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Append data to dynamic VBOs

Started by c0der_ Feb 18, 2011 at 5:04 AM 3 replies 2.3k views

Original Post

Feb 18, 2011 at 5:04 AM

How do you append data to dynamic VBOS during rendering? I don't want to render the buffer if there are too little vertices.
glBufferDataARB(GL_ARRAY_BUFFER_ARB, m_pDynamicBuffers[m_nDynamicBufferIndex].nBufferSize, pVertices, GL_DYNAMIC_COPY);

Does GL_DYNAMIC_COPY append the data or overwrite? Or perhaps I just need to store the data, append the data, and pass it into glbufferdata again with the new data, any thoughts?

karwosts

Feb 18, 2011 at 5:16 AM

Use glBufferSubData, doesn't require you to overwrite the whole buffer. You can't make a buffer any larger, but you can overwrite parts of it. If you need to resize it you call glBufferData again.

c0der_

Feb 18, 2011 at 5:50 AM

so I just create the buffer with the initial vertices and overwrite parts of it in each render call? isn't it better to just create separate static buffers rather than overwriting parts of a dynamic buffer?

Use glBufferSubData, doesn't require you to overwrite the whole buffer. You can't make a buffer any larger, but you can overwrite parts of it. If you need to resize it you call glBufferData again.

karwosts

Feb 18, 2011 at 5:55 AM

isn't it better to just create separate static buffers rather than overwriting parts of a dynamic buffer?[/quote]

All depends what you're trying to do.

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