Currently writing a camera component for FNA (basically XNA), and can't for the life of me figure out why my matrix transform isn't working as expected. This is how I calculate my view & projection matrices:
// projection
// WorldSize is something like 16x9, 20x10, etc. Basically the "simulated" world size.
// Zoom is just a float to zoom the camera.
var left = Zoom * -WorldSize.X / 2;
var right = Zoom * WorldSize.X / 2;
var bottom = Zoom * -WorldSize.Y / 2;
var top = Zoom * WorldSize.Y / 2;
const float near = 0;
const float far = 100;
var projection = Matrix.CreateOrthographicOffCenter(left, right, bottom, top, near, far);
and
// view
// Position is the position of my Camera, e.g. (10, 15), (6.51, 16.612), etc.
var position = new Vector3(Position, 0);
var target = position + Vector3.Forward;
var up = Vector3.Up;
var view = Matrix.CreateLookAt(position, target, up);
// Combine them
var combined = projection * view;
This should, by all the sources I've checked, double-checked, and triple-checked, be correct. However when I apply this matrix to my batch or effects it doesn't show anything at all:
// I would expect a white square to be rendered in the middle of the screen. Since WorldSize is
// 16x9 I would expect a 1x1 square to be clearly visible.
var batch = new SpriteBatch();
batch.begin(/* the rest */, combined);
var texture = new Texture2D(Game.GraphicsDevice, 1, 1);
texture.SetData(new []{Color.White });
batch.Draw(texture, Vector2.Zero, Color.White);
batch.End();
// Also tried just rendering lines, shows nothing
var effect = new BasicEffect(graphicsDevice)
{
VertexColorEnabled = true,
View = view,
Projection = projection
};
effect.CurrentTechnique.Passes[0].Apply();
graphicsDevice.DrawUserPrimitives(PrimitiveType.LineStrip, vertices, 0, vertices.Length - 1);
I have checked so many sources and they all do exactly like this. I even tried copy+pasting the matrix source code for a Java project I made some time back that I know works, and that didn't work either so I don't think the Matrix transforms are to blame. Anyone know what I'm doing wrong?
