Camera Relativity (and other stories)

[Firejack]

OK, this is really annoying me now.

I thought I'd fixed the problem, but I haven't. Here's what's up:

I have a nice full screen 3D world thing. I'm trying to move a camera around it - kinda like free-look mode in Counterstrike (when you get dead). We fixed up some keyboard input to move the camera up the axis, like strafing, forwards etc. Fine.

But then you put the mouse on.

When you do this, and press forwards, you CONTINUE TO MOVE ALONG THE Z AXIS, and NOT in the direction you're facing. Same for if you try strafing, you just move along the X axis regardless of the way you're looking.

This is pants.

So If someone could point us towards a tutorial or something we'd be VERY grateful.

Firejack

[Zaei]

You have to find the angle that you are facing on the XZ plane, and the XY/ZY plane (left/right, and up/down). Then, instead of simple adding a value to the Z camera value, you have to figure out a vector that defines the direction you are looking at, and move along that vector.

Also, If you are using the D3DXMatrixLookAtLH or ..RH functions, you can create a vector by adding (or subtracting, dont remember) the current camera position, and the point it is looking at, normalize that vector, and move along it.

Z.

[JaredM]

That's in the realm of 3D game theory.

[Zaei]

Thats what he's talking about...

Z.

[JaredM]

I know, I just felt like posting.

[Firejack]

Thanks.

Methinks I'll have a look at the DX8 SDK and see if/how they've done it. We tried numerous methods for the camera. One was the D3DXCameraLookAtRH or something, but that goes pants when you start looking around. You keep looking down the X axis rather than swithching to the Z axis as you turn.

Then we tried re writing the matrix ourselves, which is great for the strafing, but again goes to pot when you try to look around.

Not quite sure why...

Latest idea is to set the X, Y, Z, W properties of a quaternion for the rotation, and then turn it into a matrix and combine it with the position matrix of the camera.

Not tried it yet. Thanks for the help anyways.

FJ

[Zaei]

Think of it this way. Your object is facing in a certain direction on a circle. If you keep track of this value, you can change this to a look at point:

.x = cos(facing);
.y = cam.y;
.z = sin(facing);

Where y is in the up direction. That should solve the looking around part. When you move, simply move in the direction you are facing, instead of simply adding 1 to .x, or .z, etc.

Z.