It might be nice to combine everything required for no-slope basements into one tool, ie:

1) drop level 1 under level 0
2) drop level 0 inside basement (1 square in from walls)
3) drop water level inside basement (including walls) to be below the basement level

I also noticed that 3ARY instance 0x15 seems to contain information about whether the ground level is visible; we might be able to use this to remove the requirement for custom content (invisible tiles).

It would also be nice if the tool could determine the most likely bounding box, so that the user would be presented with reasonable choices of depth and width ranges.

Mainly, I'm hoping that this tool will make no-slope basements easier for the average user; one pass, rather than several passes.

Good idea.

I'm really wondering whether this should just be an option for the GridAdjuster...

For a basement at elevation (E)
where depth = front (F) to back (B)
and width = left (L) to right (R)
assuming delta (D) to keep basement level from conflicting with ground level (default = 0.5; may want to allow user to specify)

Change:
Water Level: from F to B and L to R to (Flat) (E - D - 0.5 (standard adjustment for water below ground) )
Level 0 (ground): from (F + 1) to (B - 1) and (L + 1) to (R - 1) to (Flat) (E - D)
Level 1 and above: from F to B and L to R to (Flat) (E + (Level - 1) * Per Level Value)

3ARY Instance 0x15 from F to B and L to R to 0 (invisible)

[Update:]
This is looking very good; simple as pie for a rectangular basement. Haven't tested non-rectangular spaces yet.

I'm fooling around with this now, to see whether changes to the water level and ground level are obsolete now that we have the change to 3ARY instance 0x15. Answer: all steps are still necessary.

One question: How to remove the invisible flags? For the moment, I've made it so that you can remove the invisible flags by running the GridAdjuster again and choosing a "Basement" pattern with an elevation >= 0. This will reset the ground level to 0 and make the specified adjustments to the other levels, plus change the ground level inside the range back to "visible".

If anyone has a better idea, please let me know.

Here is a lot made with my newest (unreleased) version of the GridAdjuster. This lot has a no-slope two-level non-rectangular basement which requires no CC at all.

I've attached screenshots for the GridAdjuster, so that you can see how easy it is. Two steps: one for the main area of the basement and one for the additional area under the porch.

Note that this basement has problems typical of all no-slope basements; some items placed next to the outside walls in the basement cannot be used. For example, if you place a TV against the outer wall, your sim may error.

Problems selecting objects next to the outer wall become more pronounced in lower level basements. I assume that the primary problem is a conflict with the sloped ground inside of the basement. Note that you can see the ground level fairly clearly in build mode as sloping black lines.

This effect should be lessened by lowering the ground level further under the sub-basement level. Right now, the GridAdjuster is defaulting to a difference of .5 So, I'm going to add a user-specifiable value which will lower the ground level (and associated water level) further.

[Update:]

Updated to version 2. Ground level is set to -312, which is basically the center of the sim world.

I'm a bit confused by post 3 since I'm not much of a lot builder. Why do we want the ground to be visible or invisible? I understand wanting invisible ground in a shallow lake/pond, so you can walk around in it. I understand invisible ground is better than placing eleventy jillion CC invisible tiles. Just don't understand how ground visibility relates to basements. Someone please dispel my ignorance?

The basement is underground, at least at the edges. If the ground is visible and at a relative elevation of 0, then you won't be able to see the basement, since it's under the ground. If the ground is visible and slopes down inside of the basement, then you just end up with a standard sloped basement. By making the ground invisible, we can see the ground outside of the basement, but inside we see the basement walls and furnishings. The invisible tile is what gives the appearance of "no slope".

I've attached a picture of the subbasement in build mode. You can clearly see the grid for the invisible sloping ground inside the outer tile of the basement as sloping black lines. If the ground was visible, you wouldn't be able to see the outer basement walls.

Is that any clearer? If not, try comparing this picture which shows the grid with my previous picture which doesn't.

More about ground elevation:
The invisible ground tiles can actually obstruct your sim's ability to access certain objects, such as TVs. They can also obstruct your ability to select objects, making the game "fussy". By moving the ground lower, we increase the slope, which decreases the amount of each basement tile which is blocked, and therefore decreases the likelihood of an invisible ground tile obstructing access to an object.

I am coming to the conclusion that the ground inside the basement should probably be at least as far under the basement as the basement is under the standard ground elevation (0).

Thanks. Let me see if I understand. The basement floor, the thing sims walk on, is just regular flooring, linoleum, carpet, what have you. The actual ground itself is *far below* the floor. I see where the "invisible slope" intersects the basement floor, and how it could block TVs and how lowering it decreases the blocked area. How very nifty! However, I now have new confusion. How is it you placed the floor at a certain level, but the ground is far below it? I know, must be obvious to builders, but I'm newbie in this area. Same sort of technique as used for making curved bridges, tree house ladders, and "floating platforms"? And this new tool does it automatically, so I don't have to adjust each tile by hand? Very neat, even if it still requires multiple uses of the tool. Sounds like a time and sanity saver.

I don't know whether you're familiar with the concept, so here is a link where we discuss no-slope basements, to give you some background:
http://www.modthesims.info/showthread.php?t=326029

With this new version of GA, you build the initial house above ground as follows:

Level 1: a dummy level which will later be inverted, to force the basement under the ground
Level 2: the lowest (and usually the only) basement level
Level 3 and above: all other basement levels and house levels

You only need to build the shell of the house (walls and flooring), then you run the GridAdjuster to specify where you want the basement floor to go. After running the GA, you can furnish the house, change the flooring, add wallpaper, build new levels, etc.

The GridAdjuster does the following things for you:
- Make the ground invisible inside of the range, so that you will be able to see the basement
- Set your levels to the elevations that you've specified within the range. Since the elevation of Level 1 must be negative, Level 1 runs from the ground level to the elevation that you've specified. Level 2 is your lowest basement level and (usually) all other levels will be a standard wall height above the previous level.
- Set the ground level to an elevation which is lower than your first (inverted) level, one tile inside of the range specified. This ensures that the ground doesn't interfere with your use of the basement. Some EPs remove this requirement, but it's simpler to do this for all EPs.
- Set the water level one tile outside of the range to an elevation which is lower than your new ground level. If there is any water inside of the basement, it can interfere with your use of the basement, so we need to keep it out of your basement.

You may find it helpful to download my "proof of concept" lot and just look at each level of the lot to see what they look like. I only included pictures of the livable levels; here is a picture showing the ground sloping down to the center of the earth (absolute 0). You can see the walls of the inverted dummy level in this picture; they look odd because the walls have been turned inside out by the inversion.

Mootilda - thanks for that and the linky.

TS2 may be on its way out, but it is so nice to see people still discovering new info about what's possible and making new tools. For those of us still playing, there's some life left in TS2.

* goes off to gain learnings *

Updated proof of concept lot to version 2. Moved ground level down substantially, which makes it much easier to access objects. No ill effects noted, although I want to do more testing with larger lots before I decide to make this value the default.

Note that the proof of concept lot does not have any of the problems described below, since it has no major vertices which are involved in the no-slope basement.

Things that I've observed during testing:

The lower the ground level, the easier it is to access objects in the basement.

Lower Bound:
A reasonable lower bound for the ground level is absolute zero. This obviously varies depending upon where a lot is placed in a neighborhood, but a reasonable value would be the neighborhood water level (312.5) less the amount that the pond water is normally located under the ground (0.5), which gives us a maximum depth of 312.0 or 1664 clicks below relative 0.

Reasonable Value:
So far, setting the ground 200 clicks down seems to keep the ground slope inside of the basement wall where it causes a minimum amount of conflict, except in the corner tiles where the ground cuts though about 1/2 of the tile (which is the best that we can hope for). Further testing may modify this value a bit, since I'm trying to find the highest ground elevation that does not conflict with tiles in the basement, except in the corners. Looks like sims can even watch TVs which have been placed against the outer wall of the basement.

Lot Pictures:
Low ground can cause problems with the lot pictures used in a packaged or binned lot, since the pictures may be taken at the ground level, which is both very low and invisible. So, the lot pictures may just look blue (ie, the sky underneath the house).

This can be fixed by replacing the lot pictures in the packaged lot; which is a known procedure. (See Reference in next post)

Lot Impostor:
Low ground can cause problems with the lot impostor in the neighborhood view, if any major vertex is below ground. When the lot impostor is created, the game seems to extrapolate the terrain between major vertexes. If the ground at the edge of the lot is at relative 0 and the next major ground vertex is very low, then the lot impostor may show a huge chasm between the house and the edge of the lot.

This is a known problem with all basement lots (even sloped ones), but the problem becomes more apparent as the ground is lowered. I have never seen mention of a solution to this problem.

It appears to be possible to work around this problem by leaving the major vertices (every 10th vertex) of the ground level at their original elevation. So far, my testing shows that this resolves the problem without severely impacting the usability of the basement.

Neighborhood Terrain:
Low ground may cause problems with the neighborhood terrain. However, my testing with the base game and with all EPs and SPs indicates that the neighborhood terrain has a tendency to "heal" itself when the lot is moved.

The main problem that I've found is when a lot is to be moved to the same position, or very close to its existing position, in the neighborhood; the chasm formed by the lot will not be healed until the lot has been placed into its new location, so it may interfere with the placement of the lot.

A workaround is to move the lot further in the neighborhood, allowing the chasm to heal, then moving it back to where you want it. (Note to myself: does this explain the problems that people occasionally have placing LotAdjusted lots?)

It also appears to be possible to minimize the lot's effect on the neighborhood terrain by avoiding lowering the major vertices on the ground level; this is the same workaround suggested for the lot impostors.

Pond Water:
It's best to drop the pond water on the lot (usually just below the ground) starting at one tile outside of the basement walls. This will ensure that the pond water cannot enter the basement and cause problems. However, this may cause the ground on those tiles to look "dry".

For an example, look at the pictures of the proof of concept lot above. You'll notice that the ground around the basement is slightly gray. No terrain paints were used on this lot; the appearance is the result of the no-slope basement process.

Invisible Tiles:
Along with the value of not requiring CC, there is another value to using the in-game method for making the ground invisible. Since this method still allows you to see the grid lines in build mode (which the CC doesn't), it is much easier to see where any potential problems are coming from.


Conclusions:

The tool should have the following features:

1) Allow user to specify whether or not they want the ground level to be lowered. [done]

2) Default ground level to a "reasonable" value. [done, although it may be possible to lower the ground level even less and retain the benefits of the current default.]

3) Allow user to specify the new ground level. [done]

4) Allow user to specify whether or not they want the water level to be lowered. [done]

5) Default water level to just under the basement level. [done]

6) Allow user to specify the new water level. [done]

7) Allow user to remove ground level invisibility. [done, although there may be a better name for the option]

8) When removing the ground level invisibility, change the default values so that the no-slope basement is undone. [done]

9) Allow user to avoid lowering the major vertices of the ground level, to work around the lot imposter and neighborhood terrain issues. [done, although there may be a better name for the option]

Requires further testing:

Just for my benefit, here's a list of things that still need to be tested or researched:

- Find optimal elevation for the ground level for a basement of -12 clicks.

Is this the reference you're looking for? Replacing the lot pictures in the packaged lot

Yes, that's it. Thank you.

[Update:]

New version of the GridAdjuster with tutorial has been uploaded.