Re: [Foxgui-users] Faded displayed (not pure)colours in OpenGL

[Pof <jd3...@gm...>]

Dear John,

Thanks for answering.
I also have a normal behaviour on Windows with Intel built-in Graphics 
(test rather many over the years).

On Windows, would you have the opportunity to test with a dedicated 
Graphics card (NVIDIA, ATI...) if you have any such hardware?

Regards,
Pof

Le 31/07/2023 à 03:38, John Selverian a écrit :
> I'm doing something similar but haven't seen any problems, but on Windows I'm using Intel UHD Graphics 630, it also looks fine on my Mac.
>
>
> -----Original Message-----
> From: Pof <jd3...@gm...>
> Sent: Sunday, July 30, 2023 5:42 PM
> To: fox...@li...
> Subject: [Foxgui-users] Faded displayed (not pure)colours in OpenGL
>
> Dear all,
>
> I have developed a Windows application based on the FoxToolkit, with 3D rendering based on FXGLVisual and FXCanvas, and for a long time I have had a nasty colour issue in the 3D rendering.
> In short:
> - pure colours (i.e. pure red, pure green and pure blue) are displayed correctly,
> - non-pure colours (i.e. with some colour channels between 0 and 1) appear quite washed out, which in my case is very annoying as I have to rely on the colour scale to interpret the data.
>
> I managed to reproduce the behaviour from the simple Fox example "gltest.cpp", with very slight modifications to the
> GLTestWindow::drawScene() member (see the end of this email). As an image is worth a thousand words, the following image
>       https://i.postimg.cc/kDrcvMpb/Open-GL-Faded-Not-Pure-Colours.png
> visually sums up the issue for non-pure colours:
> - if the built-in graphic chipset is used, the colours look fine,
> - when the NVIDIA graphics card is used, the colours appear very faded.
>
> Additional comments:
> - this issue only occurs when using the NVIDIA graphics card (it does not occur when using the built-in Intel graphics chipset),
> - my NVIDIA driver is up to date,
> - I don't blame my graphics card, as I don't have this issue with popular applications that use OpenGL (e.g.
> https://www.cloudcompare.org/), and also because this issue exists on all computers on which this was tested (I'd say at least 100),
> - it occurs with Fox 1.7.xx versions (currently using 1.7.81, with
> VC++2017 under Win11, but I had this issue for many years, so much older
> Fox releases), I could not say anything about Fox 1.6.x.
>
> Has anyone experienced this problem?
> I would be very much interested to get some hints on how to solve this,
> or at least to have an idea where to start to solve it.
>
> Thanks in advance,
> Pof
>
> ----------------------------------------------------------------
> // code modification (lines 724 to 727 of gltest.cpp)
>     const GLfloat lightAmbient[]={1.f,1.f,1.f,1.}; //{.1f,.1f,.1f,1.};
>     const GLfloat lightDiffuse[]={0.,0.,0.,1.}; //{.9f,.9f,.9f,1.};
>     const GLfloat redMaterial[]={237./255.,125./255.,49./255.,1.};
> //{1.,0.,0.,1.};
>     const GLfloat blueMaterial[]={0.,32./255.,96./ 255.,1.}; //{0.,0.,1.,1.};
> ...
>
>
>
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