| Welcome, Guest |
You have to register before you can post on our site.
|
| Latest Threads |
Final Sticker Back Standa...
Forum: Official File Specifications/Standards
Last Post: Orion Pobursky
27 minutes ago
» Replies: 2
» Views: 95
|
WeDo 2.0 electronics
Forum: Part Requests
Last Post: Dmitry
3 hours ago
» Replies: 25
» Views: 49,361
|
missing parts for star wa...
Forum: Parts Authoring
Last Post: Jeff Jones
5 hours ago
» Replies: 2
» Views: 70
|
LDraw.org 2025-06 Parts U...
Forum: LDraw.org Announcements
Last Post: Orion Pobursky
Yesterday, 20:11
» Replies: 5
» Views: 1,169
|
Part Request: Plastic Sci...
Forum: Part Requests
Last Post: Dmitry
Yesterday, 7:14
» Replies: 7
» Views: 1,684
|
Updates of the Bricklink ...
Forum: Parts Authoring
Last Post: Peter Blomberg
Yesterday, 4:52
» Replies: 7
» Views: 927
|
Possible duplicate faces ...
Forum: Parts Authoring
Last Post: Peter Blomberg
Yesterday, 4:39
» Replies: 1
» Views: 98
|
Are conditional lines ste...
Forum: Parts Authoring
Last Post: Peter Blomberg
2025-07-21, 20:59
» Replies: 1
» Views: 1,030
|
3D print LEGO element
Forum: Off-Topic
Last Post: Nate87
2025-07-21, 19:39
» Replies: 18
» Views: 9,486
|
Most Common Parts that re...
Forum: Part Requests
Last Post: Peter Blomberg
2025-07-20, 11:35
» Replies: 34
» Views: 14,832
|
|
|
| Another possible use for !FLOAT meta |
|
Posted by: N. W. Perry - 2021-09-06, 2:22 - Forum: LDraw Editors and Viewers
- Replies (2)
|
 |
(For those not familiar, !FLOAT is my proposed, imaginary meta command that temporarily overrides the displayed position and other parameters of a part in an LDraw editor or BI maker. It is intended to replace older concepts like buffer exchange, which is confusing and requires extra copies of parts to be added to a model.)
When building a model with lots of moving sections, like a Technic model, you probably build those sections as submodels or groups at orthogonal (90-degree) angles. Then when it's time to pose the model, you apply rotations to those groups or submodels.
But what if you want to change the pose? Or just revert a section back to its unrotated state for some reason? At least with LDCad, you can't always just rotate the parts the same number of degrees in the opposite direction, because you'll get rounding errors in the matrix.
If it's a submodel, of course you can always just reset the orientation. But then what if the unrotated state is non-orthogonal, like a piston rod or an angled link in the steering column?
With !FLOAT, the idea is that you supply a temporary position/orientation in the meta command, which is what will be displayed until the command is canceled. The type 1 line for the part or submodel would always contain the final or "fixed" position, which is typically what will be displayed in the last step of the model (so you can "float" a part in the building instructions, e.g.).
But if you supply a float position and just never cancel it, then it could actually be used as the position displayed in the finished model. The matrix in the type 1 line would then represent the default or unrotated position of the part, which could be an identity matrix, another orthogonal position, or a rotation of its own. You could then pose the model simply by adjusting the float position, without changing the default position and thus compounding rounding errors (or simply forgetting what that position is).
The major drawback to this usage is that the fallback display (for any software that doesn't recognize !FLOAT) would be with everything in its unrotated state, rather than nicely posed. But I suppose a good editor could get around this by having an option to save a copy of the model with the float positions inlined. And in a way, the pose of a model is more a property of its display than of its construction. The actual parts of a model are immutable and so it makes sense for them to be hard-coded, but things like which way the steering wheel is turned are changeable, and so there's some logic to having that information stored at a meta level, in a way that's perhaps more interactive and portable.
|
|
|
| Electric Power Functions IR Remote Control (58122) |
|
Posted by: Roland Melkert - 2021-09-05, 19:28 - Forum: Parts Tracker Discussion
- No Replies
|
 |
I was investigating a bug report for LDCad regarding 58122 not wanting to inline.
It turns out that is because it contains skewed and mirrored parts, which imho is not needed and should be prevented in shotcut/alias parts.
The issues are:
Rough 0.033 in other wise '1 1 1' rotation matrices (e.g 0 0 -1 0.033 1 0 1 0 0)
The blue slid direction switch is mirrored (and also has the 0.033 rounding error), using "0 0 -1 0 1 0 1 0 0" works for both red and blue sliders no need to mirror.
|
|
|
|
| Missing 2017-2021 most common parts... |
|
Posted by: tom alphin - 2021-09-05, 4:55 - Forum: Part Requests
- Replies (7)
|
|
Hey all, I've shared my "Most Common Parts" analysis in the past, as it is a good way to find common parts that are missing from the LDraw catalog.
(It's preliminary because some 2021 sets haven't been released or inventoried yet, and I need to do some normalization to map re-designed parts with new Part ID's to their legacy part Id equivalents.)
> Updated Sept 10, 2021 <
RANK, PART ID, Part Name
- #666 - 27393 - Wave / Power Blast Rounded Energy with Bar Handle
- #797 - 36017 - Weapon Sword Hilt with Dragon Head.
- #867 - 36451a - Infinity Stone.
- #1001 - 15445 - Weapon Gun Automatic Pistol with Top Clip
- #1004 - 35032a through 35032d - Various Wave / Power Bursts
- #1073 - 24183 - Life Jacket (Friends)
- #1082 - 66727 - Wheel 18 x 12 with Pin Hole and Stud
(I'm continuing to add to the list as I complete the analysis.)
Sincerely,
---tom
|
|
|
|
| Part Request: 66788 |
|
Posted by: Kristopher Wilson - 2021-08-31, 22:46 - Forum: Part Requests
- No Replies
|
|
This part is Arm and Hand Long with Technic Pin that was introduced in the LEGO Super Mario line. It is very similar to 28660, but a little longer in the curved part of the arm.
Thanks to anyone who can help!
|
|
|
|
| ldc.camera.setThirdPerson API |
|
Posted by: David Manley - 2021-08-31, 9:20 - Forum: LDraw Editors and Viewers
- Replies (2)
|
 |
(Probably for Roland but if someone else has worked this out, please chip in).
Context:
I'm trying to write a (Lua) animation script which will rotate the 3rd person view camera around the Y axis starting at the current view, rather than the start point used in the sample script. From the sample scripts, I can see the purpose of the first two arguments (helped by the description in LD4Studio documentation) but I'm struggling to understand the purpose next 3 angle (?) related arguments. The sample script in the function OnCameraFrame ...
Code: function onCameraFrame()
--Rotate a 3rd person camera around the center of the model.
local ani=ldc.animation.getCurrent()
local angle=ani:getFrameTime()/ani:getLength()*360
local cam=ldc.camera()
cam:setThirdPerson(camPos, camDist, angle+45, 25, 0)
cam:apply(0)
end
... is applying an appropriate angle change to the third parameter. From playing around a bit, it seems that parameters three, four and five are related to a x, y, z coordinate. But even though the code applies the angle delta to the X value (I think), the camera appears to rotate around the Y axis. And that confuses me as I would have though that to rotate the camera around the Y axis would have required the angle delta to be applied to the y coordinate.
I'd appreciate it if someone could clear up my misunderstanding.
Regards,
David
|
|
|
|
| [SOLVED!] coordinate-handedness confusion |
|
Posted by: KristyB - 2021-08-28, 12:31 - Forum: Rendering Techniques
- Replies (14)
|
|
What coordinate system do lDraw parts ACTUALLY use? The documentation *says* "Right handed with -y up", but shows a picture of a left-handed -y up coordinate axis.
Further - how would I go about translating the matrix to a left-handed +y-up format? I am trying to read ldr files inside of UE4, and the typical method of flopping the y/z coords and negating x/y/z is not working.
|
|
|
|
|
![[Image: 51515.png]](https://i.ibb.co/Kj79jCj/51515.png)
