[Interest] Angle needed or not?...

[Sean Harmer]

On Friday 05 July 2013 14:38:34 Ruth Ivimey-Cook wrote:
> Giuseppe D'Angelo wrote:
> > On 5 July 2013 14:27, Philippe <philwave at gmail.com> wrote:
> >> I have checked various sources but can't find a clear answer. This is my
> >> scenario:
> >> 
> >> 1) My application does not use any of the Open GL classes. Only QPainter
> >> is used. 2) My application does not use QtQuick, neither WebKit
> >> 3) My application's requirement is Windows 7 or 8, not below
> >> 4) My application has a wide user base and I don't want any problem eg.
> >> "please update your open GL drivers"> 
> > You should use an OpenGL build. It will produce a smaller "package"
> > (due to the fact that you won't have to ship ANGLE libs). You app
> > won't notice the difference as it's not using OpenGL at all (directly
> > or indirectly).
> 
> I am, like Philippe, working on a Win7/8 app: having tried using
> QtGLWidget to render a QGraphicsScene I found the loss of rendering
> quality far too much to accept. It seemed mostly to do with aliasing and
> integer maths resulting in less accurate drawing.
> 
> Are there non-QGLWidget ways of drawing that use hardware acceleration?
> Are there ways I might have improved my QGLWidget render?
> 
> Given that getting OpenGL  > v1.0 on Windows seems to require
> non-standard components, are those components usable irrespective of the
> graphics card installed? Would I have to provide instructions on
> fetching the AMD, Intel or nVidia OpenGL component along with my app?

It should just be a case of installing a recent driver from the GPU vendor. 
AMD/nVidia users will do this as a matter of course if they want anything 
other than very low resolutions. These have supported modern versions of 
OpenGL for a long time. nVidia supports OpenGL 4.3 out of the box, I'm not 
sure about AMD as I don't have any cards at present.

For Intel it's important to get a recent driver as their support for OpenGL 
has improved a lot over the last 12 months or so.

> I would like to support OpenGL as an open alternative to the
> now-apparently-moribund DirectX but it does seem DirectX still has
> significant advantages.

The only real advantage of DirectX over OpenGL on windows is that MS ensure 
that DirectX works via windows updates whereas for OpenGL you are reliant upon 
using drivers from the GPU vendors. DirectX and OpenGL have total feature 
parity in the core APIs afaik. After all they are talking to the same 
hardware.

Cheers,

Sean

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