Vehicle implementation

[BigB]

Hi all,

 

I'm newcommer to this forum, few months ago i bought Leadwerks 2.28 SDK, and i want to know if there is anyway to make a vehicle from the scratch (without using any gmf model) in C/C++, i've tried everything (i think) and i only have compiling errors. I will be very greatfull if someone can post a simple c/c++ code for vehicles ( only a cube with 4 cylinders working ).

 

Thanks in advance.

 

BigB

[AggrorJorn]

I don't have an entire example but instead of

chassis = LoadModel(abstract::chassis.gmf) 

you could use the CreateCube and CreateCylinder commands:

http://www.leadwerks.com/wiki/index.php?title=Meshes

[BigB]

I don't have an entire example but instead of

chassis = LoadModel(abstract::chassis.gmf) 

you could use the CreateCube and CreateCylinder commands:

http://www.leadwerks.com/wiki/index.php?title=Meshes

 

i've wrote this code:

 

TBody chasis=CreateBodyBox(1.2,0.5,4);

EntityType(chasis,2);

PositionEntity(chasis,Vec3(0.0,8.5,0.0));

SetBodyMass(chasis,800);

 

TVehicle car=CreateVehicle(chasis);

AddVehicleTire(car,Vec3(-0.75,8.0,0),0.3,0.25,70.0,150.0);

 

This is theoricly how it must work no?

 

If i put this code it crashes...

 

 

Then i tried that (change "car" by "chasis" on AddVehicleTire command:

 

TBody chasis=CreateBodyBox(1.2,0.5,4);

EntityType(chasis,2);

PositionEntity(chasis,Vec3(0.0,8.5,0.0));

SetBodyMass(chasis,800);

 

TVehicle car=CreateVehicle(chasis);

AddVehicleTire(chasis,Vec3(-0.75,8.0,0),0.3,0.25,70.0,150.0);

 

It doesn't crash at startup, but when i apply force by adding torque it crashes. I'm blocked, pls help.

 

Thanks in advance.

 

BigB

[ZeroByte]

Hi BigB,

 

i can't get the vehicle to work in c/c++ either, look's like you are running into the same problems as me.

 

Try changing

 

EntityType(chasis,2);

 

to

 

EntityType(chasis,1);

 

The last working vehicle example in C, was in LE 2.24 it can be found here:

 

http://forum.leadwerks.com/viewtopic.php?f=2&t=3761&p=33322&hilit=vehicle#p33322

 

It was ported to C API by pushedx, maybe it will help you.

[Canardia]

There's a bug in the engine.dll, because AddVehicleTire returns an Int, although it should return TTire. So the engine crashes when trying to call AddVehicleTire.

[ZeroByte]

Thank's for that info Lumooja, i'll try to alter the header to return TTire then.

[Canardia]

It doesn't help to change the header, since the bug is in the engine.dll. It returns more bytes from the core engine to the dll, so it overwrites unallocated memory and crashes.

[ZeroByte]

Oh ok, do you know if Josh is going to fix this ?

 

I've been trying to get vehicles going for awhile now,

 

and i'd prefer to use c/c++ for vehicles.

 

Thank's.

[Canardia]

Sure he will fix it, and I posted a bug report in the tracker also.

I think Josh needs to dedicate a few days per month for bug fixing only.

It would be nice to know beforehand when bugs are going to be fixed, for example every 8th day of the month

[ZeroByte]

Awesome, thank's for posting bug report.

 

Lol, yea a bug fix day.

[Josh]

That's incorrect:

Method AddTire:Int(position:TVec3,radius:Float,suspensionlength:Float,springconstant:Float=70.0,springdamping:Float=150.0)

 

AddTire() returns an integer.

 

I'll see about making a C++ vehicle example, although it is going to use a model. I won't do an example out of mesh primitives, because then everyone will ask how to make one with a model.

[Canardia]

Why do we need an example?

Just a simple:

TBody car=CreateBodyBox();
SetBodyMass(car,1);
TVehicle veh=CreateVehicle(car);
AddVehicleTire(veh);

Should not crash the engine, especially when veh is a valid pointer.

[macklebee]

TVehicle veh=CreateVehicle(veh);

 

youre parenting the item you are creating to itself? shouldn't that be:

TVehicle veh=CreateVehicle(car)

[Canardia]

Yes, typo.

[Josh]

Until someone posts a working example we can't be sure there isn't a problem.

[Canardia]

Here's a fully working example:

#include "engine.h"
int main(){
Initialize();
RegisterAbstractPath("c:/program files/leadwerks engine sdk");
Graphics(800,600);
TFramework fw=CreateFramework();
TBody fuselage=CreateBodyBox();
SetBodyMass(fuselage,1);
TVehicle veh=CreateVehicle(fuselage);
AddVehicleTire(veh); // crash here
while(!KeyHit()){
	UpdateFramework();
	RenderFramework();
	Flip();
}
return Terminate();
}

[Josh]

The cause is the position parameter is declared as a vec3, and it should be a byte ptr. Here is the corrected function:

Function AddVehicleTire_:Int(vehicle:TVehicle,position:Byte Ptr,radius:Float,suspensionlength:Float,springconstant:Float=70.0,springdamping:Float=150.0) "win32"
GCEnter()
Local t:TVec3=New TVec3
MemCopy(t,position,12)
Return vehicle.addtire(t,radius,suspensionlength,springconstant,springdamping)
EndFunction

 

And here is a recompiled DLL:

engine.zip

[Canardia]

Crashing stopped, but I can't see any wheels on my car:

#include "engine.h"
int main(){
Initialize();
RegisterAbstractPath("c:/program files/leadwerks engine sdk");
Graphics(800,600);
TFramework fw=CreateFramework();
TBody fuselage=CreateBodyBox();
EntityType(fuselage,1);
SetBodyMass(fuselage,1);
TVehicle veh=CreateVehicle(fuselage);
AddVehicleTire(veh,Vec3(-1,-1,0));
DebugPhysics();
MoveEntity(GetLayerCamera(GetFrameworkLayer(0)),Vec3(0,0,-10));
TBody ground=CreateBodyBox(1000,1,1000);
MoveEntity(ground,Vec3(0,-5,0));
EntityType(ground,1);
Collisions();
while(!KeyHit()){
	UpdateFramework();
	RenderFramework();
	Flip();
}
return Terminate();
}

 

In MoveEntity, the Vec3 is declared as Float Ptr, why not in AddVehicleTire also?

Function MoveEntity_(entity:TEntity,p:Float Ptr,glob:Int=0) "win32"
GCEnter()
?debug
If Not EntityExists(entity) RuntimeError "Invalid object."
?
entity.move(p,glob)
EndFunction

[Josh]

They're basically the same data type.

 

Vehicle tires are not visualized by the physics debugger, since they are just raycasts.

[Canardia]

But shouldn't tires have somekind of effect on my cubic car? It just falls flat on the floor, although the wheel should be 1 meter to the left and 1 meter under the box, so the box should at least lay a bit tilted on the floor.

[ZeroByte]

Wow, thank's for recompiled DLL Josh, that was fast.

 

And, thank's for the help Lumooja, i'm gonna go try this.

[ZeroByte]

Lumooja your code work's, just change:

 

AddVehicleTire(veh,Vec3(-1,-1,0));

 

to

 

AddVehicleTire(veh,Vec3(-1,-1,0), 0.5, 0.3, 45.0, 100.0);

[Josh]

#include "engine.h"
int main(){

       Initialize();
       RegisterAbstractPath("C:/Leadwerks Engine SDK");
       Graphics(800,600);

	TFramework fw=CreateFramework();
	DebugPhysics(1);
	Collisions(1,1,1);
	MoveEntity(GetLayerCamera(GetFrameworkLayer(0)),Vec3(0,0,-10));

	TBody fuselage=CreateBodyBox();
       EntityType(fuselage,1);
       SetBodyMass(fuselage,10);

	TLight light=CreateDirectionalLight();
	RotateEntity(light,Vec3(45,45,45));

	TMesh tire[4];

	tire[0]=CreateCylinder();
	tire[1]=CreateCylinder();
	tire[2]=CreateCylinder();
	tire[3]=CreateCylinder();

	RotateMesh(tire[0],Vec3(0,0,90));
	RotateMesh(tire[1],Vec3(0,0,90));
	RotateMesh(tire[2],Vec3(0,0,90));
	RotateMesh(tire[3],Vec3(0,0,90));


	TVehicle veh=CreateVehicle(fuselage);
       AddVehicleTire(veh,Vec3(-1,0,1),0.5,1.0,70,150);
       AddVehicleTire(veh,Vec3(1,0,1),0.5,1.0,70,150);
       AddVehicleTire(veh,Vec3(-1,0,-1),0.5,1.0,70,150);
       AddVehicleTire(veh,Vec3(1,0,-1),0.5,1.0,70,150);

	TBody ground=CreateBodyBox(100,1,100);
       MoveEntity(ground,Vec3(0,-3,0));
       EntityType(ground,1);
	RotateEntity(ground,Vec3(-5,0,0));

	while(!KeyHit()){
               UpdateFramework();

			SetEntityMatrix(tire[0],GetTireMatrix(veh,0));
			SetEntityMatrix(tire[1],GetTireMatrix(veh,1));
			SetEntityMatrix(tire[2],GetTireMatrix(veh,2));
			SetEntityMatrix(tire[3],GetTireMatrix(veh,3));

               RenderFramework();
               Flip();
       }
       return Terminate();
}

[Canardia]

Cool, I wonder why the default parameters are so useless...

I think they should be fixed to make a working default result.

[Josh]

It depends on the mass of your chassis and the position of the wheels.