We’ve all enjoyed Physics, now how about some elasticity?
Here’s a video on the prototype I am working on, the idea did come from the concept of buoyancy that iNSERT.CODE started, if we cannot use physics to achieve something, then why can’t we do it ourselves?
Here’s a start for elasticity
http://iphone.oz-apps.com/elasticity-example-in-coronasdk
cheers,
?
[import]uid: 3826 topic_id: 16204 reply_id: 316204[/import]
Great work… keep it up.
[import]uid: 86417 topic_id: 16204 reply_id: 60324[/import]
Hey JayantV,
As a firm believer in simple math and trigonometrics myself I really like stuff like this - I don’t understand why people rather use collision detection on a circle than simple pythagoras, but hey, I’m pro choice.
If you want to share your code, feel free to send it to me at
thomas
at
pinkeye
.
be
I have an idea about how you’re doing this, but I’m curious to see how you coded it. I have lots of these small exercices in math and motion myself
Cheers,
Thomas [import]uid: 70134 topic_id: 16204 reply_id: 60338[/import]
Hi JayantV,
Looks great so far and you’re quite right, a lot can be achieved without the use of collisions. I’m sure that if people got together to make and share examples like this, then we would have a fantastic base within the Code Exchange.
Of course, some people will simply take the code and use it without even bothering to look how it’s coded, but that is their loss. A missed opportunity to learn how to do something for themselves. That should be the whole point of the Code Exchange.
Anyway, I’m not sure if you’re aware, but the Buoyancy Demo that you mentioned in your post is now in the code exchange here:
http://developer.anscamobile.com/code/water-buoyancy-example
Keep up the good work. [import]uid: 74503 topic_id: 16204 reply_id: 60358[/import]
Long time ago I did something like this:
[lua]display.setStatusBar( display.HiddenStatusBar )
local physics = require(“physics”)
physics.start()
physics.setScale( 21 ) – a value that seems good for small objects (based on playtesting)
physics.setGravity( 0, 0 ) – overhead view, therefore no gravity vector
–physics.setDrawMode( “hybrid” )
local localGroup = display.newGroup()
local PI = math.pi
local PI2 = 2*PI
local Abs = math.abs
local Cos = math.cos
local Sin = math.sin
local Rnd = math.random
local Ceil = math.ceil
local Atan2 = math.atan2
local Sqrt = math.sqrt
local gScrW = display.contentWidth
local gScrH = display.contentHeight
local linePoints = {}
local moved = false
local line
–[[local loadingImage = display.newImage( “background.png”)
loadingImage.x = 240; loadingImage.y = 160
localGroup:insert ( loadingImage ) ]]–
local Images = {}
– PRELOAD USED IMAGES TO AVOID SLOW DOWNS IMAGES WILL STAY
– INVISIBLE ON STAGE AND WILL BE REMOVED WHEN YOU CALL THE
– EFFECT LIBRARIES CLEANUP FUNCTION.
Images[1] = “ball_black.png”
Images[2] = “ball_blue.png”
Images[3] = “ball_green.png”
Images[4] = “ball_orange.png”
Images[5] = “ball_pink.png”
Images[6] = “ball_purple.png”
Images[7] = “ball_red.png”
Images[8] = “ball_yellow.png”
local startBallPoinst = {}
startBallPoinst[1] = {x = -100, y = -100}
startBallPoinst[2] = {x = (gScrW*0.5), y = -100}
startBallPoinst[3] = {x = (gScrW + 100), y = -100}
startBallPoinst[4] = {x = (gScrW + 100), y = (gScrH*0.5)}
startBallPoinst[5] = {x = (gScrW + 100), y = (gScrH+100)}
startBallPoinst[6] = {x = (gScrW*0.5), y = (gScrH+100)}
startBallPoinst[7] = {x = -100, y = (gScrH+100)}
startBallPoinst[8] = {x = -100, y = (gScrH*0.5)}
– mainBall declaration
local mainBall
local borderCollisionFilter = { categoryBits = 1, maskBits = 26 } – collides with () only
– Boki —
local BumperShape = { 0,0, 0,340}
local BumperShape2 = { 0,0, 480 - display.screenOriginX*2,0}
local BumperShape3 = { 0,0, 0,340}
local BumperShape4 = { -480 + display.screenOriginX*2,0, 0,0}
local bumperBody = { friction=0.5, bounce=0.6, shape=BumperShape, filter=borderCollisionFilter }
local bumperBody2 = { friction=0.5, bounce=0.6, shape=BumperShape2, filter=borderCollisionFilter }
local bumperBody3 = { friction=0.5, bounce=0.6, shape=BumperShape3, filter=borderCollisionFilter }
local bumperBody4 = { friction=0.5, bounce=0.6, shape=BumperShape4, filter=borderCollisionFilter }
local firstLine1 = display.newLine(0 + display.screenOriginX,0, 0 + display.screenOriginX, display.contentHeight)
physics.addBody( firstLine1, “static”, bumperBody )
firstLine1:setColor( 255, 77, 28, 0 )
firstLine1.width = 2
localGroup:insert ( firstLine1 )
local firstLine2 = display.newLine( 0 + display.screenOriginX, 0, display.contentWidth - display.screenOriginX, 0)
physics.addBody( firstLine2, “static”, bumperBody2 )
firstLine2:setColor( 255, 77, 28, 0 )
firstLine2.width = 2
localGroup:insert ( firstLine2 )
local firstLine3 = display.newLine( display.contentWidth - display.screenOriginX, 0, display.contentWidth - display.screenOriginX, display.contentHeight)
physics.addBody( firstLine3, “static”, bumperBody3 )
firstLine3:setColor( 255, 77, 28, 0 )
firstLine3.width = 2
localGroup:insert ( firstLine3 )
local firstLine4 = display.newLine( display.contentWidth - display.screenOriginX, display.contentHeight, 0 + display.screenOriginX, display.contentHeight)
physics.addBody( firstLine4, “static”, bumperBody4 )
firstLine4:setColor( 255, 77, 28, 0 )
firstLine4.width = 2
localGroup:insert ( firstLine4 )
local myRoundedRect = display.newRoundedRect(display.contentWidth*0.5 - 100, display.contentHeight*0.5 - 100, 200, 200, 100)
myRoundedRect.strokeWidth = 3
myRoundedRect:setFillColor(0, 0, 0, 0)
myRoundedRect:setStrokeColor(255, 77, 28, 180)
localGroup:insert( myRoundedRect )
local centralBallCollisionFilter = { categoryBits = 16, maskBits = 5 } – collides with (4 & 1) only
local centralBallPhysics = { density = 3, friction = 0.8, bounce = 0.8, radius=32.0, filter=centralBallCollisionFilter }
local centralBall = display.newImage( “centralBall.png”)
centralBall.x = 240
centralBall.y = 160
physics.addBody( centralBall, centralBallPhysics )
centralBall.isFixedRotation = false
centralBall.linearDamping = 0.5
localGroup:insert( centralBall )
local blue = {}
local blueCollisionFilter = { categoryBits = 4, maskBits = 28 } – collides with () only
local blueBody = { density=0.5, friction=0, bounce=0.5, radius=15.0, filter=blueCollisionFilter }
local ballMarkTime = os.time()
local spawnBall = function()
local coordinates = math.random(1, 8)
local currentBall = display.newImage( Images[math.random(1, 8)], startBallPoinst[coordinates].x, startBallPoinst[coordinates].y )
physics.addBody( currentBall, blueBody )
localGroup:insert ( currentBall )
currentBall:applyForce( (centralBall.x - startBallPoinst[coordinates].x), (centralBall.y - startBallPoinst[coordinates].y), currentBall.x, currentBall.y )
currentBall.linearDamping = 0.45
currentBall.angularDamping = 0.1
currentBall.isFixedRotation = false
currentBall.isBullet = true
– RE-MARK THE TIME
ballMarkTime = os.time()
end
local lecaKulki = function( event )
local ballSpawnCounter = os.time() - ballMarkTime
– check if 1 second has passed since last spawn
if ballSpawnCounter >= 3 then
spawnBall()
end
end
local shootBall = timer.performWithDelay( 3000, lecaKulki, 20 )
– main ball physics
local mainBallCollisionFilter = { categoryBits = 8, maskBits = 5 } – collides with (4 & 1) only
local mainBallPhysics = { density=0.8, friction=0.8, bounce=0.2, radius=10.0, filter=mainBallCollisionFilter }
local mainBall = display.newImage( “ball_white.png” )
physics.addBody( mainBall, mainBallPhysics )
mainBall.isFixedRotation = true
mainBall.isFocus = true
mainBall.alpha = 0
localGroup:insert( mainBall )
– A general function for dragging physics bodies
local function dragBody( event )
local phase = event.phase
local stage = display.getCurrentStage()
local dx, dy, dst, power, speed
if “began” == phase then
mainBall.alpha = 1
mainBall.x = event.x
mainBall.y = event.y
stage:setFocus( mainBall, event.id )
elseif mainBall.isFocus then
if “moved” == phase then
dx = Abs( event.x - mainBall.x )
dy = Abs( event.y - mainBall.y )
dst = (dx*dx + dy*dy)^0.5
power = Abs((1.0-(dst/40)) * 0.7)
mainBall:applyForce( (event.x-mainBall.x)*power, (event.y-mainBall.y)*power , mainBall.x,mainBall.y )
mainBall.angularDamping = 2
mainBall.linearDamping = 2
local pt = {}
pt.x = event.x
pt.y = event.y
table.insert(linePoints,pt)
moved = true
elseif “ended” == phase or “cancelled” == phase then
stage:setFocus( body, nil )
moved = false
linePoints = {}
if ( line ) then line.alpha = 0 end
end
end
– Stop further propagation of touch event
return true
end
local function drawLine()
if ( line and #linePoints > 2 ) then line:removeSelf() end
if #linePoints > 2 then
line = display.newLine(mainBall.x,mainBall.y, linePoints[#linePoints].x,linePoints[#linePoints].y)
line:setColor(255, 77, 28, 180)
line.alpha = 1
line.width=5
localGroup:insert( line )
mainBall:toFront()
end
end
local function draw (event )
if ( moved == true ) then
drawLine()
return true
end
end
local function isInMiddle (event )
– Dystans!!!
local x = math.pow( ( centralBall.x - (display.contentWidth*0.5)), 2)
local y = math.pow( ( centralBall.y - (display.contentHeight*0.5 )), 2)
local distance = Sqrt( x+y )
if ( distance > 130 ) then
print (“alert”)
end
end
– Make object draggable
Runtime:addEventListener( “touch”, dragBody )
Runtime:addEventListener( “enterFrame” , draw)
Runtime:addEventListener( “enterFrame” , isInMiddle)[/lua] [import]uid: 12704 topic_id: 16204 reply_id: 60408[/import]