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Am 07.02.2019 um 17:31 schrieb William F Pokorny:
> Trying to avoid sliding too much sideways into work I did almost two
> years ago given I've already got more going than I'll ever finish.
Welcome to the world of POV-Ray development ;)
> - Remembered a decade ago with the objectAsIso experiments how I looked
> hard at converting other than the simplest csg to a mesh because the
> inside test performance got so slow with larger/complex csg.
>
> - Remembered Lanuhum's Blender hair scene and thinking it shouldn't
> really be that slow, even with super slow sphere_sweeps.
Let's play a game of "shapes that could benefit from internal bounding
but don't have any" ;)
> - Remembered learning early last year while finding the cause of a
> particular speckling bug, that POV-Ray does inside tests when it creates
> original rays.
Just a spontaneous thought here: Would it be worth it to cache the
result of the camera ray origin inside test, and only re-do it if the
origin changes (due to special camera or focal blur)?
> Results were not similar. This leads me to a new suspicion / unproven
> theory we are sitting on a csg inside test performance issue. One
> perhaps affecting things generally. My code changes to the text object
> only treated another problem.
I'm not so sure it's a CSG thing you're seeing. By default, POV-Ray
"flattens" CSG unions wherever possible, promoting all children to
top-level objects - presumably this is also the case with implicit
unions like the text primitive. So unless you took some measure to
specifically prevent this, you're not actually testing a CSG object.
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On 2/7/19 4:34 PM, clipka wrote:
> Am 07.02.2019 um 17:31 schrieb William F Pokorny:
>
...
>
> Let's play a game of "shapes that could benefit from internal bounding
> but don't have any" ;)
On doing the solver work I'm - a while now - very aware of the internal
bounding issues with the sphere_sweep(1). However, if memory serves,
what Lanuhum had was hundreds of thousands of short sphere_sweeps/hairs.
Why would this be so much slower than one, or several, equally screen
filling ones, if bounding is working well(2). A possible answer is the
inside test on setting up original rays is for some reason doing the
test on all the hairs.
(1) - I've made a changes to the inside test of the sphere_sweep as
currently updated for my solver changes. Specifically a change to break
out of the test loop on the first segment where the point tests inside
true. Today the test runs through all the segments no matter. It's not a
change necessary for the solver changes - just something I noticed.
(2) - His textures looked to be simple.
>
...
>
> Just a spontaneous thought here: Would it be worth it to cache the
> result of the camera ray origin inside test, and only re-do it if the
> origin changes (due to special camera or focal blur)?
>
Maybe, yes. Globally turning the inside testing off when it's not
necessary perhaps another idea, but that would add some bookkeeping to
the parser.
>
...
>
> I'm not so sure it's a CSG thing you're seeing. By default, POV-Ray
> "flattens" CSG unions wherever possible, promoting all children to
> top-level objects - presumably this is also the case with implicit
> unions like the text primitive. So unless you took some measure to
> specifically prevent this, you're not actually testing a CSG object.
Agree. It's a theory until proven.
Will say, a reason I chose the shipped ttf1.pov for the AA and not-AA
testing is there are just two top level text objects in that scene. If
any text objects will hierarchically flatten into the prime/top level
seems like those would.
Do you know offhand what sorts of measures prevent flattening? Merge
pops to mind as suppose we'd need to remember the grouping there. The
two ttf1 text objects are textured and transformed - things almost
always the case with the text /csg - but that's it.
Another test which could be done pretty quickly, I guess, would be to
hack the code to eliminate the inside test on ray initialization for
ttf1.pov testing as it really isn't needed in that scene. I might try
that later today as I'm now curious. But, I'm off to do some other stuff
at the moment.
Bill P.
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On 8-2-2019 15:35, William F Pokorny wrote:
>
> Agree. It's a theory until proven.
>
[pedantic mode]
That is an /hypothesis/ then. A /theory/ covers all the known and
accepted proofs and is generally being strengthened along the way by
'falsifications' which may, in the end, disprove it.
[/pedantic mode]
;-)
--
Thomas
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On 2/8/19 9:35 AM, William F Pokorny wrote:
> On 2/7/19 4:34 PM, clipka wrote:
> ...
>>
>> I'm not so sure it's a CSG thing you're seeing. By default, POV-Ray
>> "flattens" CSG unions wherever possible, promoting all children to
>> top-level objects - presumably this is also the case with implicit
>> unions like the text primitive. So unless you took some measure to
>> specifically prevent this, you're not actually testing a CSG object.
>
> Agree. It's a theory until proven.
>
...
>
> Another test which could be done pretty quickly, I guess, would be to
> hack the code to eliminate the inside test on ray initialization for
> ttf1.pov testing as it really isn't needed in that scene. I might try
> that later today as I'm now curious. But, I'm off to do some other stuff
> at the moment.
>
>
Only got to trying the above this morning and perhaps my - hypothesis -
is wrong... If I hacked correctly there was not a difference I'd
consider large enough not to be noise. Tried a couple other things, then
decided why not just see whether the new freetype branch is fast enough
for what I want to do with the hard and soft objects. Also measured
ttf1.pov and it was a little over 3% faster with the freetype branch.
Characters move some so exact scene to scene comparisons not all that easy.
I then merged my hard/soft_object branch into the freetype one
(experimental/freetype at commit 30308ed). Tried the soft_object.pov
scene part of the merged branch where each text object only one
character up through the isosurface to the top. It's quite a lot faster
and I'll post an image to p.b-t.b showing mostly how the characters
shift as expected.
I then tried the version where "Water" all in one text object.
Unfortunately this hangs immediately in a way which only the kill
command can stop.
In other words, the single character W works below while the comment two
character string does not.
#declare Text00 = text {
ttf "timrom.ttf" "W" 0.05, 0.001 translate <0.02,0.02,0>
// ttf "timrom.ttf" "Wa" 0.05, 0.001 translate <0.02,0.02,0>
}
---------------- Repeating a few previous perf tests for the branch.
soft_object.pov p380/freetype + hard/soft object only.
----
345.96user 0.08system 5:46.50elapsed As 'text union'
??? Immediately hangs freetype (???)
64.91user 0.04system 1:05.52elapsed Individual chars at top (-81.24%)
48.33user 0.02system 0:48.91elapsed freetype (-25.54%)
This indirectly calls into question much of my thinking. If the
initialization of the ray is calling the inside test, why doesn't it
hang too... I don't know what's going on.
---
To start though find attached two scene files of a form I've been using
to test solver/inside related changes using media. The results of
Text.pov should quite closely match Text_I.pov results if everything is OK.
They do for the freetype branch where we have just on character W.
Results do not match when the text object string is Wa in the freetype
branch. At master things work OK - well except for the speckling
differences. Perhaps doesn't explain the hang, but something wrong and
fixing that a start. Again see p.b-t.b for image results / compares.
Bill P.
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Attachments:
Download 'text_i.pov.txt' (1 KB)
Download 'text.pov.txt' (1 KB)
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Am 09.02.2019 um 19:41 schrieb William F Pokorny:
> I then tried the version where "Water" all in one text object.
> Unfortunately this hangs immediately in a way which only the kill
> command can stop.
Is that with your own merged version only, or with the "pure" freetype
branch as well?
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On 2/10/19 5:20 AM, clipka wrote:
> Am 09.02.2019 um 19:41 schrieb William F Pokorny:
>
>> I then tried the version where "Water" all in one text object.
>> Unfortunately this hangs immediately in a way which only the kill
>> command can stop.
>
> Is that with your own merged version only, or with the "pure" freetype
> branch as well?
Merged. Give me a little to get coffee, download the freetype branch
straight up, compile and run it.
Bill P.
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On 2/10/19 8:08 AM, William F Pokorny wrote:
> On 2/10/19 5:20 AM, clipka wrote:
>> Am 09.02.2019 um 19:41 schrieb William F Pokorny:
>>
>>> I then tried the version where "Water" all in one text object.
>>> Unfortunately this hangs immediately in a way which only the kill
>>> command can stop.
>>
>> Is that with your own merged version only, or with the "pure" freetype
>> branch as well?
>
> Merged. Give me a little to get coffee, download the freetype branch
> straight up, compile and run it.
>
> Bill P.
Well... Sip or two of coffee and I think I probably originally missed
the point of your question or reading it again.
The hang is happening only when I merge both the freetype branch AND my
soft/hard object branch where there are two or more characters in the
string used in the soft_object pattern -> function -> isosurface.
The soft_object.pov demo scene has both single text object of "Water"
through the isosurface to the top and individual character text objects,
through individual isosurfaces to the top given coded up as the former
is so much faster. Something true even with my text branch performance
improvements merge in too.
---
Anyway, I download the freetype branch directly off github (no github
merge into master), compiled and ran it. The text_i.pov results with two
or more characters are still scrambled (also very slow) compared to the
current master (v38) branch on github. (master 5.27sec -> freetype 18.539)
Possible I guess I'm just not waiting long enough for the first
non-black square to show, but doubt it. I've not done a debug compile
and tried to attach gdb to the running process to verify I've "really"
got a hang.
My thinking was given something is wrong in the freetype branch itself,
as shown by text_i.pov with two or more characters, that should be fixed
first. If lucky that fix fixes my "hang" issue too.
In short run text_i.pov with master and again with the freetype branch.
Results should match and they don't when I run it.
Bill P.
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Am 09.02.2019 um 19:41 schrieb William F Pokorny:
> To start though find attached two scene files of a form I've been using
> to test solver/inside related changes using media. The results of
> Text.pov should quite closely match Text_I.pov results if everything is OK.
I'm wondering whether we're seeing an inside test problem caused by y
coordinates matching a horizontal line (or maybe even just an on-curve
control point).
The old TrueType implementation was apparently prone to such issues, and
added a tiny "random" rotation to try and avoid them. I had hoped the
prism primitive would be more robust in this respect, but maybe that is
not the case.
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On 2/10/19 3:36 PM, clipka wrote:
> Am 09.02.2019 um 19:41 schrieb William F Pokorny:
>> To start though find attached two scene files of a form I've been
>> using to test solver/inside related changes using media. The results
>> of Text.pov should quite closely match Text_I.pov results if
>> everything is OK.
>
> I'm wondering whether we're seeing an inside test problem caused by y
> coordinates matching a horizontal line (or maybe even just an on-curve
> control point).
>
> The old TrueType implementation was apparently prone to such issues, and
> added a tiny "random" rotation to try and avoid them. I had hoped the
> prism primitive would be more robust in this respect, but maybe that is
> not the case.
As an issue - might exist. I've occasionally had to tweak prism point
positions to eliminate artifacts. The opposite of what you're saying -
I've not had such trouble with text objects. Due luck perhaps.
I doubt it's what's happening here. Why does the single character text
string work?
For the inside test as used by the object pattern, it's as if an
internal structure/mechanism is corrupted in the freetype branch once
there is more than one character in the text string. Once a
"text-union" is necessary internally(1) perhaps?
I'm light on text and prism test cases compared to some others. Wasn't
looking much at the text shape at all previously for the solver work
because it has/had its own. Had planned to move text to the common
solvers in part at least, but no longer necessary.
Bill P.
(1) - I'll go now and create a <union>.pov and <union>_i.pov pair using
spheres or something. Not something I have today for the text vs text_i
form of inside test verification. And... looks like I never did a prism
pair. Hmm, maybe this is a prism problem that's been sitting there all
along. Slip, sliding away....
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Am 11.02.2019 um 00:30 schrieb William F Pokorny:
> For the inside test as used by the object pattern, it's as if an
> internal structure/mechanism is corrupted in the freetype branch once
> there is more than one character in the text string. Once a
> "text-union" is necessary internally(1) perhaps?
That doesn't convince me at all. Remember, all we're using FreeType for
is constructing prisms at parse time; if FreeType were to screw up, it
would manifest as control points being out of whack, which should also
show in regular scenes. (*)
This is not what we're seeing; instead, the problem is specific to
situations where insideness tests are performed.
Single-character and multi-character test objects do indeed differ in
one important aspect, namely that single-character text objects are
instantiated as pure prisms, whereas multi-character text objects are
instantiated as unions of prisms.
I may have screwed up the way the prisms are assembled into a union -
maybe I forgot to call some important post-processing step - and I
wouldn't be too surprised if this manifested in insideness tests getting
messed up. Reference to parent object not getting set, maybe?
ATM I'm busy with other stuff; I'll look back into this issue if you
don't beat me to it.
(* The only other thing how FreeType could conceivably screw up without
immediately showing in regular renders would be by getting the
"handedness" of the prisms wrong; and as a matter of fact I'm aware of
one issue that can lead to glyphs getting flipped "inside out"; but the
"a" is not a candidate for this issue - it is more likely to be
associated with glyphs that have mirror twins.)
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