Add support for binding textures directly from a TextureSequence

Fixes #1645

Bonsai.Shaders/BindTexture.cs

@@ -58,7 +58,23 @@ public bool IndexSpecified
             get { return Index.HasValue; }
         }
 
-        IObservable<TSource> Process<TSource>(IObservable<TSource> source, Action<TSource> update)
+        /// <summary>
+        /// Binds the specified texture buffer to the specified texture unit for
+        /// each notification in an observable sequence.
+        /// </summary>
+        /// <typeparam name="TSource">
+        /// The type of the elements in the <paramref name="source"/> sequence.
+        /// </typeparam>
+        /// <param name="source">
+        /// The sequence containing the notifications indicating when to bind
+        /// the texture buffer to the specified texture unit.
+        /// </param>
+        /// <returns>
+        /// An observable sequence that is identical to the source sequence but where
+        /// there is an additional side effect of binding the texture buffer to the
+        /// specified texture unit.
+        /// </returns>
+        public IObservable<TSource> Process<TSource>(IObservable<TSource> source)
         {
             return Observable.Defer(() =>
             {
@@ -76,43 +92,25 @@ IObservable<TSource> Process<TSource>(IObservable<TSource> source, Action<TSourc
                                 : null;
                         }
 
+                        texture ??= input as Texture;
+
                         if (texture != null)
                         {
-                            var index = Index;
-                            var textureId = index.HasValue ? ((TextureSequence)texture).Textures[index.Value] : texture.Id;
+                            var textureId = Index is int index
+                                ? ((TextureSequence)texture).Textures[index]
+                                : texture.Id;
                             shader.Update(() =>
                             {
                                 GL.ActiveTexture(TextureSlot);
                                 GL.BindTexture(TextureTarget, textureId);
                             });
                         }
-                        else if (update != null) shader.Update(() => update(input));
+
                         return input;
                     });
             });
         }
 
-        /// <summary>
-        /// Binds the specified texture buffer to the specified texture unit for
-        /// each notification in an observable sequence.
-        /// </summary>
-        /// <typeparam name="TSource">
-        /// The type of the elements in the <paramref name="source"/> sequence.
-        /// </typeparam>
-        /// <param name="source">
-        /// The sequence containing the notifications indicating when to bind
-        /// the texture buffer to the specified texture unit.
-        /// </param>
-        /// <returns>
-        /// An observable sequence that is identical to the source sequence but where
-        /// there is an additional side effect of binding the texture buffer to the
-        /// specified texture unit.
-        /// </returns>
-        public IObservable<TSource> Process<TSource>(IObservable<TSource> source)
-        {
-            return Process(source, update: null);
-        }
-
         /// <summary>
         /// Binds each texture buffer in an observable sequence to the specified
         /// texture unit for each notification in an observable sequence.
@@ -132,12 +130,7 @@ public IObservable<TSource> Process<TSource>(IObservable<TSource> source)
         /// in the sequence to the specified texture unit.
         /// </returns>
         public IObservable<Texture> Process(IObservable<Texture> source)
-        {
-            return Process(source, input =>
-            {
-                GL.ActiveTexture(TextureSlot);
-                GL.BindTexture(TextureTarget, input != null ? input.Id : 0);
-            });
-        }
+            // This overload only exists for documentation reasons
+            => Process<Texture>(source);
     }
 }