Using 48\x-yTANG Primitives > Monorail Switch Points

[Gerald Lasser]

Due to my comment reviewing part s/2880s09.dat on using a "48\1-8tang" primitive to smoothen the part when doing primitive substitution.

First of all why: Here's how the part looks when the Prim-Subst (PS) is turned on:
   

The top and bottom surfaces reach over the refined cyli/edges

To overcome this issue the 48\1-8tang could be used.

Now here's the issue, when using PS, LDView increases the number of sections in a circle from either 16 or 48 to 96, this works also with the tanges primitives. I have created already the 48\1-16tang and to make use of the PS in the 49949 part.

I noticed that LDView will smoothen the inner-segment, but keeps the outer one always at 16 division, even if the 48\tang primitive has the outer segment done with 48 divisions as well, so that is what we will get without PS (left) and with PS (right)
   

As this ends up now with a pretty wide segment, it cannot be used at the bottom of the part.
For the top part it is working, see this code: (becuase of the overlap, when PS is ON, you can see that it will fit nicely)

Code:

0 BFC INVERTNEXT
1 16 -277 0 354 0 0 304 0 20 0 -274 0 0 48\1-8cylo.dat
1 10 -277 0 354 0 0 304 0 1 0 -274 0 0 48\1-8tang.dat
4 10 -62.0418 0 160.2549 -59.1762 0 162.6611 -57.8241 0 162.6609 -39.0005 0 127
4 10 -62.0418 0 160.2549 -39.0005 0 127 -54.462 0 73 -76.11376 0 147.541
4 10 -84 0 138.164 -88 0 134.955 -91.9248 0 136.6084 -76.11376 0 147.541
4 10 -164 0 95.525 -168 0 94.303 -179.07856 0 93.99044 -160.6592 0 100.8514
4 10 -164 0 95.525 -160.6592 0 100.8514 -142.24896 0 107.72332 -88 0 -80
4 10 -107.74496 0 125.69498 -91.9248 0 136.6084 -88 0 134.955 -88 0 -80
3 10 -125 0 116.716 -107.74496 0 125.69498 -88 0 -80
3 10 -125 0 116.716 -88 0 -80 -142.24896 0 107.72332
3 10 -252 0 77.426 -277 0 80 -257.07584 0 80
4 10 -248 0 77.663 -252 0 77.426 -257.07584 0 80 -237.328 0 82.3564
3 10 -84 0 138.164 -76.11376 0 147.541 -54.462 0 73
4 10 -248 0 77.663 -237.328 0 82.3564 -217.57408 0 84.6991 -248 0 -80
4 10 -168 0 -80 -248 0 -80 -217.57408 0 84.6991 -198.3248 0 89.3434
4 10 -168 0 -80 -198.3248 0 89.3434 -179.07856 0 93.99044 -168 0 94.303

48\1-8tang looks like this:

Code:

0 Name: 48\1-8tang.dat
0 Author: Gerald Lasser [GeraldLasser]
0 !LDRAW_ORG Unofficial_48_Primitive
0 !LICENSE Redistributable under CCAL version 2.0 : see CAreadme.txt

0 BFC CERTIFY CCW

3 16 1 0 0 1 0 .06554 .9914 0 .1305
3 16 .98285 0 .19548 .9659 0 .2588 .9914 0 .1305
3 16 .94894 0 .32211 .9239 0 .3827 .9659 0 .2588
3 16 .89882 0 .44326 .866 0 .5 .9239 0 .3827
3 16 .83323 0 .55676 .7934 0 .6088 .866 0 .5
3 16 .7535 0 .66081 .7071 0 .7071 .7934 0 .6088

Now the question is if the outer segment could stay at 48 segments as well, would that be feasible.
Where is the prim-substitution defined?

[Magnus Forsberg]

Where is the prim-substitution defined?

There is a slider control under "Edit/Preferences/Primitives"

   

I'm not sure but I think there is a difference between "Primitive substitution/Curve quality" and substitution of primitives.
In my image I have it set to a value that will create 8 sections on a 1-4ndis, even though we definitely don't have any 32-sided primitives in the library. If you set it to a higher value the number of sections will increse. And if you go too high, it will create the effect you see in your images.

The curve quality in LDView is not dependant of the existance of a hi-res primitive. Am I right Travis?

[Gerald Lasser]

There is a slider control under "Edit/Preferences/Primitives"

I'm not sure but I think there is a difference between "Primitive substitution/Curve quality" and substitution of primitives.
In my image I have it set to a value that will create 8 sections on a 1-4ndis, even though we definitely don't have any 32-sided primitives in the library. If you set it to a higher value the number of sections will increse. And if you go too high, it will create the effect you see in your images.

The curve quality in LDView is not dependant of the existance of a hi-res primitive. Am I right Travis?

I forgot about the slider, this makes LDView Interpolate circles, there is what it does:

Code:

Setting    16 SegPrim   48 SegPrim
0              16          48
1              16          48
2              32          48
3              32          48
4              48          48
5              48          48
6              64          64
7              64          64
8              80          80
9              80          80
10             96          96
11             96          96

But the treatment I refer to is where there are, how should i call them, fixed points, like the 1-4NDIS (which has only one)  or the TANG primitive, ther TANG interpolation makes only sense on the "inner" side of the tangens.

For the TANG LDView keeps the outer points of the lo-res primitives.

It would be good to have also hi-res fixed points.

[Travis Cobbs]

The curve quality in LDView is not dependant of the existance of a hi-res primitive. Am I right Travis?

Setting LDView to use hi-res primitives will use those where it finds them (in place of the equivalent standard-res primitive). That means that, where there is a 48/ version of a primitive, that will be used instead of the standard version (with 16 segments).

The curve quality setting is mostly independent of this. If you set the curve quality to be 48 segments or more, then all primitives will use whatever is set in curve quality. (Note that 48/ primitives will look identical to standard primitives in this case, as the curve quality setting doesn't multiply the base number of segments, but instead provides a minimum number of segments.)

Note also that the "Use high-resolution primitives when available" setting is independent of the "Primitive Substitution" setting. So you can do that even if primitive substitution is disabled. To be honest, though, the "Use high-resolution primitives when available" setting isn't all that useful. It's generally better to just increase the curve quality.

[Magnus Forsberg]

OK, then let me rephrase that.


The display of a curve is not dependant of the existance of a hi-res primitive.
Where, and when, will LDView "use" the hi-res primitive?

   

The table on the right show how many segments will be displayed on screen, depending on the level setting and PS on/off.
Why is my table different from the one from Gerald?

I'm trying to understand if/when I am required to upload a corresponding hi-res version of every curved primitive in normal resolution.
Do any other software perform this "primitive substitution".

[Travis Cobbs]

OK, then let me rephrase that.


The display of a curve is not dependant of the existance of a hi-res primitive.
Where, and when, will LDView "use" the hi-res primitive?



The table on the right show how many segments will be displayed on screen, depending on the level setting and PS on/off.
Why is my table different from the one from Gerald?

I'm trying to understand if/when I am required to upload a corresponding hi-res version of every curved primitive in normal resolution.
Do any other software perform this "primitive substitution".

If you check the box for LDView to use hi-res primitives when available, it should do so when it encounters them and they exist. However, you should definitely not add a high-resolution version of a primitive just for this. The only files in p/48 should be primitives that show up in some part file with a 48 prefix.

I'm not sure where Gerald got the numbers in his table. They aren't right. Your tables match what I expect (which is simply 8 × level when high-resolution primitive substitution isn't enabled).

As I mentioned before, I think the "Use high-resolution primitives when available" setting is not very useful. You should instead adjust the curve quality.

[Willy Tschager]

I love all the theory but I'd like to get the monorail parts certified. So simple question and hopefully simple answer:

What shall I do?  

w.

[Gerald Lasser]

If you check the box for LDView to use hi-res primitives when available, it should do so when it encounters them and they exist. However, you should definitely not add a high-resolution version of a primitive just for this. The only files in p/48 should be primitives that show up in some part file with a 48 prefix.

I'm not sure where Gerald got the numbers in his table. They aren't right. Your tables match what I expect (which is simply 8 × level when high-resolution primitive substitution isn't enabled).

As I mentioned before, I think the "Use high-resolution primitives when available" setting is not very useful. You should instead adjust the curve quality.

I did use the TANG prim to count, may be not the best choice.

But I am looking at the other side to the TANG Primitive, the lines in DARK PINK. The GREEN lines are subject to the sub-division (both show now a 48-Prim), those are fine.

My question is around the dark pink lines. You get the sketch on the right, when a 48\1-16tang is used and Primitive Substitution is turned on (even when the 48\1-16tang is designed like the left sketch).
That's why I (previously) submitted the 48\1-16tang in that way and not designed as on the left. It was a "what does LDView draw?" choice

However, now I am the opinion that the 48\x-xtang primitives would make more sense, if the DARK PINK lines would stay as they are on the left, if PS is turned on. This would enable us to make smooth curves where there is a thin wall, e.g. the Monorail switches.

I hope you understand my concern.

   

[Willy Tschager]

I'm still eager to hear from you what I shall do with this part?

w.

[Gerald Lasser]

@willy, I will certify it in the meantime, as the part itself is ok for the standard application.

I would like to hear from Travis on my last post. Then we can still redo this section of the part.

sorry for my late responses, being on the lakeside most of the day :-)

[Magnus Forsberg]

@willy, I will certify it in the meantime, as the part itself is ok for the standard application.

I was just looking at this and thinking the same. The part is OK, as it is.
 
But something strange is going in the example file you provided.
I find it very odd that LDView is replacing a hi-res file with what looks like a lo-res version.

[Travis Cobbs]

I did use the TANG prim to count, may be not the best choice.

But I am looking at the other side to the TANG Primitive, the lines in DARK PINK. The GREEN lines are subject to the sub-division (both show now a 48-Prim), those are fine.

My question is around the dark pink lines. You get the sketch on the right, when a 48\1-16tang is used and Primitive Substitution is turned on (even when the 48\1-16tang is designed like the left sketch).
That's why I (previously) submitted the 48\1-16tang in that way and not designed as on the left. It was a "what does LDView draw?" choice

However, now I am the opinion that the 48\x-xtang primitives would make more sense, if the DARK PINK lines would stay as they are on the left, if PS is turned on. This would enable us to make smooth curves where there is a thin wall, e.g. the Monorail switches.

I hope you understand my concern.

I apologize. In this one instance, it looks like it could make sense to submit the 48\ version of the part, even if it's not directly used in any files.

Having said that, since I don't feel that that setting of LDView is very useful, I'm not sure if it not working right here is a big deal.