尝试在 Lua/Love2D 中绘制平台时出错

Question

这里是 Lua/游戏开发的新手。我正在尝试编写代码来绘制我的游戏背景。对于与设置相关的事情，我有四个不同的精灵表：

• 背景 - 包​​含绘制的游戏“背景图像”
• 平台 - 包含游戏的平台精灵
• objectsBig - 包含背景中相对较大的绘制对象（例如岩石、海藻等）
• objectsSmall - 包含相对较小的绘制对象（较小的岩石、植物等）

我创建了一个名为generateQuads() 的函数，该函数位于我的Util.lua 文件中，给定一个精灵表，它将它拼接成精灵表中的不同精灵并返回这些精灵。如下：

-- Function to generate quads/cut the spritesheet
function generateQuads(atlas, tileWidth, tileHeight)
    local sheetWidth = atlas:getWidth() / tileWidth
    local sheetHeight = atlas:getHeight() / tileHeight
local sheetCounter = 1
local quads = {}

-- for every line of the sprite sheet
for y = 0, sheetHeight - 1 do
    -- for every piece in the width
    for x = 0, sheetWidth - 1 do
        -- quads generated will be the ones specified by tileWidth and tileHeight
        quads[sheetCounter] = love.graphics.newQuad(x * tileWidth, y * tileHeight, tileWidth, 
            tileHeight, atlas:getDimensions())
        sheetCounter = sheetCounter + 1
    end
end

return quads

end

我还有一个名为Map 的类，用于包含地图的信息。以下是其中的功能：

设置类的功能

function Map:init()
    -- Load the background sprite into variable
    -- Each is 500x500, total is 1500x500
    self.background = love.graphics.newImage('Graphics/platform/background/full.png')

-- Load all the ground platforms into variable
-- Each is 60x30, total is 240x30
self.platforms = love.graphics.newImage('Graphics/platform/ground/all.png')

-- Load all the bigger misc objects into variable
-- Each is 15x20, total is 15x120
self.objectsBig = love.graphics.newImage('Graphics/platform/objects/15x20/all.png')

-- Load all the smaller misc objects into variable
-- Each is 15x15, total is 60x15
self.objectsSmall = love.graphics.newImage('Graphics/platform/objects/15x15/all.png')

-- Setting the size for each of the variables IN PIXELS
self.backgroundWidth = 500
self.backgroundHeight = 1500

self.platformWidth = 60
self.platformHeight = 30

self.objectsBigWidth = 15
self.objectsBigHeight = 20

self.objectsSmallWidth = 15
self.objectsSmallHeight = 15

-- Setting the map size IN TILES
-- EXPERIMENTAL, CHECK AGAIN
self.mapWidth = 432
self.mapHeight = 243

-- Setting the width of the map IN PIXELS (in relation to platforms)
self.mapWidthPixels = self.backgroundWidth
self.mapHeightPixels = self.backgroundHeight

-- Storing our map features
self.tiles = {}

-- Storing the camera points, starting from the bottom
-- The 243 is the VIRTUAL_HEIGHT, which we needed to subtract to account for the
-- offset of the screen
self.camX = 0
self.camY = self.backgroundHeight - 243

-- Cutting each of the spritesheets
self.backgroundSprite = generateQuads(self.background, self.backgroundWidth, self.backgroundHeight)
self.platformSprite = generateQuads(self.platforms, self.platformWidth, self.platformHeight)
self.objectsBigSprite = generateQuads(self.objectsBig, self.objectsBigWidth, self.objectsBigHeight)
self.objectsSmallSprite = generateQuads(self.objectsSmall, self.objectsSmallWidth, self.objectsSmallHeight)

-- 'Setting' the tiles for the map to be background 
for y = 1, self.mapHeight do
    for x = 1, self.mapWidth do
        self:setTile(x, y, BACKGROUND)
    end
end

-- 'Setting' the platform tiles for where we start
for x = 1, self.mapWidth do
    self:setTile(x, self.mapHeight - 303, GROUND_MIDDLE)
end
end

在 X、Y 坐标中“设置”瓷砖应该在哪里的功能

function Map:setTile(x, y, tile)
    -- The table 'tiles' is going to store what tile should be in what x and y position
    -- subtracting y by 1 so that it's 0 indexed, not 1 indexed
    self.tiles[(y - 1) * self.mapWidth + x] = tile
end

返回 X、Y 坐标中的瓷砖的功能

function Map:getTile(x, y, tile)
    -- This function is going to tell us what tile is set at this x and y position
    return self.tiles[(y - 1) * self.mapWidth + x]
end

更新功能

function Map:update(dt)
    -- Moving the camera depending on the key being pressed
    if love.keyboard.isDown('w') then
        -- up movement, clamped between 0 and the other
        self.camY = math.max(0, math.floor(self.camY - SCROLL_SPEED * dt))
    elseif love.keyboard.isDown('a') then
        -- left movement
        self.camX = math.max(0, math.floor(self.camX - SCROLL_SPEED * dt))
    elseif love.keyboard.isDown('s') then
        -- down movement, subtracting VIRTUAL_HEIGHT to account for the screen offset
        self.camY = math.min(self.backgroundHeight - VIRTUAL_HEIGHT, math.floor(self.camY + SCROLL_SPEED * dt))
    elseif love.keyboard.isDown('d') then
        -- right movement
        self.camX = math.min(self.backgroundWidth - VIRTUAL_WIDTH, math.floor(self.camX + SCROLL_SPEED * dt))
    end
end

渲染函数

function Map:render()
    for y = 1, self.mapHeight do
        for x = 1, self.mapWidth do
            -- Drawing the background first
            love.graphics.draw(self.background, self.backgroundSprite[self:getTile(x, y)],
                (x - 1) * self.backgroundWidth, (y - 1) * self.backgroundHeight)
            love.graphics.draw(self.platform, self.platformSprite[self:getTile(x, y)],
                (x - 1) * self.platformWidth, (y - 1) * self.platformHeight)
        end
    end
end

我要做的是拼接每个精灵表，并设置背景和底部图块，以便我可以看到底层。我试图通过为我的精灵表中的组件提供数字来做到这一点，例如，在背景为 1500x500 的精灵表中，整个事物被认为是“一个”精灵，并被视为这样。它的数字 1 在变量中给出。另一个例子是一个 240x30 的平台 spritesheet，其中每个 60x30 被认为是“一个”精灵，并给定一个相应的数字，如下所示：

-- Know where the platforms are in the spritesheet
GROUND_LEFT = 1
GROUND_RIGHT = 2
GROUND_SMALL = 3
GROUND_MIDDLE = 4

-- Know where the backgrounds are in the spritesheet
BACKGROUND = 1

[...]

然后我想将每个存储在 self.tiles 列表中，以便我可以随时从表中访问它们（请注意，其中大部分来自 mario 的 CS50 实现，所以我明白如果我有任何概念错误）。但是，当我运行此代码时，出现以下错误：

Error

Error

Map.lua:135: bad argument #1 to 'draw' (Texture expected, got nil)


Traceback

[C]: in function 'draw'
Map.lua:135: in function 'render'
main.lua:48: in function 'draw'
[C]: in function 'xpcall'

本质上，我只是想知道一种设置底部平台图块的方法，然后能够遍历地图并“设置”其他对象精灵的位置。单独的背景效果很好，但是一旦我添加了：

-- 'Setting' the platform tiles for where we start
    for x = 1, self.mapWidth do
        self:setTile(x, self.mapHeight - 303, GROUND_MIDDLE)
    end

和

love.graphics.draw(self.platform, self.platformSprite[self:getTile(x, y)],
            (x - 1) * self.platformWidth, (y - 1) * self.platformHeight)

行，程序不会运行。

感谢任何帮助！

编辑：我遇到错误的那一行是self.platform。

Answer 1

我之前也遇到过同样的问题，结果是在输入变量时出现了拼写错误。查看您的代码，我发现没有self.platform，而是有self.platforms。

尝试：

love.graphics.draw(self.platforms, self.platformSprite[self:getTile(x, y)],
        (x - 1) * self.platformWidth, (y - 1) * self.platformHeight)