Add an option to disable the post-effect shader

src/main/java/com/minelittlepony/unicopia/Config.java

@@ -48,6 +48,9 @@ public class Config extends com.minelittlepony.common.util.settings.Config {
     public final Setting<Boolean> simplifiedPortals = value("compatibility", "simplifiedPortals", false)
             .addComment("Disables dynamic portal rendering");
 
+    public final Setting<Boolean> disableShaders = value("compatibility", "disableShaders", false)
+            .addComment("Disables post-effect shaders used by the corruption mechanic");
+
     public final Setting<Long> fancyPortalRefreshRate = value("client", "fancyPortalRefreshRate", -1L)
             .addComment("Sets the refresh rate of portals when using fancy portal rendering")
             .addComment("Set to -1 (default) for unlimited");

src/main/java/com/minelittlepony/unicopia/client/render/shader/ViewportShader.java

@@ -43,14 +43,24 @@ public class ViewportShader implements SynchronousResourceReloader, Identifiable
     }
 
     public void loadShader(@Nullable Identifier shaderId) {
+
         if (shader != null) {
-            shader.close();
+            try {
+                shader.close();
+            } catch (Throwable ignored) {
+            } finally {
+                shader = null;
+            }
         }
 
         if (shaderId == null) {
             return;
         }
 
+        if (Unicopia.getConfig().disableShaders.get()) {
+            return;
+        }
+
         try {
             shader = new LoadedShader(client, shaderId);
         } catch (IOException e) {
@@ -67,6 +77,10 @@ public class ViewportShader implements SynchronousResourceReloader, Identifiable
     }
 
     public void render(float tickDelta) {
+        if (Unicopia.getConfig().disableShaders.get()) {
+            return;
+        }
+
         if (shader != null && client.player != null) {
             RenderSystem.disableBlend();
             RenderSystem.disableDepthTest();