No render in Scala

package com.personasubrosa

import org.lwjgl.{
  BufferUtils => BU
  , LWJGLException
}
import org.lwjgl.opengl.{
  ARBBufferObject => ARBBO
  , ARBFragmentShader => ARBFS
  , ARBShaderObjects => ARBSO
  , ARBVertexBufferObject => ARBVBO
  , ARBVertexShader => ARBVS
  , Display
  , DisplayMode
  , GLContext
  , GL11 => GL
}

object Main {

  def initDisplay(): Unit = {

    try {
      Display.setDisplayMode( new DisplayMode(Config.windowX, Config.windowY) )
      Display.create()
    } catch {
      case e: LWJGLException => {
        e.printStackTrace()
        sys.exit(1)
      }
    }

  }

  def initGL(): Unit = {
    GL.glMatrixMode(GL.GL_PROJECTION)
    GL.glLoadIdentity()
    GL.glOrtho(0, Config.windowX, 0, Config.windowY, 1, -1)
    GL.glMatrixMode(GL.GL_MODELVIEW)
  }

  def createVBOID(): Int = {
    if(GLContext.getCapabilities().GL_ARB_vertex_buffer_object) {
      val buffer = BU.createIntBuffer(1)
      ARBBO.glGenBuffersARB(buffer)
      buffer.get(0)
    } else {
      0
    }
  }

  def buildVertices(vertexPosBuffer: Int): Unit = {

    var vertices = BU.createFloatBuffer(6).put(Array(-0.5f, -0.5f, 0.5f, -0.5f, 0, 0.5f))

    ARBBO.glBindBufferARB(ARBVBO.GL_ARRAY_BUFFER_ARB, vertexPosBuffer)
    ARBBO.glBufferDataARB(ARBVBO.GL_ARRAY_BUFFER_ARB, vertices, ARBBO.GL_STATIC_DRAW_ARB)

  }

  def createShader(source: String, shaderType: Int): Int = {
    val shader = ARBSO.glCreateShaderObjectARB(shaderType)
    ARBSO.glShaderSourceARB(shader, source)
    ARBSO.glCompileShaderARB(shader)
    if (ARBSO.glGetObjectParameteriARB(shader, ARBSO.GL_OBJECT_COMPILE_STATUS_ARB) == GL.GL_FALSE) {
      throw new Exception("Compile Failed")
    }
    shader
  }

  def createProgram(vstr: String, fstr: String): Int = {

    val program = ARBSO.glCreateProgramObjectARB()
    val vertShader = createShader(vstr, ARBVS.GL_VERTEX_SHADER_ARB)
    val fragShader = createShader(fstr, ARBFS.GL_FRAGMENT_SHADER_ARB)
    ARBSO.glAttachObjectARB(program, vertShader)
    ARBSO.glAttachObjectARB(program, fragShader)
    ARBSO.glLinkProgramARB(program)
    if (ARBSO.glGetObjectParameteriARB(program, ARBSO.GL_OBJECT_LINK_STATUS_ARB) == GL.GL_FALSE) {
      throw new Exception("Link Failed")
    }
    program

  }

  def renderGL(vertexPosBuffer: Int, program: Int): Unit = {

    GL.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT)
    //GL.glClearColor(0,0,0.8f,1);

    ARBSO.glUseProgramObjectARB(program)
    val vertexPosAttrib = ARBVS.glGetAttribLocationARB(program, "pos")
    ARBVS.glEnableVertexAttribArrayARB(vertexPosAttrib)
    ARBVS.glVertexAttribPointerARB(vertexPosAttrib, 2, GL.GL_FLOAT, false, 0, 0)

    GL.glDrawArrays(GL.GL_TRIANGLES, 0, 3)

  }

  def main(args: Array[String]): Unit = {

    initDisplay()
    initGL()

    val vertexPosBuffer = createVBOID()
    buildVertices(vertexPosBuffer)

    val vs = "attribute vec2 pos;" +
    		"void main() { gl_Position = vec4(pos, 0, 1); }"
    val fs = "precision mediump float;" +
    		"void main() { gl_FragColor = vec4(0, 0.8, 0, 1); }"
    val program = createProgram(vs, fs)



    while (!Display.isCloseRequested()) {
      renderGL(vertexPosBuffer, program)
      Display.update()
      Display.sync(60)
    }
    Display.destroy()

  }

}