[android-developers] Re: opengles question (to change content of vertexbuffer used in gldrawarrays)

Do not call glBufferSubData, use glBufferData instead. The former is
dog slow on most mobile GPUs for various reasons (pipeline stall if
that buffer is currently in use etc.).

Also, do not use Buffer.put(int index, float value) if you can instead
use the bulk put operations. For direct Buffers that's one JNI call
per float which is way to costly. Note however that bulk puts are slow
up until Android 2.3 as well. See
http://www.badlogicgames.com/wiki/index.php/Direct_Bulk_FloatBuffer.put_is_slow

On 2 Mai, 23:50, elix <emr...@gmail.com> wrote:
> Thanks adam.
>
> I asked this topic in stackoverflow and it is solved. Simply; update
> the coordinate data within the buffer object by using put(index,
> value) method and then call glbuffersubdata() method.
> Here is detailed answers:http://stackoverflow.com/questions/5849566/how-to-change-the-content-...
>
> On May 2, 8:21 pm, Adam Hammer <adamhamm...@gmail.com> wrote:
>
>
>
>
>
>
>
> > Just use get and put on the buffer with your data.memory layout can
> > vary but typically is xyzxyzxyz which would be the 9 floats that
> > define your 3 vertices.
>
> > Adam
>
> > On May 1, 12:27 pm, emre onal <emr...@gmail.com> wrote:
>
> > > I have some triangle polygons and drawing them in a traditional way:
> > > (android-java code)
>
> > > gl.glDrawArrays(GL10.GL_TRIANGLES, i, j);
>
> > > I want to update the vertex coordinates of the triangles. All of the
> > > tutorials I've found use an initial vertex data then only apply
> > > transformations to them. I need to change each vertex coordinate
> > > independently.
>
> > > I change the content of the array which is used to create the related
> > > vertexbuffer but it doesn't make any change on the screen. Rebuilding the
> > > vertexbuffer on eachframe doesn't seem to be right way I guess.
>
> > > Can you point out any example source code at least, if you know any?
>
> > > --
>
> > > Emre

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