Hello!
The animation of the translation is working right now. Thank you, also for
the explications.
Now I'm trying to use the slerpThis-function to animate a rotation. I'm not
sure, if I passed the values right. Probably not, because it's not working
:-) Thus, another easy problem to solve:
I have written this function:
void rotation_x(Quaternion cube_init_qua, Quaternion cube_end_qua, int
frame_current, int frame_total){
Matrix cube_move;
cube_move.setIdentity();
Quaternion q;
float slerp_value = frame_current/frame_total; //to get a value
between 0 and 1
beginEditCP(cube_trans, Transform::MatrixFieldMask);
q.slerpThis(cube_init_qua,cube_end_qua,slerp_value);
cube_move.setTransform(cube_init,q); //cube_init =
Vec3f(0,10,0)
cube_trans->setMatrix(cube_move);
endEditCP(cube_trans, Transform::MatrixFieldMask);
}
And this is being called by
rotation_x(Quaternion(Vec3f(1,0,0),0), Quaternion(Vec3f(1,0,0),30),
frame_current, frame_total);
in the display-Function.
Thank you again!
alex
----- Original Message -----
From: "Carsten Neumann" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Thursday, February 21, 2008 6:56 PM
Subject: Re: [Opensg-users] Animation of a translation
> Hello Alexandra,
>
> Alexandra Wolyniec wrote:
>> Hello!
>> I'm trying to form a translation by using functions.
>> So I wrote this function to make an easy transformation along the y axis:
>>
>> void animation_vertical(Vec3f cube_init_vec, Vec3f cube_end_vec, int
>> frame_total){
>>
>> Matrix cube_move;
>> cube_move.setIdentity();
>> for (frame_current=0; frame_current<=frame_total; frame_current++){
>> beginEditCP(cube_trans, Transform::MatrixFieldMask);
>> int cube_move_y =
>> cube_init_vec.getValues()[1]+(osgabs(cube_end_vec.getValues()[1]-cube_init_vec.getValues()[1])/frame_total*frame_current);
>> cube_move.setTranslate(0,cube_move_y,0);
>> cube_trans->setMatrix(cube_move);
>> endEditCP(cube_trans, Transform::MatrixFieldMask);
>> }
>> }
>
> you do not need a loop here. Computer animation works like stop motion
> movies: You set up the scene and take a picture of it, then modify it
> for the next picture. Whether you do the modification in many small
> steps (like in the loop above) or just use the values computed in the
> last iteration of the loop is not visible as no images are taken of the
> intermediate steps.
> So, to move an object from A to B over the course of 100 frames, you
> basically do the following:
>
> in keyboard:
> run = true;
> frame_current = 0;
> frame_total = 100;
>
> in display:
> if run == true and frame_current <= frame_total:
> compute a position C as the linear interpolation between A and B,
> based on the ratio of frame_current/frame_total.
> place your object at C
>
> render the scene.
>
>> With the keyboard function I'm activating the type of the animation
>> (because there will be some more animations) and the running of the
>> animation itself. In addition I set the duration of the animation to
>> zero:
>>
>> void keyboard(unsigned char k, int x, int y){
>> switch (k){
>> case '1' : run = true;
>> typ_animation = 1;
>> dauer = 0;
>> break;
>> }
>> }
>>
>> After that I use the display function to let the animation go on. As I
>> have understood this method, this function is being called and called by
>> glutDisplayFunc(display); in the SetupGlut. (Sorry, after adapting to
>> french my english gets more and more worse :-/) So, that's why I thought
>> it will redraw each new frame position of the animation.
>
> do you also have a glutIdleFunc? That should be a function that just
> calls glutPostRedisplay, because otherwise your display function will
> only be called in reaction to certain "events" that require a refresh of
> the screen content (e.g. resizing/moving the window).
> Also, when the user presses a recognized key (like '1') you probably
> also want to issue a glutPostRedisplay.
>
>> void display(void){
>>
>> if(run==true && dauer<300){
>> switch(typ_animation){
>> case 1: animation_vertical(Vec3f(0,5,0), Vec3f(0,20,0),
>> dauer);
>> break;
>> }
>> dauer++;
>> }
>> mgr->redraw();
>> }
>> }
>>
>> All in all, it changes the positions, but it does not show the animation
>> between. Why?! What do I have to change?
>
> My guess would be the lack of a glutIdleFunction, will already display
> the animation. But please also try to understand why the loop in
> animate_vertical is not required.
>
> Hope it helps,
> Carsten
>
>
>
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