第 7 章 — 声音和音乐

local backGroup
local mainGroup
local uiGroup

local explosionSound
local fireSound


local function updateText()
    livesText.text = "Lives: " .. lives
    scoreText.text = "Score: " .. score
end

    ship:addEventListener( "tap", fireLaser )
    ship:addEventListener( "touch", dragShip )

    explosionSound = audio.loadSound( "audio/explosion.wav" )
    fireSound = audio.loadSound( "audio/fire.wav" )
end

local function onCollision( event )

    if ( event.phase == "began" ) then

        local obj1 = event.object1
        local obj2 = event.object2

        if ( ( obj1.myName == "laser" and obj2.myName == "asteroid" ) or
             ( obj1.myName == "asteroid" and obj2.myName == "laser" ) )
        then
            -- Remove both the laser and asteroid
            display.remove( obj1 )
            display.remove( obj2 )

            -- Play explosion sound!
            audio.play( explosionSound )

            for i = #asteroidsTable, 1, -1 do
                if ( asteroidsTable[i] == obj1 or asteroidsTable[i] == obj2 ) then
                    table.remove( asteroidsTable, i )
                    break
                end
            end

        elseif ( ( obj1.myName == "ship" and obj2.myName == "asteroid" ) or
                 ( obj1.myName == "asteroid" and obj2.myName == "ship" ) )
        then
            if ( died == false ) then
                died = true

                -- Play explosion sound!
                audio.play( explosionSound )

                -- Update lives
                lives = lives - 1
                livesText.text = "Lives: " .. lives

                if ( lives == 0 ) then
                    display.remove( ship )
                    timer.performWithDelay( 2000, endGame )
                else
                    ship.alpha = 0
                    timer.performWithDelay( 1000, restoreShip )
                end
            end
        end
    end
end

local function fireLaser()

    -- Play fire sound!
    audio.play( fireSound )

    local newLaser = display.newImageRect( mainGroup, objectSheet, 5, 14, 40 )
    physics.addBody( newLaser, "dynamic", { isSensor=true } )
    newLaser.isBullet = true
    newLaser.myName = "laser"

    newLaser.x = ship.x
    newLaser.y = ship.y
    newLaser:toBack()

    transition.to( newLaser, { y=-40, time=500,
        onComplete = function() display.remove( newLaser ) end
    } )
end

local explosionSound
local fireSound
local musicTrack

    explosionSound = audio.loadSound( "audio/explosion.wav" )
    fireSound = audio.loadSound( "audio/fire.wav" )
    musicTrack = audio.loadStream( "audio/80s-Space-Game_Looping.wav")
end

local composer = require( "composer" )

-- Hide status bar
display.setStatusBar( display.HiddenStatusBar )

-- Seed the random number generator
math.randomseed( os.time() )

-- Reserve channel 1 for background music
audio.reserveChannels( 1 )

audio.reserveChannels( 1 )命令告诉 Solar2D 音频库保留通道 1。 保留后，除非我们明确命令它，否则不会在通道上播放任何音频文件。接下来，让我们降低通道 1 的整体音量。 当您从

这实质上是告诉音频系统以

-- Reserve channel 1 for background music
audio.reserveChannels( 1 )
-- Reduce the overall volume of the channel
audio.setVolume( 0.5, { channel=1 } )

50% 音量 (0.5)播放通道 1 上的任何音频文件。 如果您觉得音乐相对于音效而言太大声或太安静，您可能需要在游戏中调整此音量。现在，保存 main.lua 并返回到编辑器中的 game.lua。 当场景完全显示在屏幕上时，我们将开始播放音乐，因此在 scene:show() 函数的 "did" 阶段条件中，添加以下行

-- show()
function scene:show( event )

    local sceneGroup = self.view
    local phase = event.phase

    if ( phase == "will" ) then
        -- Code here runs when the scene is still off screen (but is about to come on screen)

    elseif ( phase == "did" ) then
        -- Code here runs when the scene is entirely on screen
        physics.start()
        Runtime:addEventListener( "collision", onCollision )
        gameLoopTimer = timer.performWithDelay( 500, gameLoop, 0 )
        -- Start the music!
        audio.play( musicTrack, { channel=1, loops=-1 } )
    end
end

loops=-1告诉音频系统无限重复（循环）该文件。这些添加应该会在您的应用程序中播放音乐。 确保保存修改后的 main.lua 和 game.lua 文件，然后重新启动模拟器。 玩游戏，您现在应该听到循环的音乐曲目以及音效。