Use UBOs for the TBO renderer

Like #455, this sets our uniforms via a UBO rather than having separate
ones for each value. There are a couple of small differences:

 - Have a UBO for each monitor, rather than sharing one and rewriting it
   every monitor. This means we only need to update the buffer when the
   monitor changes.

 - Use std140 rather than the default layout. This means we don't have
   to care about location/stride in the buffer.

Also like #455, this doesn't actually seem to result in any performance
improvements for me. However, it does make it a bit easier to handle a
large number of uniforms.

Also cleans up the generation of the main monitor texture buffer:

 - Move buffer generation into a separate method - just ensures that it
   shows up separately in profilers.
 - Explicitly pass the position when setting bytes, rather than
   incrementing the internal one. This saves some memory reads/writes (I
   thought Java optimised them out, evidently not!). Saves a few fps
   when updating.
 - Use DSA when possible. Unclear if it helps at all, but nice to do :).

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

@@ -10,61 +10,49 @@ import com.mojang.blaze3d.platform.GlStateManager;
 import com.mojang.blaze3d.systems.RenderSystem;
 import dan200.computercraft.ComputerCraft;
 import dan200.computercraft.client.render.text.FixedWidthFontRenderer;
+import dan200.computercraft.core.terminal.Terminal;
+import dan200.computercraft.core.terminal.TextBuffer;
+import dan200.computercraft.shared.util.Colour;
 import dan200.computercraft.shared.util.Palette;
 import net.minecraft.client.renderer.texture.TextureUtil;
 import net.minecraft.util.math.vector.Matrix4f;
 import org.lwjgl.BufferUtils;
 import org.lwjgl.opengl.GL13;
 import org.lwjgl.opengl.GL20;
+import org.lwjgl.opengl.GL31;
 
 import java.io.InputStream;
+import java.nio.ByteBuffer;
 import java.nio.FloatBuffer;
 
+import static dan200.computercraft.client.render.text.FixedWidthFontRenderer.getColour;
+
 class MonitorTextureBufferShader
 {
+    public static final int UNIFORM_SIZE = 4 * 4 * 16 + 4 + 4;
+
     static final int TEXTURE_INDEX = GL13.GL_TEXTURE3;
 
     private static final FloatBuffer MATRIX_BUFFER = BufferUtils.createFloatBuffer( 16 );
-    private static final FloatBuffer PALETTE_BUFFER = BufferUtils.createFloatBuffer( 16 * 3 );
 
     private static int uniformMv;
 
     private static int uniformFont;
-    private static int uniformWidth;
-    private static int uniformHeight;
     private static int uniformTbo;
-    private static int uniformPalette;
+    private static int uniformMonitor;
 
     private static boolean initialised;
     private static boolean ok;
     private static int program;
 
-    static void setupUniform( Matrix4f transform, int width, int height, Palette palette, boolean greyscale )
+    static void setupUniform( Matrix4f transform, int tboUniform )
     {
         MATRIX_BUFFER.rewind();
         transform.store( MATRIX_BUFFER );
         MATRIX_BUFFER.rewind();
         RenderSystem.glUniformMatrix4( uniformMv, false, MATRIX_BUFFER );
 
-        RenderSystem.glUniform1i( uniformWidth, width );
+        GL31.glBindBufferBase( GL31.GL_UNIFORM_BUFFER, uniformMonitor, tboUniform );
-        RenderSystem.glUniform1i( uniformHeight, height );
-
-        PALETTE_BUFFER.rewind();
-        for( int i = 0; i < 16; i++ )
-        {
-            double[] colour = palette.getColour( i );
-            if( greyscale )
-            {
-                float f = FixedWidthFontRenderer.toGreyscale( colour );
-                PALETTE_BUFFER.put( f ).put( f ).put( f );
-            }
-            else
-            {
-                PALETTE_BUFFER.put( (float) colour[0] ).put( (float) colour[1] ).put( (float) colour[2] );
-            }
-        }
-        PALETTE_BUFFER.flip();
-        RenderSystem.glUniform3( uniformPalette, PALETTE_BUFFER );
     }
 
     static boolean use()
@@ -116,10 +104,9 @@ class MonitorTextureBufferShader
 
             uniformMv = getUniformLocation( program, "u_mv" );
             uniformFont = getUniformLocation( program, "u_font" );
-            uniformWidth = getUniformLocation( program, "u_width" );
-            uniformHeight = getUniformLocation( program, "u_height" );
             uniformTbo = getUniformLocation( program, "u_tbo" );
-            uniformPalette = getUniformLocation( program, "u_palette" );
+            uniformMonitor = GL31.glGetUniformBlockIndex( program, "u_monitor" );
+            if( uniformMonitor == -1 ) throw new IllegalStateException( "Could not find uniformMonitor uniform." );
 
             ComputerCraft.log.info( "Loaded monitor shader." );
             return true;
@@ -159,4 +146,50 @@ class MonitorTextureBufferShader
         if( uniform == -1 ) throw new IllegalStateException( "Cannot find uniform " + name );
         return uniform;
     }
+
+    public static void setTerminalData( ByteBuffer buffer, Terminal terminal )
+    {
+        int width = terminal.getWidth(), height = terminal.getHeight();
+
+        int pos = 0;
+        for( int y = 0; y < height; y++ )
+        {
+            TextBuffer text = terminal.getLine( y ), textColour = terminal.getTextColourLine( y ), background = terminal.getBackgroundColourLine( y );
+            for( int x = 0; x < width; x++ )
+            {
+                buffer.put( pos, (byte) (text.charAt( x ) & 0xFF) );
+                buffer.put( pos + 1, (byte) getColour( textColour.charAt( x ), Colour.WHITE ) );
+                buffer.put( pos + 2, (byte) getColour( background.charAt( x ), Colour.BLACK ) );
+                pos += 3;
+            }
+        }
+
+        buffer.limit( pos );
+    }
+
+    public static void setUniformData( ByteBuffer buffer, Terminal terminal, boolean greyscale )
+    {
+        int pos = 0;
+        Palette palette = terminal.getPalette();
+        for( int i = 0; i < 16; i++ )
+        {
+            double[] colour = palette.getColour( i );
+            if( greyscale )
+            {
+                float f = FixedWidthFontRenderer.toGreyscale( colour );
+                buffer.putFloat( pos, f ).putFloat( pos + 4, f ).putFloat( pos + 8, f );
+            }
+            else
+            {
+                buffer.putFloat( pos, (float) colour[0] ).putFloat( pos + 4, (float) colour[1] ).putFloat( pos + 8, (float) colour[2] );
+            }
+
+            pos += 4 * 4; // std140 requires these are 4-wide
+        }
+
+        int width = terminal.getWidth(), height = terminal.getHeight();
+        buffer.putInt( pos, width ).putInt( pos + 4, height );
+
+        buffer.limit( UNIFORM_SIZE );
+    }
 }

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

@@ -14,11 +14,9 @@ import dan200.computercraft.client.render.text.FixedWidthFontRenderer;
 import dan200.computercraft.client.util.DirectBuffers;
 import dan200.computercraft.client.util.DirectVertexBuffer;
 import dan200.computercraft.core.terminal.Terminal;
-import dan200.computercraft.core.terminal.TextBuffer;
 import dan200.computercraft.shared.peripheral.monitor.ClientMonitor;
 import dan200.computercraft.shared.peripheral.monitor.MonitorRenderer;
 import dan200.computercraft.shared.peripheral.monitor.TileMonitor;
-import dan200.computercraft.shared.util.Colour;
 import dan200.computercraft.shared.util.DirectionUtil;
 import net.minecraft.client.renderer.BufferBuilder;
 import net.minecraft.client.renderer.IRenderTypeBuffer;
@@ -39,7 +37,8 @@ import org.lwjgl.opengl.GL31;
 import javax.annotation.Nonnull;
 import java.nio.ByteBuffer;
 
-import static dan200.computercraft.client.render.text.FixedWidthFontRenderer.*;
+import static dan200.computercraft.client.render.text.FixedWidthFontRenderer.FONT_HEIGHT;
+import static dan200.computercraft.client.render.text.FixedWidthFontRenderer.FONT_WIDTH;
 
 public class TileEntityMonitorRenderer extends TileEntityRenderer<TileMonitor>
 {
@@ -172,22 +171,13 @@ public class TileEntityMonitorRenderer extends TileEntityRenderer<TileMonitor>
 
                 if( redraw )
                 {
-                    ByteBuffer monitorBuffer = getBuffer( width * height * 3 );
+                    ByteBuffer terminalBuffer = getBuffer( width * height * 3 );
-                    for( int y = 0; y < height; y++ )
+                    MonitorTextureBufferShader.setTerminalData( terminalBuffer, terminal );
-                    {
+                    DirectBuffers.setBufferData( GL31.GL_TEXTURE_BUFFER, monitor.tboBuffer, terminalBuffer, GL20.GL_STATIC_DRAW );
-                        TextBuffer text = terminal.getLine( y ), textColour = terminal.getTextColourLine( y ), background = terminal.getBackgroundColourLine( y );
-                        for( int x = 0; x < width; x++ )
-                        {
-                            monitorBuffer.put( (byte) (text.charAt( x ) & 0xFF) );
-                            monitorBuffer.put( (byte) getColour( textColour.charAt( x ), Colour.WHITE ) );
-                            monitorBuffer.put( (byte) getColour( background.charAt( x ), Colour.BLACK ) );
-                        }
-                    }
-                    monitorBuffer.flip();
 
-                    GlStateManager._glBindBuffer( GL31.GL_TEXTURE_BUFFER, monitor.tboBuffer );
+                    ByteBuffer uniformBuffer = getBuffer( MonitorTextureBufferShader.UNIFORM_SIZE );
-                    GlStateManager._glBufferData( GL31.GL_TEXTURE_BUFFER, monitorBuffer, GL20.GL_STATIC_DRAW );
+                    MonitorTextureBufferShader.setUniformData( uniformBuffer, terminal, !monitor.isColour() );
-                    GlStateManager._glBindBuffer( GL31.GL_TEXTURE_BUFFER, 0 );
+                    DirectBuffers.setBufferData( GL31.GL_UNIFORM_BUFFER, monitor.tboUniform, uniformBuffer, GL20.GL_STATIC_DRAW );
                 }
 
                 // Nobody knows what they're doing!
@@ -195,7 +185,7 @@ public class TileEntityMonitorRenderer extends TileEntityRenderer<TileMonitor>
                 GL11.glBindTexture( GL31.GL_TEXTURE_BUFFER, monitor.tboTexture );
                 GlStateManager._activeTexture( GL13.GL_TEXTURE0 );
 
-                MonitorTextureBufferShader.setupUniform( matrix, width, height, terminal.getPalette(), !monitor.isColour() );
+                MonitorTextureBufferShader.setupUniform( matrix, monitor.tboUniform );
 
                 Tessellator tessellator = Tessellator.getInstance();
                 BufferBuilder buffer = tessellator.getBuilder();

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

@@ -7,6 +7,7 @@ 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;
 import net.minecraft.util.math.BlockPos;
@@ -32,6 +33,7 @@ public final class ClientMonitor extends ClientTerminal
 
     public int tboBuffer;
     public int tboTexture;
+    public int tboUniform;
     public DirectVertexBuffer buffer;
 
     public ClientMonitor( boolean colour, TileMonitor origin )
@@ -63,15 +65,15 @@ public final class ClientMonitor extends ClientTerminal
 
                 deleteBuffers();
 
-                tboBuffer = GlStateManager._glGenBuffers();
+                tboBuffer = DirectBuffers.createBuffer();
-                GlStateManager._glBindBuffer( GL31.GL_TEXTURE_BUFFER, tboBuffer );
+                DirectBuffers.setEmptyBufferData( GL31.GL_TEXTURE_BUFFER, tboBuffer, GL15.GL_STATIC_DRAW );
-                GL15.glBufferData( GL31.GL_TEXTURE_BUFFER, 0, GL15.GL_STATIC_DRAW );
                 tboTexture = GlStateManager._genTexture();
                 GL11.glBindTexture( GL31.GL_TEXTURE_BUFFER, tboTexture );
                 GL31.glTexBuffer( GL31.GL_TEXTURE_BUFFER, GL30.GL_R8UI, tboBuffer );
                 GL11.glBindTexture( GL31.GL_TEXTURE_BUFFER, 0 );
 
-                GlStateManager._glBindBuffer( GL31.GL_TEXTURE_BUFFER, 0 );
+                tboUniform = DirectBuffers.createBuffer();
+                DirectBuffers.setEmptyBufferData( GL31.GL_UNIFORM_BUFFER, tboUniform, GL15.GL_STATIC_DRAW );
 
                 addMonitor();
                 return true;
@@ -113,6 +115,12 @@ public final class ClientMonitor extends ClientTerminal
             tboTexture = 0;
         }
 
+        if( tboUniform != 0 )
+        {
+            RenderSystem.glDeleteBuffers( tboUniform );
+            tboUniform = 0;
+        }
+
         if( buffer != null )
         {
             buffer.close();

src/main/resources/assets/computercraft/shaders/monitor.frag

@@ -4,10 +4,13 @@
 #define FONT_HEIGHT 9.0
 
 uniform sampler2D u_font;
-uniform int u_width;
-uniform int u_height;
 uniform usamplerBuffer u_tbo;
-uniform vec3 u_palette[16];
+
+layout(std140) uniform u_monitor {
+    vec3 u_palette[16];
+    int u_width;
+    int u_height;
+};
 
 in vec2 f_pos;