Hi,
I will try to explain what I'm trying to do through an example (instead of a
diagram. :-) ). It's not complicated, but abstract.
Imagine that a camera (you) is looking to 2 meshes, resting on the floor and
positioned 5u apart from each other. You want to set a certain velocity to
mesh #1 making it to hit mesh #2. You can accomplish that by calculating a
vector3 velo = K * (normalize(pos2 - pos1))] -- pos1 and pos2 in world space
- velo in relative space. Let's keep the vector3 velo for using it later.
But instead of just setting the velocity to mesh #1, you want to visualize a
genmesh arrow, over mesh #1 and pointing towards mesh #2. The arrow genmesh
was previously modeled in Blender, with the care to position its origin on
(0,0,0) and its arrowhead on (1,0,0). You will set the origin of your arrow
transform to the origin of mesh #1. Then the arrow will appear over mesh #1,
pointing to (1,0,0).
The question is: how to orientate the arrow transform to make it visually
point to mesh #2? Everything should be independent of camera-space. The
usage of LookAt() is clear for orientating cameras, but how to correctly use
it on meshes? How to take into account the orientation of the modeled arrow
(1,0,0)? Remember that the vector3 velo, which is our given direction, is
relative to the origin of both the body and the arrow.
Note that this procedure is intended to allow a user to visualize concretely
the abstract concept of a vector, and to preview the trajectory of moving
bodies. As you might guess, I'm not building a game, but an educational
tool!!
I would be very glad to give any further information, including code
snippets if needed.
Thank you!
Best regards,
Mario.
_____
De: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Em nome de Amir Taaki
Hi,
I'm not too clear what you're trying to do... Maybe a diagram could help?
If you are trying to make an arrow that stays in a fixed position but points
in a constant direction as the player moves about (like a compass would),
you can try to actually parent its position to the camera but alter its
rotation to point at the direction you wish.
On 11/29/06, Mario Lapin <[EMAIL PROTECTED]> wrote:
Hi all,
I'm putting the question back to the top of the list, in the hope that
someone else might read it. I'm trying hard to solve it, though
unsuccessfully. TIA.
--
I'm coding a visual representation of an arrow-like vector that would make
it possible for the user to actually see a direction in 3D space, for
educational purposes. First, it would be possible for the user to move
(rotate) the arrow, turning it to a new direction, returned as a world-space
csVector3. Second, the user might also supply a world-space csVector3, and
then the arrow should point to it. The 3D vector representation was modeled
on Blender as an arrow starting at (0,0,0) and pointing to (1,0,0), in CS
coordinate system, and then a MeshWrapper is instantiated from the
iMeshFactoryWrapper loaded from file.
Well, the first objective was achieved with the following code :
csRef<iMeshWrapper> arrow;
csVector3 direction;
...
direction =
(arrow->GetMovable()->GetTransform().This2OtherRelative(csVector3(0, 1,
0)));
However, I can't realize how to do the contrary, i.e.,, having the arrow to
point to a given "csVector3 direction" in world space. I supposed that the
following code might work, but it doesn't:
// Given direction
csVector3 direction(...);
...
csReversibleTransform trans;
trans = arrow->GetMovable()->GetTransform();
csVector3 trans_direction = trans.Other2ThisRelative(direction);
trans.LookAt(trans_direction, trans.GetUp());
arrow ->GetMovable()->SetTransform(trans);
I ask you if someone could kindly suggest how to obtain the desired results,
as I've ran out of ideas!!! I would be very glad to give any other required
information.
Thank you in advance!
Best regards,
Mario.
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