Hinge joint

[AggrorJorn]

I am trying to make a catapult which uses a hinge joint. Calculating the angle goes well but now I need to add a force to the catapult to shoot something. Sofar no luck with my hinge.

 

if KeyHit(KEY_SPACE)==1 then
	pos = catapult:GetPosition(1)
	catapultBody = CreateBodyPivot(pos)
	catapultBody: SetPosition( pos )
	catapultJoint = CreateJointHinge(catapultBody, catapult, pos, catapult.mat:K() )

	--Fire catapult with force
	catapult:AddTorque( Vec3( 0, 0, 10 ) )

end

 

Any suggestions?

[AndyGFX]

Hmm ... a haven't experiencies with this phys. things, but i have other idea.

Make 1st phase as animation (rotate catapult arm) and then apply force to the thing throwed from catapult. Your idea is good, but from my point of view, not all in-game solution you have to make "totaly" real

[macklebee]

Just using physics gives decent results... but I agree with Andy that faking the catapult throwing an object can give just as good of results and might actually give you more control over the object being shot.

 

require("scripts/constants/keycodes")
require("scripts/math/math")
RegisterAbstractPath("")
Graphics(800,600)

fw = CreateFramework()
fw.main.camera:SetPosition(Vec3(-3,6,-6))

light = CreateDirectionalLight()
light:SetRotation(Vec3(45,-45,-40) ,1)

groundphy = CreateBodyBox(100,1,100)
ground = CreateCube(groundphy)
ground:SetScale(Vec3(100,1,100))
groundphy:SetPosition(Vec3(0,-6,0))
groundphy:SetCollisionType(1)

slingphy = CreateBodyBox(12,.5,.5)
sling = CreateCube(slingphy)
sling:SetScale(Vec3(12,.5,.5))
sling:SetColor(Vec4(1,1,0,1))
slingphy:SetCollisionType(1)
slingphy:SetMass(100)

stopphy = CreateBodyBox(.2,1,1,slingphy)
stop = CreateCube(stopphy)
stop:SetScale(Vec3(.1,1,1))
stop:SetColor(Vec4(0,0,1,1))
stopphy:SetPosition(Vec3(6.2,0,0),1)
stopphy:SetCollisionType(1)

fulcrumphy = CreateBodyBox(.5,2,.5)
fulcrum = CreateCube(fulcrumphy)
fulcrum:SetScale(Vec3(.5,2,.5))
fulcrum:SetColor(Vec4(0,1,0,1))
fulcrumphy:SetPosition(Vec3(-3,-1.5,0),1)

joint = CreateJointHinge(fulcrumphy,slingphy,Vec3(-3,0,0),Vec3(0,0,1))
SetHingeJointLimits(joint,-75,45)

camerapitch=fw.main.camera.rotation.x
camerayaw=fw.main.camera.rotation.y  
SetPhysicsQuality(0)
trigger = 0 
while KeyHit(KEY_ESCAPE)==0 do
dx=Curve((MouseX()-Round(GraphicsWidth()/2))/4.0,dx,3.0/AppSpeed())        
       dy=Curve((MouseY()-Round(GraphicsHeight()/2))/4.0,dy,3.0/AppSpeed())        
       MoveMouse(Round(GraphicsWidth()/2),Round(GraphicsHeight()/2))        
       camerapitch=camerapitch+dy        
       camerayaw=camerayaw-dx        
       fw.main.camera:SetRotationf(camerapitch,camerayaw,0,1)

if KeyHit(KEY_SPACE)==1 then
	if trigger == 0 then
		trigger = 1
		slingphy:SetMassCenter(Vec3(-6,0,0))
		slingphy:AddForce(Vec3(0,.1,0))
	else
		trigger = 0
		slingphy:SetMassCenter(Vec3(6,0,0))
		slingphy:AddForce(Vec3(0,.1,0))

	end
end

if KeyHit(KEY_F)==1 then
	ammophy = CreateBodyBox(.25,.25,.25)
	ammo = CreateCube(ammophy)
	ammo:SetScale(Vec3(.25,.25,.25))
	ammo:SetColor(Vec4(1,0,1,1))
	ammophy:SetCollisionType(1)
	ammophy:SetMass(1)
               ammophy:SetFriction(1,.25)
	ammophy:SetPosition(Vec3(4.5,-4,0),1)
end

fw:Update()
fw:Render()
SetBlend(1)
DrawText("Press SPACE to Fire or Reset Catapult",0,20)
DrawText("Press F to Load Ammo in Catapult",0,40)
if ammo~= nil then
	DrawText("Ammo Position: "..ammo:GetPosition(1).x,0,60)
end
SetBlend(0)
Flip(0)
end

[AggrorJorn]

Thanks for the advice you guys. I will experience with an animation and shooting from a controlled spot as well as with complete physics.