Modeler plugin with Vertex Normal vmap related tools for LightWave Modeler v9.5 or newer.

Currently this plugin is focused around smooth group functionality. It provides commands to assign smooth groups to polygons and to update/generate a vertex normal map with normals based on the assigned smooth groups.

Commands provided by this plugin:

• PB Set Smooth Groups...
• PB Select By Smooth Group...
• PB Update VNormals
• PB Clear VNorms From Verts
• PB Clear VNorms On Surfs
  

For proper normal generation the plugin assumes that polygons are convex and planar, and it only processes polygons with at least 3 points. If other polygons are involved then that may cause incorrect vertex normals.

For smooth groups to apply between surfaces, there has to be regular surface based smoothing between them. You can then control if you actually want smoothing or not by smooth group assignment. The other way around is however not possible. You can't force smooth group based smoothing between polygons that wouldn't be smoothed by LW's standard smoothing.

There are 16 smooth groups. However you'll notice that there are two button rows, so each smooth group button has an upper and lower half, similar to the layer buttons in Modeler. Using the upper half, which hilights the entire button, will work as one would expect smooth groups to typically work. Those will be referred to as "active" smooth groups.

The lower half are so called "passive" smooth groups. If a polygon has a passive smooth group assignment it means that the polygon will affect smoothing of vertex normals of adjacent polygons with active smooth group assignment to the same group, but the active polygons will not affect the normals of the passive polygon.

If you only intend to use "classic" smooth group functionality then you can skip the remainder of this section, as it's only relevant to understanding passive smooth groups.

What this means in practice is that you can ensure a certain polygon remains flat, vertex normals point in the same direction as the polygon normal, while adjacent polygons are smoothed to meet up with the flat polygon. As opposed to normal smoothing between surfaces where the vertex normal ends up as an average between the polygons.

It's also possible to have a set of polygons to have active smoothing between them, while using that smoothed result to act as a passive smoothing source of other actively smoothed polygons. More on that a bit later.

In situations where several polygons, with a mix of passive and active smooth groups, share vertices it can get a little complicated and take some practice how to do assignments. It helps to roughly understand the calculation process.

Normally, for active groups, all polygon normals in the same group are averaged together to get a smoothed vertex normal. However if a polygon with a passive group is involved, the vertex normal will be "locked" to the passive contributor's normal, so that any actively smoothed neighbor polygons will be smoothed to meet up with the passive polygons.

Where it gets a bit complicated is that you may want to some polygons to be smoothed between them, but then have that resulting smoothing act as a passive source towards other adjacent polygons. Imagine a capsule shape, where you'd like the cylinder part to be smoothed between the cylinder polygons only, so that normals are flat along the cylinder axis. But you'd like the hemispherical caps to be smoothed so they meet up with the cylinder portion.
This can be achieved by making the cylinder polygons be part of the same active smooth group of a higher number, say 2, but also have a passive group assignment of any lower number, in this case 1. The hemispherical cap polygons are then actively assigned to group 1, which makes them smooth between themselves but also makes sure that they smooth towards the cylinder polygons where those are adjacent.

The way that works is because the groups are processed a bit like layers or passes, where the higher the group number, the higher the priority. During processing it starts with the highest group number and works downward.

So in the capsule example above, the active smoothing for group 2 is processed first. That makes the cylinder polygons smooth circular around the axis, but with no smoothing along the axis since the cap polygons don't interact with group 2. Then during the next pass, group 1 is processed.When a cap polygon with active smoothing is adjacent to a cylinder polygon, with passive smoothing in group 1, the vertex normals from the previous pass (i.e. group 2) are used.


Assign or remove smooth groups to selected polygons. If no polygons are selected then the command applies to all polygons in the FG layers.

When the dialog displays, the initial button states will reflect the smooth groups used by the current selection. In the image above this would mean that all polygons in the selection have active group 1 and passive group 3 assigned to them. For the groups 5 to 8 there are mixed assignments, visualized by the light grey borders on the buttons. The different mixed state visualizations (in above image) mean the following:

Group 5	There are polygons with active smooth group 5, and polygons without any assignment to group 5.
Group 6	There are polygons with passive group 6, and polygons without any assignment to group 6.
Group 7	There are polygons with active group 7, polygons with passive group 7, and polygons without any assignment to group 7.
Group 8	There are polygons with active group 8 and polygons with passive group 8. There no polygons that without any group 8 assignment at all.

Leaving mixed-state buttons unchanged, when clicking OK, will leave the smooth group assignments for those particular groups unchanged in the polygons as well. Using the above image as en example, if you were to toggle the passive group 3 button off and the clicked OK, it would remove the passive group 3 assigment from all polygons, but leave all other group assignment as they were.

Keyboard hotkeys can also be used for the group buttons. They are the same as the layer hotkeys in LW. The number keys 0 - 9 (not the numeric key pad), hold SHIFT for passive groups. To access groups 11 - 16 you have to hold the CTRL key.

Description of the other buttons in the dialog:

History	A list of the last couple of smooth group assigments. Keyboard shortcut PageUp can also be used to move up through the history. The list looks like the one below for "Used", except it doesn't have any polygon counts.
Used	A list of all smooth group combinations that are in use, i.e. assigned, to all polygons in the FG layers. The entries consist of a list of active smooth groups followed by a list of passive smooth groups, separated by "::". The values in parentheses at the end are the number of polygons that use that particular smooth group combo.
Clear All	Clear all buttons.
Update VNorms	If enabled, automatically performs the same task as the "PB Update VNormals" command when the dialog is closed with OK.

Select polygons based on smooth group assignments.

"Select" will select polygons that have any matching group assigment(s), while "Select SG Combo" will only select polygons that have the exact same smooth group combination as specified.

This dialog only displays group buttons for groups that are actually used by any polygons. If there are no smooth group assignments at all to any polygon then all buttons will be disabled. The dialog will still open and allow "Select SG Combo", which will select polygons without any smooth groups.

Just like with the "PB Set Smooth Groups" group buttons, the upper half of the buttons are active smooth groups and the lower half are passive smooth groups. Except both active and passive can be selected independently from eachother in this dialog, in order to make it possible to specifically select passive and/or active groups.

If only a single polygon is selected, when invoking this command, then the dialog will automatically set the group buttons to reflect the group assignments of that polygon. Making it easier to quickly select all polygons that have the same smooth groups as the selected polygon.

The "Used" button is the same as for the "PB Set Smooth Groups" command.

If "Clear Selection" is enabled then any previous selection is cleared, otherwise any new selections are just added.

The "A | P" button pairs are quick select buttons to set or clear all group buttons. Clicking the left A set all active group buttons, and P for all passive group buttons. The right A and P buttons clear all active or passive groups buttons.

The hotkeys for group buttons are the same as described for "PB Set Smooth Groups", but there's additionally CTRL+a which sets all passive and active group buttons, and CTRL+i which inverts the buttons.

Update/Create the vertex normal map, named "PB_VNormals", with vertex normals based on smooth groups (and surface smoothing). Automatically assigns the map to all involved surfaces that do not have any "Vertex Normal Map" set yet. If a surface already has some other map set, then you have to manually change it to "PB_VNormals" if you want it to use that.

This command ignores polygon selections and updates all polygons in the FG layers.

Works like the regular "Clear Map" command in Modeler, but operates on the "PB_VNormals" vertex normal map.

Sets "Vertex Normal Map" to "None" on all surfaces that are set to "PB_VNormals".

Copyright © 2018 Georg Fischer

This software is provided 'as-is', without any express or implied warranty.  In no event will the author be held liable for any damages arising from the use of this software.

Permission is granted to anyone to use this software for personal projects, commercial projects, and redistribute it freely, subject to the following restrictions:

1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software.
2. This notice may not be removed or altered from any distribution.
3. This software may not be sold individually or as a part of a package.