Pro Android with Kotlin

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225
CHAPTER 9: User Interface
var triangle:Triangle? = null
var square:Square? = null
var program:Int? = 0
val vbo = IntArray(2) // vertex buffers
val ibo = IntArray(2) // index buffers
val vMatrix:FloatArray = FloatArray(16)
val projMatrix:FloatArray = FloatArray(16)
val mvpMatrix:FloatArray = FloatArray(16)
The method onSurfaceCreated() just gets called once by the system when the OpenGL 
rendering is ready to go. We use it to set some rendering flags and to initialize the shaders.
// Called once to set up the view's
// OpenGL ES environment.
override fun onSurfaceCreated(gl: GL10?, config:
javax.microedition.khronos.egl.EGLConfig?) {
// enable face culling feature
GLES20.glEnable(GL10.GL_CULL_FACE)
// specify which faces to not draw
GLES20.glCullFace(GL10.GL_BACK)
// Set the background frame color
GLES20.glClearColor(0.0f, 0.0f, 0.0f, 1.0f)
val vertexShader = loadShader(
GLES20.GL_VERTEX_SHADER,
vertexShaderCode)
val fragmentShader = loadShader(
GLES20.GL_FRAGMENT_SHADER,
fragmentShaderCode)
// create empty OpenGL ES Program
program = GLES20.glCreateProgram()
// add the vertex shader to program
GLES20.glAttachShader(program!!, vertexShader)
// add the fragment shader to program
GLES20.glAttachShader(program!!, fragmentShader)
// creates OpenGL ES program executables
GLES20.glLinkProgram(program!!)
GLES20.glGenBuffers(2, vbo, 0) // just buffer names
GLES20.glGenBuffers(2, ibo, 0)

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