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 😁