singe/docs/learn/09-pictures.singe

-- Lesson 9:  Pictures.  The finished script, exactly as the lesson ends.
dofile("Singe/Framework.singe")

local SHIP_SPEED  = 3
local SHOT_SPEED  = 6
local ROCK_COUNT  = 6
local STAR_COUNT  = 40
local START_LIVES = 3
local HIT_SCORE   = 10

local shipSprite = spriteLoad(DIR .. "art/ship.png")
local rockSprite = spriteLoad(DIR .. "art/rock.png")
local shotSprite = spriteLoad(DIR .. "art/shot.png")
local starSprite = spriteLoad(DIR .. "art/star.png")

local screenWidth  = overlayGetWidth()
local screenHeight = overlayGetHeight()
local shipWidth    = spriteGetWidth(shipSprite)
local shipHeight   = spriteGetHeight(shipSprite)
local rockWidth    = spriteGetWidth(rockSprite)
local rockHeight   = spriteGetHeight(rockSprite)
local shotWidth    = spriteGetWidth(shotSprite)
local shotHeight   = spriteGetHeight(shotSprite)

local shipX   = (screenWidth - shipWidth) / 2
local shipY   = screenHeight - shipHeight - 4
local goLeft  = false
local goRight = false
local rocks   = {}
local shots   = {}
local stars   = {}
local score   = 0
local lives   = START_LIVES
local over    = false


function drawHud()
    overlayPrint(1, 1, "SCORE " .. score)
    overlayPrint(50, 1, "LIVES " .. lives)
    if over then
        overlayPrint(25, 8, "GAME OVER")
        overlayPrint(17, 10, "PRESS 1 TO PLAY AGAIN")
    end
end


function drawRocks()
    for _, rock in ipairs(rocks) do
        spriteDraw(rockSprite, rock.x, rock.y)
    end
end


function drawShots()
    for _, shot in ipairs(shots) do
        spriteDraw(shotSprite, shot.x, shot.y)
    end
end


function drawStars()
    for _, star in ipairs(stars) do
        spriteDraw(starSprite, star.x, star.y)
    end
end


function newRock(rock)
    rock.x     = math.random(0, screenWidth - rockWidth)
    rock.y     = -rockHeight - math.random(0, 160)
    rock.speed = math.random(8, 20) / 10
end


function onInputPressed(what)
    if over then
        if what == SWITCH_START1 then
            startGame()
        end
        return
    end
    if what == SWITCH_LEFT then
        goLeft = true
    elseif what == SWITCH_RIGHT then
        goRight = true
    elseif what == SWITCH_BUTTON1 then
        shots[#shots + 1] = { x = shipX + shipWidth / 2 - shotWidth / 2, y = shipY }
    end
end


function onInputReleased(what)
    if what == SWITCH_LEFT then
        goLeft = false
    elseif what == SWITCH_RIGHT then
        goRight = false
    end
end


function onOverlayUpdate()
    overlayClear()
    updateStars()
    if not over then
        updateShip()
        updateShots()
        updateRocks()
    end
    drawStars()
    drawRocks()
    drawShots()
    spriteDraw(shipSprite, shipX, shipY)
    drawHud()
    return OVERLAY_UPDATED
end


function onShutdown()
    spriteUnload(shipSprite)
    spriteUnload(rockSprite)
    spriteUnload(shotSprite)
    spriteUnload(starSprite)
end


function overlapping(ax, ay, aw, ah, bx, by, bw, bh)
    if ax + aw <= bx then
        return false
    end
    if bx + bw <= ax then
        return false
    end
    if ay + ah <= by then
        return false
    end
    if by + bh <= ay then
        return false
    end
    return true
end


function startGame()
    shipX = (screenWidth - shipWidth) / 2
    score = 0
    lives = START_LIVES
    over  = false
    shots = {}
    for i = 1, ROCK_COUNT do
        rocks[i] = {}
        newRock(rocks[i])
    end
end


function updateRocks()
    for _, rock in ipairs(rocks) do
        rock.y = rock.y + rock.speed
        if rock.y > screenHeight then
            newRock(rock)
        end
        if overlapping(shipX, shipY, shipWidth, shipHeight, rock.x, rock.y, rockWidth, rockHeight) then
            newRock(rock)
            lives = lives - 1
            if lives <= 0 then
                over = true
            end
        end
    end
end


function updateShip()
    if goLeft then
        shipX = shipX - SHIP_SPEED
    end
    if goRight then
        shipX = shipX + SHIP_SPEED
    end
    if shipX < 0 then
        shipX = 0
    end
    if shipX > screenWidth - shipWidth then
        shipX = screenWidth - shipWidth
    end
end


function updateShots()
    for i = #shots, 1, -1 do
        local shot = shots[i]
        local gone = false

        shot.y = shot.y - SHOT_SPEED
        if shot.y + shotHeight < 0 then
            gone = true
        end
        for _, rock in ipairs(rocks) do
            if not gone and overlapping(shot.x, shot.y, shotWidth, shotHeight, rock.x, rock.y, rockWidth, rockHeight) then
                newRock(rock)
                score = score + HIT_SCORE
                gone  = true
            end
        end
        if gone then
            table.remove(shots, i)
        end
    end
end


function updateStars()
    for _, star in ipairs(stars) do
        star.y = star.y + star.speed
        if star.y > screenHeight then
            star.y = 0
            star.x = math.random(0, screenWidth - 1)
        end
    end
end


for i = 1, STAR_COUNT do
    stars[i] = { x = math.random(0, screenWidth - 1), y = math.random(0, screenHeight - 1), speed = math.random(1, 3) / 4 }
end

startGame()