Question

I thought it would be simple as:

 Vector3 point = Vector3.Transform(originalPoint, worldMatrix);

But apparently not… It make’s the point’s numbers shoot into the thousands.

Basically, what I’m trying to do is creating a collision system and every two points in this system is a line, so basically I want to collide lines. I want the lines to be able to scale, rotate, and translate based on a world matrix (so that the collision lines are in tune with the object’s scale, rotation, and translation).

I’ve been trying for hours now and I can’t seem to figure it out. I’ve tried multiplying by the View Matrix as well and while that is the closest to what I want, it seems to switching between two sets of numbers! It would be perfect if it stayed with the one set, I have no idea why it keeps changing…

Any help, please? 🙁

Edit: To add a little, I’m constantly updating the points in an Update call. But I don’t know if that would change anything, either way the points = originalpoints first.

Steve H:
One line would have two points, so:

originalPoint[0] = new Vector3(-42.5f, 0f, 0f);
originalPoint[1] = new Vector3(42.5f, 0f, 0f);
point[0] = Vector3.Transform(originalPoint[0], worldMatrix);
point[1] = Vector3.Transform(originalPoint[1], worldMatrix);`

At first, point[0] & [1] equals the same as originalPoint[0] & [1]. But, the moment I move my player even just a few pixels…

point[0] = (-5782.5f, 0f, 0f)
point[1] = (-5697.5, 0f, 0f)

The player’s position is -56.0f.

My worldMatrix goes as:

_world = Matrix.Identity // ISROT
       * Matrix.CreateScale(_scale) // This object's scale
       * Matrix.CreateFromQuaternion(_rotation) // It's rotation
       * Matrix.CreateTranslation(_offset) // The offset from the centre
       * Matrix.CreateFromQuaternion(_orbitRotation) // It's orbit around an object
       * _orbitObjectWorld // The object to base this world from
       * Matrix.CreateTranslation(_position); // This object's position

The objects display properly in graphics. They scale, rotate, translate completely fine. They follow the orbit’s scale, rotation, and translation too but I haven’t tested orbit much, yet.

I hope this is enough detail…

Edit: Upon further research, the original points are also being changed… 😐 I don’t get why that’s happening. They’re the exact same as the new points…

Answer 1

I figured out my problem… -_-

So, after I create the line points, I do this at the end:

originalLines = collisionLines;

collisionLines & originalLines are both Vector3[] arrays.

I guess just by making one equal the other, it’s like they’re the exact same and changing one changes the other… that is something I did not know.

So I made this function:

void CreateOriginalPoints()
{
    _originalPoints = new Vector3[_collisionPoints.Length];

    for (int i = 0; i < _collisionPoints.Length; i++)
        _originalPoints[i] = _collisionPoints[i];
}

And this solves the problem completely. It now makes complete sense to me why this problem was happening in the first place.

Thanks a lot Donnie & Steve H. I know you two didn’t answer my question but it got me to poke around even deeper until I found the answer.