的FloatBuffer而不是浮动为什么[]？ [英] Why FloatBuffer instead of float[]?

问题描述

我一直在用我的Andr​​oid code FloatBuffers一段时间（从一些opengles教程中复制），但我不明白到底是什么，这种结构是，为什么它是必要的。

I've been using FloatBuffers in my Android code for a while (copied it from some opengles tutorial), but I cannot understand exactly what this construct is and why it is needed.

例如该code（或类似）我在许多许多人的code和Android的教程，请参阅：

For example this code (or similar) I see in many many peoples' code and android tutorials:

float[] vertices = ...some array...

ByteBuffer vbb = ByteBuffer.allocateDirect(vertices.length * 4); 
vbb.order(ByteOrder.nativeOrder());    // use the device hardware's native byte order
FloatBuffer fb = vbb.asFloatBuffer();  // create a floating point buffer from the ByteBuffer
fb.put(vertices);    // add the coordinates to the FloatBuffer
fb.position(0);      // set the buffer to read the first coordinate

这看起来太过冗长，凌乱的东西而据我可以告诉是float数组大约只是一个花哨的包装。

This seems awfully verbose and messy for something which as far as I can tell is just a fancy wrapper around of an array of floats.

问题：

• 有什么理由这种类型的类（ByteBuffer的，FloatBuffer），而不是任何其他类型的集合或简单的花车阵？

• What is the justification for this type of class (ByteBuffer, FloatBuffer), as opposed to any other kind of collection or simple array of floats?

什么是背后将其转换成一个FloatBuffer之前创建的ByteBuffer的想法？

What's the idea behind creating a ByteBuffer before converting it into a FloatBuffer?

推荐答案

主要的原因是性能：的ByteBuffers和其他NIO类使加速操作时避免需要将数据复制到与本机code接口（通常一个临时缓冲器）。

The main reason is performance: ByteBuffers and the other NIO classes enable accelerated operations when interfacing with native code (typically by avoiding the need to copy data into a temporary buffer).

这是pretty的重要的，如果你是做了很多的OpenGL渲染调用，例如。

This is pretty important if you are doing a lot of OpenGL rendering calls for example.

原因首先创建一个ByteBuffer的是，你要使用的allocateDirect调用创建的直接的字节的缓冲区，这得益于加速操作。然后，从这个共享同一内存中创建一个FloatBuffer。该FloatBuffer本身不具有allocateDirect方法，出于某种原因，这就是为什么你必须通过ByteBuffer中去。

The reason for creating a ByteBuffer first is that you want to use the allocateDirect call to create a direct byte buffer, which benefits from the accelerated operations. You then create a FloatBuffer from this that shares the same memory. The FloatBuffer doesn't itself have an allocateDirect method for some reason, which is why you have to go via ByteBuffer.

这篇关于的FloatBuffer而不是浮动为什么[]？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！