using joystick to rotate object « cocos2d for iPhone

cocos2d for iPhone » Programming » cocos3d

using joystick to rotate object

(8 posts) (3 voices)

Started 7 months ago by Bunnyrabbit
Latest reply from Bill Hollings

Tags:

Bunnyrabbit
Member

Hi,
I've just started to use this framework and it seems great, but I’m having some problems implementing my ideas.
I try to rotate a large object with the joystick in center of the screen, but I don’t seem to get what I want.
Here’s the code:

CGPoint delta = ccpMult(playerDirectionControl, dt * 10.0);
CC3MeshNode* bunny = (CC3MeshNode*)[self getNodeNamed:@"bunny"];
NSLog(@"dx:%f dy%f:" ,delta.x, delta.y);
CC3Vector4 quaternion = bunny.quaternion;
double angle = sqrt(delta.x * delta.x + delta.y * delta.y);
CC3Vector4 axisQuat = CC3Vector4Make(delta.x * sin(angle/2), delta.x * sin(angle/2), 0.0, cos(angle/2));
CC3Vector4 quatMult = [self quatMult:quaternion second:axisQuat];
[bunny setQuaternion:quatMult];

If I understand correctly, I should get coordinates from the joystick and create a quaternion from them
and then multiply it with the present quaternion of the object.
Any suggestions?

Posted 7 months ago #

eozkucur1
Member
Hi, I achieved a similar requirement with the following method:
```
[centerNode.transformMatrix rotateBy:cc3v(delta.x,0,-delta.y)];
centerNode.rotation=[centerNode.transformMatrix extractRotation];
```
The second line was needed because the transformMatrix will be calculated from location, rotation and scale properties after updateBeforeTransform method (correct me if I am wrong)
Posted 7 months ago #
Bunnyrabbit
Member

Thanks, but it's not exactly what I'm looking for. I would like to reset the joystick after every use, so that every new joysticking would rotate the object by it's new coordinates. Maybe I should somehow create another node to hold the object after every rotation.

Posted 7 months ago #
eozkucur1
Member

If I got it right, you need additive rotation with the joystick. That method actually applies additive rotation. The transformation matrix holds the current rotation of the object, and applying delta rotation adds to the rotation. I can control the pitch and roll of an aircraft with joystick through that method.

Posted 7 months ago #
Bunnyrabbit
Member

Yes. Additive is what I need. That's why I was asking about the quaternions.

Posted 7 months ago #
Bill Hollings
Moderator

@Bunnyrabbit

The next version of cocos3d will be released this week, and it includes a series of rotateBy:... methods that might be of use in situations like this.

...Bill

Posted 7 months ago #
Bunnyrabbit
Member

Thanks, it'll be great.

Posted 7 months ago #
Bill Hollings
Moderator

@Bunnyrabbit

And this week includes today! :-)

cocos3d 0.6.2 is available now.

...Bill

Posted 7 months ago #

RSS feed for this topic

Reply

You must log in to post.