First person shooter camera movement

Question

I am making an FPS in XNA. I cannot seem to make a FPS camera that I can move Forward, Back, Side to Side using the keyboard. How do I do that?

Answer 1

here is some basic code that will work for you.

//class scope fields
Vector3 camPosition, camTarget;


//in the camera Update method
Matrix ViewToWorld = Matrix.Invert(view);

if(/* W key is down */)
{
   camPositon += viewToWorld.Forward * speed;//speed should include a factor of frame delta time
   camTarget += viewToWorld.Forward * speed;
}

// same code as above for S key but use viewToWorld.Backward instead

if(/* D key is down */)
{
   camPositon += viewToWorld.Right * speed;
   camTarget += viewToWorld.Right * speed;
}

//same code as above for A key but use viewToWorld.Left instead

view = Matrix.CreateLookAt(camPosition, camTarget, Vector3.Up);