passed to update each frame).
    love.graphics.print("dt: " .. love.timer.getDelta(), 50, 100)
end
​

[9] 获取时间毫秒数（至于从何开始计算的就不清楚了，自查 Wiki 吧）

function love.load()
    -- Get time before the code to be timed.
    t_start = love.timer.getTime()
    -- Load 10 fonts.
    for i=13,22 do
        local f = love.graphics.newFont(i)
        love.graphics.setFont(f)
    end 
    -- Get time after.
    t_end = love.timer.getTime()
end
function love.draw()
    love.graphics.print("Spent ".. (t_end-t_start) .. " seconds loading 10 fonts.", 50, 50)
end
​

[10] 获取按键

function love.load()
    love.graphics.setFont(love.graphics.newFont(11))
end

function love.draw()
    -- Checks whether the return key is down or not.
    if love.keyboard.isDown("return") then
        love.graphics.print("The return key is down.", 50, 50)
    else
        love.graphics.print("The return key isn't down.", 50, 50)
    end
end
​

下一篇预告：创建使用动画
代码挺多的，需要好好看看 😁