如何根据玩家的方向偏移子弹对象

如何解决如何根据玩家的方向偏移子弹对象

我正在运行 lua 5.1 和 love2d 11.3.0

在我的演示中，我有一个自上而下的射击游戏。出于视觉目的，角色看起来像这样......从这个自上而下的角度你可以看到，他正在举起武器。

我的问题是我很难弄清楚如何让他的子弹从他的枪尖开始，无论他面对什么方向，或者他在屏幕上的位置。 目前，子弹总是从这个身体的中心射出。我已经尝试调整下面的 bullet.x 和 bullet.y 属性，但这是一个不尊重玩家方向的静态变化......

function spawnBullet()
    local bullet = {}
    bullet.x = player.x
    bullet.y = player.y
    bullet.speed = 500
    bullet.direction = playerMouseAngle()
    table.insert(bullets,bullet)
end

完整的游戏逻辑：

-- top down shooter game demo 2021

function love.load()

    -- create table to collect sprite assets
    sprites = {}
    sprites.bg = love.graphics.newImage('graphics/bg_grass.jpg')
    sprites.hero = love.graphics.newImage('graphics/hero.png')

    -- create table for our player hero
    player = {}
    player.x = love.graphics.getWidth() / 2
    player.y = love.graphics.getHeight() / 2
    player.speed = 360
    player.injured = false
    player.injuredSpeed = 270

    -- create table for player bullets
    bullets = {}

    -- game state,timer and score globals
    gameState = 1
    maxTime = 2
    timer = maxTime
    score = 0

end

function love.update(dt)

    if gameState == 2 then

        -- player speed will be adjusted below
        local moveSpeed = player.speed

        -- adjust player speed if player was injured
        if player.injured then moveSpeed = player.injuredSpeed end

        -- player moves right
        if love.keyboard.isDown("d") and player.x < love.graphics.getWidth() -
            50 then player.x = player.x + moveSpeed * dt end

        -- player moves left
        if love.keyboard.isDown("a") and player.x > 50 then
            player.x = player.x - moveSpeed * dt
        end

        -- player moves up
        if love.keyboard.isDown("w") and player.y > 50 then
            player.y = player.y - moveSpeed * dt
        end

        -- player moves down
        if love.keyboard.isDown("s") and player.y < love.graphics.getHeight() -
            50 then player.y = player.y + moveSpeed * dt end
    end

    -- make bullets move in desired direction
    for i,b in ipairs(bullets) do
        b.x = b.x + (math.cos(b.direction) * b.speed * dt)
        b.y = b.y + (math.sin(b.direction) * b.speed * dt)
    end

    -- remove the bullets from the game once they go off-screen
    for i = #bullets,1,-1 do
        local b = bullets[i]
        if b.x < 0 or b.y < 0 or b.x > love.graphics.getWidth() or b.y >
            love.graphics.getHeight() then table.remove(bullets,i) end
    end

    -- manage game state and timer
    if gameState == 2 then
        timer = timer - dt
        if timer <= 0 then
            maxTime = 0.95 * maxTime
            timer = maxTime
        end
    end
end

function love.draw()

    -- setup background
    love.graphics.push()
    love.graphics.scale(0.20,0.20)
    love.graphics.draw(sprites.bg,0)
    love.graphics.pop()

    -- click to begin
    if gameState == 1 then
        love.graphics.printf('Click anywhere to begin!',50,love.graphics.getWidth(),"center")
    end

    -- display score
    love.graphics.printf('score: ' .. score,love.graphics.getHeight() - 100,"center")

    -- adjust player color if player gets injured
    if player.injured then love.graphics.setColor(1,0) end
    -- draw player
    love.graphics.draw(sprites.hero,player.x,player.y,playerMouseAngle(),nil,sprites.hero:getWidth() / 2,sprites.hero:getHeight() / 2)

    -- display player bullets
    for i,b in ipairs(bullets) do
        love.graphics.circle("fill",b.x,b.y,10,100)
    end
end

-- enable player direction based on mouse movement
function playerMouseAngle()
    return
        math.atan2(player.y - love.mouse.getY(),player.x - love.mouse.getX()) +
            math.pi
end

-- define bullet properties
function spawnBullet()
    local bullet = {}
    bullet.x = player.x
    bullet.y = player.y
    bullet.speed = 500
    bullet.direction = playerMouseAngle()
    table.insert(bullets,bullet)
end

-- game state determins shooting player bullets...
function love.mousepressed(x,y,button)
    if button == 1 and gameState == 2 then
        spawnBullet()
        -- ..or starting the game
    elseif button == 1 and gameState == 1 then
        gameState = 2
        maxTime = 2
        timer = maxTime
        score = 0
    end
end

提前感谢您提供任何提示

解决方法

您在旅行期间已经掌握了所需的数学知识...

-- make bullets move in desired direction
for i,b in ipairs(bullets) do
    b.x = b.x + (math.cos(b.direction) * b.speed * dt)
    b.y = b.y + (math.sin(b.direction) * b.speed * dt)
end

只需要稍微调整一下即可创建子弹

local bullet = {}
bullet.speed = 500
bullet.direction = playerMouseAngle()
bullet.x = player.x +(math.cos(bullet.direction + 0.5) * (sprites.hero:getWidth() / 2))
bullet.y = player.y +(math.sin(bullet.direction + 0.5) * (sprites.hero:getWidth() / 2))
table.insert(bullets,bullet)

猜测规模。您可能需要将 /2 更改为其他内容，例如 *0.75。