Loader.kt

fun Texture(image: BufferedImage): Texture {
    val width = image.width
    val height = image.height
    val size = width * height

    val pixels = IntArray(size)
    image.getRGB(0, 0, width, height, pixels, 0, width)
    
    val buffer = ByteBuffer.allocate(size * 4)  //   --comment

    //val stack = MemoryStack.stackPush()                   --uncomment
    //val buffer = stack.malloc(size * 4)                   --uncomment

    for (y in 0 until height) {
        for (x in 0 until width) {
            val pixel = pixels[x + y * height]

            buffer.put(((pixel shr 16) and 0xFF).toByte())  //r
            buffer.put(((pixel shr 8) and 0xFF).toByte())   //g
            buffer.put((pixel and 0xFF).toByte())           //b
            buffer.put(((pixel shr 24) and 0xFF).toByte())  //a
        }
    }
    buffer.flip()

    val textureId = genTextures()
    glBindTexture(GL_TEXTURE_2D, textureId)

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE)
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE)

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST)
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST)

    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, buffer)
    //MemoryStack.stackPop()                                --uncomment

    return Texture(textureId)
}