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On 2021-02-10 6:58 PM (-4), Cousin Ricky wrote:
> I figured out how to model a flexible lamp neck [snip]
Sneak preview. The harlequin colors are there for testing.
That other lamp in the left background is a rudimentary place holder
that I've been using for the past 5 years.
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Attachments:
Download 'desklamp-sneak_preview.jpg' (63 KB)
Preview of image 'desklamp-sneak_preview.jpg'
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Cousin Ricky <ric### [at] yahoo com> wrote:
> On 2021-02-10 6:58 PM (-4), Cousin Ricky wrote:
> > I figured out how to model a flexible lamp neck [snip]
>
> Sneak preview. The harlequin colors are there for testing.
>
> That other lamp in the left background is a rudimentary place holder
> that I've been using for the past 5 years.
It looks neat, as something out of toy story ! I find the neck a little too
uniformly reflective, is there conserve_energy with fresnel and IOR dependant
reflection? Some blurry reflections would really 'shine' here... but reflected
checker could of course be an artistic choice.
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Cousin Ricky <ric### [at] yahoocom> wrote:
> On 2021-02-10 6:58 PM (-4), Cousin Ricky wrote:
> > I figured out how to model a flexible lamp neck [snip]
>
> Sneak preview. The harlequin colors are there for testing.
>
> That other lamp in the left background is a rudimentary place holder
> that I've been using for the past 5 years.
Well, you've certainly spent a lot of time honing this object.
The textures are very nice, and they really replicate the real thing.
The base just looks - real. The shape, the gloss, the texture on the toggle
switch, the press-fitting of the lamp neck. Even the little gap between the
base and the floor, where the felt pad presumably is.
The light bulb looks real as well. I looks like thin glass with a thin layer of
kaolin powder coated onto the inside.
It's neat that the texture on the outside of the shade "peeks out" a bit beyond
the inner white.
Should be interesting to see your power cord, and the lit final product.
Of course you're going to want to give the neck spline a bit of non-uniform
wiggle, and from a math and rigging perspective, one would have to define a
minimum radius that the FMC/Greenfield style neck can achieve and somehow
disallow sharper bends. Just a math/programming observation and a puzzle to
suggest. :)
Your placeholder has that antialiasing artifact that just got brought up.
The square in front of it is rather bright - a trick of the lighting and
falloff?
That thing is gonna look _real_ with an HDR environment. :O
As always, very nice, very meticulous work.
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On 2021-02-20 7:24 PM (-4), Bald Eagle wrote:
> Cousin Ricky <ric### [at] yahoocom> wrote:
>>
>> Sneak preview. The harlequin colors are there for testing.
>>
>> That other lamp in the left background is a rudimentary place holder
>> that I've been using for the past 5 years.
>
> Well, you've certainly spent a lot of time honing this object.
> The textures are very nice, and they really replicate the real thing.
>
> The base just looks - real. The shape, the gloss, the texture on the toggle
> switch, the press-fitting of the lamp neck. Even the little gap between the
> base and the floor, where the felt pad presumably is.
That _is_ the felt (or rubber) pad. It's just dark like a shadow.
> The light bulb looks real as well. I looks like thin glass with a thin layer of
> kaolin powder coated onto the inside.
This was a v3.7 render, so I used a layered texture in lieu of
finish-level Fresnel. The material macro autodetects v3.8 and would
just go straight for the finish-level Fresnel, but you have me wondering
if I should bother. When I look at a frosted bulb IRL (actually, an LED
lookalike), it looks like there's some SSLT going on there, but I wasn't
going to bother with it. Maybe the layered texture looks more realistic
than the finish-level Fresnel?
> It's neat that the texture on the outside of the shade "peeks out" a bit beyond
> the inner white.
That's a happy side effect of an attempt to avoid the radiosity
artifacts that would otherwise manifest when the lamp is switched on.
When I first coded the place holders, I ended up with nasty white spots
all over my render rig until I set no_radiosity on the fixtures. But I
only want to do this for the inside of the hood.
> Should be interesting to see your power cord, and the lit final product.
The power cord is still in my "future plans" bin. I'm thinking about
commandeering the Rope module from the object collection, as it may have
already solved the issues that will certainly turn up. My biggest
concern here is the plug: different countries have different standards,
and I'm wondering if the plug should be its own module with
international options.
> Of course you're going to want to give the neck spline a bit of non-uniform
> wiggle, and from a math and rigging perspective, one would have to define a
> minimum radius that the FMC/Greenfield style neck can achieve and somehow
> disallow sharper bends. Just a math/programming observation and a puzzle to
> suggest. :)
A minimum radius will naturally fall out of the constraints that I put
in the lamp macro. I'm glad you're going to work on the wiggle. ;)
> Your placeholder has that antialiasing artifact that just got brought up.
Yes, it is creepy, but I explained why I'd rather live with it.
> The square in front of it is rather bright - a trick of the lighting and
> falloff?
Yes, that's exactly what that is. The light source uses the bulb radius
as its fade distance, which results in very bright illumination near the
light, and a rapid falloff as the distance increases. If you look
carefully, you'll notice that the dark squares closest to the lamp are
also somewhat lighter.
> That thing is gonna look _real_ with an HDR environment. :O
That's half the intention.
Notice the flying saucer shaped reflection in the blue stripe of the
hood: that is the distorted reflection of a second place holder lamp
outside the right of the frame. Only with hyper-white illumination can
such a reflection be realistic. Even so, the light is only 10% of
normal brightness, because I'm only using it as a fill. (The visible
place holder is also a fill. The main light source happens not to be
reflected anywhere.)
One problem that concerns me is reflections of lit bulbs. If the
reflecting surface has a specular or Phong highlight, you end up with
twice the reflected light. For this render environment, I tentatively
solved this by setting no_reflection on the place holder's bulb, but
this results in a highlight that doesn't reflect the extent of the bulb.
When I release the source code for the lamp, there will be a parameter
to turn the reflection on or off, and let the user decide what to do
with highlights--unless someone has a better idea.
> As always, very nice, very meticulous work.
Thanks!
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On 2021-02-20 7:24 PM (-4), Bald Eagle wrote:
>
> Of course you're going to want to give the neck spline a bit of non-uniform
> wiggle, and from a math and rigging perspective, one would have to define a
> minimum radius that the FMC/Greenfield style neck can achieve and somehow
> disallow sharper bends. Just a math/programming observation and a puzzle to
> suggest. :)
Not sure how to prevent this kind of accident.
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Attachments:
Download 'lamp-xtreme_bend.jpg' (21 KB)
Preview of image 'lamp-xtreme_bend.jpg'
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Cousin Ricky <ric### [at] yahoocom> wrote:
> On 2021-02-20 7:24 PM (-4), Bald Eagle wrote:
> >
> > Of course you're going to want to give the neck spline a bit of non-uniform
> > wiggle, and from a math and rigging perspective, one would have to define a
> > minimum radius that the FMC/Greenfield style neck can achieve and somehow
> > disallow sharper bends. Just a math/programming observation and a puzzle to
> > suggest. :)
>
> Not sure how to prevent this kind of accident.
Hire better people at the manufacturing plant?
Don't treat the lamp like a 1971 American Tourister?
I would say toggle an algorithm on or off to allow the modeler the freedom to do
whatever they want.
When on:
A simple algorithm might be to define two bounding spheres centered at the shade
opening and at the center of the base top, and then just do simple collision
detection. Translate the offending spline position away from the base, and then
maybe check to see that it's not intersecting the floor / desk top, etc.
Reading back over this, it occurred to me that a way to disallow such a
too-sharp bend would be to define a minimum radius and then do collision testing
with the sphere defined by the prior inflection points - if that makes sense.
But that brings up an issue I was puzzling over when I was trying to crumple a
cardboard box - I wanted to create the wrinkles and creases and folds, but
define some sort of constraint so that the sum of all of those things was the
same as the original height of the cardboard...
When I was going through all of the Bezier spline stuff, I recall coming across
a way to calculate the arc length of a curve.... but that will have to wait
until I get a second wind.
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On 2021-02-21 1:08 AM (-4), Cousin Ricky wrote:
> On 2021-02-20 7:24 PM (-4), Bald Eagle wrote:
>
>> thin layer of
>> kaolin powder coated onto the inside.
>
> This was a v3.7 render, so I used a layered texture in lieu of
> just go straight for the finish-level Fresnel, but you have me wondering
> lookalike), it looks like there's some SSLT going on there, but I wasn't
> than the finish-level Fresnel?
This is a simplified version of the bulb texture. Of course, the
production texture will have emission and allow for colored glass.
There are subtle differences between POV-Ray versions. Note the wimpy
highlight on the left edge of the v3.5 sphere. This is likely due to AA
pre-clipping.
The value of sotd_c_Ambient is, of course, zero for this radiosity render.
----------[BEGIN CODE EXCERPT]-----------
material
{ #if (version < 3.8)
#declare s_Annot = "Layered texture"
texture
{ pigment { rgb 1 }
finish
{ diffuse 0.75
ambient 0.75 * sotd_c_Ambient
}
}
texture
{ pigment { rgbf 1 }
finish
{ reflection { 0 1 fresnel } conserve_energy
specular 6.67
roughness 0.001
}
}
#else
#declare s_Annot = "Finish-level Fresnel"
texture
{ pigment { rgb 1 }
finish
{ fresnel 1
reflection { 0 1 } conserve_energy
specular albedo 1
roughness 0.001
diffuse 0.75
ambient 0.75 * sotd_c_Ambient
}
}
#end
interior { ior 1.523 }
}
-----------[END CODE EXCERPT]------------
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Attachments:
Download 'frosted_glass_versions-pbi.jpg' (43 KB)
Preview of image 'frosted_glass_versions-pbi.jpg'
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On 2021-02-21 2:40 PM (-4), Bald Eagle wrote:
>
> When I was going through all of the Bezier spline stuff, I recall coming across
> a way to calculate the arc length of a curve.... but that will have to wait
> until I get a second wind.
For a circular arc, by definition it's
arc_length = angle_in_radians * radius_of_curvature
to me, but can probably be explained to a 5 year old on Numberphile.
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Cousin Ricky <ric### [at] yahoocom> wrote:
> On 2021-02-21 2:40 PM (-4), Bald Eagle wrote:
> >
> > When I was going through all of the Bezier spline stuff, I recall coming across
> > a way to calculate the arc length of a curve....
> to me, but can probably be explained to a 5 year old on Numberphile.
https://www.mathsisfun.com/calculus/arc-length.html
I guess it's easier than I recall, or was presented to be.
I suppose tidying it all up for the 4 Bernstein polynomials may look a wee bit
messy, but it probably shouldn't be too bad, since I went well past that and
into the weeds of Gaussian curvature territory...
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"Bald Eagle" <cre### [at] netscapenet> wrote:
> I guess it's easier than I recall, or was presented to be.
Or not, but apparently there are libraries that do it, so maybe they can be used
somehow, or just the simple multiple-line-segment method would be good enough
for the present purpose.
https://raphlinus.github.io/curves/2018/12/28/bezier-arclength.html
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