Hi!
Basically I’ve run into this: bodies with high velocity sometimes pass through other bodies.
I’ve researched on the subject and found this great explanation:
http://stackoverflow.com/a/8308118
It’s said there that Box2D uses Continuous Collision Detection between dynamic and static objects to solve this problem. And if you want such behavior between dynamic bodies body.isBullet must be set to true.
I’ve found that it really works with static bodies. However with dynamic bodies tunneling still occurs. It’s like CCD still won’t turn on for them.
Example that illustrates the issue:
local physics = require "physics"
physics.start();
physics.setDrawMode("hybrid")
physics.setScale( 60 )
physics.setGravity( 0, 0 )
--these won't help
physics.setPositionIterations( 16 )
physics.setVelocityIterations( 8 )
local screenW, screenH, halfW = display.contentWidth, display.contentHeight, display.contentWidth\*0.5
local circleR=30
local circleLinearDamping=5
local puckPhysicsProp = {density=1, friction=.2, bounce=0.5, radius=circleR}
local function circleTouched(event)
local target = event.target
if event.phase== "began" then
target:applyLinearImpulse(-276, -163, target.x, target.y)
end
end
targetCircle = display.newCircle(300, 200, circleR)
targetCircle:setFillColor(128)
bulletCircle = display.newCircle(350, 270, circleR)
physics.addBody(targetCircle, "dynamic", puckPhysicsProp)
physics.addBody(bulletCircle, "dynamic", puckPhysicsProp)
bulletCircle.isBullet = true
targetCircle.isFixedRotation=true
bulletCircle.isFixedRotation=true
targetCircle.linearDamping=circleLinearDamping
bulletCircle.linearDamping=circleLinearDamping
targetCircle.isSleepingAllowed=false
bulletCircle.isSleepingAllowed=false
bulletCircle:addEventListener("touch", circleTouched)
targetCircle2 = display.newCircle(300, 500, circleR)
targetCircle2:setFillColor(128)
bulletCircle2 = display.newCircle(350, 570, circleR)
physics.addBody(targetCircle2, "static", puckPhysicsProp)
physics.addBody(bulletCircle2, "dynamic", puckPhysicsProp)
bulletCircle2.isBullet = true
targetCircle2.isFixedRotation=true
bulletCircle2.isFixedRotation=true
targetCircle2.linearDamping=circleLinearDamping
bulletCircle2.linearDamping=circleLinearDamping
targetCircle2.isSleepingAllowed=false
bulletCircle2.isSleepingAllowed=false
bulletCircle2:addEventListener("touch", circleTouched) I’ve submitted it as case #12818. [import]uid: 13989 topic_id: 23269 reply_id: 323269[/import]