Added linear interpolation between updates to mesh batch.

Cleaned up code.

src/SlatedGameToolkit.Framework/GameEngine.cs

@@ -164,7 +164,10 @@ namespace SlatedGameToolkit.Framework {
                         //Updates.
                         manager.update(updateDeltaTime.TotalSeconds <= 0 ? timePassedFromLastUpdate.TotalSeconds : updateDeltaTime.TotalSeconds);
                         timePassedFromLastUpdate -= updateDeltaTime;
-                        if (updateDeltaTime.TotalSeconds <= 0) break;
+                        if (updateDeltaTime.TotalSeconds <= 0) {
+                            timePassedFromLastUpdate = TimeSpan.Zero;
+                            break;
+                        }
                     }
 
                     timePassedFromLastRender += difference;

src/SlatedGameToolkit.Framework/Graphics/Render/Camera.cs

@@ -4,15 +4,27 @@ using SlatedGameToolkit.Framework.Utilities;
 
 namespace SlatedGameToolkit.Framework.Graphics.Render
 {
-    public class Camera {
-        private bool viewUpdated = true, projectionUpdated = true, orthographic;
-        public virtual Vector3 Up { get; set; } = Vector3.UnitY;
+    public class Camera : IMoveable {
+        private bool viewUpdated = true, projectionUpdated = true, orthographic = false;
+
         private Vector3 position, lookAt;
         private float nearField = 0.01f, farField = 100f;
         private float width, height;
         private Matrix4x4 lookAtMatrix = Matrix4x4.Identity;
         private Matrix4x4 view = Matrix4x4.Identity, projection;
+        
+        /// <summary>
+        /// Position updates the camera without changing camera orientation if true.
+        /// Otherwise, camera will always attempt to look in the direction of the point given by the LookAt vector.
+        /// </summary>
+        /// <value>Whether or not to change orientation while moving camera position.</value>
+        public bool LockedOrientation { get; set; } = false;
 
+        /// <summary>
+        /// The up direction of the camera.
+        /// </summary>
+        /// <value>A vector representing the up direction of the camera.</value>
+        public Vector3 Up { get; set; } = Vector3.UnitY;
         public event EventHandler projectionUpdateEvent;
 
         public bool Orthographic {
@@ -31,7 +43,9 @@ namespace SlatedGameToolkit.Framework.Graphics.Render
                 return position;
             }
             set {
+                Vector3 orientation = CameraFront;
                 this.position = value;
+                if (LockedOrientation) CameraFront = orientation;
                 viewUpdated = true;
             }
         }
@@ -120,6 +134,8 @@ namespace SlatedGameToolkit.Framework.Graphics.Render
             }
         }
 
+        public Vector3 MoveTo { get; set; }
+
         public Camera(float width, float height) {
             if (width <= 0) throw new ArgumentException("Width can't be less than or equal to 0.");
             if (height <= 0) throw new ArgumentException("Height can't be less than or equal to 0.");

src/SlatedGameToolkit.Framework/Graphics/Render/Camera2D.cs

@@ -10,12 +10,23 @@ namespace SlatedGameToolkit.Framework.Graphics.Render
 
             set {
                 base.Position = new Vector3(value, base.Position.Z);
-                base.CameraFront = -Vector3.UnitZ;
+            }
+        }
+
+        public new Vector2 MoveTo {
+            get {
+                return new Vector2(base.MoveTo.X, base.MoveTo.Y);
+            }
+
+            set {
+                base.MoveTo = new Vector3(value, base.MoveTo.Z);
             }
         }
 
         public Camera2D(int width, int height) : base(width, height) {
             this.Orthographic = true;
+            this.LockedOrientation = true;
+            this.CameraFront = -Vector3.UnitZ;
         }
     }
 }

src/SlatedGameToolkit.Framework/Graphics/Render/IMoveable.cs

@@ -0,0 +1,22 @@
+using System.Numerics;
+
+namespace SlatedGameToolkit.Framework.Graphics.Render
+{
+    public interface IMoveable
+    {
+        /// <summary>
+        /// A vector describing the position this object should move to.
+        /// This is then used to smooth the movement to the intermediate renders.
+        /// 
+        /// </summary>
+        /// <value>A vector describing the new position of the object by the end of the update.</value>
+        Vector3 MoveTo { get; set; }
+
+
+        /// <summary>
+        /// The current position of the entity.
+        /// </summary>
+        /// <value>A vector describing the current objects position.</value>
+        Vector3 Position { get; set; }
+    }
+}

src/SlatedGameToolkit.Framework/Graphics/Render/MeshBatch.cs

@@ -11,13 +11,14 @@ using SlatedGameToolkit.Framework.Utilities;
 namespace SlatedGameToolkit.Framework.Graphics.Render
 {
     public class MeshBatch : IDisposable {
-        public GLContext GLContext {get; private set; }
         private const int VERTEX_LENGTH = 9;
+        private bool disposed;
+        private float batchDelta;
+        public GLContext GLContext {get; private set; }
         private int projALoc, viewALoc, modelALoc, texturedALoc;
         private Camera camera;
         private RenderProgram renderProgram;
         private ITexture texture;
-        private bool disposed;
         private VertexArrayBuffers vertexBuffers;
         public bool Batching { get; private set; }
 
@@ -59,10 +60,17 @@ namespace SlatedGameToolkit.Framework.Graphics.Render
             GLContext.UniformMatrix4fv(projALoc, 1, false, camera.ProjectionMatrix.ToColumnMajorArray());
         }
 
-        public virtual void Begin(Matrix4x4 modelsMatrix) {
+        /// <summary>
+        /// Begins a mesh batch for rendering.
+        /// </summary>
+        /// <param name="modelsMatrix">The models matrix.</param>
+        /// <param name="delta">The time elapsed since the last update.</param>
+        public virtual void Begin(Matrix4x4 modelsMatrix, double delta) {
             if (Batching) throw new InvalidOperationException("This batch is already started.");
             this.Batching = true;
             this.modelsMatrix = modelsMatrix;
+
+            this.batchDelta = (float)delta;
         }
 
         /// <summary>
@@ -70,6 +78,14 @@ namespace SlatedGameToolkit.Framework.Graphics.Render
         /// </summary>
         /// <param name="mesh">Draws the given mesh.</param>
         public virtual void Draw(IMesh mesh) {
+            IMoveable moveable = mesh as IMoveable;
+            if (moveable != null) {
+                if (GameEngine.UpdatesPerSecond <= 0) {
+                    camera.Position = camera.MoveTo;
+                } else {
+                    camera.Position = camera.Position + (camera.MoveTo - camera.Position) * batchDelta;
+                }
+            }
             if (mesh.Texture?.Handle != this.texture?.Handle) {
                 Flush();
                 this.texture = mesh.Texture;
@@ -121,6 +137,12 @@ namespace SlatedGameToolkit.Framework.Graphics.Render
         protected virtual void Flush() {
             texture?.Use();
             renderProgram.Use();
+            if (GameEngine.UpdatesPerSecond <= 0) {
+                camera.Position = camera.MoveTo;
+            } else {
+                camera.Position = camera.Position + (camera.MoveTo - camera.Position) * batchDelta;
+            }
+
             vertexBuffers.BufferVertices(data, true);
             vertexBuffers.BufferIndices(indices, true);
             GLContext.UniformMatrix4fv(modelALoc, 1, false, modelsMatrix.ToColumnMajorArray());

src/SlatedGameToolkit.Framework/StateSystem/StateManager.cs

@@ -37,14 +37,14 @@ namespace SlatedGameToolkit.Framework.StateSystem
             addState(initialState);
         }
 
-        internal void update(double delta) {
+        internal void update(double timeStep) {
             if (nextState != null) {
                 if (currentState.Deactivate() & nextState.Activate()) {
                     currentState = nextState;
                     nextState = null;
                 }
             }
-            currentState.Update(delta);
+            currentState.Update(timeStep);
         }
         
         internal void render(double delta) {

src/SlatedGameToolkit.Framework/StateSystem/States/IState.cs

@@ -29,8 +29,8 @@ namespace SlatedGameToolkit.Framework.StateSystem.States
         /// Called in intervals dependent on game loop chosen for every update cycle.
         /// Only called on if this state is the active state, indicated on the last status method called on this implementation (acitvate, and deactivate).
         /// </summary>
-        /// <param name="delta">The time in seconds that has passed since the last update.</param>
-        void Update(double delta);
+        /// <param name="timeStep">The change in time between the updates in seconds. If fixed, this amounts to the portion of time between the set update rate. If unlocked, represents the actual amount of time passed since the last update.</param>
+        void Update(double timeStep);
 
         /// <summary>
         /// Called in intervals dependent on game loop chose for every render cycle.

src/SlatedGameToolkit.Tools/Commands/GraphicalPlaygroundCommand.cs

@@ -19,6 +19,7 @@ namespace SlatedGameToolkit.Tools.Commands
                     interactable.Tell("Engine is already running!");
                     return true;
                 }
+
                 GameEngine.Ignite(new MainState());
                 return true;
             } else if (args[0].Equals("stop")) {

src/SlatedGameToolkit.Tools/Utilities/Playground/MainState.cs

@@ -77,26 +77,26 @@ namespace SlatedGameToolkit.Tools.Utilities.Playground
 
         public void Render(double delta)
         {
-            renderer.Begin(Matrix4x4.Identity);
+            renderer.Begin(Matrix4x4.Identity, delta);
             renderer.Draw(logo);
             renderer.Draw(textureTester);
             renderer.Draw(untextured);
             renderer.End();
         }
 
-        public void Update(double delta)
+        public void Update(double timeStep)
         {
             if (Keyboard.IsKeyPressed(SDL.SDL_Keycode.SDLK_DOWN)) {
-                camera.Position += new Vector2(0, (float)(-0.5f * delta));
+                camera.MoveTo += new Vector2(0, (-0.25f)) * (float) timeStep;
             }
             if (Keyboard.IsKeyPressed(SDL.SDL_Keycode.SDLK_UP)) {
-                camera.Position += new Vector2(0, (float)(0.5f * delta));
+                camera.MoveTo += new Vector2(0, (0.25f)) * (float) timeStep;
             }
             if (Keyboard.IsKeyPressed(SDL.SDL_Keycode.SDLK_LEFT)) {
-                camera.Position += new Vector2((float)(-0.5f * delta), 0);
+                camera.MoveTo += new Vector2((-0.25f) * (float) timeStep, 0);
             }
             if (Keyboard.IsKeyPressed(SDL.SDL_Keycode.SDLK_RIGHT)) {
-                camera.Position += new Vector2((float)(0.5f * delta), 0);
+                camera.MoveTo += new Vector2((0.25f) * (float) timeStep, 0);
             }
         }
     }