Wow, wonderful work again. Yes this blue isn't really Citroen but the model is
close enough to go for a GS. I only remember a brown metallic one (break
version) a friend lend me ages ago for two weeks...

And I'm still driving a ten years old Xsara Picasso... (I didn't dare to model
it so far)

Best regards,
Michael

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https://www.youtube.com/watch?v=CGYPHWOAt94

After some hundreds of variants, I found a combination of constraints
which work decently for most situations. The problem is that it's a bit
unstable, and only works as expected half of the times you run the
sim... I suspect is not BPP, but the Bullet library itself. Anyhow, when
it works, you can play with it as long as you want, and it will never
break, as you can see on the above video. :)

--
Jaime

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On 03/02/2013 8:53 AM, Jaime Vives Piqueres wrote:
> https://www.youtube.com/watch?v=CGYPHWOAt94

Impressive.

-- 
Regards
     Stephen

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Jaime Vives Piqueres wrote:

> After some hundreds of variants, I found a combination of constraints
> which work decently for most situations.

looks great! The only point where it looked a bit jerky was when driving
up the stairs. With the steering / braking system, do you mean you set
the position / forces of the front wheels and the car follows it
based on friction with the ground?

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Le 03/02/2013 09:53, Jaime Vives Piqueres nous fit lire :
> https://www.youtube.com/watch?v=CGYPHWOAt94
> 
> After some hundreds of variants, I found a combination of constraints
> which work decently for most situations. The problem is that it's a bit
> unstable, and only works as expected half of the times you run the
> sim... I suspect is not BPP, but the Bullet library itself. Anyhow, when
> it works, you can play with it as long as you want, and it will never
> break, as you can see on the above video. :)
> 

Great. Awesome.

To be even better IMOH, could you somehow pattern the wall and may be a
bit the black ground. A large checker on the wall, and maybe some lines
on the ground ? Aim: to ease my view of inertia / non-drifting rear
wheels on sequence where only the car, the ground and the wall are. So
far on such sequence, I cannot assert that the car is not gliding.

The first step of stair has an unrealistic front wheel move (jumping
from one rotation to another).

before the ramp, there seems to be some stick/shadow under the front
right wheel, as if something was broken.

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Am 03.02.2013 18:33, schrieb Le_Forgeron:

> Great. Awesome.
>
> To be even better IMOH, could you somehow pattern the wall and may be a
> bit the black ground. A large checker on the wall, and maybe some lines
> on the ground ? Aim: to ease my view of inertia / non-drifting rear
> wheels on sequence where only the car, the ground and the wall are. So
> far on such sequence, I cannot assert that the car is not gliding.

Seconded. (I had the impression/expectation however that the car /is/ 
gliding, bu with the current ground it remains inconclusive.)

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> looks great! The only point where it looked a bit jerky was when
> driving up the stairs. With the steering / braking system, do you
> mean you set the position / forces of the front wheels and the car
> follows it based on friction with the ground?

   Thanks to Koppi addition of definable keyboard shortcuts, I was able
to assign a key for acceleration, another for braking, and two more for
the steering to left and right:

   + the acceleration key just applies some angular speed to the tires,
which rotate freely around a hinge constraint. Using high friction on
the wheels and the ground, the car starts rolling...

   + the braking key cuts the power and also blocks the free rotation of
the wheels hinge. Again, friction does it's work and the cars stops
reasonably well.

   + the left/right keys turn on the motors of a pair of hinge
constraints attached to the wheels, on the appropriate direction. I
didn't need to implement any sort of differential... still don't know
why, but the car acts as if there is one. For the rest, I totally
disregarded any other things like caster, camber, toe, ackerman, etc...

   Apart from that, there is a simplistic suspension joining the steering
hinges with the chassis: this is where most of the failed attempts were
wasted, trying to find a combination that worked well and didn't break
under the forces involved.

   Oh, ...and the jerky moment at the stairs was me pressing left/right
to find a better attack point, as the power was not enough for a frontal
approach... :)

--
jaime

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El 03/02/13 18:33, Le_Forgeron escribió:
> To be even better IMOH, could you somehow pattern the wall and may be
> a bit the black ground. A large checker on the wall, and maybe some
> lines on the ground ? Aim: to ease my view of inertia / non-drifting
> rear wheels on sequence where only the car, the ground and the wall
> are. So far on such sequence, I cannot assert that the car is not
> gliding.

   Ah, yes... there were some ground markings on the sim, but I misplaced
them on the render and are below the ground. You're right that it
assists greatly on perceiving the realism on the motion... but I didn't
think on patterning the wall too: thanks for the idea.

   Oh, and of course it's sliding like mad in turns, mainly because the
angular speed of the wheels is not controllable at the moment, but just
fixed and continuous once you press the accelerator key (until you hit
the brake key). But I like drifting very much... ;)

> The first step of stair has an unrealistic front wheel move (jumping
> from one rotation to another).

   As I said to Christian, it was me pressing left/right as mad trying to
get a better attack angle...

> before the ramp, there seems to be some stick/shadow under the front
> right wheel, as if something was broken.

   It's the lower control arm of the wheel, which flexes under the
chassis weight. And no, it isn't broke (not in that run, tough it breaks
sometimes). It's the GS model which is missing some geometry there... my
fault, as I'm the one that modeled it. :)

   I'm just polishing some details and will commit the LUA script later,
then will post on my site the customized POV export to render it using
the already available GS model.

--
Jaime

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>> looks great! The only point where it looked a bit jerky was when
>> driving up the stairs. With the steering / braking system, do you
>> mean you set the position / forces of the front wheels and the car
>> follows it based on friction with the ground?
>
>    Thanks to Koppi addition of definable keyboard shortcuts, I was able
> to assign a key for acceleration, another for braking, and two more for
> the steering to left and right:
>
>    + the acceleration key just applies some angular speed to the tires,
> which rotate freely around a hinge constraint. Using high friction on
> the wheels and the ground, the car starts rolling...
>
>    + the braking key cuts the power and also blocks the free rotation of
> the wheels hinge. Again, friction does it's work and the cars stops
> reasonably well.
>
>    + the left/right keys turn on the motors of a pair of hinge
> constraints attached to the wheels, on the appropriate direction. I
> didn't need to implement any sort of differential... still don't know
> why, but the car acts as if there is one. For the rest, I totally
> disregarded any other things like caster, camber, toe, ackerman, etc...
>
>    Apart from that, there is a simplistic suspension joining the steering
> hinges with the chassis: this is where most of the failed attempts were
> wasted, trying to find a combination that worked well and didn't break
> under the forces involved.
>
>    Oh, ...and the jerky moment at the stairs was me pressing left/right
> to find a better attack point, as the power was not enough for a frontal
> approach... :)
>
> --
> jaime
>
>
Unless you modeled some rigid link between two wheels you don't need to 
model any diferential. The motor wheels are powered indepently and can 
rotate at different speed as needed.

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El 03/02/13 20:32, clipka escribió:
> Seconded. (I had the impression/expectation however that the car /is/
> gliding, bu with the current ground it remains inconclusive.)

http://www.youtube.com/watch?v=FVfJZaxe93E

--
jaime

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