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如何在love2d中设置车轮接头

love2d game-physics box2d

1

advice · 技术社区 · 6 年前

我目前正在尝试在Love2d中创建一个简单的2d汽车,但我在弄清楚如何将车轮接头连接到车身上时遇到了问题。

https://love2d.org/wiki/love.physics.newWheelJoint

joint = love.physics.newWheelJoint( body1, body2, x, y, ax, ay, collideConnected )

要创建车轮连接,您需要传递4个数字(x,y,a x,a y),但我不知道这些值应该是什么。每次我的车撞到地上,整个东西都会吓坏并爆炸。

正如你在下面看到的,我只是使用一个简单的 PolygonShape 和两个 CircleShapes 我想把它们附在一起。

function Car:create()
    local object = {}

    local x = 300
    local y = 300

    local width = 120
    local height = 40
    local size = 20

    local hasCollision = false

    object.frame = Car:createFrame(x, y, width, height)
    object.frontWheel = Car:createWheel(x + width/4, y + height, size)
    object.backWheel = Car:createWheel(x - width/4, y + height, size)

    -- Unsure what values I should use for these.
    frontJoint = love.physics.newWheelJoint(object.frame.body, object.frontWheel.body, 400, 300, 400, 300, hasCollision)
    rearJoint = love.physics.newWheelJoint(object.frame.body, object.backWheel.body, 350, 300, 0, 0,  hasCollision)

    -- Trying to adjust the values to see if that helps, unsure what these should be.
    frontJoint:setSpringFrequency(1)
    frontJoint:setSpringDampingRatio(2)

    return object   
end

function Car:createFrame(x, y, width, height)
    local frame = {}

    frame.body = love.physics.newBody(world, x, y, "dynamic")
    frame.shape = love.physics.newRectangleShape(0, 0, width, height)
    frame.fixture = love.physics.newFixture(frame.body, frame.shape, 5) -- A higher density gives it more mass.

    return frame
end

function Car:createWheel(x, y, size)
    local wheel = {}

    wheel.body = love.physics.newBody(world, x, y, "dynamic") 
    wheel.shape = love.physics.newCircleShape(size) 
    wheel.fixture = love.physics.newFixture(wheel.body, wheel.shape, 1) 
    wheel.fixture:setRestitution(0.25)

    return wheel
end

1 回复 | 直到 6 年前

1

2

advice 6 年前

我必须更深入地研究box2d的文档,并且能够了解哪里出了问题。我可以用下面的代码让它工作。

function Car:createJoint(frame, wheel, motorSpeed, maxMotorTorque)
    local hasCollision = false
    local freq = 7
    local ratio = .5

    local hasChanged = true

    local yOffset = wheel:getY() - frame:getY()

    local joint = love.physics.newWheelJoint(frame, wheel, wheel:getX(), wheel:getY(), 0, 1, hasCollision)
    joint:setSpringFrequency(freq)
    joint:setSpringDampingRatio(ratio)

    joint:setMotorSpeed(motorSpeed)
    joint:setMaxMotorTorque(maxMotorTorque)

    return joint
end

希望这能帮助其他人寻找 newWheelJoint .