I have a Model named cube to which I load in LoadContent(): cube = Content.Load<Model>("untitled");.
In
the Draw Method I call DrawModel:
private void DrawModel(Model m, Matrix world)
{
foreach (ModelMesh mesh in m.Meshes)
{
foreach (BasicEffect effect in mesh.Effects)
{
effect.EnableDefaultLighting();
effect.View = camera.View;
effect.Projection = camera.Projection;
effect.World = world;
}
mesh.Draw();
}
}
camera is of
the Camera type, a class I've setup. Right now it is instantiated in
the initialization section with
the graphics aspect ratio and
the translation (world) vector of
the model, and
the Draw loop calls
the camera.UpdateCamera(); before drawing
the models.
class Camera
{
#region Fields
private Matrix view; // View Matrix for Camera
private Matrix projection; // Projection Matrix for Camera
private Vector3 position; //
Position of Camera
private Vector3 target; // Point camera is "aimed" at
private float aspectRatio; //Aspect Ratio for projection
private float speed; //Speed of camera
private Vector3 camup = Vector3.Up;
#endregion
#region Accessors
/// <summary>
/// View Matrix of
the Camera -- Read Only
/// </summary>
public Matrix View
{
get { return view; }
}
/// <summary>
/// Projection Matrix of
the Camera -- Read Only
/// </summary>
public Matrix Projection
{
get { return projection; }
}
#endregion
/// <summary>
/// Creates a new Camera.
/// </summary>
/// <param name="AspectRatio">Aspect Ratio to use for
the projection.</param>
/// <param name="
Position">Target coord to aim camera at.</param>
public Camera(float AspectRatio, Vector3 Target)
{
target = Target;
aspectRatio = AspectRatio;
ResetCamera();
}
private void Rotate(Vector3 Axis, float Amount)
{
position = Vector3.Transform(position - target, Matrix.CreateFromAxisAngle(Axis, Amount)) + target;
}
/// <summary>
/// Resets Default Values of
the Camera
/// </summary>
private void ResetCamera()
{
speed = 0.05f;
position = target + new Vector3(0f, 20f, 20f);
projection = Matrix.CreatePerspectiveFieldOfView(MathHelper.PiOver4, aspectRatio, 0.5f, 100f);
CalculateViewMatrix();
}
/// <summary>
/// Updates
the Camera. Should be first thing done in Draw loop
/// </summary>
public void UpdateCamera()
{
Rotate(Vector3.Right, speed);
CalculateViewMatrix();
}
/// <summary>
/// Calculates
the View Matrix for
the camera
/// </summary>
private void CalculateViewMatrix()
{
view = Matrix.CreateLookAt(position,target, camup);
}
I'm trying to create
the camera so that it can orbit
the center of
the model. For a test I am calling Rotate(Vector3.Right, speed); but it rotates almost right but gets to a point where it "flips." If I rotate along a different axis Rotate(Vector3.Up, speed); everything seems OK in that direction.
So I guess, can someone tell me what I'm not accounting for in
the above code I wrote? Or point me to an example of an orbiting camera that can be fixed on an arbitrary point?
