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From: BGB <cr88192@gmail.com>
Newsgroups: comp.arch
Subject: Re: Misc: Applications of small floating point formats.
Date: Sat, 3 Aug 2024 15:29:44 -0500
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On 8/3/2024 1:44 PM, Chris M. Thomasson wrote:
> On 8/2/2024 10:33 PM, Lawrence D'Oliveiro wrote:
>> On Fri, 2 Aug 2024 21:14:33 -0500, BGB wrote:
>>
>>> On 8/2/2024 8:35 PM, Lawrence D'Oliveiro wrote:
>>>
>>>> On Fri, 2 Aug 2024 17:18:17 -0700, Chris M. Thomasson wrote:
>>>>
>>>>> Taking a screen shot? glReadPixels is okay, right?
>>>>
>>>> That means grabbing the whole screen, regardless of what else it might
>>>> be showing, assuming your window it not occluded, and it further
>>>> assumes you have a screen to grab from. This kind of precludes running
>>>> the renderer as a batch, background process.
>>>
>>> The glReadPixels call doesn't grab an image from the OS desktop, but
>>> rather from one of the internal framebuffers associated with the OpenGL
>>> context.
>>
>> Still lousy performance, though. That is simply not considered a serious
>> usage scenario for OpenGL. And not for any other on-screen 3D API, as far
>> as I’m aware.
> 
> Afaict, it's fine for taking a snapshot. I used it to create the 
> following animation as a series of frames:
> 
> Fractal Boom Box:
> 
> https://youtu.be/n13GHyYEfLA

Yeah.

If you want it for a screenshot or final rendered output, it is fine.

If you want to fetch images to feed back into textures, maybe not so 
great performance-wise, but if offline rendering and one doesn't have 
FBOs, it is fine...

Like, one doesn't need to try to hold 60 fps for their batch renderer or 
something.



Only obvious drawbacks I see is mostly:
One needs an OpenGL implementation (that works to some acceptable level);
It is not a raytracer, if one wants/cares about raytracing.

But, as I see it, which is "better" more depends on desired use-case:
   Want "photorealism" or a "realistic" look,
     use a raytracer/path-tracer;
   Want something cartoon like, rasterization makes sense.
     And, as I see it, may actually be preferable in terms of aesthetics.

If you want bright, brightly colored, and glossy, rasterization gives 
this effect easily. If you want something dimly lit and "grungy", then 
raytracing is a good fit.


But, if one wants stylized cartoon-like humanoid characters in a 
raytraced setting, it looks a bit, off.


And, likewise, if one wants rasterization, OpenGL serves this use case well.

And, if you want a raytracer, look elsewhere.


....