use bulk drawing

src/js/net/minecraft/client/render/BlockRenderer.js

@@ -10,9 +10,7 @@ window.BlockRenderer = class {
         let boundingBox = new BoundingBox(0.0, 0.0, 0.0, 1.0, 1.0, 1.0);
 
         for (let face = 0; face < 6; face++) {
-            this.tessellator.startDrawing();
             this.renderFace(world, typeId, boundingBox, face, x, y, z);
-            this.tessellator.draw(group);
         }
     }
 

src/js/net/minecraft/client/render/Tessellator.js

@@ -14,22 +14,34 @@ window.Tessellator = class {
     startDrawing() {
         this.verticies = [];
         this.uv = [];
+        this.index = [];
     }
 
     addVertexWithUV(x, y, z, u, v) {
+        // Add vertex
         this.verticies.push(x);
         this.verticies.push(y);
         this.verticies.push(z);
 
+        // Add UV
         this.uv.push(u);
         this.uv.push(v);
+
+        // Add index
+        let index = this.index.length / 6;
+        this.index.push(index + 0);
+        this.index.push(index + 2);
+        this.index.push(index + 1);
+        this.index.push(index + 0);
+        this.index.push(index + 3);
+        this.index.push(index + 2);
     }
 
     draw(group) {
         let geometry = new THREE.BufferGeometry();
         geometry.setAttribute('position', new THREE.BufferAttribute(new Float32Array(this.verticies), 3));
         geometry.setAttribute('uv', new THREE.BufferAttribute(new Float32Array(this.uv), 2));
-        geometry.setIndex(new THREE.BufferAttribute(new Uint32Array([0, 2, 1, 0, 3, 2]), 1));
+        geometry.setIndex(new THREE.BufferAttribute(new Uint32Array(this.index), 1));
 
         let mesh = new THREE.Mesh(geometry, this.material);
         group.add(mesh);

src/js/net/minecraft/client/world/ChunkSection.js

@@ -27,6 +27,7 @@ window.ChunkSection = class {
         this.dirty = false;
         this.group.clear();
 
+        renderer.blockRenderer.tessellator.startDrawing();
 
         for (let x = 0; x < ChunkSection.SIZE; x++) {
             for (let y = 0; y < ChunkSection.SIZE; y++) {
@@ -43,6 +44,8 @@ window.ChunkSection = class {
                 }
             }
         }
+
+        renderer.blockRenderer.tessellator.draw(this.group);
     }
 
     getBlockAt(x, y, z) {