kotlin opengl trouble

//renderer
package com.stuff.vitali.rubicscubeopengl

import android.content.Context
import android.opengl.GLES20.*
import android.opengl.GLSurfaceView
import android.util.Log
import java.nio.ByteBuffer
import java.nio.ByteOrder
import javax.microedition.khronos.egl.EGLConfig
import javax.microedition.khronos.opengles.GL10

class MyRenderer(val context: Context) : GLSurfaceView.Renderer {
    private var shaderProgramId: Int? = null
    private var colorUniformLocation: Int? = null
    private var positionAttrLocation: Int? = null

    companion object{
        const val TAG = "MY_RENDERER_TAG"
    }

    override fun onSurfaceCreated(unused: GL10?, config: EGLConfig?) {
        glClearColor(0f, 0f, 0f, 1f)
        val vertShader = ShaderUtils.createShader(context, GL_VERTEX_SHADER, R.raw.vertex_shader)
        val fragShader = ShaderUtils.createShader(context, GL_FRAGMENT_SHADER, R.raw.fragment_shader)
        shaderProgramId = ShaderUtils.createProgramm(vertShader, fragShader)
        Log.d(TAG, "After creating programm")
        glUseProgram(shaderProgramId!!)
        Log.d(TAG, "After using shader")
        val vertices = floatArrayOf(-0.5f, -0.2f, 0.0f, 0.2f, -0.5f, -0.2f)
        val vertexData = ByteBuffer.allocateDirect(vertices.size * 4).order(ByteOrder.nativeOrder()).asFloatBuffer()
        vertexData.put(vertices)
        colorUniformLocation = glGetUniformLocation(shaderProgramId!!, "fr_Color")
        glUniform4f(colorUniformLocation!!, 0f, 0f, 1f, 1f)
        positionAttrLocation = glGetAttribLocation(shaderProgramId!!, "v_position")
        vertexData.position(0)
        glVertexAttribPointer(positionAttrLocation!!, 2, GL_FLOAT, false, 0, vertexData)
        glEnableVertexAttribArray(positionAttrLocation!!)


    }
    override fun onDrawFrame(unused: GL10?) {
        glClear(GL_COLOR_BUFFER_BIT)
        glDrawArrays(GL_TRIANGLES, 0, 3)
    }

    override fun onSurfaceChanged(unused: GL10?, width: Int, height: Int) {
        glViewport(0, 0, width, height)
    }


}