Cleaned up code and added some parameter checks.

Removed some unused code fragments from older plans.

src/SlatedGameToolkit.Framework/Exceptions/OpenGLException.cs

@@ -4,7 +4,6 @@ namespace SlatedGameToolkit.Framework.Exceptions
 {
     public class OpenGLException : Exception {
         public OpenGLException() : base() {
-
         }
 
         public OpenGLException(string message) : base(message) {

src/SlatedGameToolkit.Framework/Graphics/OpenGL/GLFunctionDelegates.cs

@@ -23,4 +23,5 @@ namespace SlatedGameToolkit.Framework.Graphics.OpenGL
     internal delegate void GLDeleteProgramPipelines(uint size, UIntPtr[] pipelines);
     internal delegate void GLBindProgramPipeline(UIntPtr pipeline);
     internal delegate void GLUseProgramStages(UIntPtr pipeline, GLEnums bitField, UIntPtr program);
+    internal delegate uint GLGetError();
 }

src/SlatedGameToolkit.Framework/Graphics/OpenGL/Programs/GLProgram.cs

@@ -19,7 +19,6 @@ namespace SlatedGameToolkit.Framework.Graphics.OpenGL.Programs
 
         public GLProgram(bool separable = true) {
             this.context = WindowContextsManager.CurrentWindowContext();
-            context.MakeCurrent();
             createProgram = Marshal.GetDelegateForFunctionPointer<GLCreateProgram>(SDL.SDL_GL_GetProcAddress("glCreateProgram"));
             if (createProgram == null) throw new FrameworkSDLException();
             deleteProgram = Marshal.GetDelegateForFunctionPointer<GLDeleteProgram>(SDL.SDL_GL_GetProcAddress("glDeleteProgram"));
@@ -39,7 +38,7 @@ namespace SlatedGameToolkit.Framework.Graphics.OpenGL.Programs
             }
         }
 
-        public void Use() {
+        public virtual void Use() {
             useProgram(handle);
         }
 

src/SlatedGameToolkit.Framework/Graphics/OpenGL/Programs/GLShaderProgram.cs

@@ -13,7 +13,8 @@ namespace SlatedGameToolkit.Framework.Graphics.OpenGL.Programs
         private readonly GLAttachShader attachShader;
         private readonly GLDetachShader detachShader;
         private GLBindAttribLocation bindAttribLocation;
-        public GLShaderProgram(WindowContext context, bool separable = true, params GLShader[] shaders) : base(separable) {
+        public GLShaderProgram(bool separable = true, params GLShader[] shaders) : base(separable) {
+            if (shaders.Length == 0) throw new ArgumentException("Requires at least one shader for shader program.");
             this.shaders = shaders;
             attachShader = Marshal.GetDelegateForFunctionPointer<GLAttachShader>(SDL.SDL_GL_GetProcAddress("glAttachShader"));
             if (attachShader == null) throw new FrameworkSDLException();

src/SlatedGameToolkit.Framework/Graphics/OpenGL/Shaders/GLFragmentShader.cs

@@ -7,7 +7,7 @@ using SlatedGameToolkit.Framework.Graphics.Window;
 namespace SlatedGameToolkit.Framework.Graphics.OpenGL.Shaders
 {
     public class GLFragmentShader : GLShader {
-        public GLFragmentShader(WindowContext context, string shader) : base() {
+        public GLFragmentShader(string shader) : base() {
             Handle = createShader(GLEnums.GL_FRAGMENT_SHADER);
             shaderSource(Handle, 1, shader, null);
             compileShader(Handle);

src/SlatedGameToolkit.Framework/Graphics/OpenGL/Shaders/GLVertexShader.cs

@@ -7,7 +7,7 @@ using SlatedGameToolkit.Framework.Graphics.Window;
 namespace SlatedGameToolkit.Framework.Graphics.OpenGL.Shaders
 {
     public class GLVertexShader : GLShader {
-        public GLVertexShader(WindowContext context, string shader) : base() {
+        public GLVertexShader(string shader) : base() {
             Handle = createShader(GLEnums.GL_VERTEX_SHADER);
             shaderSource(Handle, 1, shader, null);
             compileShader(Handle);

src/SlatedGameToolkit.Framework/StateSystem/Manager.cs

@@ -25,6 +25,10 @@ namespace SlatedGameToolkit.Framework.StateSystem
         /// <param name="initialState">The name of the initial state.</param>
         /// <param name="states">The initial set of game states to be added.</param>
         internal Manager(IState initialState) {
+            backgroundColour.r = 0.5f;
+            backgroundColour.g = 0.5f;
+            backgroundColour.b = 0.5f;
+            
             if (initialState == null) throw new ArgumentNullException("initialState");
             thread = Thread.CurrentThread;
             this.states = new Dictionary<string, IState>();

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

@@ -1,6 +1,6 @@
 using System;
-using SlatedGameToolkit.Framework;
 using SlatedGameToolkit.Framework.Graphics.OpenGL.Programs;
+using SlatedGameToolkit.Framework.Graphics.OpenGL.Shaders;
 using SlatedGameToolkit.Framework.Graphics.Window;
 using SlatedGameToolkit.Framework.StateSystem;
 using SlatedGameToolkit.Framework.StateSystem.States;
@@ -37,6 +37,7 @@ namespace SlatedGameToolkit.Tools.Utilities.GraphicalPlayground
         public void Initialize(Manager manager)
         {
             window = new WindowContext("SlatedGameToolkit Playground");
+            shader = new GLShaderProgram();
             window.RaiseToTop();
         }