Sand/dust with fluid dynamics physics

Solar2D Daily Builds and Public Releases
#1

It’s possible to develop game that reproduce sand/dust with fluid dynamics physics?

Like this:
http://appbank.us/iphone/ipad-iphone-sand-play-with-sand-the-movements-are-so-real-you-can-even-make-a-sand-clock [import]uid: 8982 topic_id: 14839 reply_id: 314839[/import]

#2

Hi,

of course… easy with corona…

i would say… the sand are small balls…
if you want dust… use particle candy …

BR [import]uid: 9592 topic_id: 14839 reply_id: 54815[/import]

#3

There are examples of code for this?
I don’t know Corona and If I buy Corona for iPhone it’s included a support service? [import]uid: 8982 topic_id: 14839 reply_id: 54816[/import]

#4

here’s an example to do something like this.
but honestly, the performance on an actual device is not very satisfying…

This works great with particle counts up to 100, but then it gets sloppy. I created this with much bigger objects (bouncing balls) and quickly changed it to “sand mode”. There has to be a better solution, but you should get the idea:

-- Project: PhysicsTest  
-- Description: particle physics test  
--  
-- 2011 finefin  
  
local physics = require("physics")  
physics.start()  
physics.setGravity( 0, 40 )  
--physics.setDrawMode( "hybrid" )  
  
-- A general function for dragging physics bodies  
local function dragBody( event )  
 local t = event.target  
   
 local phase = event.phase  
 if "began" == phase then  
 display.getCurrentStage():setFocus( t )  
 t.isFocus = true  
 -- Store initial position  
 t.x0 = event.x - t.x  
 t.y0 = event.y - t.y  
 if event.x \> t.x then  
 t.rotation = t.rotation - 10  
 elseif event.x \< t.x then  
 t.rotation = t.rotation + 10  
  
 end  
 -- Make body type temporarily "kinematic" (to avoid gravitional forces)  
 event.target.bodyType = "kinematic"   
 -- Stop current motion, if any  
 event.target:setLinearVelocity( 0, 0 )  
 event.target.angularVelocity = 0  
   
 elseif t.isFocus then  
 if "moved" == phase then  
 t.x = event.x - t.x0  
 t.y = event.y - t.y0  
 elseif "ended" == phase or "cancelled" == phase then  
 display.getCurrentStage():setFocus( nil )  
 t.isFocus = false  
  
 -- Switch body type back to "dynamic", unless we've marked this sprite as a platform  
 if ( not event.target.isPlatform ) then  
 event.target.bodyType = "dynamic"  
 end  
 end  
 end  
 -- Stop further propagation of touch event!  
 return true  
end  
  
-- create world  
local wallLeft = display.newRect( 0, -50, 10, 530 )  
physics.addBody( wallLeft, "static", { friction=0.5 } )  
  
local wallRight = display.newRect( 310, -50, 10, 530 )  
physics.addBody( wallRight, "static", { friction=0.5 } )  
  
local platform1 = display.newRect( 0, 50, 200, 10 )  
physics.addBody( platform1, "static", { friction=0.5 } )  
platform1.rotation = 10  
platform1:addEventListener( "touch", dragBody )  
platform1.isPlatform = true  
  
local platform2 = display.newRect( 120, 150, 200, 10 )  
physics.addBody( platform2, "static", { friction=0.5 } )  
platform2.rotation = -10  
platform2:addEventListener( "touch", dragBody )  
platform2.isPlatform = true  
  
local platform3 = display.newRect( 0, 250, 200, 10 )  
physics.addBody( platform3, "static", { friction=0.5 } )  
platform3.rotation = 10  
platform3:addEventListener( "touch", dragBody )  
platform3.isPlatform = true  
  
-- create table for all particles  
local balls = {}  
  
-- remove particles that are out of bound  
local function ifOutOfBounds (event)  
 for i,val in pairs(balls) do  
 if(val.y \> 480) or (val.y \< -50) then   
 val:removeSelf();  
 balls[i] = nil;  
 end  
 end  
  
end  
  
local randomBall = function()  
 -- create ball  
 local ball  
 ball = display.newRect( 160, -20, 1, 1 )  
 ball.x = 160; ball.y = -20  
 physics.addBody( ball, { density=1, friction=0.6, bounce=0.1, radius=1 } )  
 ball.angularVelocity = math.random(800) - 400  
 -- add ball to table  
 balls[#balls + 1] = ball   
end  
  
Runtime:addEventListener( "enterFrame", ifOutOfBounds )  
timer.performWithDelay( 10, randomBall, -1 )

cheers
-finefin
[import]uid: 70635 topic_id: 14839 reply_id: 54827[/import]

#5

I don’t think so actually. Fact of the matter is that doing something like that simulation is very CPU intensive and will not come out nicely via a scripting language. It’s not as easy as AlenB thinks it is, box2d is not designed for that kind of simulation. [import]uid: 86662 topic_id: 14839 reply_id: 56211[/import]