[Bug 83442] [IVB regression] glTexSubImage2D performance

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=83442

--- Comment #12 from Mark Newiger <mark.newiger at seefront.com> ---
I compiled the 10.3 Mesa version and can confirm that the sample code is now
performing better than the 8.0.4 Mesa version.
It also turned out that some glPixelStoragei() calls where causing the
performance drop. I forgot to add this in the sample code.
I was using the following lines to split one large 1920x1080 sideByside Bitmap
into 2 texture objects:
// Storing left texture.
glPixelStorei(GL_UNPACK_ROW_LENGTH, 1920);
glPixelStorei(GL_UNPACK_SKIP_PIXELS, 0);
glTexSubImage2D(...)
// Storing right texture.
glPixelStorei(GL_UNPACK_ROW_LENGTH, 1920);
glPixelStorei(GL_UNPACK_SKIP_PIXELS, 960);
glTexSubImage2D(...)
For some reason glTexSubImage2D() together with these glPixelStoragei() calls
are performing better with the old Mesa version.
I am now splitting the 1920x1080 texture inside the shader so I do not need the
glPixelStoragei() calls any more. In total I gained a performance increase as
glTexSubImage2D() without changing the pixel storage is behaving better with
the new Mesa versions. 

I guress this ticket can be set to fixed then.

Thanks.

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