Re: [Csgl-users] rendering speed slower using GDIGLContext than if using ContolGLContext

[Lloyd D. <ll...@ga...>]

Well Aron,

I must confess your mail as a bit unclear to me. particularly the second
part.
In fact I understand what you want to do, but not clearly which problem you
have.

And I want some precision too.

> So far, I've been using a ControlGLContext but ControlGLContext.ToImage()
> throws an exception ("Invalid parameter used" from the Bitmap
constructor).
do you mean that
...
Bitmap img = new Bitmap(b[2], b[3],
System.Drawing.Imaging.PixelFormat.Format24bppRgb);
...
(code snippet of ToImage)
throw an exception ?

just a try, hack OpenGLContext and replace the last line of ToImage()
that is:
OpenGLException.Assert() by glGetError() ....


> I've been looking at GDIGLContext (which feels like the right way to go?)
> and I have been able to make it work, but the rendering takes about twice
> the time
I can't really help, this is the domain of the driver ...
Although I am thinking to make a HARDWARE_ACCELERATED flag visible, this
flags doesn't seem to exist on X-Windows (so far, according to what I read
in my doc) so I have some hesitation....

> compared to that when I use a ControlGLContext - event if the code
> in OnPaint() is never run.
what do you mean ?
even if OpenGL call doesn't draw on screen they take time.
In fact it seems that the GDI context is sotware OpenGL and all the computer
power lie on the CPU, which is more slower than the GPU for OpenGL calls....

> I would like to use CsGL 1.4.0 but using this version, the volumes
rendered
> using 2D and 3D textures have way too large distances between the textures
> (the distance between the textures - i.e. the number of textures - varies
> with the object's distance to the camera). Also, the problem above isn't
> solved by using 1.4.0. So I stick to CsGL 1.3.2. Any ideas or suggestions?
I clearly not understand what difference between 1.3.2 &  1.4.0 make you
stick to 1.3.2...
I would like to know to correct 1.4....

cheers,
Lloyd