Frictionless space physics - GameCreators Forum

Author

Message

Mcine

10

Years of Service

User Offline

Joined: 9th Jan 2016

Location:

Posted: 17th Jan 2016 13:23

Link

Hey,

How can I do frictionless physics for my spacegame ?
I have zeroed the gravity and sprite frictions.
I have 2 sprites joined with distancejoint and other sprite is static.
When I give the dynamic sprite an impulse (upwards), it will rotate around the static one, but the movement keeps getting slower.
How can I remove all frictions, so that the velocity is constant.

- McIne

Back to top

Profile PM

Ancient Lady

Valued Member

22

Years of Service

User Offline

Joined: 17th Mar 2004

Location: Anchorage, Alaska, USA

Posted: 31st Jan 2016 22:24

Link

Look at the SetSpritePhysicsRestitution and SetSpritePhysicsDamping commands in addition to the SetSpritePhysicsFriction that I suspect you are using.

The first sets the bounciness and the second is the one that will cause something to slow down.

Cheers,
Ancient Lady

Back to top

Profile PM

Mcine

10

Years of Service

User Offline

Joined: 9th Jan 2016

Location:

Posted: 1st Feb 2016 13:25

Link

Thanks for the answer. I need to check all those through.
I think I have damping and friction set to 0, but have not set restitution since I thought it would not matter.

Back to top

Profile PM

Mcine

10

Years of Service

User Offline

Joined: 9th Jan 2016

Location:

Posted: 1st Feb 2016 19:05

Link

That did not help..

I create the sprites like this (one static and one dynamic)
SetSpriteSize(p1,50,50)
SetSpritePositionByOffset(p1,300,300)
setspritephysicson (p1, 2)
SetSpriteShapeCircle(p1,0,0,25)
SetSpritePhysicsFriction(p1,0)
SetSpritePhysicsDamping(p1,0)
SetSpritePhysicsMass(p1,1)
SetSpritePhysicsRestitution (p1,1)

And I create a distance joint between them and put other in motion and it slows down.

Back to top

Profile PM

CJB

Valued Member

22

Years of Service

User Offline

Joined: 10th Feb 2004

Location: Essex, UK

Posted: 3rd Feb 2016 11:33

Link

You could cheat with a Joint Motor:

// Project: spacefriction 
// Created: 2016-02-03
// set window properties
SetWindowTitle( "spacefriction" )
SetWindowSize( 1024, 768, 0 )

SetPhysicsScale(0.4)

p1 = createsprite(0)
setspritecolor(p1,255,255,255,255)
SetSpriteSize(p1,50,50)
SetSpritePositionByOffset(p1,500,500)
setspritephysicson (p1, 2)
SetSpriteShapeCircle(p1,0,0,25)
SetSpritePhysicsFriction(p1,0)
SetSpritePhysicsDamping(p1,0)
SetSpritePhysicsMass(p1,10)
SetSpritePhysicsRestitution(p1,0)
SetSpritePhysicsAngularDamping(p1,0)

p2 = createsprite(0)
setspritecolor(p2,255,255,255,255)
SetSpriteSize(p2,50,50)
SetSpritePositionByOffset(p2,300,300)
setspritephysicson (p2, 1)
SetSpriteShapeCircle(p2,0,0,25)
SetSpritePhysicsFriction(p2,0)
SetSpritePhysicsDamping(p2,0)
SetSpritePhysicsMass(p2,10)
SetSpritePhysicsRestitution(p2,0)
SetSpritePhysicsAngularDamping(p2,0)

CreateRevoluteJoint(1,p1,p2,GetSpriteXByOffset(p2),GetSpriteYByOffset(p2),0)

SetPhysicsGravity(0,0)

SetJointMotorOn( 1, -10, 10000 )

SetViewZoom(1.1) // just using this to quickly turn off physics walls.

// set display properties
SetVirtualResolution( 1024, 768 )
SetOrientationAllowed( 1, 1, 1, 1 )

do
    Print( ScreenFPS() )
    StepPhysics(0.16)
    Sync()
loop

+ Code Snippet

// Project: spacefriction 
// Created: 2016-02-03
// set window properties
SetWindowTitle( "spacefriction" )
SetWindowSize( 1024, 768, 0 )

SetPhysicsScale(0.4)

p1 = createsprite(0)
setspritecolor(p1,255,255,255,255)
SetSpriteSize(p1,50,50)
SetSpritePositionByOffset(p1,500,500)
setspritephysicson (p1, 2)
SetSpriteShapeCircle(p1,0,0,25)
SetSpritePhysicsFriction(p1,0)
SetSpritePhysicsDamping(p1,0)
SetSpritePhysicsMass(p1,10)
SetSpritePhysicsRestitution(p1,0)
SetSpritePhysicsAngularDamping(p1,0)

p2 = createsprite(0)
setspritecolor(p2,255,255,255,255)
SetSpriteSize(p2,50,50)
SetSpritePositionByOffset(p2,300,300)
setspritephysicson (p2, 1)
SetSpriteShapeCircle(p2,0,0,25)
SetSpritePhysicsFriction(p2,0)
SetSpritePhysicsDamping(p2,0)
SetSpritePhysicsMass(p2,10)
SetSpritePhysicsRestitution(p2,0)
SetSpritePhysicsAngularDamping(p2,0)

CreateRevoluteJoint(1,p1,p2,GetSpriteXByOffset(p2),GetSpriteYByOffset(p2),0)

SetPhysicsGravity(0,0)

SetJointMotorOn( 1, -10, 10000 ) 

SetViewZoom(1.1) // just using this to quickly turn off physics walls.

// set display properties
SetVirtualResolution( 1024, 768 )
SetOrientationAllowed( 1, 1, 1, 1 )

do
    Print( ScreenFPS() )
    StepPhysics(0.16)
    Sync()
loop

V2 T1 (Mostly)
Phone Tap!
Uzmadesign

Back to top

Profile PM Email Website

Ancient Lady

Valued Member

22

Years of Service

User Offline

Joined: 17th Mar 2004

Location: Anchorage, Alaska, USA

Posted: 4th Feb 2016 02:43

Link

And it might be possible that the 'SetSpritePhysicsMass(p1,1)' command is resetting the Friction and Damping. Try moving it to just after the 'SetSpriteSize(p1,50,50)' call.

Cheers,
Ancient Lady

Back to top

Profile PM

Sorry your browser is not supported!

Newcomers AppGameKit Corner / Frictionless space physics