1 files changed, 63 insertions, 0 deletions
diff --git a/source/graphics/Camera2D.cs b/source/graphics/Camera2D.cs
new file mode 100644
index 0000000..1bae764
--- /dev/null
+++ b/source/graphics/Camera2D.cs
@@ -0,0 +1,63 @@
+using System;
+using Celesteia.Resources;
+using Microsoft.Xna.Framework;
+using Microsoft.Xna.Framework.Graphics;
+
+namespace Celesteia.Graphics {
+    public class Camera2D {
+        private GraphicsDevice _graphicsDevice;
+        
+        // Viewport macros.
+        private int ViewportX => _graphicsDevice.Viewport.X;
+        private int ViewportY => _graphicsDevice.Viewport.Y;
+        private int ViewportWidth => _graphicsDevice.Viewport.Width;
+        private int ViewportHeight => _graphicsDevice.Viewport.Height;
+
+        private int _zoom = 0;
+        public int ScaledZoom { get; private set; } = 0;
+        // The zoom value of the camera.
+        public int Zoom {
+            get { return _zoom; }
+            set {
+                _zoom = MathHelper.Clamp(value, 1, 8);
+                ScaledZoom = _zoom * ResourceManager.INVERSE_SPRITE_SCALING;
+            }
+        }
+
+        public Camera2D(GraphicsDevice graphicsDevice) {
+            _graphicsDevice = graphicsDevice;
+            Zoom = 2;
+        }
+
+        // The camera's center.
+        public Vector2 Center = Vector2.Zero;
+
+        private float _rotation;
+        // The rotation applied to the camera.
+        public float Rotation {
+            get { return _rotation; }
+            set { _rotation = value % 360f; }
+        }
+
+        /*
+            Creates a matrix with the following steps:
+                - Create a translation to match (0, 0) to the center point of the camera.
+                - Apply Z rotation.
+                - Scale according to zoom value and inverse sprite scaling.
+                - Always round the viewport width and height to prevent half-pixel rounding issues.
+        */
+        private float maxScale = 0f;
+        public Matrix GetViewMatrix() {
+            maxScale = MathF.Max(MathF.Ceiling(ViewportWidth / 1920f), MathF.Ceiling(ViewportHeight / 1080f));
+            return Matrix.CreateTranslation(-Center.X, -Center.Y, 0f) * 
+                Matrix.CreateRotationZ(Rotation) *
+                Matrix.CreateScale(ScaledZoom, ScaledZoom, 1f) * 
+                Matrix.CreateScale(maxScale, maxScale, 1f) *
+                Matrix.CreateTranslation(ViewportWidth / 2f, ViewportHeight / 2f, 0f);
+        }
+
+        // Transform the viewport relative mouse position to the inverse view matrix to get the pointer's position in the world.
+        public Vector2 ScreenToWorld(Point point)
+        => Vector2.Transform(new Vector2(point.X - ViewportX, point.Y - ViewportY), Matrix.Invert(GetViewMatrix()));
+    }
+}
+\ No newline at end of file