Right Setup for Drawing?
Hello!
I''m currently coding an 3d presentation engine, which load all
parameters from a special file including some nicely interpolated keyframes and links to an unlimited amount of 3D Models.
I''ve designed like Flash, so all keyframes are stored in a timeline, the objects have no properties like position,rotation ect.
It looks like this:
Engine->
Scene->
Timeline(has all animation data)
3DModel1
3DModel2
ParticleEmmitter1
....
Now I have A Problem, if I just change only the position OR the
the rotation OR the scaling, it looks nicely.
But if I change by example the position and the scaling, the objects get other positions:
glTranslate(1.0,1.0,0.0); == Translation to 1,1,0
BUT:
glTranslate(1.0,1.0,0.0);
glScale(0.5,0.5,0.5); == Translation to 0.5,0.5,0
And If you combine the whole thing with glRotate it ends up
in a nightmare.
I just want to rotate/scale the graphic objects attached to the
timeline, but there position in worldspace shoudn''t be altered by
the Rotation/Scaling.
I hope you understand my problem, I think I have to include some
tricky use of glPush/Pop but I don''t know how and I''m running out
of time, otherwise I could implement a Matrixclass, but for now I need a simple and fast solution
THANKS ALOT!
PS:
This is my Timeline::OnDraw() Function, which is called BEFORE
the other objects are drawn:
glLoadIdentity();
CVector3 CameraPos = ((CCamera *)Parent()->Child())->Location;
CVector3 CameraRot = ((CCamera *)Parent()->Child())->Rotation;
if (active) // If The Timeline Is Running
{
if (currentkey < number_of_keyframes) currentkey++; //If There Are Other Frames Waiting
else if(repeat) currentkey = 0;
}
//Camera
glTranslatef(-CameraPos.GetX(), -CameraPos.GetZ(), -CameraPos.GetY());
glRotatef(CameraRot.GetX(),1.0f,0,0);
glRotatef((float)360.0 - CameraRot.GetY(),0,1.0f,0);
//Timeline
glRotatef(pKeyFrame[currentkey].Rotation.GetX(), 1.0, 0.0, 0.0);
glRotatef(pKeyFrame[currentkey].Rotation.GetY(), 0.0, 1.0, 0.0);
glRotatef(pKeyFrame[currentkey].Rotation.GetZ(), 0.0, 0.0, 1.0);
glTranslatef(pKeyFrame[currentkey].Position.GetX(),pKeyFrame[currentkey].Position.GetY(),pKeyFrame[currentkey].Position.GetZ());
glScalef(pKeyFrame[currentkey].Scaling.GetX(),pKeyFrame[currentkey].Scaling.GetY(),pKeyFrame[currentkey].Scaling.GetZ());
Material = pKeyFrame[currentkey].Material;
GiveToChildren();
THANKS ONCE AGAIN!
check out some site on linear algebra or better yet get a book out of the library about it itll explain everything better.
but basically any operations (translate,rotate,scale) happen on the current matrix if u use glLoadIdentity() this is the identity matrix located at (0,0,0) in world space thus any rotate call u make after that will rotate around that point (0,0,0) if u go translate(1,0,0) + then do a rotate the rotation will occur around worldspace position(1,0,0).
what u want to do is rotate/scale around the objects center right?
well translate the object until its at (0,0,0) do the rotation/scaling and then translate back
but basically any operations (translate,rotate,scale) happen on the current matrix if u use glLoadIdentity() this is the identity matrix located at (0,0,0) in world space thus any rotate call u make after that will rotate around that point (0,0,0) if u go translate(1,0,0) + then do a rotate the rotation will occur around worldspace position(1,0,0).
what u want to do is rotate/scale around the objects center right?
well translate the object until its at (0,0,0) do the rotation/scaling and then translate back
you mean I should first rotate translate the camera, then translate back to origin rotate/scale and then translate to
current position of the 3DModel/Particle/whatever.
There is just one thing I don''t understand, when do I have to
draw the object, at the end of whole process or somewhere between
Thanks
current position of the 3DModel/Particle/whatever.
There is just one thing I don''t understand, when do I have to
draw the object, at the end of whole process or somewhere between
Thanks
Help!!
I can''t get it working.
Perhabs I should explain it in more detail:
I want to rotate the object:
at 0,0,0 I call glRotate.
then I glTranslate to the position.
then I draw it.
BUT if I rotate lets say 90 deg around the x-axis, and then
translate to lets say 10,20,0, it will end up somewhere else
in worldspace.
My Question is How can do a Rotation in Localspace only, while
the translation in worldspace is not affected?
To the Point, the model should always be by example at 10,10,20
(worldspace), while the rotation can be completly different.
THANKS
I can''t get it working.
Perhabs I should explain it in more detail:
I want to rotate the object:
at 0,0,0 I call glRotate.
then I glTranslate to the position.
then I draw it.
BUT if I rotate lets say 90 deg around the x-axis, and then
translate to lets say 10,20,0, it will end up somewhere else
in worldspace.
My Question is How can do a Rotation in Localspace only, while
the translation in worldspace is not affected?
To the Point, the model should always be by example at 10,10,20
(worldspace), while the rotation can be completly different.
THANKS
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