private void initializeVertexBuffer() {
FloatBuffer vertexPositionsBuffer = BufferUtils.createFloatBuffer( vertexPositions.length );
vertexPositionsBuffer.put( vertexPositions );
vertexPositionsBuffer.flip();
positionBufferObject = glGenBuffers();
glBindBuffer( GL_ARRAY_BUFFER, positionBufferObject );
glBufferData( GL_ARRAY_BUFFER, vertexPositionsBuffer, GL_STREAM_DRAW );
glBindBuffer( GL_ARRAY_BUFFER, 0 );