仅修改特定元素类型的VBO缓冲区数据？ [英] Modifying only a specific element type of VBO buffer data?

问题描述

现在，我有我的VBO使用单缓冲器，它有顶点，texcoord和颜色的元素。

现在，可以有效地只更新texcoords没有更新顶点/颜色？

解决方案

您可以将VBO的特定范围映射到用户内存中 glMapBufferRange 。当然，如果顶点，颜色和texcoord数据是交错的，它将等效于

如果您的VBO是：

  [XYZ XYZ XYZ XYZ RGBA RGBA RGBA RGBA TxTy TxTy TxTy TxTy] 
  

您只能通过映射缓冲区的最后部分（ [TxTy TxTy TxTy TxTy] ）来上传纹理坐标更新它。您也可以使用 glBufferSubData 执行此操作。

但如果您使用交错数据：

  [XYZ RGBA TxTy XYZ RGBA TxTy XYZ RGBA TxTy XYZ RGBA TxTy] 
  

那么你不能更新缓冲区的一部分。

I have my VBO using single buffer at the moment, it has vertex, texcoord and color elements.

Now, is it possible to update efficiently only the texcoords without updating the vertex/color as well? It should be the same efficiency as having separate buffers updated.

解决方案

You can map a specific range of your VBO into user memory using glMapBufferRange. Of course, if your vertex, color and texcoord data are interleaved, it will be equivalent to a glMapBuffer.

EDIT:

If your VBO is:

[XYZ XYZ XYZ XYZ RGBA RGBA RGBA RGBA TxTy TxTy TxTy TxTy]

You can upload only the texture coordinates by mapping the last part of the buffer ([TxTy TxTy TxTy TxTy]) and update it. You can also use glBufferSubData to do that. It would be faster to update that buffer than the full one.

But if you use interleaved data:

[XYZ RGBA TxTy XYZ RGBA TxTy XYZ RGBA TxTy XYZ RGBA TxTy]

Then you cannot update part of the buffer.

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