Loading a model and giving physics to it

Troubleshooting physics
1

I was testing my abilities in jMonkey when I tried to modfy the HelloPhysics exemple, so I tried to switch the cannonball:

[java]

public void makeCannonBall() {

/** Create a cannon ball geometry and attach to scene graph. /

Spatial ball_spa = defaultBall.clone();

ball_spa.setLocalScale(0.5f);

rootNode.attachChild(ball_spa);



/* Position the cannon ball and activate shadows /

ball_spa.setLocalTranslation(cam.getLocation());

ball_spa.setShadowMode(ShadowMode.CastAndReceive);

/* Make the ball physcial with a mass > 0.0f /

ball_phy = new RigidBodyControl(2f);

/* Add physical ball to physics space. /

ball_spa.addControl(ball_phy);

ball_phy.attachDebugShape(floor_mat);

bulletAppState.getPhysicsSpace().add(ball_phy);

/* Accelerate the physcial ball to shoot it. */

ball_phy.setLinearVelocity(cam.getDirection().mult(15f));

}

[/java]

defaultBall is a Spatial initied in simpleInitApp

[java] defaultBall = assetManager.loadModel(“Models/esfera/Sphere.mesh.xml”);[/java]



So, how you can see, in “ball_phy.attachDebugShape(floor_mat);” I took the prove, the ball_phy is launched in time and from position very differents.

2

So what?

3

Sorry, I “forget” the problem -.-





bad english

4

Would you believe it.

5

Ok, my english is weak to explain that, I will update a video and post it here.

6

Slow internet(Brazil), in 135min I post it here…

7

I guess the thing is that your spatial is not a Geometry with a mesh of type Sphere.

8

Here is: youtube video (I put a small video but have all the informations…)



The first ball is the Spatial and the second is the RigidBodyControl(I launched only one time).

9

I changed the method a little basing on HelloCollision exemple and here is:

[java]

public void makeCannonBall() {

/** Create a cannon ball geometry and attach to scene graph. /

Spatial ball_spa = defaultBall.clone();

ball_spa.setLocalScale(0.5f);

rootNode.attachChild(ball_spa);



/* Position the cannon ball and activate shadows /

ball_spa.setLocalTranslation(cam.getLocation());

ball_spa.setShadowMode(ShadowMode.CastAndReceive);

CollisionShape ballShape =

CollisionShapeFactory.createMeshShape((Node) ball_spa);

/* Make the ball physcial with a mass > 0.0f /

ball_phy = new RigidBodyControl(ballShape, 2f);

/* Add physical ball to physics space. /

ball_spa.addControl(ball_phy);

ball_phy.attachDebugShape(floor_mat);

bulletAppState.getPhysicsSpace().add(ball_phy);

/* Accelerate the physcial ball to shoot it. */

ball_phy.setLinearVelocity(cam.getDirection().mult(15f));

}

[/java]



It doesn’t afected anything.

10

A mesh shape cannot be moved, use createDynamicMeshShape to create a movable hull shape. But since this is a sphere I suggest using a SphereCollisionShape,

11

So, all ok if the sphere was not created in jMonkey (was in blender)? I can use SphereCollisionShape?

12

My hero!! :wink:

The code worked that way:

[java]

public void makeCannonBall() {

/** Create a cannon ball geometry and attach to scene graph. /

Spatial ball_spa = defaultBall.clone();

rootNode.attachChild(ball_spa);



/* Position the cannon ball and activate shadows /

ball_spa.setLocalTranslation(cam.getLocation());

ball_spa.setShadowMode(ShadowMode.CastAndReceive);

SphereCollisionShape ballShape = new SphereCollisionShape(0.5f);

/* Make the ball physcial with a mass > 0.0f /

RigidBodyControl ball_phy = new RigidBodyControl(ballShape, 2f);

/* Add physical ball to physics space. /

ball_spa.addControl(ball_phy);

ball_phy.attachDebugShape(floor_mat);

bulletAppState.getPhysicsSpace().add(ball_phy);

/* Accelerate the physcial ball to shoot it. */

ball_phy.setLinearVelocity(cam.getDirection().mult(15f));

}

[/java]