[osg-users] Significant drop in frame rate when updating from OSG 3.2.1 to 3.4.0

[Robert Osfield]

Hi Werner,

Great to her you got to the bottom of this issue, amazing how such a
small and innocuous looking change can have such a dramatic impact.

BTW, the short hand for setting the binding in OSG-3.4 onwards is:

  geometry-setNormalArray(array, osg::Array::BIND_PER_VERTEX);

The separate setNormalBinding(...) method is now deprecated as
osg::Array itself now manages the Binding rather than osg::Geometry.

Robert.

Robert.

On 31 March 2017 at 14:39, Werner Modenbach <Werner.Modenbach at texion.eu> wrote:
> Hi Robert,
>
> final analysis:
>
> In our software we did the following patch to make it run with high fps in
> master of 3.4 branch:
>
>              osgNormals = new osg::Vec3Array;
>
> +            osgNormals->setBinding(osg::Array::BIND_PER_VERTEX);
>
>              geometry->setNormalArray(osgNormals.get());
>
>              geometry->setNormalBinding(osg::Geometry::BIND_PER_VERTEX);
>
>
>
> Obviously we have to set the binding in the array itself and the
> setNormalBinding works but has poor performance.
>
> Now we are happy again :-)
>
> - Werner -
>
>
> Am 31.03.2017 um 13:11 schrieb Werner Modenbach:
>
> Hi Robert,
>
> the 3.4.0 tagged version is OK with the frame rate.
> We discovered your commit in the 3.4 branch causing the problem:
>
> From 1f1c21772ae0dd10a93cd31ab81bf563802b7b2d Mon Sep 17 00:00:00 2001
>
> From: Robert Osfield <robert at openscenegraph.com>
>
> Date: Thu, 3 Nov 2016 11:31:07 +0000
>
> Subject: Added check against binding type of array to decide whether it's
>
>  appropriate to assign array to VBO.
>
> diff --git a/src/osg/Geometry.cpp b/src/osg/Geometry.cpp
>
> index 779e8cd..244bf25 100644
>
> --- a/src/osg/Geometry.cpp
>
> +++ b/src/osg/Geometry.cpp
>
> @@ -445,7 +445,7 @@ bool Geometry::getDrawElementsList(DrawElementsList&
> drawElementsList) const
>
>
>
>  void Geometry::addVertexBufferObjectIfRequired(osg::Array* array)
>
>  {
>
> -    if (_useVertexBufferObjects)
>
> +    if (_useVertexBufferObjects &&
> array->getBinding()==Array::BIND_PER_VERTEX)
>
>      {
>
>          if (!array->getVertexBufferObject())
>
>          {
>
>
> The question is: Why is the viewer frame rate OK, even it is built with the
> same version we are using?
> What are we doing different to the viewer?
>
> Thanks so much for your excellent work!
>
> - Werner -
>
> Am 28.03.2017 um 18:22 schrieb Robert Osfield:
>
> Hi Wener,
>
> On 28 March 2017 at 16:24, Werner Modenbach <Werner.Modenbach at texion.eu>
> wrote:
>>
>> I know it is actually not your duty giving help here but you are very
>> familiar with the driver calls and it would help a lot if you can provide
>> an idea what kind of setting might cause this issue.
>
>
> I'm a very occasional Windows user so really don't have much experience with
> Windows drivers to be able help with driver settings.
>
> It's a long shot, but have your tried the OSG-3.4 branch or OSG master as
> these both contain a range of bug fixes/OSG improvements, there is chance
> that something has changed that might fix things.
>
> Whatever the cause is it seems to be some small OpenGL state difference
> between OSG-3.2 and OSG-3.4.0, I'm afraid I don't know what this might be.
> Perhaps using a 3rd party OpenGL debugging tool might help here - capture
> all the GL calls for 3.2.x and 3.4.x and see what the differences are.
>
> Robert.
>
>
>
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