Sorry, this one is on me, I confused practically everything in OP. I should have consulted my notes.

The correct repro is:

• Play any level.
• Fast-forward 5 minutes.
• Press and hold the 1-physics-update-rewind hotkey.
• During this rewinding,
  • start to right-click scroll (press and hold),
  • or zoom with the wheel (rotate several notches),
  • or select skills by hotkey.

Observed for right-click scrolling:

• You have a 50 % chance that the starting click for hold-to-scroll fails. If this click fails, the subsequent holding also fails, guaranteed. You have to release right mouse button and re-click-and-hold.
  
• Rewinding continues correctly, it doesn't depend on the scrolling's failure or success.
  

Observed for zooming with the wheel:

• For each of the mouse wheel notches individually, you have a 50 % chance that it will fail.
  
• Rewinding continues correctly, it doesn't depend on the zoom's failure or success.
  

Observed for skill selection by hotkey:

• The skill has a 50 % chance to get selected.
  
• Rewinding stops. It doesn't depend on the skill selection's failure or success; it always stops.
  

Expected: Rewinding always continues, and the second input always succeeds.

The 50 % probability is on small levels: Automaton Maintenance, or Save Our Souls. On big, laggy levels, the probability of failing increases. I fail to right-click scroll with 70 % or 80 % on Space Program 10,000 BC.

The probability of failure increases during in-game times such as x:x9, x:x8, x:x7. It's lower immediately after an internal 10-second savestate around x:x1, x:x2.

---

I'll copy this into OP in a few days.

As WillLem says: Who can repro this on Windows?

-- Simon

I still think that this is important. I don't build NL levels; if others see potential problems with these ideas (outline instead of filled pink rectangle), please bring up those problems.

It's conceivable to draw the areas of only some gadgets as outline. When a gadget affects terrain (e.g., one-way arrows), you can, e.g., fully fill the matching terrain, and not paint the air. The important fix will be that huge water areas don't generate huge pink blobs that are hard on the eyes.

I'd like to prod WillLem to consider this. People activate these helper tools when they need to know the details, therefore you want maximally clear helpers.

-- Simon

CE 1.0.1
NL 12.14

Clear Physics Mode shows the silhouettes of all gadgets in rotating colors. There is a global timer, and the color of the silhouettes is that timer modulo N in the circle of fully-saturated colors (red, orange, yellow, ..., cyan, pink, red).

Enough with that! I use Clear Physics Mode when details matter, and I don't want this distracting color clashing.

In 1.0.1 Clear Physics Mode, lemmings are dark-blue (0, 0, FF). Instead, make lemmings medium-blue (80, 80, FF). That's easier to see than dark blue (this alone will be an improvement!) and it will remain sufficiently different from the cyan athletes (0, FF, FF).

Now you can make gadgets dark green (0, 80, 0) and you won't step on any toes.

Pick other colors than what I propose, I'm happy to try other choices.

-- Simon

CE 1.0.1
NL 12.14 and other versions from years ago.
Wine 10.6

• Start a level.
• If it's a small level, zoom in until you can scroll.
• Scroll with the hold-to-scroll feature. E.g., map this to the right mouse button in NL's options, then scroll by holding the right mouse button.
• While you hold-to-scroll, press a skill hotkey to select a different skill.

Practically everything is wrong in this OP, see my next post instead.

Observed: You have a ~50 % chance to select the new skill. Otherwise, the skill key has no effect and the old skill remains selected. (The hold-to-scroll will always continue to scroll correctly, whether the new skill selects or not.)

Expected instead: The new skill gets selected for certain. (And the hold-to-scroll will always continue to scroll.)

-- Simon

Saturated Addition

Here's some small talk from board game night this weekend. Consider the following mathematical operation, which I'll call a saturated sum, or saturated addition.

• Input: A finite list (x₁, x₂, ...) of real numbers. It's okay if the list is empty. Order doesn't matter, but the list is not a set nonetheless: We allow multiple copies of the same number in the list, and it makes a difference.
  
• Output: A real number.
  
• Steps:
  
  • If the list is empty, return 0. Otherwise, continue with the next step.
    
  • Compute the sum s of the list, i.e., compute s = x₁ + x₂ + ...
    
  • Find the maximum max(x₁, x₂, ...). If the sum s is bigger than this maximum, return this maximum. Otherwise, continue with the next step.
    
  • Find the minimum min(x₁, x₂, ...). If the sum s is smaller than this minimum, return this minimum. Otherwise, return s.
    

Very nice. Examples:

• The saturated sum of (3, 4, 5) is 5.
  
• The saturated sum of (20, −1, −2, −3) is 14.
  
• The saturated sum of the empty list is 0.
  
• For x fixed, the saturated sum of the nonempty list (x, x, x, ...) is x.
  

Questions:

• How common is saturated addition? E.g., I would like to use this in Lix to add the speed of overlapping flingers/batters. Where else does this appear?
  
• We made up the name "saturated addition". Does it have a more canonical name?
  
• In higher dimensions, is component-wise saturated addition base-invariant? No, see below.
  

---

We can lift saturated addition: Lists(ℝ) → ℝ to a multi-dimensional saturated addition Lists(ℝ^d) → ℝ^d. Conduct saturated addition component-wise, i.e., in each of the d dimensions, conduct saturated addition separately. You'll get a point in ℝ^d as final output of the d one-dimensional saturated additions.

This depends on the choice of base of ℝ^d.

Proof: Consider the two-entry list ((1, 0), (0, 1)) of points in ℝ². The component-wise saturated addition yields (1, 1).

Now we recompute that in a rotated base. First, rotate both list entries counter-clockwise around the origin by an eigth. We get the list ((1/√2, 1/√2), (−1/√2, 1/√2)) of rotated points. The component-wise saturated sum is now (0, 1/√2). When we rotate (0, 1/√2) back clockwise by an eigth, it becomes (1/2, 1/2), which fails to match the earlier result (1, 1). End of proof.

Lix physics are on a two-dimensional space, but there is a clear choice of base: the gravity axis and the horizontal axis. It's natural in Lix to depend on this base and not worry about it.

-- Simon

I agree, the spirit and common interpretation of the bad rule (help solve, unless you had known the solution before) is the same as of the weak guideline (don't spoil it immediately if you had known it before).

-- Simon

Quote from: Silken Healer on June 17, 2025, 09:26:43 PMHow will they know if the part they solved is used in the final solution correctly

To the specific argument that I'm making, it's irrelevant.

A and B are in the chat. A has solved the level before. From watching, B gets three ideas, X, Y, Z, but only Z is correct. Under the bad rule (help solve, unless you had known the solution before), A is disallowed from writing X, Y, or Z, but B is allowed to write all of X, Y, Z. Now, A doesn't care about X or Y. But having been disallowed from writing Z feels wrong to A after A sees B write Z. It's irrelevant to A what B thinks/knows here.

-- Simon

Single-Player Lemmings Streams

Consider livestreaming your solving. It's fun!

You can stream to Twitch, to Youtube, you can host your own RTMP server/webchat and link people to that, you have many options. Announce your streams in advance on the forums, then forumers can join your chat.

There are two main styles to stream single-player puzzles:

• No spoilers allowed in chat; this is the more common style, or
  
• viewers are actively encouraged to help solve.

There are nuances among both of the styles. darkshoxx forbids spoilers and considers even UI explanation in chat a spoiler.

I've always encouraged active solving; the idea is: If you join chat, you should be allowed to participate fully. If you weren't allowed to help solve, you'd have to limit your chat to irrelevant smalltalk. I wouldn't want to inflict that on you. (To solve 100 % hint-free, I'll solve off-stream.)

With active solving encouraged, again, there are nuances. It's hard to pin down what I really want. I've written: "Help solve, unless you had already known the full solution by heart." There is a problem here: This rule forbids hints that other people in the same chat are allowed to write after they live-solve a part of the puzzle in their head.

I'm beginning to think that my rule is bogus (help solve, unless you had known the solution before). There should be a rough guideline that you shouldn't outright spoil the solution immediately at the beginning. What that means in detail should be interpretation of the viewer, i.e., the guideline should remain largely unenforced. If you pop into my chat and want to give hints, you should give hints.

-- Simon

In May and June, I've streamed thrice, for a total of 10 hours.

I've got through ~30 % of the Level of the Year nominations on stream. I've given every played level a good shot, solving many level, and making progress on the others. Of every author with a nomination, I've played at least one level.

Mobiethan, Pieuw, and Icho watched live. Thanks for hanging in the chat!

I'm happy with the invested time. The mix of nominations is wonderful, with varied puzzle difficulty. It shows the creativity and spirit of the Lemmings community. Among the played levels, I have some secret favorites already, but I won't name any for now, lest it skew the polls.

I'll review the remaining unplayed levels offline before the voting. There had to be ad-hoc level selection during the livestream. If I didn't hit your best entry by chance, I'd still like to have tried it.

-- Simon

Stream is over! Recording will remain for 14 days at:

https://www.twitch.tv/simonnaar

-- Simon

Video: Splat ruler freezes CE for 5-10 seconds (70 seconds long, 4.4 MB)

This is an excerpt from my stream 3 weeks ago. I've had already played CE for 2 hours here.

-- Simon

Forestidia saw this in 0.10.29 again.

Forestidia's report

-- Simon

Thanks!

I have to investigate whether we draw from current state onto the new savestate (that we allocate), or if the current state becomes the savestate (and we allocate a new current state), drawing from savestate onto current state.

This can merge all of the following 3 phenomena,

(a) missing bridge slap during stutter,
(b) all terrain becomes black,
(c) failed VRAM allocation,

... into a consistent world-view: The theory will be: When a monitor turns off, something happens with Lix's window behind the scenes, all VRAM drawing during this short time has no effect (but won't crash), and all VRAM allocations with this window in this short time fail (and crash because Lix chooses to crash then). In case (a), Lix wants to draw only a brick, but in case (b), Lix wants to load an old savestate including all of its saved terrain.

Leftover consistency problem: Why does the terrain in case (b) become black ... it should remain the terrain from before loading the savestate, then, right? Details, details.

In any case, more to investigate.

All of this has given me ideas to ask directly in the Allegro IRC: How does an Allegro 5 window react to monitor turn-off, such stutter etc., and should the usercode (Lix) react or should Allegro react.

-- Simon

Do you put large water areas?

Another solution, then, is to draw only the outline of the trigger rectangle in the contrastful color. The inner area can be fully/mostly transparent.

-- Simon

All right, Sunday (in two days) at 14:00 UTC. See you!

-- Simon