irrBullet 0.1.8 - Bullet physics wrapper

[Virion]

how to move an object without accelerating and decelerating? sorry i'm new to game physics.

[cobra]

Virion:

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irr::matrix4 mat = rigidbody->getWorldTransform();
mat.setTranslation(irr::core::vector3df(20,20,20));

rigidbody->setWorldTransform(mat);

[Virion]

thx for the help cobra. now i'm trying to rotate my object when i pressing a button. it works fine at first but when it reaches 90 degree it won't rotate anymore.

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matrix4 mat = body->getWorldTransform();
vector3df rot = mat.getRotationDegrees();
mat.setRotationDegrees(rot - vector3df(0, 1 * speed, 0));
body->setWorldTransform(mat);

thx in advance

[Brainsaw]

Sounds like a gimbal lock to me (an issue that did cost me about a week to workaround in IrrOde).

In IrrOde it works like this: when a Gimbal Lock is detected the Irrlicht scenenode's rotation is not updated (Gimbal locks are a problem of the Euler angles, quaternions don't have such problems).

[Zurzaza]

Virion:

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irr::matrix4 mat = rigidbody->getWorldTransform();
mat.setTranslation(irr::core::vector3df(20,20,20));

rigidbody->setWorldTransform(mat);

it won't work if the body isn't set as kinematic body. In order to move an object "legally" into the bullet world is to set it as kinematic body

[Virion]

Virion:

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irr::matrix4 mat = rigidbody->getWorldTransform();
mat.setTranslation(irr::core::vector3df(20,20,20));

rigidbody->setWorldTransform(mat);

it won't work if the body isn't set as kinematic body. In order to move an object "legally" into the bullet world is to set it as kinematic body

weird. i set my body to kinematics and it won't work anymore.

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body->setCollisionFlags(ECF_KINEMATIC_OBJECT);

then i set it back to character object and it works again. but still the rotation is locked at 90 degree.

[Zurzaza]

weird. i set my body to kinematics and it won't work anymore.

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body->setCollisionFlags(ECF_KINEMATIC_OBJECT);

then i set it back to character object and it works again. but still the rotation is locked at 90 degree.

hmm..it looks very strange.
From the bullet official manual (p.22), it only says that kinematic bodies can be animated by te user:

Kinematic rigidbodies: can be animated by the user, but there will be only one-way interaction: dynamic objects will be pushed away but there is no influence from dynamics objects

So, i can't explain why your object can be moved

[cobra]

Zurzaza:

It most certainly can be positioned without first being set to kinematic.

You misunderstood what the documentation says.

Kinematic objects are useful for things like character controllers, because they will affect dynamic objects but will themselves not be affected.


Virion:

I'll have to look in to your problem when I have more time. Sorry.
If you figure it out before then, please let me know.

[griffin2000]

Looks very cool. Apologies if I'm being dense, but how do you go about building it on Visual Studio ?

I see some CMake files further down in the source tree (in some of the sub folders of irrBullet-0.1.65\source\bheaders\Bullet\BulletCollision) but nothing in the root Source folder.

[cobra]

griffin2000:

I believe I posted some light instructions in previous pages of this thread.

Also, irrBullet 0.1.7 will have Visual Studio project files and pre-built libs.

[Leo [Teh one]]

---problem solved---
cobra, thanks for so cool wrapper!

[ent1ty]

thx for the help cobra. now i'm trying to rotate my object when i pressing a button. it works fine at first but when it reaches 90 degree it won't rotate anymore.

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matrix4 mat = body->getWorldTransform();
vector3df rot = mat.getRotationDegrees();
mat.setRotationDegrees(rot - vector3df(0, 1 * speed, 0));
body->setWorldTransform(mat);

thx in advance

The problem with this is, that getWorldTransform() returnd wrong rotation. My workaround was, to store the rotation manually in a variable, instead of getting it from the body

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int RotY= 0;
IRigidBody* Body;

...

void rotate(float degrees)
{
    rotY+= degrees;
    matrix4 mat= body->getWorldTransform(); //we get the transform, just to get correct translation and won't use the rotation from it
    mat.setRotationDegrees(vector3df(0, rotY, 0));
    body->setWorldTransform(mat);
}

[cobra]

You could also try changing "vector3df rot" from mat.getRotationDegrees() to

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body->getCollisionShape()->getSceneNode()->getAbsoluteTransformation().getRotation()

I'll fix this for 0.1.7. Apparently copying over OpenGL matrix from Bullet to Irrlicht doesn't have the right rotation, but from Irrlicht to Bullet it does.

[Birdman]

This files gives me trouble in Softbody.h:
#include <map.h>
#include <vector.h>
Both files seems to be missing, maybe i did something wrong?

This happens to me with 1.65 only.

[cobra]

This files gives me trouble in Softbody.h:
#include <map.h>
#include <vector.h>
Both files seems to be missing, maybe i did something wrong?

This happens to me with 1.65 only.

Change map.h to just map, and vector.h to just vector.


This is already fixed for 0.1.7, which will be out by January 5th.