Single '3 untouching circles' physics body?

[nameless1]

a body that is 3 triangles not touching spaced out can be achieved modifying the multi body ex:

local car = display.newImage( "car.png" )
local roofShape = { -20,-10, 20,-10, 20,10, -20,10 }
local hoodShape = { 0,-35, 37,30, -37,30 }
local trunkShape = { 0,-37, 37,-10, 23,34, -23,34, -37,-10 }
 physics.addBody( car, "dynamic",
    { density=3.0, friction=0.5, bounce=0.2, shape=roofShape },
    { density=6.0, friction=0.6, bounce=0.4, shape=hoodShape },
    { density=4.0, friction=0.5, bounce=0.4, shape=trunkShape }
)

if i want 3 circles (ie the physics body is 3 big dots not touching
) how would i do so if specifying radius=number always takes the same origin for each circle and {x=} doesnt seem to work?

    { density=3.0, friction=0.5, bounce=0.2, radius=30 },
    { density=6.0, friction=0.6, bounce=0.4, radius=40, x=50 }, --x not working, makes at same spot

i can always use shape= to make 3 blocky circles, but i’d need a utility to generate like 80 xy sets to get smooth collision/rubbing…not sure if viable resource-wise.

[aclementerodrguez]

You’re making some changes in your code that aren’t consistent with the Solar2D documentation. The parameter ‘x’ within the table for creating a body doesn’t exist, which is why it has no effect.

I think what you want to do can be achieved with joints. Check the documentation on joints, and you might find something that helps you accomplish what you’re aiming for.

[Kan98]

The current Box2D version of Solar2D does not provide x and y parameters for a circle body. You can either use a polygon shape to make it manually, or refer to the method mentioned by @aclementerodrguez.

Additionally, there is a version of Solar2D’s Box2D v3 that supports the circle body.

physics.addBody(object, "dynamic", {circle = {radius = r, x = x, y = y}})

This version also includes many features and changes compared to the current Box2D version in Solar2D.

You can find it here:

Box2D 3.1 Ported to Solar2D for iOS and Android

We have successfully ported Box2D 3.1 to Solar2D, which now supports iOS, Android, osx, windows. Compared to Box2D v2, Box2D 3.1 has seen a significant performance improvement. You can download and test it here: Box2D 3.1 for Solar2D We hope to merge this version into the official release, but we are currently unsure of how to proceed to allow Box2D v2 and Box2D v3 to coexist. [box2d v2.3.0 vs box2d v3 in Solar2d Game Engine]

[nameless1]

Using joints the “distance” type seems to come closest to the multi-body car ex.
It requires defining 3 separate bodies, and I couldn’t get them completely springless with the settings…I think there’s overlap between the density/friction/bounce/etc properties of each body and the settings for both joints overlapping at one body but I don’t know. Would opt for using the car method with a single body and polygonal circles if u don’t need smooth collisions.

--sort of springy distance; obj1, obj2, obj1Anchor, obj2Anchor. set anchors at center of each object and use .length to change line length; otherwise just pick the point inbetwen for both for normal movement or just 0,0,0,0
	self.body=physics.newJoint("distance", self.body1,self.body2 ,0,0,0,0)
	self.bdy=physics.newJoint("distance", self.body3,self.body2 ,0,0,0,0)
		-- self.body.dampingRatio=1 --0 is alot of oscillations; 1 is no oscillations
		-- self.body.frequency=3000000 -- low value maes join soft and contract east
		-- self.body.length=20 --can increase with buttkon press etc
		-- self.bdy.dampingRatio=1 
		-- self.bdy.frequency=3000000 
		-- self.bdy.length=20 -