added simple camera

MLEM.Extended/Extensions/CameraExtensions.cs

@@ -0,0 +1,14 @@
+using Microsoft.Xna.Framework;
+using MonoGame.Extended;
+using Camera = MLEM.Cameras.Camera;
+
+namespace MLEM.Extended.Extensions {
+    public static class CameraExtensions {
+
+        public static RectangleF GetVisibleArea(this Camera camera) {
+            var start = camera.ToWorldPos(Vector2.Zero);
+            return new RectangleF(start, camera.ToWorldPos(new Vector2(camera.Viewport.Width, camera.Viewport.Height) - start));
+        }
+
+    }
+}

MLEM.Extended/MLEM.Extended.csproj

@@ -10,7 +10,7 @@
         <PackageProjectUrl>https://github.com/Ellpeck/MLEM</PackageProjectUrl>
         <RepositoryUrl>https://github.com/Ellpeck/MLEM</RepositoryUrl>
         <PackageLicenseUrl>https://github.com/Ellpeck/MLEM/blob/master/LICENSE</PackageLicenseUrl>
-        <Version>1.0.2</Version>
+        <Version>1.0.3</Version>
     </PropertyGroup>
 
     <ItemGroup>

MLEM/Cameras/Camera.cs

@@ -0,0 +1,46 @@
+using Microsoft.Xna.Framework;
+using Microsoft.Xna.Framework.Graphics;
+using MLEM.Extensions;
+
+namespace MLEM.Cameras {
+    public class Camera {
+
+        public Vector2 Position;
+        public float Scale;
+        public Matrix ViewMatrix {
+            get {
+                var pos = -this.Position * this.Scale;
+                if (this.roundPosition)
+                    pos = pos.Floor();
+                return Matrix.CreateScale(this.Scale, this.Scale, 1) * Matrix.CreateTranslation(new Vector3(pos, 0));
+            }
+        }
+        public Vector2 LookingPosition => this.Position + new Vector2(this.Viewport.Width / 2, this.Viewport.Height / 2) / this.Scale;
+        public Viewport Viewport => this.graphicsDevice.Viewport;
+
+        private readonly bool roundPosition;
+        private readonly GraphicsDevice graphicsDevice;
+
+        public Camera(GraphicsDevice graphicsDevice, bool roundPosition = true) {
+            this.graphicsDevice = graphicsDevice;
+            this.roundPosition = roundPosition;
+        }
+
+        public void LookAt(Vector2 worldPos) {
+            this.Position = worldPos - new Vector2(this.Viewport.Width / 2, this.Viewport.Height / 2) / this.Scale;
+        }
+
+        public Vector2 ToWorldPos(Vector2 pos) {
+            return Vector2.Transform(pos, Matrix.Invert(this.ViewMatrix));
+        }
+
+        public Vector2 ToCameraPos(Vector2 pos) {
+            return Vector2.Transform(pos, this.ViewMatrix);
+        }
+
+        public (Vector2 topLeft, Vector2 bottomRight) GetVisibleArea() {
+            return (this.ToWorldPos(Vector2.Zero), this.ToWorldPos(new Vector2(this.Viewport.Width, this.Viewport.Height)));
+        }
+
+    }
+}

MLEM/MLEM.csproj

@@ -10,7 +10,7 @@
         <PackageProjectUrl>https://github.com/Ellpeck/MLEM</PackageProjectUrl>
         <RepositoryUrl>https://github.com/Ellpeck/MLEM</RepositoryUrl>
         <PackageLicenseUrl>https://github.com/Ellpeck/MLEM/blob/master/LICENSE</PackageLicenseUrl>
-        <Version>1.0.8</Version>
+        <Version>1.0.9</Version>
     </PropertyGroup>
 
     <ItemGroup>