Contact (Français)

Les Contacts sont des objets crées pour gérer les collisions dans les mondes.

Fonctions

Contact:getChildren	Gets the child indices of the shapes of the two colliding fixtures.	0.9.0
Contact:getFixtures	Gets the two Fixtures that hold the shapes that are in contact.	0.9.2
Contact:getFriction	Get the friction between two shapes that are in contact.
Contact:getNormal	Get the normal vector between two shapes that are in contact.
Contact:getPosition	Get the location of the contact point between two shapes.		0.8.0
Contact:getPositions	Returns the contact points of the two colliding fixtures.	0.8.0
Contact:getRestitution	Get the restitution between two shapes that are in contact.
Contact:getSeparation	Get the separation between two shapes that are in contact.		0.8.0
Contact:getVelocity	Get the linear impact velocity of a contact.		0.8.0
Contact:isEnabled	Returns whether the contact is enabled.	0.8.0
Contact:isTouching	Returns whether the two colliding fixtures are touching each other.	0.8.0
Contact:resetFriction	Resets the contact friction to the mixture value of both fixtures.	0.8.0
Contact:resetRestitution	Resets the contact restitution to the mixture value of both fixtures.	0.8.0
Contact:setEnabled	Enables or disables the contact.	0.8.0
Contact:setFriction	Sets the contact friction.	0.8.0
Contact:setRestitution	Sets the contact restitution.	0.8.0
Object:release	Immediately destroys the object's Lua reference.	11.0
Object:type	Gets the type of the object as a string.
Object:typeOf	Checks whether an object is of a certain type.
World:setCallbacks	Sets functions to be called when shapes collide.	0.8.0

Supertypes

• Object (Français)

Exemples

-- Démonstration de l'utilisation correcte des Contacts afin d'éviter une « tentative d'utiliser un contact détruit. »
-- La parties les plus importantes sont physics.collisionOnEnter, love.update et love.draw.

local screen = {
    x = 500,
    y = 500,
}
local color = {
    blue = {0.23, 0.25, 0.59, 1},
    purple = {0.25, 0.09, 0.28, 1},
    white = {0.89, 0.91, 0.90, 1},
}

local physics = {
    normals = {},
}

-- Source: https://www.love2d.org/forums/viewtopic.php?p=17018&sid=5c8509cf6b97e3ce5aab1bc49e85acc5#p17018
local function draw_arrow(x1, y1, x2, y2)
    local head_length = 10
    local head_angle = math.pi * 0.2
    love.graphics.line(x1, y1, x2, y2)
    local a = math.atan2(y1 - y2, x1 - x2)
    love.graphics.polygon('fill', x2, y2, x2 + head_length * math.cos(a + head_angle), y2 + head_length * math.sin(a + head_angle), x2 + head_length * math.cos(a - head_angle), y2 + head_length * math.sin(a - head_angle))
end


function physics.collisionOnEnter(fixture_a, fixture_b, contact)
    local dx,dy = contact:getNormal()
    dx = dx * 30
    dy = dy * 30
    local point = {contact:getPositions()}
    for i=1,#point,2 do
        local x,y = point[i], point[i+1]
        -- Cache les valeurs au sein des contacts, car rien ne garantit
        -- qu'ils soient encore valide par la suite à l'intérieur de l'image temporelle.
        table.insert(physics.normals, {x,y, x+dx, y+dy})
    end

    -- N'utilisez pas les contacts après le retour de cette fonction.
end

function love.load()
    love.physics.setMeter(64)
    local can_bodies_sleep = true
    physics.world = love.physics.newWorld(0, 9.8, can_bodies_sleep)
    physics.world:setCallbacks(physics.collisionOnEnter)

    physics.geo = {}
    for y=0,1 do
        local side = {}
        side.body = love.physics.newBody(physics.world, screen.x/2, screen.y * y)
        side.shape = love.physics.newRectangleShape(screen.x, 50)
        side.fixture = love.physics.newFixture(side.body, side.shape)
        table.insert(physics.geo, side)
    end
    for x=0,1 do
        local side = {}
        side.body = love.physics.newBody(physics.world, screen.x * x, screen.y/2)
        side.shape = love.physics.newRectangleShape(50, screen.y)
        side.fixture = love.physics.newFixture(side.body, side.shape)
        table.insert(physics.geo, side)
    end

    physics.bouncers = {}
    for y=50,screen.y-50,50 do
        for x=50,screen.x-100,50 do
            local ball = {}
            ball.body = love.physics.newBody(physics.world, x, y, "dynamic")
            ball.shape = love.physics.newCircleShape(20)
            ball.fixture = love.physics.newFixture(ball.body, ball.shape, 1)
            ball.fixture:setRestitution(0.9)
            ball.body:setMass(50)
            ball.body:setLinearVelocity(100, 10)
            table.insert(physics.bouncers, ball)
        end
    end

    love.graphics.setBackgroundColor(color.blue)
    love.window.setMode(screen.x, screen.y)
end

function love.update(dt)
    -- La mise à jour du monde (physics.world:update(dt)) déclenchera collisionOnEnter
    physics.world:update(dt)

    if love.keyboard.isDown("space") then
        for _,ball in ipairs(physics.bouncers) do
            ball.body:applyLinearImpulse(0, 1000)
        end
    elseif love.keyboard.isDown("escape") then
        love.event.quit()
    end
end

function love.draw()
    love.graphics.setColor(color.purple)
    for i,side in ipairs(physics.geo) do
        love.graphics.polygon("fill", side.body:getWorldPoints(side.shape:getPoints()))
    end
    for i,ball in ipairs(physics.bouncers) do
        love.graphics.circle("fill", ball.body:getX(), ball.body:getY(), ball.shape:getRadius())
    end

    love.graphics.setColor(color.white)
    love.graphics.printf("smoosh balls with space", 5,5, 200, "left")
    love.graphics.printf(string.format("%i contacts", #physics.normals), screen.x-100,5, 100, "right")
    love.graphics.printf("arrows show contact normals", 5,screen.y-20, 200, "left")

    -- Utilise nos normales en cache
    for key,args in pairs(physics.normals) do
        local x1, y1, x2, y2 = unpack(args)
        draw_arrow(x1, y1, x2, y2)
        physics.normals[key] = nil
    end
end

Voir également

• World:setCallbacks (Français)
• World:getContactList (Français)
• love.physics

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