anchor.diff:  
       color = new Vector4.all(1.0);
   
  -    rebuildBuffer();
       vertexBuffer = gl.createBuffer();
       indexBuffer = gl.createBuffer();
  +    rebuildBuffer();
   
       reset();
     }
  
positive.code:       indices[i + 3] = j + 2;
        indices[i + 4] = j + 3;
        indices[i + 5] = j + 1;
        print(j + 3);
      }
  
      gl.bindBuffer(ELEMENT_ARRAY_BUFFER, indexBuffer);
  
negative.code:   }
  
    flush() {
      gl.bindBuffer(ARRAY_BUFFER, vertexBuffer);
      gl.bufferData(ARRAY_BUFFER, vertices, DYNAMIC_DRAW);
      gl.bindBuffer(ELEMENT_ARRAY_BUFFER, indexBuffer);
  
      //offsets and strides are by byte, thus multiplied by 4
      gl.vertexAttribPointer(shaderProgram.attributes[vertPosAttrib], 3, FLOAT, false, vertexSize * 4, 0);
  