_BIT)

      const fieldOfView = 45 * Math.PI / 180
      const aspect = gl.canvas.clientWidth / gl.canvas.clientHeight
      const zNear = 0.1
      const zFar = 100.0
      const projectionMatrix = mat4.create()
      mat4.perspective(projectionMatrix, fieldOfView, aspect, zNear, zFar)

      const modelViewMatrix = mat4.create()
      mat4.translate(modelViewMatrix, modelViewMatrix, [-0.0, 0.0, -6.0])
      mat4.rotate(modelViewMatrix, modelViewMatrix, cubeRotation, [0.0, 0.0, 1.0])
      mat4.rotate(mod