Automatically disable and re-enable Optifine's Fast Render setting before rendering a video

src/main/java/com/replaymod/compat/optifine/DisableFastRender.java

@@ -0,0 +1,37 @@
+package com.replaymod.compat.optifine;
+
+import com.replaymod.render.events.ReplayRenderEvent;
+import net.minecraft.client.Minecraft;
+import net.minecraftforge.fml.client.FMLClientHandler;
+import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;
+
+public class DisableFastRender {
+
+    private final Minecraft mc = Minecraft.getMinecraft();
+
+    private boolean wasFastRender = false;
+
+    @SubscribeEvent
+    public void onRenderBegin(ReplayRenderEvent.Pre event) {
+        if (!FMLClientHandler.instance().hasOptifine()) return;
+
+        try {
+            wasFastRender = (boolean) OptifineReflection.gameSettings_ofFastRender.get(mc.gameSettings);
+            OptifineReflection.gameSettings_ofFastRender.set(mc.gameSettings, false);
+        } catch (IllegalAccessException e) {
+            e.printStackTrace();
+        }
+    }
+
+    @SubscribeEvent
+    public void onRenderEnd(ReplayRenderEvent.Post event){
+        if (!FMLClientHandler.instance().hasOptifine()) return;
+
+        try {
+            OptifineReflection.gameSettings_ofFastRender.set(mc.gameSettings, wasFastRender);
+        } catch (IllegalAccessException e) {
+            e.printStackTrace();
+        }
+    }
+
+}