Re: [osg-users] moving object along rotated vector
Hi, as you've seen, q*f in OSG is shorthand for (qc * fq * q). It's the opposite of what one might expect. There are some inconsistencies... go here: http://article.gmane.org/gmane.comp.graphics.openscenegraph.user/43425 Also, like you said, rotations can be visualised either from the coordinate system's point of view or the object's. See also here: http://article.gmane.org/gmane.comp.graphics.openscenegraph.user/37721 cheers jp On 01/07/10 17:43, Tom Pearce wrote: The various methods we're talking about for figuring out a forward vector are rotating in different directions - here's a bit of test code to confirm. Code: FILE* fp = fopen(printout.txt, w); osg::Vec3 f(0., 1., 0.); osg::Quat fq(0., 1., 0., 0.); osg::Quat q(osg::DegreesToRadians(45.0), osg::Vec3(0., 0., 1.)); osg::Quat qc = q.conj(); osg::Vec3 r1 = q*f; osg::Vec3 r2 = (q * fq * qc).asVec3(); osg::Vec3 r3 = q.inverse() * f; fprintf(fp, quat * vec: %f %f %f\n, r1.x(), r1.y(), r1.z()); fprintf(fp, q * fq * qc: %f %f %f\n, r2.x(), r2.y(), r2.z()); fprintf(fp, q.inverse*f: %f %f %f\n, r3.x(), r3.y(), r3.z()); fclose(fp); Results: quat * vec: -0.707107 0.707107 0.00 q * fq * qc: 0.707107 0.707107 0.00 q.inverse*f: 0.707107 0.707107 0.00 Since the test rotation you've been using is close to pi/2, it looks like the axis is switched... but really, it's just rotated in the opposite direction than you expect. When you get a rotation quat out of of a PAT or MatrixTransform, (I guess) it's giving you the coordinate system transform. When you transform a coordinate system in one direction, it's equivalent to rotating vectors in the opposite direction. So if you try and rotate a vector directly by this transform, ie by doing quat*vec, your forward vector will be rotated an equal amount but in the opposite direction from how the model appears on the screen. By doing quat * vec * quat.conj(), or by doing quat.inverse() * vec, you're applying the coordinate system transform to your vector, and everything works out such that your forward vector and your on-screen model have rotated together. I'm still quite new to these maths, so please, an expert should pitch in! I am basing this all on my own experiences with moving objects around in osg. Cheers, Tom[/code] -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=29611#29611 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org -- This message is subject to the CSIR's copyright terms and conditions, e-mail legal notice, and implemented Open Document Format (ODF) standard. The full disclaimer details can be found at http://www.csir.co.za/disclaimer.html. This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. MailScanner thanks Transtec Computers for their support. ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] moving object along rotated vector
Hi, q*f in OSG is shorthand for (qc * fq * q). It's the opposite of what one might expect. There are some inconsistencies... My approach is always to try it the way I think it should work, and when it doesn't, start playing with the multiplication order - eventually something works. It does mess with my head a bit when I try and understand the math, but in the end as long as my code does what I want, I'm don't worry much. Just out of curiosity, does anyone know why quat*vec3 was implemented the way it was? Everything I've read (outside of osg) about using quats to rotate points (ie vectors) says q*fq*qc is the way to do it. Cheers, Tom -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=29633#29633 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] moving object along rotated vector
Hi, On 02/07/10 17:36, Tom Pearce wrote: Hi, q*f in OSG is shorthand for (qc * fq * q). It's the opposite of what one might expect. There are some inconsistencies... My approach is always to try it the way I think it should work, and when it doesn't, start playing with the multiplication order - eventually something works. It does mess with my head a bit when I try and understand the math, but in the end as long as my code does what I want, I'm don't worry much. Just out of curiosity, does anyone know why quat*vec3 was implemented the way it was? Everything I've read (outside of osg) about using quats to rotate points (ie vectors) says q*fq*qc is the way to do it. I think it's merely a convenient overload of * that matches matrix*vec... If you go look at the math in the Quat function, it does qc*vq*q. jp Cheers, Tom -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=29633#29633 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org -- This message is subject to the CSIR's copyright terms and conditions, e-mail legal notice, and implemented Open Document Format (ODF) standard. The full disclaimer details can be found at http://www.csir.co.za/disclaimer.html. This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. MailScanner thanks Transtec Computers for their support. ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] moving object along rotated vector
Hi, you'll have to give me more details on your coordinate system. If your object default to pointing in +X, to move it backward you will need to use Q*-X. How are you rotating the object? About which axis? jp On 01/07/10 01:22, Sanat Talmaki wrote: Hi jp, Thanks for those suggestions. I implemented them but I am probably still doing something wrong as the behavior is not as expected. I used the debugger to check the values of the vectors but the numbers dont make sense to me. Thus is the case of Down arroy key and thus I used (0, -1, 0) as my default forward pointing vector. But what I observed is the object moving forward and its y-value increasing instead of decreasing. Initial position = positionArray = (132.86, 78.277, 18.48) Initial attitude= quat = (0, 0, 0.719, 0.695) vector = quat*(0,-1,0) = (0.99, 0.035, 0.00) vector*2 = (1.998, 0.069, 0) PositionArray = PositionArray + vector*2 = (134.86, 78.34, 18.48) --- code: Code: positionArray = PATCurrent-getPosition(); quat = PATCurrent-getAttitude(); vector = quat.operator *(osg::Vec3(0, 1.0, 0.0)); vector.operator *=(2); positionArray = positionArray.operator +(vector); PATCurrent-setPosition(positionArray); Best, Sanat -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=29556#29556 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org -- This message is subject to the CSIR's copyright terms and conditions, e-mail legal notice, and implemented Open Document Format (ODF) standard. The full disclaimer details can be found at http://www.csir.co.za/disclaimer.html. This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. MailScanner thanks Transtec Computers for their support. ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] moving object along rotated vector
I have bought some models of motor vehicles and found that some have the X axis as forwards and some the Y axis, which can cause confusion when you are tryiong to orient and move a model. If you load up a model on its own in osgviewer you will see the rear of the model if the Y axis is forwards, the side if X is forwards. The Quat returned by getAttitude is the rotation from the default orientation. The four components represent a vector and an angle - but let the OSG code worry about that. Try something like this: osg::Quat Qmodel = osg::Quat(0.0, osg::Vec3(0.0,1.0,0.0)); osg::Quat Qturn = osg::Quat(0.1, osg::Vec3(0.0,0.0,1.0)); osg::Vec3 pos, vel; //initialise pos, vel //loop Qmodel = Qmodel*Qturn; vel = Qturn*vel; pos = pos + vel; model-setAttitude (Qmodel); model-setPosition(pos); //end loop Your model should go round in circles, moving the way it's facing. -Original Message- From: osg-users-boun...@lists.openscenegraph.org [mailto:osg-users-boun...@lists.openscenegraph.org] On Behalf Of Sanat Talmaki Sent: 01 July 2010 00:28 To: osg-users@lists.openscenegraph.org Subject: Re: [osg-users] moving object along rotated vector *** WARNING *** This mail has originated outside your organization, either from an external partner or the Global Internet. Keep this in mind if you answer this message. Hi Tom, Could you tell me where you read up the quaternion parts that helped you figure out the code you posted. I went through some stuff on the wiki and another pdf on quaternions that I found. But in both those cases, they refer to a quat as something causing rotation from vector v1 to v2. So in this case when we call PAT-getAttitude() and get a quat, what exactly are we getting, which 2 vectors are we rotating between ? Secondly, I'm also a little confused as to what the 4 values in a quat object represent Thanks! Sanat -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=29557#29557 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.or g This email and any attachments are confidential to the intended recipient and may also be privileged. If you are not the intended recipient please delete it from your system and notify the sender. You should not copy it or use it for any purpose nor disclose or distribute its contents to any other person. MBDA UK Limited, a company registered in England and Wales, registration number 3144919 whose registered office is at Six Hills Way, Stevenage, Hertfordshire, SG1 2DA, England. __ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email __ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] moving object along rotated vector
Hi, I tried a slightly different approach from using Quaternions and so far its working. After using the debugger in visual studio and checking the angle returned by the function- PAT- getAttitude().getRotate(angle, vector); angleDegrees = osg::RadiansToDegrees(angle); The angle always pointed in the direction of the vector I wanted my object to move along. This gave me the idea to simply use cos and sin of that angle and increment current x and y position from PAT by the vlaue of cos(angle) and sin(angle) respectively. So I did: y = sin(angle); x = cos(angle); positionArray.y() -= y; //or + for up key positionArray.x() -= x; //set PAT to new position array. And because with sin and cos of angle 90 giving +ve and -ve values just from the function, it takes care of forward backward movement even when facing the wrong way eg- if i've rotated enough to be facing backwards and then hit forward, the x, y values from the angle between 180 to 270 give -ve values and so it moves the object back keeping the UP key logic intact. Hope I was able to explain what I tried to do. Thanks for the help though, I will try and figure out how to do this using Quat. Best, Sanat -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=29601#29601 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] moving object along rotated vector
Hi Rob, Yes I have faced that situation that you're talking about. Infact I had to rotate my model by 90 in the initial PAT while placing my model in the scene. Else the front of my model was facing the +ve x-axis in osg. I understood the pos vector which I'll get from my PAT but wasn't clear about what you initialized the vel vector. Is it just (1,1,1) ? (assuming I want to move forward/back by 1 unit on each keyboard hit) Thanks Sanat. -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=29602#29602 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] moving object along rotated vector
No, it will be (1,0,0) if the X axis is forwards, (0,1,0) if the Y axis is forwards. -Original Message- From: osg-users-boun...@lists.openscenegraph.org [mailto:osg-users-boun...@lists.openscenegraph.org] On Behalf Of Sanat Talmaki Sent: 01 July 2010 13:46 To: osg-users@lists.openscenegraph.org Subject: Re: [osg-users] moving object along rotated vector *** WARNING *** This mail has originated outside your organization, either from an external partner or the Global Internet. Keep this in mind if you answer this message. Hi Rob, Yes I have faced that situation that you're talking about. Infact I had to rotate my model by 90 in the initial PAT while placing my model in the scene. Else the front of my model was facing the +ve x-axis in osg. I understood the pos vector which I'll get from my PAT but wasn't clear about what you initialized the vel vector. Is it just (1,1,1) ? (assuming I want to move forward/back by 1 unit on each keyboard hit) Thanks Sanat. -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=29602#29602 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.or g This email and any attachments are confidential to the intended recipient and may also be privileged. If you are not the intended recipient please delete it from your system and notify the sender. You should not copy it or use it for any purpose nor disclose or distribute its contents to any other person. MBDA UK Limited, a company registered in England and Wales, registration number 3144919 whose registered office is at Six Hills Way, Stevenage, Hertfordshire, SG1 2DA, England. __ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email __ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] moving object along rotated vector
Hi jp, I missed your earlier post. But here's what I'm doing: The coordinate system for my object is pointing to the +ve Y-Axis (into the screen). When I hit the UP key I increment Y value by 1 and DOWN decrement by 1. I use the LEFT and RIGHT keys to rotate about (0,0,1). I am able to get the object to move the way I want without using quat and using only the angle from the getAttitude().getRotate(angle, vector) function. But I believe I'll need to use quat for something in future so wanted to know how to do this using quat. Thanks, Sanat -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=29608#29608 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] moving object along rotated vector
The various methods we're talking about for figuring out a forward vector are rotating in different directions - here's a bit of test code to confirm. Code: FILE* fp = fopen(printout.txt, w); osg::Vec3 f(0., 1., 0.); osg::Quat fq(0., 1., 0., 0.); osg::Quat q(osg::DegreesToRadians(45.0), osg::Vec3(0., 0., 1.)); osg::Quat qc = q.conj(); osg::Vec3 r1 = q*f; osg::Vec3 r2 = (q * fq * qc).asVec3(); osg::Vec3 r3 = q.inverse() * f; fprintf(fp, quat * vec: %f %f %f\n, r1.x(), r1.y(), r1.z()); fprintf(fp, q * fq * qc: %f %f %f\n, r2.x(), r2.y(), r2.z()); fprintf(fp, q.inverse*f: %f %f %f\n, r3.x(), r3.y(), r3.z()); fclose(fp); Results: quat * vec: -0.707107 0.707107 0.00 q * fq * qc: 0.707107 0.707107 0.00 q.inverse*f: 0.707107 0.707107 0.00 Since the test rotation you've been using is close to pi/2, it looks like the axis is switched... but really, it's just rotated in the opposite direction than you expect. When you get a rotation quat out of of a PAT or MatrixTransform, (I guess) it's giving you the coordinate system transform. When you transform a coordinate system in one direction, it's equivalent to rotating vectors in the opposite direction. So if you try and rotate a vector directly by this transform, ie by doing quat*vec, your forward vector will be rotated an equal amount but in the opposite direction from how the model appears on the screen. By doing quat * vec * quat.conj(), or by doing quat.inverse() * vec, you're applying the coordinate system transform to your vector, and everything works out such that your forward vector and your on-screen model have rotated together. I'm still quite new to these maths, so please, an expert should pitch in! I am basing this all on my own experiences with moving objects around in osg. Cheers, Tom[/code] -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=29611#29611 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] moving object along rotated vector
Hi,
to get a vector to where the object is pointing, just multiply the
default point-to-front vector, I assume (1,0,0) in your case, with the
quaternion you have for the rotation. Then add this vector multiplied by
some amplitude to the current position.
jp
On 30/06/10 00:16, Sanat Talmaki wrote:
Hi,
I am attaching a screenshot of what I am trying to do. In the screenshot you
can see 2 objects placed on a terrain. The lower one is rotated about Z axis
and I use the keyboard UP and DOWN keys to move the object along the Y-axis in
the terrain.
However even after I have rotated the object, I am not able to figure out how
to get the new vector along which the object is now pointing.
I figured I would find the angle I have rotated the object by using Quat and
then depending on angle value 0-90, 90-180, 180-270 or 270-360, find the
tangent of the angle and move it that way. But I'm sure im complicating things
here.
The code I'm using to move the object and rotate is pasted below: (i've only
copied the cases for Up and rotate right as down and left are identical)
else if ( ea.getKey()==osgGA::GUIEventAdapter::KEY_Up)
{
std::cout textBox-getText() std::endl;
positionArray = PATCurrent-getPosition();
//vector = PATCurrent-getAttitude().asVec3();
PATCurrent-getAttitude().getRotate(angle,vector);
angleDegrees = osg::RadiansToDegrees(angle);
y = positionArray.y();
x = positionArray.x();
x += vector.x();
y += 1;
positionArray.y()=y;
positionArray.x()=x;
PATCurrent-setPosition(positionArray);
return true;
}
else if ( ea.getKey()==osgGA::GUIEventAdapter::KEY_Right)
{
//use key right to rotate the object to the right
quat = PATCurrent-getAttitude();
quat.getRotate(angle, vector);
angleDegrees = osg::RadiansToDegrees(angle);
//if angle is 0 make it 360
if(angleDegrees= 1)
{
angleDegrees = 360;
}
angleDegrees -= 1;
quat.makeRotate(osg::DegreesToRadians(angleDegrees),vector);
PATCurrent-setAttitude(quat);
//PATCurrent-setPosition(vector);
}
If you can tell me what I am missing out here I'd be very thankful.
Also, if there is some literature out there that deals with this, I'd be more
than happy to study it.
Thanks,
Sincerely,
Sanat
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Re: [osg-users] moving object along rotated vector
Hi jp, I'm not sure if I've entirely followed what you were saying but here's what I thought I you meant- positionArray = PATCurrent-getPosition(); vector = PATCurrent-getAttitude().asVec3()*(osg::Vec3 (1, 0, 0)); xTemp = vector.x(); yTemp = vector.y(); zTemp = vector.z(); xTemp *= 1; yTemp *= 1; zTemp *= 1; x = PositionArray.x() + xTemp; y = PositionArray.y() + yTemp; z = PositionArray.z() + zTemp; //then set current position using x,y,z and set as new PAT position. Correct me if I'm wrong.. Thanks! Sanat -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=29525#29525 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] moving object along rotated vector
Hi, On 30/06/10 17:05, Sanat Talmaki wrote: Hi jp, I'm not sure if I've entirely followed what you were saying but here's what I thought I you meant- positionArray = PATCurrent-getPosition(); vector = PATCurrent-getAttitude().asVec3()*(osg::Vec3 (1, 0, 0)); skip the asVec3, you want to multiply by the orientation Quat. IOW you want to rotate your object's default front vector to where it is pointing in space. Quat = PATCurrent-getAttitude(); vector = Quat * osg::Vec3 (1, 0, 0) now vector would point to where your object is pointing. xTemp = vector.x(); yTemp = vector.y(); zTemp = vector.z(); xTemp *= 1; yTemp *= 1; zTemp *= 1; you should be able to scale the unit direction vector by a single multipy (see the Vec headers). Instead of *1, you should multiply by some scale that makes sense for you. x = PositionArray.x() + xTemp; y = PositionArray.y() + yTemp; z = PositionArray.z() + zTemp; same here, you can just add two vectors, you don't need to add component wise manually. //then set current position using x,y,z and set as new PAT position. Correct me if I'm wrong.. hope it works... jp Thanks! Sanat -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=29525#29525 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org -- This message is subject to the CSIR's copyright terms and conditions, e-mail legal notice, and implemented Open Document Format (ODF) standard. The full disclaimer details can be found at http://www.csir.co.za/disclaimer.html. This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. MailScanner thanks Transtec Computers for their support. ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] moving object along rotated vector
Hi, I've been doing it this way, works like a charm: Say your forward vector is (0, 1, 0), pointing along the y axis, make an with from this by adding a real coordinate (4th coordinate) of zero - (0, 1, 0, 0). You also have a rotation quat q, and take it's conjugate to get q_prime. Then multiply as below to get the new forward quat, then get the vector from that. q_prime = q.conj(); osg::Quat forward_quat(0., 1., 0. 0.); osg::Quat rotated_foward = q * forward_quat * q_prime; osg::Vec3 new_forward_vec = rotated_forward.asVec3(); I'm no expert so take this with a grain of salt, but when I tried the method JP outlined (which was my first shot at doing it) the rotated vector wasn't correct (or at least not what I expected). Looking up quaterion rotation online, wikipedia for example, I found the method I described above. Of course, JP's method works spot on for what to do with your object when you're moving it along your newly rotated forward vector by however far you want to move it. Cheers, Tom -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=29533#29533 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] moving object along rotated vector
Hi jp, Thanks for those suggestions. I implemented them but I am probably still doing something wrong as the behavior is not as expected. I used the debugger to check the values of the vectors but the numbers dont make sense to me. Thus is the case of Down arroy key and thus I used (0, -1, 0) as my default forward pointing vector. But what I observed is the object moving forward and its y-value increasing instead of decreasing. Initial position = positionArray = (132.86, 78.277, 18.48) Initial attitude= quat = (0, 0, 0.719, 0.695) vector = quat*(0,-1,0) = (0.99, 0.035, 0.00) vector*2 = (1.998, 0.069, 0) PositionArray = PositionArray + vector*2 = (134.86, 78.34, 18.48) --- code: Code: positionArray = PATCurrent-getPosition(); quat = PATCurrent-getAttitude(); vector = quat.operator *(osg::Vec3(0, 1.0, 0.0)); vector.operator *=(2); positionArray = positionArray.operator +(vector); PATCurrent-setPosition(positionArray); Best, Sanat -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=29556#29556 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] moving object along rotated vector
Hi Tom, Could you tell me where you read up the quaternion parts that helped you figure out the code you posted. I went through some stuff on the wiki and another pdf on quaternions that I found. But in both those cases, they refer to a quat as something causing rotation from vector v1 to v2. So in this case when we call PAT-getAttitude() and get a quat, what exactly are we getting, which 2 vectors are we rotating between ? Secondly, I'm also a little confused as to what the 4 values in a quat object represent Thanks! Sanat -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=29557#29557 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
[osg-users] moving object along rotated vector
Hi,
I am attaching a screenshot of what I am trying to do. In the screenshot you
can see 2 objects placed on a terrain. The lower one is rotated about Z axis
and I use the keyboard UP and DOWN keys to move the object along the Y-axis in
the terrain.
However even after I have rotated the object, I am not able to figure out how
to get the new vector along which the object is now pointing.
I figured I would find the angle I have rotated the object by using Quat and
then depending on angle value 0-90, 90-180, 180-270 or 270-360, find the
tangent of the angle and move it that way. But I'm sure im complicating things
here.
The code I'm using to move the object and rotate is pasted below: (i've only
copied the cases for Up and rotate right as down and left are identical)
else if ( ea.getKey()==osgGA::GUIEventAdapter::KEY_Up)
{
std::cout textBox-getText() std::endl;
positionArray = PATCurrent-getPosition();
//vector = PATCurrent-getAttitude().asVec3();
PATCurrent-getAttitude().getRotate(angle,vector);
angleDegrees = osg::RadiansToDegrees(angle);
y = positionArray.y();
x = positionArray.x();
x += vector.x();
y += 1;
positionArray.y()=y;
positionArray.x()=x;
PATCurrent-setPosition(positionArray);
return true;
}
else if ( ea.getKey()==osgGA::GUIEventAdapter::KEY_Right)
{
//use key right to rotate the object to the right
quat = PATCurrent-getAttitude();
quat.getRotate(angle, vector);
angleDegrees = osg::RadiansToDegrees(angle);
//if angle is 0 make it 360
if(angleDegrees = 1)
{
angleDegrees = 360;
}
angleDegrees -= 1;
quat.makeRotate(osg::DegreesToRadians(angleDegrees),vector);
PATCurrent-setAttitude(quat);
//PATCurrent-setPosition(vector);
}
If you can tell me what I am missing out here I'd be very thankful.
Also, if there is some literature out there that deals with this, I'd be more
than happy to study it.
Thanks,
Sincerely,
Sanat
--
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http://forum.openscenegraph.org/viewtopic.php?p=29505#29505
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