Can you believe we’ve been doing these for two months? Crazy. To celebrate I’m going to be doing a rather technical update, which several people have told me that they wanted. So you’ll get everything, including badly drawn diagrams using my trackball, and my oddly disjoint ramblings.

Today, I finally got the grappling hook in the game, as in you spawn it and equip it and doesn’t crash or break or anything. But there’s many different glitches I need to fix before I can show you off. So for today’s update I thought I’d talk you guys through the logic of how it’s (already should, but doesn’t quite yet) operate.

As I mentioned before in various places, but many of you may not have yet seen. I’m basing the behavior against an old SNES game that very few people have heard of called “Umihara Kawase,” a game which I was introduced to back in 2004 by a TASVideos run.

So let’s talk about grappling hooks and the properties thereof. First off, let’s talk about how the stretch mechanics works. If you remember back to your physics class, we’re going to be using pretty much just the spring equation to calculate this. This is simply F = kx, where k is a constant that we’re going to define in a config file, and x is how far the rope is stretched from “rest.” Of course, you can make the rope’s rest length longer and shorter while you swing around. So all we need to do is calculate how long the rope is. Well… how do we do that? Especially considering that the rope might wind up going around blocks.

Well, we need to keep track of where the rope has bent around something, of course. So, let’s talk about what defines a corner point. Well, first it needs to be anchored to the block it’s curving around somehow, so it needs an anchor point, which is typically one of the corners of a specific block. But blocks share corners in a tile based world, so we need to know which block it’s curving around. Which means we need to keep track of a list of these pairs of values, one tile coordinate, and one spacial coordinate.

But the real source of complexity in this problem is the ability to add and remove blocks. Most other games that I’m aware of with an interesting and complicated grappling hook (Umihara Kawase, Worms, Hedgewars, I’m sure there are more than a few others), don’t have to worry about mutable terrain. We do. This means that at any time one of the blocks that an anchor point is sitting against can simply disappear. What happens then? Or what happens if a block is placed over the line?

Well, in the case of a block disappearing, we want to detect that and then move the anchor point toward the midpoint of the line formed by the previous and next anchor points. Unless the anchor point that disappeared was the hook. In that case we just want to break the connection and watch the poor sap plummet to his doom. Actually, I’m probably going to change that up a bit and just make gravity nom the hook, rather than making the line disappear, but right now I just want it good enough to get on the screen and start testing so I didn’t implement it.

After we flag the anchor point as moving (over the course of several frames) towards the midpoint, we also need to check the lines before and after to make sure that we didn’t accidentally drag the line into the wall as a result of the move. We also need to check to see if we’re close enough to the middle to remove the anchor point entirely and treat it as a straight shot through.

How about for the case where a block appears in our path? Well! That’s actually similar to (but not the same as) the case where you’re moving around and the line runs into the wall. So I can just write one set of rules to handle that.

If the path between point A and point B is blocked, we first must determine all of the tiles that it’s colliding with. Then figure out which one is the closest. This will be our working block. Now there’s two cases here. The first case is when you’re looking at the block face on, in which case you’re going to need to consider the two corners that you can see. The second case is looking at the tile edge on, which means you need to consider the two opposite corners.

We consider one side, then the other, which means that I eventually need to introduce a randomness element so it doesn’t consistently favor one path over the other. Anyway in the first case we try the left corner, and check to see if we can actually go around this way (by checking the tiles adjacent to the corner), then if that works, we repeat the algorithm until it returns that we made it (so we try to draw another line between the corner and the far point, discover that we’re travelling through the block again, and then aim at the other corner.) Additionally, there are some checks that prevent doubling back or doing otherwise impossible things. This is a rather crude depth first search through sort of an impromptu graph. I don’t even keep a visited list, those I might need to in future iterations of the code for reasons of not having infinite loops.

There also are other cases, for instance you’re swinging around a wall and your grapple pulls away from the wall, we need to detect that (by detecting that the angle formed is greater than 180 degrees.)

There are some more complicated bits, but it’s now 5AM in my part of the world, and I have to get up at 9AM to start work again on this stuff. Hopefully, we’ll be able to show this off in the next few days. Sorry, I jumped the gun a bit and promised Tiy that I was going to make a video on it when I got it done in a day or two (which was like 4 days ago…), I had some code problems that slowed me down dealing with unimplemented areas of C++11 that I expected to be there (specifically the function I wanted was std::deque::insert(DestInterator locationToInsert, SourceIterator begin, SourceIterator end); I expected it to return an iterator, because when you call insert on deques it invalidates all current iterators to the deque, but it didn’t, because it hadn’t been implemented yet.)

As far as what everyone else has been doing, I honestly have no clue. I’ve managed to wall myself off to work on this for a few days, and it’s been a bit stressful, but ultimately rewarding. This was really fun to work on, and thank you so much for your indulgence. And I hope this wasn’t too boring or frankly terrible oh my god I can’t believe you call that drawing what is wrong with you.

Welcome to the update, ladies and gentlemen.  My name is Omni, I’ll be your guide for today.

Once upon a time earlier today, I spent several hours resolving a bug where certain object items would not scan.  And although I could reproduce the issue, it was strange that sometimes I’d scan the same item and it would work.  Eventually, working together with Tiy, we stumbled across the actual problem.  It was a difference in the metadata.  A empty Variant and a Variant containing an empty VariantMap are two different things.  And items spawned by different parts of the code were spawned in very subtly different ways.  I spent a good  solid 9 hours working on this issue before I hit on that, so my total committed code output for today was 9 lines added, 13 removed.  Whoo.  I’m also in the middle of making money a thing with scanning items and connecting that to the UI.  But that will have to be finished tomorrow because that one bug killed me today.

Kyren is going through and cleaning up some of our core code to be less easy to screw up.  Because she wound up running into some bugs that revolved around references to objects living longer that the objects themselves.  And our core code shouldn’t be that easy to shoot yourself in the foot like that.  So she’s updating some of the older code to be both a) more efficient and b) less brittle.  So that’s pretty awesome.  She also put clothes on those poor, poor NPCs.

Bartwe is also going through the core code and tuning performance.  He’s modifying some of the hotter string functions and various other things to avoid unnecessary copies.  He also troubleshot a problem that involved SDL lying about the true size of the window :O

Anyways, now that the NPCs have covered their shameful nudity, I can show you a picture of a bunch of NPCs walking around.  Here they are, just derping right along.

Tomorrow, kyren’s wife is going to go to New Orleans, I think she’s dragging kyren along with her.  So she might be out of commission.  I’ll be gone Sunday, spending time with the old man.  I’m unsure what everyone else’s plans are for Father’s Day weekend.  How about you guys?  What are you planning on doing if anything?

Hi there,

I have been officially restricted from trolling during the daily update. :P

Today, I mostly worked on bug fixes for the crafting interface and the 3dprinter, (they use the same backend of the code).  There were some issues with certain recipes not showing up, and with some items being able to be “eaten” by the printer then they shouldn’t have been.  As well as some crashing bugs.  Then I worked on my laptop moving data around and properly upgrading the hard drive, (I had previously just thrown the hard drive in an installed Linux, I’m going back and making sure my dual boot works properly and that my data is backed up off of my old HD and that’s taking time.  Exciting, I know).  Recently, I did some big asset changes that eliminated lots of redundant information (inventory items and automatic 3dprinter recipes for objects), and we’re just generating that on the fly now.  My next project is going to be rather boring.  Bug hunting!

Kyren made a huuuuuuuuuge merge, and now we have humanoid NPCs.  They’re naked for right now, and they only walk left and right.  But it’s a really big change.  The game’s coming together!  And I’m excited :D

Bartwe is working on the damage system, doing scaled knockbacks and he recently rewrote the status effect system.  Huge change.  Lots of redundant code eliminated.

Tiy’s been helping out Bartwe and I deal with the ridiculous numbers of config files that need to be mutated from the recent changes.  Lots of hard work, hat’s off to him.

Work has moved from Glitch Castle to Apex Heights on the dungeon design front.  And Armagon added a frying pan that goes bang when you hit someone with it.

That’s it for today.  Good job PaRappa, you can go on to the next stage now. (Noting my previous restriction on trolling, this link has nothing to do with Starbound).