Reset the BufferUploader state on Linux

GlStateManager.glDeleteBuffers clears a buffer before deleting it on
Linux - I assume otherwise there's memory leaks on some drivers? - which
clobbers BufferUploader's cache. Roll our own version which resets the
cache when needed.

Also always reset the cache when deleting/creating a DirectVertexBuffer.

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

@@ -163,7 +163,6 @@ public class TileEntityMonitorRenderer implements BlockEntityRenderer<TileMonito
                 MonitorTextureBufferShader shader = RenderTypes.getMonitorTextureBufferShader();
                 shader.setupUniform( monitor.tboUniform );
 
-                // TODO: Switch to using a VBO here? Something to avoid having to do the
                 VertexConsumer buffer = bufferSource.getBuffer( RenderTypes.MONITOR_TBO );
                 tboVertex( buffer, matrix, -xMargin, -yMargin );
                 tboVertex( buffer, matrix, -xMargin, pixelHeight + yMargin );

src/main/java/dan200/computercraft/client/util/DirectBuffers.java

@@ -6,7 +6,9 @@
 package dan200.computercraft.client.util;
 
 import com.mojang.blaze3d.platform.GlStateManager;
+import com.mojang.blaze3d.systems.RenderSystem;
 import com.mojang.blaze3d.vertex.BufferUploader;
+import net.minecraft.Util;
 import org.lwjgl.opengl.GL;
 import org.lwjgl.opengl.GL15C;
 import org.lwjgl.opengl.GL45C;
@@ -20,6 +22,7 @@ import java.nio.ByteBuffer;
 public class DirectBuffers
 {
     public static final boolean HAS_DSA;
+    static final boolean ON_LINUX = Util.getPlatform() == Util.OS.LINUX;
 
     static
     {
@@ -32,6 +35,23 @@ public class DirectBuffers
         return HAS_DSA ? GL45C.glCreateBuffers() : GL15C.glGenBuffers();
     }
 
+    /**
+     * Delete a previously created buffer.
+     *
+     * On Linux, {@link GlStateManager#_glDeleteBuffers(int)} clears a buffer before deleting it. However, this involves
+     * binding and unbinding the buffer, conflicting with {@link BufferUploader}'s cache. This deletion method uses
+     * our existing {@link #setEmptyBufferData(int, int, int)}, which correctly handles clearing the buffer.
+     *
+     * @param type The buffer's type.
+     * @param id   The buffer's ID.
+     */
+    public static void deleteBuffer( int type, int id )
+    {
+        RenderSystem.assertOnRenderThread();
+        if( ON_LINUX ) DirectBuffers.setEmptyBufferData( type, id, GL15C.GL_DYNAMIC_DRAW );
+        GL15C.glDeleteBuffers( id );
+    }
+
     public static void setBufferData( int type, int id, ByteBuffer buffer, int flags )
     {
         if( HAS_DSA )
@@ -40,9 +60,9 @@ public class DirectBuffers
         }
         else
         {
-            if( type == GL45C.GL_ARRAY_BUFFER ) BufferUploader.reset();
+            if( type == GL15C.GL_ARRAY_BUFFER ) BufferUploader.reset();
             GlStateManager._glBindBuffer( type, id );
-            GlStateManager._glBufferData( type, buffer, GL15C.GL_STATIC_DRAW );
+            GlStateManager._glBufferData( type, buffer, flags );
             GlStateManager._glBindBuffer( type, 0 );
         }
     }
@@ -55,9 +75,9 @@ public class DirectBuffers
         }
         else
         {
-            if( type == GL45C.GL_ARRAY_BUFFER ) BufferUploader.reset();
+            if( type == GL15C.GL_ARRAY_BUFFER ) BufferUploader.reset();
             GlStateManager._glBindBuffer( type, id );
-            GlStateManager._glBufferData( type, 0, GL15C.GL_STATIC_DRAW );
+            GlStateManager._glBufferData( type, 0, flags );
             GlStateManager._glBindBuffer( type, 0 );
         }
     }

src/main/java/dan200/computercraft/client/util/DirectVertexBuffer.java

@@ -6,6 +6,7 @@
 package dan200.computercraft.client.util;
 
 import com.mojang.blaze3d.systems.RenderSystem;
+import com.mojang.blaze3d.vertex.BufferUploader;
 import com.mojang.blaze3d.vertex.VertexBuffer;
 import com.mojang.blaze3d.vertex.VertexFormat;
 import com.mojang.math.Matrix4f;
@@ -29,6 +30,7 @@ public class DirectVertexBuffer extends VertexBuffer
         if( DirectBuffers.HAS_DSA )
         {
             RenderSystem.glDeleteBuffers( vertextBufferId );
+            if( DirectBuffers.ON_LINUX ) BufferUploader.reset(); // See comment on DirectBuffers.deleteBuffer.
             vertextBufferId = GL45C.glCreateBuffers();
         }
     }
@@ -57,4 +59,11 @@ public class DirectVertexBuffer extends VertexBuffer
     {
         return actualIndexCount;
     }
+
+    @Override
+    public void close()
+    {
+        super.close();
+        if( DirectBuffers.ON_LINUX ) BufferUploader.reset(); // See comment on DirectBuffers.deleteBuffer.
+    }
 }

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

@@ -6,7 +6,6 @@
 package dan200.computercraft.shared.peripheral.monitor;
 
 import com.mojang.blaze3d.platform.GlStateManager;
-import com.mojang.blaze3d.systems.RenderSystem;
 import dan200.computercraft.client.util.DirectBuffers;
 import dan200.computercraft.client.util.DirectVertexBuffer;
 import dan200.computercraft.shared.common.ClientTerminal;
@@ -105,7 +104,7 @@ public final class ClientMonitor extends ClientTerminal
 
         if( tboBuffer != 0 )
         {
-            RenderSystem.glDeleteBuffers( tboBuffer );
+            DirectBuffers.deleteBuffer( GL31.GL_TEXTURE_BUFFER, tboBuffer );
             tboBuffer = 0;
         }
 
@@ -117,7 +116,7 @@ public final class ClientMonitor extends ClientTerminal
 
         if( tboUniform != 0 )
         {
-            RenderSystem.glDeleteBuffers( tboUniform );
+            DirectBuffers.deleteBuffer( GL31.GL_UNIFORM_BUFFER, tboUniform );
             tboUniform = 0;
         }