Hi,
thank you. Yes I have different angles all the time.
I realized that I really need quaternions. So I am learning and implementing
that. Already I am able to use glMultMatrixf(Matrix) so I don't use
glRotatef anymore. However, even using this method, the rotation works
exactly as with glRotate... Did I miss something?
I did:
--------------------
[self CreateFromAxisAngle:1.0f y:0.0f z:0.0f degrees:xrot];
[self CreateFromAxisAngle:0.0f y:1.0f z:0.0f degrees:yrot];
[self CreateFromAxisAngle:0.0f y:0.0f z:1.0f degrees:zrot];
[self MultiplyQuaternion:qx byQuaternion:qy];
[self MultiplyQuaternion:q byQuaternion:qz];
[self CreateMatrix];
glMultMatrixf(Matrix);
--------------------
where
--------------------
- (void)CreateFromAxisAngle:(GLfloat)xx y:(GLfloat)yy z:(GLfloat)zz
degrees:(GLfloat)degrees
{
GLfloat angle = (GLfloat)((degrees / 180.0f) * pi);
GLfloat result = (GLfloat)sin( angle / 2.0f );
if(xx){
qx.m_w = (GLfloat)cos( angle / 2.0f );
qx.m_x = xx * result;
qx.m_y = yy * result;
qx.m_z = zz * result;
}
else if(yy){
qy.m_w = (GLfloat)cos( angle / 2.0f );
qy.m_x = xx * result;
qy.m_y = yy * result;
qy.m_z = zz * result;
}
else{
qz.m_w = (GLfloat)cos( angle / 2.0f );
qz.m_x = xx * result;
qz.m_y = yy * result;
qz.m_z = zz * result;
}
}
and where
--------------------
- (void)MultiplyQuaternion:(glQuaternion)a byQuaternion:(glQuaternion)b
{
q.m_w = (b.m_w * a.m_w) - (b.m_x * a.m_x) - (b.m_y * a.m_y) - (b.m_z *
a.m_z);
q.m_x = (b.m_w * a.m_x) + (b.m_x * a.m_w) + (b.m_y * a.m_z) - (b.m_z *
a.m_y);
q.m_y = (b.m_w * a.m_y) + (b.m_y * a.m_w) + (b.m_z * a.m_x) - (b.m_x *
a.m_z);
q.m_z = (b.m_w * a.m_z) + (b.m_z * a.m_w) + (b.m_x * a.m_y) - (b.m_y *
a.m_x);
}
and where
--------------------
- (void)CreateMatrix
{
// First row
Matrix[ 0] = 1.0f - 2.0f * (q.m_y * q.m_y + q.m_z * q.m_z);
Matrix[ 1] = 2.0f * (q.m_x * q.m_y + q.m_z * q.m_w);
Matrix[ 2] = 2.0f * (q.m_x * q.m_z - q.m_y * q.m_w);
Matrix[ 3] = 0.0f;
// Second row
Matrix[ 4] = 2.0f * (q.m_x * q.m_y - q.m_z * q.m_w);
Matrix[ 5] = 1.0f - 2.0f * (q.m_x * q.m_x + q.m_z * q.m_z);
Matrix[ 6] = 2.0f * (q.m_z * q.m_y + q.m_x * q.m_w);
Matrix[ 7] = 0.0f;
// Third row
Matrix[ 8] = 2.0f * (q.m_x * q.m_z + q.m_y * q.m_w);
Matrix[ 9] = 2.0f * (q.m_y * q.m_z - q.m_x * q.m_w);
Matrix[10] = 1.0f - 2.0f * (q.m_x * q.m_x + q.m_y * q.m_y);
Matrix[11] = 0.0f;
// Fourth row
Matrix[12] = 0;
Matrix[13] = 0;
Matrix[14] = 0;
Matrix[15] = 1.0f;
}
Best Regards
--
Lorenzo
email: email@hidden
> From: email@hidden
> Date: Sun, 19 Sep 2004 15:59:54 -0400 (EDT)
> To: email@hidden
> Subject: Re: Rotations
>
>
> In a message dated 9/19/04 4:08:50 AM, email@hidden writes:
>
>> No sorry,
>> this didn't solve the problem. The object still rotates on the original
>> "X"
>> axis. Instead since I firstly rotated the "Y" axis, now rotating by an
>> "X"
>> angle, should rotate the object on its own current local "X" axis. And
>> this
>> doesn't happen. How to fix this? Any other idea?
>
> So the Object "local" system are not changing with translatef.
>
> Do you have the same or different value for xrot and yrot?
> example:
> glRotatef(45,0,0,0);
> glRotatef(90,0,0,0);
>
> if you don't you could try glRotatef(XYrot,1,1,0);
>
> And you probably want to send your reply to
> the OpenGL-dev instead of Cocoa-dev this time :)
>
>
>
> BinarySpike
>
>
>
>
>
>
>
>
>
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Mac-opengl mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/mac-opengl/email@hidden
This email sent to email@hidden
