## Slay Tutorial four published

Tutorial four of my reimagining of the game Slay continues.

This was an interesting bit of code to write, particularly setting the player hexagons. Then I tried to do too much in one go, adding the forts at the same time. I split this into separate functions.

It makes extensive use of recursion and that handy trick when you work with hexagons, the IsValidHex() function which tells you which six of the surrounding eight locations are valid. This is needed because the map is stored in a 2d array so in a 3×3 block, the centre location is surrounded by eight locations.

When you use hexagons, it’s more like a brick wall with each alternate row moved over a bit.  Now every location is surrounded by six adjacent locations just like in a hexagon grid. It turns out that a very simple function can tell you which of the 8 surrounding locations are valid.

In the grid I’m using, which runs in rows horizontally either 1,3 or 5,7 cells are invalid depending on whether the row is odd or even.

Here is a normal block of 3 x 3 locations.

```7 0 1
6 x 2
5 4 3```

But if I slide it over by 2 characters you get this.

```  7 0 1     or     7 0 1
6 x 2               6 x 2
5 4 3            5 4 3```

So by ignoring the bold locations, you can simulate a hexagon grid.

I’ve also added Debug mode which toggles with the tab key and introduced a blockId to each hex so you can see which hexes are lumped together. In Debug mode, the BlockId is printed out over the hex as in the screenshot. I’ve used the SDL_ttf library to draw the text. It slows down the screen update by a factor of 40x but is just fast enough to do 60 frames per second.

It’s interesting that the Ubuntu code running under Hyper-V is actually a lot faster than the Windows code.  As with previous tutorials, the code includes conditional compilation so it will compile and run under Windows or Linux.

Note, this code is not quite perfect. It now has three bugs:

1. The map generator occasionally produces a map with a 2nd smaller continent separated by one hex from the main continent.
2. Toggling Debug mode a lot makes it behave oddly. I thought I’d fixed that but I’m not so sure.
3. Some blocks of contiguous hexes (all the same colour) lack forts.

## Thinking about Slay tutorial 7- Game AI

Having just published Slay Tutorial three, making the Onslaught game play well as a computer opponent(well up to 8 of them)  has been weighing on my mind. I have played the original Slay perhaps a couple of thousand times, so I’m reasonably familiar with strategy.

There’s almost 500 games on the Slay game chooser screen shown with four different sizes of islands; the four boxes. Usually by the time I’ve played through all games here (probably taking 18 months to two years) , I can start again and have forgotten what it was like. Plus I think it randomises the starting positions so you get a lot of replay value.

In the first Slay Tutorial I published a map of the tutorials and so far am sticking to it. Tutorial seven is the one for the game AI and its on my mind. I play all the Slay games at the same top intelligence level and even it sometimes makes stupid mistakes like leaving an area vulnerable to splitting and losing all units due to starvation.

The main aim of any player is to expand their territory at the expense of other players. Joining territories can be one tactic as its lets you support the bigger units. The 2 point unit is a Peasant then there’s Spearmen (6 points) , Knights (18 point) and Baron (54 points).  Getting a Knight early on gives you a big advantage as it can defeat castles and too often I’ve seen a territory with one or two spearmen get trapped by castles and destroyed in a few turns.

Likewise putting a castle down early on can secure a territory for a while. Or if you have a larger area, a couple of castles can shield your flanks so you can focus yoyr troops against one enemy and not worry about other players moving in.

### Self Playing

In Slay once you are eliminated the games plays through until one player beats everyone else. But self-playing can also be a useful way to have computer players learn. One possibility is to try and implement a “matchbox” AI. This was done with Tic-Tac-Toe (noughts and crosses for us Brits) with Menace, Now it may be that Onslaught is too complex to implement that but there’s a lot of RAM available, so if I can limit the number of setups that it recognises then maybe?

Anyway there’s a fair bit of time and Tutorials 4-6 to do before I get to Tutorial seven.

### PS

If you move the mouse over the About Me, you’ll see a link to a page that has short cut links to all blog posts along with the title of each.  It’s a quicker way of navigating.

## Slay tutorial three published

This is a typical map produced by the generator. One large continent with coloured hexagons from 8 players arranged in clumps and individual hexes. It’s not quite perfect- in the top right corner there is a single blue hex but its not bad.

I’ve just published Slay tutorial three with the source code in the file onslaught2.zip on GitHub. I’m quite pleased with the map generator which is based on the one I devised for Empire and which I covered in an earlier blog post.  It does a lot and quick enough that when you press the N key it can generate a new map in a fraction of a second.  C + SDL2 is very fast even when drawing nearly a thousand hexagons every frame. It’s mostly in just one file (for now) with timing code and a data file for generating maps in separate files. The main file is just over 600 lines long.

As it needed a fair bit of debugging, I made it cross-compile in Windows or Linux (and probably Mac OS but that’s not tested). You can load the solution file in Windows with Visual Studio or put the files into a Folder with Visual Studio Code on Linux. Included in the zip file is the assets folder which has all the individual hex graphics and a .vscode folder with JSO files for doing the build with clang on Linux.  I’ve compiled it and run on both Windows and Linux. The SDL2 Window is 1300 x 768 pixels wide.

## lldb-mi no longer exists

This is debugging vs code with lldb. It seems as of clang-10, it’s no longer supported which is a pita. I’d been working on the Onslaught code and something wasn’t working so I thought I’d try to debug it.  However the debugger wouldn’t start. Investigating a bit further and I found this discussion thread on the GitHub cpp tools.

I have to say this. I find Linux development quite frustrating at times because of things like this. Something that worked in an earlier version of clang has been removed. Why? There’s a similar issue with Ubuntu 18.04 compared to 20.04 running in Hyper-V VM. With 18.04 I can use the clipboard to copy and paste between Windows and Ubuntu, but so far I have been unable to do it in 20.04.

You spend ages wasting time trying to find answers. I find Windows development with C# much less problematic. Open source developers sometimes don’t appear to take the needs of their users as seriously as say commercial developers do.

So now I’m looking a for a better way to debug C/C++ programs from vs code. There is a lldb – vs code adapter as well as native debug and Code LLDB (see screenshots) so I’ll investigate and see if any of these work. Or I can just study my code and work out in my head why it isn’t working!