Created
September 17, 2022 19:26
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löve - fluid simulation using verlet integration
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| local love = love | |
| local lg = love.graphics | |
| local random = love.math.random | |
| local function dist(x1, y1, x2, y2) | |
| return math.sqrt((x2 - x1)^2 + (y2 - y1)^2) | |
| end | |
| local function length(x, y) | |
| return math.sqrt(x^2 + y^2) | |
| end | |
| local function normalize(x, y) | |
| local len = length(x, y) | |
| return x / len, y / len | |
| end | |
| local points = {} | |
| local gravity = 0.4 | |
| local bounce = 0.0 | |
| local numIterations = 1 | |
| local draggingPoint | |
| local dragOffsetX, dragOffsetY | |
| local attracting = false | |
| local attractX, attractY | |
| local fluidImage = lg.newImage("fluid.png") | |
| local fluidShader = lg.newShader [[ | |
| vec4 effect(vec4 color, Image texture, vec2 tc, vec2 sc) { | |
| vec4 p = Texel(texture, tc); | |
| p.rgb = color.rgb; | |
| p.a = floor(p.a + 0.2); | |
| return p * color; | |
| } | |
| ]] | |
| local fluidCanvas = lg.newCanvas() | |
| local function addPoint(x, y, radius, bouyancy, color) | |
| local p = {x = x, y = y, radius = radius, bouyancy = bouyancy, color = color, oldX = x, oldY = y} | |
| table.insert(points, p) | |
| return p | |
| end | |
| local fluidBalls = {} | |
| for i = 1, 1500 do | |
| local p = addPoint(random(0, lg.getWidth()), random(0, lg.getHeight()), 10, 10, {0.1, 0.5, 0.9}) | |
| p.drawRadius = 10 * 3 | |
| table.insert(fluidBalls, p) | |
| end | |
| local otherBalls = {} | |
| table.insert(otherBalls, addPoint(lg.getWidth() / 2, 0, 50, 1, {1,1,1})) | |
| function love.update(dt) | |
| attracting = love.mouse.isDown(2) | |
| attractX, attractY = love.mouse.getPosition() | |
| -- update velocities | |
| for i, p in ipairs(points) do | |
| local vx = p.x - p.oldX | |
| local vy = p.y - p.oldY | |
| p.oldX = p.x | |
| p.oldY = p.y | |
| if not p.pin then | |
| p.x = p.oldX + vx | |
| p.y = p.oldY + vy + gravity | |
| if attracting then | |
| local d = dist(p.x, p.y, attractX, attractY) | |
| local dx, dy = attractX - p.x, attractY - p.y | |
| p.x = p.x + dx * 1 / d | |
| p.y = p.y + dy * 1 / d | |
| end | |
| end | |
| end | |
| for i = 1, numIterations do | |
| for _, p1 in ipairs(points) do | |
| for _, p2 in ipairs(points) do | |
| if p1 ~= p2 then | |
| local d = dist(p1.x, p1.y, p2.x, p2.y) | |
| if d < p1.radius + p2.radius then | |
| local totalB = p1.bouyancy + p2.bouyancy | |
| local space = (p1.radius + p2.radius - d) / totalB | |
| local dirX, dirY = normalize(p2.x - p1.x, p2.y - p1.y) | |
| local space1 = space * (p1.bouyancy / totalB) | |
| local space2 = space * (p2.bouyancy / totalB) | |
| p1.x = p1.x - dirX * space1 | |
| p1.y = p1.y - dirY * space1 | |
| p2.x = p2.x + dirX * space2 | |
| p2.y = p2.y + dirY * space2 | |
| end | |
| end | |
| end | |
| end | |
| if draggingPoint then | |
| draggingPoint.x = love.mouse.getX() - dragOffsetX | |
| draggingPoint.y = love.mouse.getY() - dragOffsetY | |
| end | |
| end | |
| -- update constraints | |
| for _, p in ipairs(points) do | |
| local vx = p.x - p.oldX | |
| local vy = p.y - p.oldY | |
| if p.y + p.radius > lg.getHeight() then | |
| p.y = lg.getHeight() - p.radius | |
| p.oldY = p.y + vy * bounce | |
| end | |
| if p.x + p.radius > lg.getWidth() then | |
| p.x = lg.getWidth() - p.radius | |
| p.oldX = p.x + vx * bounce | |
| elseif p.x - p.radius < 0 then | |
| p.x = p.radius | |
| p.oldX = p.x + vx * bounce | |
| end | |
| end | |
| end | |
| function love.mousepressed(x, y, b) | |
| if b == 1 then | |
| for i, p in ipairs(points) do | |
| if dist(p.x, p.y, x, y) <= p.radius then | |
| draggingPoint = p | |
| dragOffsetX = x - p.x | |
| dragOffsetY = y - p.y | |
| break | |
| end | |
| end | |
| end | |
| end | |
| function love.mousereleased(x, y, b) | |
| if b == 1 then | |
| draggingPoint = nil | |
| end | |
| end | |
| function love.draw() | |
| for _, p in ipairs(otherBalls) do | |
| lg.setColor(p.color) | |
| lg.circle("fill", p.x, p.y, p.drawRadius or p.radius) | |
| end | |
| lg.setCanvas(fluidCanvas) | |
| lg.clear() | |
| for i, p in ipairs(fluidBalls) do | |
| lg.setColor(p.color) | |
| lg.draw(fluidImage, p.x, p.y, 0, 1, 1, fluidImage:getWidth()/2, fluidImage:getHeight()/2) | |
| --local dx, dy = p.x - p.oldX, p.y - p.oldY | |
| --lg.draw(fluidImage, p.x, p.y, math.atan2(dy, dx), 1 + length(dx, dy) / 10, 1 - length(dx, dy) / 50, fluidImage:getWidth()/2, fluidImage:getHeight()/2) | |
| --lg.circle("fill", p.x, p.y, p.drawRadius or p.radius) | |
| end | |
| lg.setCanvas() | |
| lg.setColor(0.1, 0.7, 0.9) | |
| lg.setShader(fluidShader) | |
| lg.draw(fluidCanvas) | |
| lg.setShader() | |
| end | |
| function love.keypressed(k) | |
| if k == "escape" then | |
| love.event.quit() | |
| end | |
| end |
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And here is
fluid.png: