// RenderUtils

def applyCamera(cam: Camera, eye: Vector3): Unit = {
  GL11.glViewport(cam.viewport.x, mc.displayHeight - cam.viewport.end.y, cam.viewport.width, cam.viewport.height)
  GL11.glClear(GL11.GL_DEPTH_BUFFER_BIT)
  GL11.glMatrixMode(GL11.GL_PROJECTION)
  loadMatrix(cam.transposedProjectionMatrix)
  GL11.glMatrixMode(GL11.GL_MODELVIEW)
  loadMatrix(cam.transposedViewMatrix)
  GL11.glTranslated(-eye.x, -eye.y, -eye.z)
}

// cam (custom view entity)

class CameraEntity extends Entity(snapshot) {
  val camera = new Camera(null, null, null)

  def updateCamera(viewport: Rectangle): Boolean = {
    camera.viewport = viewport
    camera.projectionMatrix = MathUtils.createProjectionMatrixAsPerspective(30, 0.05, 50, viewport.width, viewport.height)
    camera.viewMatrix = MathUtils.createMatrixAsLookAt(getPositionVector, Vector3.Zero, Vector3(0, 1, 0))
    camera.isValid
  }

  override def entityInit(): Unit = ()

  override def writeEntityToNBT(tagCompound: NBTTagCompound): Unit = ()

  override def readEntityFromNBT(tagCompound: NBTTagCompound): Unit = ()
}

// draw
GlStateManager.pushMatrix()
if (cam.updateCamera(utils.revertScale(screenBounds))) {
  RenderUtils.applyCamera(cam.camera, cam.getPositionVector)
  MFWorldRenderer.renderWorld(cam, snapshot)
  RenderUtils.setupOverlayRendering()
}
GlStateManager.popMatrix()