Sprite Physics On/Off/Setting Values

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thoromyr

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Posted: 16th Dec 2016 21:47

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Doing a simple game using sprite physics and it appears that I've hit some undocumented features.

Specifically, if I set a sprite up for physics and use it and it dies I can make it invisible, turn physics off and all is good.

But, if I resurrect the sprite and re-enable physics then it starts with its previous physics velocity (linear and angular). No problem, right? You just set those to the desired values (zero, in this case). Nope, using SetSpritePhysicsVelocity() and SetSpritePhysicsAngularVelocity() are both ignored.

Hmmm... well, then... okay, instead of SetSpritePhysicsOff() I can use SetSpritePhysicsDelete(). After all, the documentation says you can use that to change the mode or shape so using SetSpritePhysicsOn() should restore physics to the sprite, right? Apparently not. Or, maybe you have to do more than just call SetSpritePhysicsOn() again?

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Markus

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Posted: 17th Dec 2016 10:53 Edited at: 17th Dec 2016 11:03

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Quote: "sing SetSpritePhysicsVelocity() and SetSpritePhysicsAngularVelocity() are both ignored."

i made a test, its not ignored.

+ Code Snippet

rem
rem AGK Application 2.0.22
rem MR

SetWindowSize(800,600,0)

SetVirtualResolution(100,100)

SetPhysicsDebugOn()

SetPhysicsScale( 0.1)

//SetPhysicsGravity(0,100)
SetPhysicsGravity(0,10)

SetPhysicsWallBottom(1)

spr=StartSprite()
SetSpritePhysicsImpulse(spr,0,0,20,0)

do
	print("Press A for Stop, B for Continue, Esc for End")

	if GetRawKeyReleased(65)
		SetSpritePhysicsOff(spr)
		SetSpriteVisible(spr,0)
	endif

	if GetRawKeyReleased(66)
		SetSpriteVisible(spr,1)
		SetSpritePhysicsOn(spr,2)
		SetSpritePhysicsVelocity(spr,0.0 , 0.0)
		SetSpritePhysicsAngularVelocity(spr,0.0)
	endif
	
	if GetRawKeyReleased(27)
		exit
	endif
	
	Sync()
	
loop

end
                
Function StartSprite()

	spr = CreateSprite(0)
	SetSpriteSize(spr,10.0,10.0)
	SetSpritePhysicsMass(spr,1)
	SetSpritePhysicsOn(spr,2) //Dynamic
	
endfunction spr

AGK (Steam) V2.0.22 : Windows 10 Pro 64 Bit : AMD (16.12.1) Radeon R7 265 : Mac mini OS Sierra (10.12)

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Mobiius

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Joined: 27th Feb 2003

Location: The Cold North

Posted: 19th Dec 2016 14:42

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Try setting a force inverse to the velocity to stop it, rather than trying to directly apply a velocity. (Because that's how physics works.

)

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Markus

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Posted: 19th Dec 2016 22:37 Edited at: 19th Dec 2016 22:46

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naah, velocity is the result from a force with mass x all the time.
if it is set to zero the gravity will made a acceleration but nothing else. i think its not necessary to use a force as brake.
giving the velocity a value is more problematic (for collision system) because the acceleration is not simulated.

i guess the reason can be a mistyped sprite handle or the call order of commands.

AGK (Steam) V2.0.22 : Windows 10 Pro 64 Bit : AMD (16.12.1) Radeon R7 265 : Mac mini OS Sierra (10.12)

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CJB

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Location: Essex, UK

Posted: 23rd Dec 2016 15:41

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Without seeing code, we're shooting in the dark. My suspicion is you may be using the incorrect value sprite ID (a common mistake is to use the Image ID instead of the Sprite ID and can be tricky to spot if loading images and building sprites at the same time). Post some code highlighting the problem and we can help fix it.

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AppGameKit Classic Chat / Sprite Physics On/Off/Setting Values