train piston help

Solar2D General Questions/Discussion
#1

Hello i am trying to create a train piston (see jpeg). i am using kwik and plan to write the code and paste it into the project. Can somewhere tell me where to begin? i am lost.

#2

What jpeg? I think you need to use the image paste button in the rich text editor.

#3

sorry bout that… lets see if this works

#4

Ok, this is off the top of my head, but the list of components you’d need are:

anchor object for the wheel

wheel

pivot joint anchored to the anchor object and joining to the wheel

piston bar

pivot joint joining the wheel to the piston bar

pump object (moves left/right inside the canister)

pivot joint joining the piston bar to the pump object

a pair of fixed objects for the inside of the canister for the pump object to run between

#5

Here’s some code to get you started:

local physics = require ("physics") physics.start() physics.setGravity(0, 0) physics.setDrawMode("hybrid") --anchor object for the wheel local anchor = display.newRect( 0, 0, 10, 10 ) anchor.x, anchor.y = 100, 100 physics.addBody(anchor,"static") --wheel local wheel = display.newCircle( 100, 100, 100 ) physics.addBody( wheel, "dynamic", {radius=100} ) --pivot joint anchored to the anchor object and joining to the wheel local wheeljoint = physics.newJoint("pivot",anchor,wheel,100,100) --piston bar local bar = display.newRect( 0, 0, 300, 20 ) bar.x, bar.y = 250, 190 physics.addBody(bar,"dynamic",{filter={groupIndex=-1}}) --pivot joint joining the wheel to the piston bar local barjoint = physics.newJoint("pivot",wheel,bar,bar.x-150,bar.y) --pump object (moves left/right inside the canister) local pump = display.newRect( 0, 0, 20, 18 ) pump.x, pump.y = 400, 190 physics.addBody(pump, "dynamic", {friction=0}) --pivot joint joining the piston bar to the pump object local pumpjoint = physics.newJoint("pivot",bar,pump,pump.x,pump.y) --a pair of fixed objects for the inside of the canister for the pump object to run between local toprunner = display.newRect(0, 0, 300, 20) local bottomrunner = display.newRect(0, 0, 300, 20) toprunner.x, toprunner.y = 380, 80 bottomrunner.x, bottomrunner.y = 380, 120 physics.addBody(toprunner,"static",{filter={groupIndex=-1}}) physics.addBody(bottomrunner,"static",{filter={groupIndex=-1}}) -- finally, move the pump object into the canister so we avoid the messy maths pump.y = 100
#6

thank you! 

I will give it my best shot!

#7

What jpeg? I think you need to use the image paste button in the rich text editor.

#8

sorry bout that… lets see if this works

#9

Ok, this is off the top of my head, but the list of components you’d need are:

anchor object for the wheel

wheel

pivot joint anchored to the anchor object and joining to the wheel

piston bar

pivot joint joining the wheel to the piston bar

pump object (moves left/right inside the canister)

pivot joint joining the piston bar to the pump object

a pair of fixed objects for the inside of the canister for the pump object to run between

#10

Here’s some code to get you started:

local physics = require ("physics") physics.start() physics.setGravity(0, 0) physics.setDrawMode("hybrid") --anchor object for the wheel local anchor = display.newRect( 0, 0, 10, 10 ) anchor.x, anchor.y = 100, 100 physics.addBody(anchor,"static") --wheel local wheel = display.newCircle( 100, 100, 100 ) physics.addBody( wheel, "dynamic", {radius=100} ) --pivot joint anchored to the anchor object and joining to the wheel local wheeljoint = physics.newJoint("pivot",anchor,wheel,100,100) --piston bar local bar = display.newRect( 0, 0, 300, 20 ) bar.x, bar.y = 250, 190 physics.addBody(bar,"dynamic",{filter={groupIndex=-1}}) --pivot joint joining the wheel to the piston bar local barjoint = physics.newJoint("pivot",wheel,bar,bar.x-150,bar.y) --pump object (moves left/right inside the canister) local pump = display.newRect( 0, 0, 20, 18 ) pump.x, pump.y = 400, 190 physics.addBody(pump, "dynamic", {friction=0}) --pivot joint joining the piston bar to the pump object local pumpjoint = physics.newJoint("pivot",bar,pump,pump.x,pump.y) --a pair of fixed objects for the inside of the canister for the pump object to run between local toprunner = display.newRect(0, 0, 300, 20) local bottomrunner = display.newRect(0, 0, 300, 20) toprunner.x, toprunner.y = 380, 80 bottomrunner.x, bottomrunner.y = 380, 120 physics.addBody(toprunner,"static",{filter={groupIndex=-1}}) physics.addBody(bottomrunner,"static",{filter={groupIndex=-1}}) -- finally, move the pump object into the canister so we avoid the messy maths pump.y = 100
#11

thank you! 

I will give it my best shot!