Allow rendering a monitor tile multiple times in a tick

Shader mods may perform multiple passes when rendering a tile, so
monitors will be drawn transparently on later passes. In order to
prevent this we allow drawing the a single tile multiple times in a
tick.

Author: SquidDev

src/main/java/dan200/computercraft/client/render/TileEntityMonitorRenderer.java

@@ -47,19 +47,20 @@ private void renderMonitorAt( TileMonitor monitor, double posX, double posY, dou
 
         if( originTerminal == null ) return;
         TileMonitor origin = originTerminal.getOrigin();
+        BlockPos monitorPos = monitor.getPos();
 
-        // Ensure each monitor is rendered only once
+        // Ensure each monitor terminal is rendered only once. We allow rendering a specific tile
+        // multiple times in a single frame to ensure compatibility with shaders which may run a 
+        // pass multiple times.
         long renderFrame = ComputerCraft.getRenderFrame();
-        if( originTerminal.lastRenderFrame == renderFrame )
+        if( originTerminal.lastRenderFrame == renderFrame && !monitorPos.equals( originTerminal.lastRenderPos ) )
         {
             return;
         }
-        else
-        {
-            originTerminal.lastRenderFrame = renderFrame;
-        }
 
-        BlockPos monitorPos = monitor.getPos();
+        originTerminal.lastRenderFrame = renderFrame;
+        originTerminal.lastRenderPos = monitorPos;
+
         BlockPos originPos = origin.getPos();
         posX += originPos.getX() - monitorPos.getX();
         posY += originPos.getY() - monitorPos.getY();

src/main/java/dan200/computercraft/shared/peripheral/monitor/ClientMonitor.java

@@ -2,6 +2,7 @@
 
 import dan200.computercraft.shared.common.ClientTerminal;
 import net.minecraft.client.renderer.GlStateManager;
+import net.minecraft.util.math.BlockPos;
 
 import java.util.HashSet;
 import java.util.Iterator;
@@ -14,6 +15,7 @@ public class ClientMonitor extends ClientTerminal
     private final TileMonitor origin;
 
     public long lastRenderFrame = -1;
+    public BlockPos lastRenderPos = null;
     public int[] renderDisplayLists = null;
 
     public ClientMonitor( boolean colour, TileMonitor origin )