More tutorial and scripting improvements

Hey everyone, it’s been months since my last dev blog update! As you will hopefully have seen, I recently announced the coming release of GearBlocks into early access for November 9th.

A lot of my time lately was spent preparing for this announcement. The trailer video was the biggest chunk of this work: planning, building content in game (including many new built-in constructions!), capturing footage, and editing it all together. I also improved the Steam store page and website with new screenshots, gifs, blurb, presskit, etc.

Tutorial scenario

I recently took the game to a local indie meetup, and had a few people try out the tutorial scenario. It was really useful and informative to watch people play it in person. The feedback was somewhat sobering though, some found it too complicated and struggled with information overload!

So I made some changes to the tutorial to try and simplify the information presented to players, and added more code to handle edge cases where players were getting stuck.

I’ve also set up a new build configuration for a special demo build with just the tutorial scenario in it, which I’m planning to use for the Steam Next Fest (coming on October 9th).

Lua scripting

I’ve continued to improve the Lua scripting interfaces, exposing more properties and methods for manipulating parts and constructions, adding more tool interfaces, and more vector / quaternion math stuff.

Further improvements were made to some of the included script mods, including the builder tool extensions (now with the ability to set / snap the pivot position & orientation, change the manipulators to work in world or local space, etc.)

Kit building

For the trailer video I wanted to show time lapses of some constructions being built. I also want to try creating scenarios where the player follows instructions to build pre-designed blueprint constructions, a bit like building from a model kit.

So I implemented a feature I’m calling “kit building”, to cater for both of these situations. Parts can now be assigned a stage index and constructions have an active stage that can be set (where any of their parts in higher stages than the active one are hidden).

I made a script mod tool for setting part stage indices, and previewing a construction’s stages. I actually used this tool when capturing for the trailer, just manually advancing through the stages in order, revealing the parts.

I also prototyped a kit building scenario with a simple Lua script to allow the player to advance through a blueprint construction’s stages, automatically spawning the parts they need to build that stage. This idea has potential I think, but will need work to make it more user friendly.

Minor demo update

I decided to release another quick demo update, out now with some fixes and other small tweaks:-

  • Minor UI improvements, including a new “getting started” window that shows some helpful pointers when launching into a new game.
  • Improved attachment locking undo / redo (single command for multiple attachments).
  • Bug fixes (including fixing the differential idler gear centre-of-mass again).

New map, and tutorial finished

Hey all, I’ve made a fair amount of progress on the game over the past month, so let’s get into what I’ve been up to.

“Gary Island” map

One conundrum I had while designing the tutorial scenario was where to locate it (i.e. which map to use and whereabouts on that map).  I could have used one of the existing maps but they are all pretty large and “open plan”, which made it hard to lay out the scene for the tutorial.  I needed something small with clear boundaries that spatially confine the player.

For a while I had been resistant to the idea of adding another map for the tutorial scenario, but it became apparent that this was going to be necessary, and worthwhile investing the time and effort in.  So I decided to make a new map, an island surrounded by water, with a 250×250 m playable area.

For long time followers of the game’s development, I resurrected the water from those old procedural island maps!  I was also reluctant to do this actually, as introducing water brings about a whole host of implications (what happens when you go in the water? buoyancy? drag? sound & particle effects? player swimming animations?)  So for now the water is beyond the map boundary and is just there for visual effect.

As usual, first I started with making the terrain height map:


Then, painted the textures (reusing those from the other maps):


Finally, added details (e.g. grass) and trees:


Overall I’m quite pleased with how the map turned out.  It has a central area (which I’ve used for the tutorial scenario), and other areas that are connected via paths for a bit of variety.  I’m thinking this will be good for other scenarios, and also as a general starter map for players.

Water reflection optimisations

After bringing back the water, I needed to do some performance optimisations to the old reflection rendering implementation (water reflections are rendered using another camera with a view that is flipped upside relative to the main camera).

I improved the code by eliminating some expensive per-frame calls (GameObject.Find(), GetComponent(), etc.) and getting rid of GC allocs.  I also reduced the level of detail during the reflection render (by overriding the LOD bias, turning off terrain details, and reducing the tree LOD switch distance).

Finally, I added a “video options” setting to make the water reflection rendering only include the terrain & sky, or be turned off altogether (falling back to a reflection probe).

Tutorial scenario

To finish the final iteration of the tutorial scenario, first I had to create a scene in the new map.  I laid out all the constructions, checkpoints, and so on for each of the tutorial stages that the player completes in sequence.

Then I worked on the scenario scripting, organising the Lua scripts by breaking them up into the tutorial stages.  The scripts are responsible for tracking player progress through the tasks they have to complete for each stage, showing a UI window with instructions (text and videos), and helping the player get back on track if they make a mistake.  This turned out to be a huge amount of work, but I think the results turned out really well.

Here’s a sneak peak of the start of the tutorial scenario:


So the tutorial scenario is now (more or less) complete, which is a huge milestone, as that was the last major task before early access release.  There’s still a bunch of work to do, but I’m now in a position to prepare the game for release which is very exciting!

Part resizing indicator

I’ve implemented another indicator that shows unit dimension numbers near a part when resizing it with the resize manipulator.


This makes it much easier to see the part dimensions while resizing, as it saves having to look down at the part UI overlay.

Script mods

The script mods included with the game have continued to develop.  For example, I implemented a “builder tool extensions” script mod that provides an interface with options for precise part placement.

I also improved and added to the various debug tools, and added a simple “hello world” example.  I can’t wait to see what script mods of their own players can come up with!

Tutorial, optimisations, and other improvements

Hey everyone, time for another long overdue update on what I’ve been up to lately!  I’ve mostly been focused back on building the in-game tutorial scenario, but I’ve also continued working on the game, both adding features to support scenarios, and making other general improvements.

Performance Optimisation

I noticed some performance issues, particularly with a large number of parts or constructions, so I decided to spend some time addressing these.

UI optimisations:

  • UI elements now only resize themselves to content when something changes, rather than every update.
  • Improved performance of link and part intersection indicators when looping through part instances.
  • Improved the compass overlay implementation (no longer sets gameobjects active / inactive).
  • Optimised the scene tool UI’s construction list update.

Other optimisations:

  • Removed unnecessary calculations from the construction update function.
  • Eliminated the composite update function altogether.
  • Eliminated or simplified some other fixed update functions.

These changes save over 1 ms on the main thread when there are a lot of parts / constructions in the scene (totalling a couple thousand parts or so).

Speaking of which, I’ve also investigated using Unity jobs to move work off the main thread.  This has the potential for some more significant performance improvements.

Here’s what I have planned:

  1. Gear and pulley wheel behaviour constraint updates – The code that figures out if a pair of gears are engaged, and the location of their engaged “teeth” (info that’s then used to update the ConfigurableJoints).  This could be done in parallel in jobs I think.
  2. Wheel behaviour constraint updates – Each wheel does a CapsuleCast and some other trickery to approximate a cylinder that smoothly rolls on the ground.  This is a prime candidate for using the CapsulecastCommand instead.
  3. Part selection’s “find valid attachments” code – Does a lot of OverlapBox calls if a large number of parts are selected, should be perfect case for replacing with the OverlapBoxCommand.
  4. Collision contact reporting (used for impact sounds etc.) – Horribly inefficient at the moment, but Unity just introduced the Physics.ContactEvent, which should be exactly what I need to improve this.

All but the first of these tasks will require upgrading to Unity 2022.2 though, which feels a bit risky at the moment.  I’m going to hold off until the LTS version comes out.

Unity 2021 upgrade

In the meantime however, I have upgraded to Unity 2021.3 LTS.  I had tried upgrading to 2021 a while ago, but found a couple of game breaking issues.  These seem to have been fixed now, and the upgrade went pretty smoothly this time.

The only slight issue is that old saved construction preview images now won’t load (compressed image size needs to be multiple of 4), but this can be resolved just by re-saving them first.

Building improvements

I’ve made various minor improvements and fixes to the building system:

  • The part selection pivot point can no longer be moved below the ground, preventing a construction from being “lost” underground.
  • Now only the move manipulator handle has “drag thresholding”, the translation handles move instantly.
  • Engagement indicators are now shown for all gears in the part selection during alignment.
  • Commands are now added to the undo / redo history when links are removed while detaching parts.
  • Fixed a bug where destroying an unfrozen construction didn’t add a command to the undo / redo history.


I’ve also made a few minor improvements and additions to the parts:

  • Implemented a resizable “L Plate” part, useful for connecting stuff at right angles.
  • Added checks for player distance and facing direction to the control wheel part behaviour (prevents the control wheel from being used when the player is too far away).
  • Added a light part behaviour option to disable shadow casting, useful if you want to save performance for a construction with a large number of lights.
  • Fixed a bug where spring damper / linear actuator pistons could be attached to the wrong alignment point.

Here’s what the L Plate part looks like:

Lua scripting

I’ve worked on various new features that are available for use from within Lua scripts (as scenarios or script mods), mostly to support what I need for the tutorial scenario.

Video player

Implemented an in-game video player, with an interface that allows video players to be created from Lua scripts.  Here’s a test Lua script, showing a video playing in a window:

I’m planning on using this to show short explanatory video clips in the tutorial scenario.

Scroll list UI element

Implemented a scroll list UI element, can be added to a window like any other element, but then other elements can be added to it (including more scroll lists!)  For example the undo / redo command history script mod can now show a larger history that can be scrolled through:

Unlabelled UI elements

Added unlabelled variants of the slider, input field, and dropdown UI elements for more flexibility.  Shown here in this Lua UI unit test:

Profiling metrics

Exposed performance profiler metrics (e.g. memory, rendering etc.), so that script mods can implement custom profiler UI windows, for example:

Tutorial scenario

My original plan was to have multiple little tutorial scenarios, each one introducing a few new concepts at a time.  As I mentioned in a previous post, this idea turned out to be a bit boring in practice, and didn’t really create a good first impression for the game.

So then I pivoted to having one large scenario with a lot of things to do in it, essentially combining the separate tutorials into one that are followed through step by step.  However as I started to build this out I realised it was getting too big and complicated.  Apart from anything else, performance was getting to be marginal with so much going on in the scene at once.

So, I went back to the drawing board and reworked my design, trying to really focus on what concepts I wanted to introduce in each tutorial stage, and what concepts to reinforce from previous stages.

The result is a bit more pared back than what I had before, but I think it should still be fun.  It will still be a single scenario / scene containing multiple activities that the player goes through, but with less extraneous stuff.

The first few activities will get the player used to activating and using part behaviours, using the construction menu, and so on.

After which, each activity will require the player to do something (e.g. attach a control wheel, reposition a gear, link some pulleys, etc) that will allow them to open a box with a part inside.  When they’ve completed all the activities they can collect all the parts together and build something out of it, as the final step (using everything they’ve learned so far).

For example, the first of these activities is to simply use the builder tool to move a weight and place it on a platform.  Things ramp up in complexity from there!

The design is now complete, I have built all the individual constructions for the scenario, and made a good start on the Lua scripting.  I’m planning on making another (small) map for the game, to be used for this tutorial (and any others to follow).

This tutorial scenario is really there to get new players used to using the building controls, it doesn’t go much beyond that.  I would like to also build additional tutorial scenarios that teach advanced use of gears, mechanical principles, have more complex puzzles to solve etc.  These will have to come after the early access release though.

Tutorials, new features and parts

Hey all, here’s an update on what I’ve been working on for the past couple of months.

Tutorial scenarios

The main challenge I’ve had lately is with the design of the tutorial scenarios, my original idea for these didn’t work out to my liking.  They ended up being rather boring and didn’t give a very good first impression of the game.  So I decided to try a new direction to create a more entertaining experience for first time players while introducing some basic concepts.

Unfortunately this will likely mean scrapping some of the work I’ve already done, but hopefully I can reuse some of it at least.  For now I’ll say no more about the new tutorial scenario design, until I’m further along with it and more confident that it’s going to work out.

I found all this rather dispiriting and frustrating to be honest, so to try and keep myself motivated and move things forward, I’ve also been working on some other stuff!

Building improvements

Recently I’ve been playing the game a lot (to build content for the tutorial scenarios and trailer video), this has highlighted some bugs and other usability annoyances, which I’ve been fixing as I find them.

For example:-

  • When detaching selected parts from other ones, the attachment types between them would be lost, and after re-attaching them you’d have to change the attachments back to the desired type.  Now, the types are saved while the selection is being moved, and restored after re-attachment.
  • Part highlighting has been improved so that tools only highlight parts relevant to them (e.g. only paintable parts for painter tool).
  • Fixed several bugs (such as parts sometimes not attaching to engaged gears, random rotation after freezing a construction, part duplication issues, and so on).


On the subject of annoyances, I built a race car to showcase on the race track map, which was fun to drive around but really emphasised the need for proper braking.

Electric motors provide regen braking by running them backwards, but this was hard to control.  If a vehicle’s wheels had insufficient grip they’d slip and the motor would spin up in reverse.  So I made some changes to the motor part behaviour to address this:-

  • Above a certain speed a “braking direction” is now set, which is then used to prevent the motor from spinning in reverse after coming to a stop during braking (the braking direction is reset once directional control is released).
  • Added a separate tweakable value for braking torque.

Electric motor regen may not provide enough braking on its own however, and so I’ve now implemented a new braking part behaviour for wheels (that can be activated by a bound key).  This makes driving vehicles way more controllable and enjoyable.

When braking is enabled, a brake disc is shown inside the wheel.


I plan on adding separate brake and clutch parts in the future that will also make use of this same part behaviour implementation.

Analog joystick control

After spending some time driving vehicles around, I couldn’t resist implementing something that would greatly improve the experience – analog control.  More specifically, being able to bind a joystick axis to a controllable part behaviour (such as a motor).


This, in combination with braking, transforms the enjoyment of driving vehicles in the game.  It is optional however, and the regular bound keys are still a decent method of control.

Chase camera

Another thing I couldn’t resist adding was a “chase” camera, which is now selectable when the player is seated.  It’s similar to the existing third-person camera except that side-to-side movement is smoothly locked behind the seated player, and the mouse can only move the camera up and down.

This camera mode makes driving vehicles in a third-person view much easier, as you don’t have to manually track the vehicle by moving the mouse.

More parts and improvements

Again, after spending time driving vehicles, I wanted to improve how leaving seats worked:-

  • Rather than having to look down at a seat to leave it, you can now simply press the “jump” action (i.e. Space by default).
  • When leaving a seat, if possible the player is now repositioned at a free position in front or to the side of the seat, rather than on top.  This is more better for a vehicle with a roof for example, where before the player would just be repositioned on top of the roof.

I also improved some other part behaviours (e.g. key bind for differential locking, tweakable light brightness) and added several more parts (e.g. seat, gear, steering wheel, connectors) to facilitate some of the example constructions I’ve been making.

Grabber tool

Finally, I decided to implement the last remaining tool in the game, the “grabber” tool.  Although this wasn’t a particularly high priority, it was quick to implement and I wanted to get it done so that I have the option to include it in the tutorial scenarios, without having to go back and modify them later.

The grabber tool allows constructions to be moved around as physical objects, i.e. without freezing them first.

It has two modes, “grab” and “shove”:-

  1. Target part of a construction, then click the left mouse button and drag, to grab that part and drag the construction around by it.
  2. Target part of a construction, hold the right mouse button to charge up, then release to apply a shove force to that part of the construction.

The grab and shove forces are configurable, as is the ability to have free or locked rotation while grabbing.

What about the full game release?

Before the early access release of the game, there are two main tasks left I need to get done: finish the in-game tutorials and make a trailer video.

The tutorial scenarios have not progressed to where I would have liked by now, but I needed a break from them to clear my head, and work on something else.  Anyway, now I really need to focus back on finishing the tutorial scenarios, finish building content for the trailer video, and get that captured and edited.

I was hoping to release the game before the end of the year, but unfortunately it’s now looking like the date will have to slip by a few months.

This is really disappointing I know, but by way of compensation, I’ve decided to do another demo release update soon, which will include many of the improvements mentioned in this post, so keep your eye out for that!

Supporting features for tutorials

Hey everyone, here’s a quick update on progress over the past month.  I spent most of my time working on the tutorial scenarios, but also implementing some features that support the scenarios while also being beneficial to the game more broadly.

Attachment locking

For the tutorials, I wanted to be able to prevent the player from detaching certain parts from constructions in those scenarios.

So, I implemented an “attachment locking” feature, which allows attachments to be set as locked, preventing them from being modified or deleted.  Parts that are connected with locked attachments are selected together.

To toggle an attachment locked / unlocked, you just target it and press Left Shift + E.  The attachment’s UI indicator shows when it is locked.


Also, there are now options in the selection menu for locking / unlocking attachments of all selected parts.


Now, when setting up the tutorial scenarios, it’s easy to specify which parts should be non-detachable.

Besides, this feature is just generally useful while building I think.  It allows for creating “sub-constructions” that can’t be accidentally broken apart, but can still be detached from the rest of the construction as a single entity.

Compass HUD

For scenarios that use checkpoints, I thought it would be good to try and direct the player towards those checkpoints.  I figured the same solution could also be used to help the player find “lost” constructions.

So, I decided to add a compass HUD to the top of the screen.  It shows cardinal directions based on the player’s facing direction, as well as the direction to any constructions in the scene.

Parts can optionally override the default icon shown, this allows checkpoints to have their own icon to be more easily identifiable.



As I mentioned, the bulk of my time was spent working on the tutorial scenarios.  This is proving a lot more time consuming than I’d hoped, but I am making progress.  I have the first five tutorials mostly done now, and I’m working on the sixth one, which should hopefully cover most of the remaining basic building concepts.

I’ve also started thinking about more open ended scenarios.  As a test I made a “timed lap” scenario around one of the race track routes.  This worked out pretty well, so I’m going to make a few more of these to include with the game.


Help screen

As a supplement to the tutorial scenarios, I’ve also overhauled the help UI screen to be a better user guide and reference.  I added sections on various topics such as spawning a construction, spawning and attaching parts, changing attachment types, and so on.


I removed the page linking to the old tutorial videos, as some of them are out of date since the builder tool changes a while back.


Lastly, I’ve started looking into adding localisation (for translating in-game text for different languages).

I decided to go with Unity’s own localisation package, it seems to do everything required and I didn’t see any need to go with a third party solution.

Integrating this package and setting up the locales (i.e. languages) was nice and easy.  Right now I have English, French, Italian, German, Spanish, and Russian locales, I can add more later as needed.

As a test, I set up localisation just for the UI menu and screen heading text.  I used Google sheets to make a text translation table (just using Google translate for now), and imported that into the game.

This process worked pretty well, but the prospect of localising all the other in-game text is a bit daunting, I suspect the translation table will end up being pretty large.  I’ll have to prioritise the most important stuff and do it in stages.  Hopefully I can find some volunteers to help with the translations!

Scenario mode and Lua scripting continued

Hi all, time for a long overdue progress update on the scenario mode, Lua scripting, and tutorials.  This will continue on from the last blog post so check that out if you haven’t already.  Okay, let’s get stuck in!

Code interfaces

Exposing the game’s events and global variables to Lua scripting was a good start, but only allows the scripts to do pretty basic stuff.  To properly open things up, scripts need access to entities in the game (such as players, tools, constructions, parts, and so on), so I’ve added interfaces for a whole bunch of classes in the game code and registered them to be accessible from Lua scripts.

I won’t go through everything in detail here, but here’s a brief overview of some of these interfaces:


  • State properties (is frozen, total mass, velocity, etc.)
  • List of parts making up the construction.
  • Methods to get a member part from an index, for moving the construction, and so on.


  • Part’s attachments (allowing access to each attachment’s position, connected part, etc.)
  • Material properties (mass, strength, is paintable, etc.)
  • List of part behaviours.


  • State properties (camera mode, is in free flight, velocity, etc.)
  • Targeter (to get currently targeted part).
  • Part inventory (mode, available part catalogue, etc.)
  • Toolbox (to get the active tool and the part selection).


  • State properties (pivot part, is currently aligning, etc.)
  • Currently selected parts.
  • Methods to modify the part selection.

This is by no means a comprehensive list, but hopefully gives a flavour of what’s available.  I’ve made functions accessible from Lua scripts that can get hold of the game’s construction and player instances, and then interrogate / manipulate them via these interfaces.

More UI features and proxies

Following on from the UI windowing system I covered in the previous blog post, I’ve made more UI elements available that can be added to a window from Lua scripting: toggle, slider, drop-down menu, input field, and picture (displays an image texture).


To support the interfaces, UI features, and Lua scripting in general, I had to add some more proxies for Unity types and static methods.  These are: Quaternion, Time, Input (for raw input as opposed to key bound input actions), Texture (includes a function to load textures from file), and Rect.

Script mods

A Lua script can serve many purposes, but I think they essentially fall into two main use cases, a scenario script or a “script mod”.  A scenario script is loaded and run automatically when the player starts playing a scenario and is there to configure the game for that particular scenario.  Whereas a script mod can be loaded at any point and can implement a tool, a custom UI, and so on.

Lua scripts can be loaded from any path location using the debug console, but I’ve added a UI screen for an easier way to load script mods from a “standard” location (this being a ScriptMods folder alongside the SavedConstructions and SavedGames folders).  This UI screen also allows for publishing script mods to the workshop and loading those downloaded from the workshop.


I’ve written some simple tools as script mods that make use of some of the interfaces mentioned earlier.

  • Player tool: displays player’s ID and current state (position, velocity, etc.)
  • Construction tool: displays current number of constructions, allows debug functionality to be enabled (e.g. “show part bounds”), and for a construction to be made non-targetable or even invisible.
  • Part inspector: shows targeted part’s ID and current state (position, rotation, etc.)
  • Attachment inspector: shows targeted attachment’s position, connected part, etc.

Here’s an image showing all of these tool scripts running at once:


Some of these tools are useful for making scenarios, and they also serve as examples of how to write script mods, so I’ll include them with the game.

For example, the part inspector can be used to find out the IDs of parts and constructions in a scene, and then those IDs can be used in a scenario script to reference those particular part or construction instances.  Another example use would be preventing certain parts from being detachable or constructions from being targeted.


For the tutorials and other scenarios I wanted to have “checkpoints”, i.e. a way for a Lua script to detect when a player or construction enters a particular area in the scene.  So I’ve added a new checkpoint part that can be placed in the scene and defines a trigger volume (actually a couple of variations, a box or cylinder).  These parts don’t do much on their own but they provide enter / exit events for Lua scripts to handle and implement useful behaviour.

The checkpoint parts need to be static (i.e. non movable under physics), so I had to implement a way to make a part be “pinned” (i.e. its parent rigidbody remains kinematic, even when the construction is unfrozen).  This will also be needed for making a building foundation part which I want to add in the future to allow for buildings and other static constructions.

Here’s what the checkpoints look like, note they also have a customisable text label:


I’m excited about what’s now possible using checkpoints and scenario scripts, for example: timed laps with split times, obstacle courses, mini-games (e.g. vehicle based soccer, robot golf), you name it!


One of the main motivations behind scenario mode and Lua scripting are the in-game tutorials, and I’m making decent progress with these although it is slow going.  It’s quite tough trying to break down the game’s complexities into simple incremental steps that gradually build upon the player’s knowledge.

Here’s what I have made so far:

Tutorial 1

  1. Briefly covers player movement (should be pretty familiar to anyone not living under a rock! :))
  2. Spawns a go-kart in front of the player.
  3. Introduces the construction menu and has the player use it to unfreeze the go-kart and turn it on.
  4. Gets the player used to controlling a construction by driving the go-kart, ending the tutorial once they reach a target speed.

Tutorial 2

  1. Starts with an upside down go-kart.
  2. Introduces the builder tool and has the player use it to freeze the go-kart and select a pivot point.
  3. Introduces the translation and rotation manipulators and gets the player to use them to pick up and rotate the go-kart to be right side up.
  4. Once the player unfreezes the go-kart, has them drive it over to a checkpoint.

Tutorial 3

  1. Starts with a go-kart with no wheels, and some loose wheels next to it.
  2. Has the player use the builder tool to position and freeze the go-kart, ready for building.
  3. Gets the player to pick up a wheel, use the rotation manipulator to rotate it, and align it to one of the go-kart’s axles.
  4. Once they attach the first wheel, has the player attach the rest.
  5. Introduces the concept of attachments, and has the player target the wheel attachments and cycle them to rotary bearings.
  6. Once the player unfreezes the go-kart, has them drive it through a sequence of checkpoints.

Tutorial 4 is still in progress but will likely introduce the idea of detaching and moving parts, and the builder tool UI for spawning new parts.

I’m trying to make each tutorial build upon the previous one, and be a little more challenging for the player each time.  As you can see I still have a way to go with this, I’m hoping things will go a bit faster now that I’ve implemented most of the game code support.

I reckon I’ll probably end up with around ten basic tutorials, and that’s just covering the essentials of building.  I might make a second more advanced series of tutorials to cover mechanical concepts, but we’ll see how things go.

Summing up

Recently I’ve also done a major Unity upgrade to 2020 (I tried 2021 but it broke some UI stuff), and plowed through a whole load of bug fixes.

Next up will be to continue working on the tutorial scenarios, and try to get those done as soon as possible.  I’ll also try adding some other simple scenarios, and I’m sure there’ll be one or two other supporting features I’ll need to implement in the game itself.  That’s it for this update, thanks for reading!

Scenario mode and Lua scripting

Hey everyone, over the past month I’ve been back to working on the scenario mode.  One of the last things I want to get done before the initial early access release is to add some in-game tutorials, and I think it makes most sense to do this using the scenario system.

I figured the best way for the scenario mode to be flexible enough to support tutorials, as well as other kinds of challenges, would be to do it via dynamic scripting.  So for each scenario there’d be a script that gets loaded at run-time, hooks into the game, and implements the tutorial / challenge logic.  This would allow for user created challenges and mini-games that players can share on the workshop.

Choosing a scripting language

The first step was to choose what scripting language to use.  This had me thinking about modding more broadly, it made sense to keep this in mind when deciding on a scripting approach.

A lot of Unity games with scripting support for mods do it by loading assemblies at run-time, which works because the Mono back-end uses JIT compilation.  This is quite an open ended option for modders, they can write scripts in C# and use whatever assemblies are available from the game.

However, I’m using the IL2CPP back-end to eke out as much performance as possible, which by its nature is an AOT compiler and cannot load arbitrary assemblies at run-time.  So, I needed to use some kind of run-time interpreter.

I narrowed it down to two options and spent some time with both to evaluate them in the game:-

C# using Roslyn C#

  • This is a Unity asset that provides run-time compilation of C# scripts.
  • It doesn’t work with IL2CPP directly (the JIT vs AOT thing again), but there’s the dotnow CIL interpreter which integrates with it and executes CIL on IL2CPP platforms.
  • However, dotnow is in early development, and has some inherent limitations.
  • I came up against some problems with dotnow, nothing that couldn’t be worked around, but it’s definitely a more involved process.
  • The C# language is overkill really for creating scenarios, but might make sense for modding the game more generally.

Lua using the MoonSharp interpreter

  • This is an interpreter written in C#, no JIT, so it works with IL2CPP.
  • It’s been around for a while, development doesn’t seem that active, but I think it’s pretty stable at this point.
  • I found hooking up Lua scripts into the game with MoonSharp to be quick and easy.
  • Lua is more than sufficient for making scenarios, and I think would be simpler to learn for players wanting to create their own.

After this investigation and considering the points mentioned above, I decided to go with the Lua option, at least for the scenario mode and other basic mods.  If I ever decide to support more complex modding (e.g. adding new part behaviours or other direct interactions with the physics engine), then C# would probably make more sense, but this will be something to revisit in the future.

Loading and running Lua scripts

I implemented a Lua script “manager” to handle loading Lua script files from any specified path, unloading of scripts, and to keep track of the lifetime of active scripts.  It’s the only code in the game that directly references the MoonSharp interpreter, which it uses to configure and execute the scripts.

The manager also calls two specific global functions in each active Lua script if they are defined, “Update” and “Cleanup”.  The former is called every game update, and the latter is called on a script just before it is unloaded.

Lastly, the manager provides functions for other game code to register types and object instances with MoonSharp.  This is what enables Lua scripts to interface with game code and do useful things.

Events and variables

The GearBlocks code architecture is built extensively around ScriptableObjects, particularly for events and global variables which are used to communicate between separate subsystems.  I covered this in some detail here if you’re interested:
ScriptableObjects For Fun and Profit.

Not only was this approach useful for decoupling game code, but it also made it easy to add a debug console that allows for tweaking variables and raising events from within the game for testing and experimentation purposes.  There’s more info on this here: Debug console.

It was similarly easy to expose these same events and variables to Lua scripts.  Each event and variable ScriptableObject asset now registers its type and instance with the Lua script manager.  This lets Lua scripts read / write variables, and raise / handle events.  It means a Lua script can configure the game for a particular scenario, for example a tutorial could disable certain game features, and then unlock them as the player progresses through the tutorial.

Here’s a basic Lua script registering an event handler and modifying a game variable, note the use of the Cleanup function to remove the event handler:

local function onGameReady()
    -- The game is ready, so initialise stuff here.
    ShowFPS.value = true -- Turn on the FPS display.

-- Add a handler to the GameReady event.
GameReady.handler.add( onGameReady )

function Cleanup()
    -- Script is about to be unloaded, so cleanup here.
    ShowFPS.value = false -- Turn off the FPS display.
    GameReady.handler.remove( onGameReady ) -- Remove the event handler.

I added two new events (handled by the Lua script manager) for loading and unloading Lua scripts.  These events are called by the game’s UI code when starting a new scenario mode game to load the Lua script for that scenario, and to unload it when finished.  Because these events are available in the debug console, it’s easy to load and unload Lua scripts while the game is running, and it also allows players to run their own custom scripts to mod the game!


Some of the events and variables now available to Lua scripts depend on Unity types: Vector3 and Color32.  Rather than expose these directly to Lua, I created proxies for them – wrappers that contain an instance of the relevant type, and expose a subset of their properties and methods.  These proxy types are registered with the script manager to be made available in Lua scripts, both for using with the associated events and variables, and also for using the types directly (e.g. for doing vector math operations).


In order for Lua scripts to access player input, the relevant game interfaces and the input system are now registered with the Lua script manager.  This exposes the enums for input action IDs, and functions for finding if the key bound to an action is triggered or held.

Here’s an example Lua script that checks if a particular input action is triggered, note the use of the Update function to poll the input:

local function onGameReady()
    -- The game is ready, so initialise stuff here.
    ShowFPS.value = true -- Turn on the FPS display.

-- Add a handler to the GameReady event.
GameReady.handler.add( onGameReady )

function Update()
    -- For no good reason lets toggle the FPS display
    -- whenever the jump key is pressed!
    if InputActions.isTriggered( actionID_Jump ) then
        ShowFPS.value = not ShowFPS.value

function Cleanup()
    -- Script is about to be unloaded, so cleanup here.
    ShowFPS.value = false -- Turn off the FPS display.
    GameReady.handler.remove( onGameReady ) -- Remove the event handler.

Custom user interfaces

Finally, I’ve implemented a basic UI system that registers itself with the Lua script manager, and allows Lua scripts to create their own custom user interfaces.  This is required for tutorials to relay instructions to the player and so on, but it’ll also be useful for creating custom tools and mods in the game.

A script can create a UI window (or multiple windows if needed), and then add UI elements to it.  So far I’ve implemented text label and button elements, but I’ll be adding more as I go.

Here’s an example Lua script that creates a window and adds a text label and a button to it, note the alignment options I’ve exposed to Lua scripting for positioning and sizing the window and the elements within it:

local function onTextButtonClick()
    print( 'Text button was clicked' )

local function onGameReady()
    -- The game is ready, so initialise stuff here.

    -- Create a UI window.
    Win = Windows.createWindow()
    Win.setAlignment( align_RightEdge, 20, 200 ) -- Width 200, offset 20 from right edge of screen.
    Win.setAlignment( align_TopEdge, 80, 250 )   -- Height 250, offset 80 from top edge of screen.
    Win.title = 'Test window'
    Win.isDraggable = true true )

    -- Add a text label.
    Label = Win.createLabel()
    Label.setAlignment( align_HorizEdges, 10, 10 ) -- Offset 10 from left and right edges of window.
    Label.setAlignment( align_VertEdges, 50, 10 )  -- Offset 50 from bottom edge and 10 from top edge of window.
    Label.alignment = textAnc_MiddleCenter
    Label.fontSize = 18
    Label.text = 'Hello world'

    -- Add a text button.
    TextButton = Win.createTextButton()
    TextButton.setAlignment( align_HorizCentre, 0, 100 ) -- Width 100, centered horizontally in window.
    TextButton.setAlignment( align_BottomEdge, 10, 30 )  -- Height 30, offset 10 from bottom edge of window.
    TextButton.onClick.add( onTextButtonClick )
    TextButton.text = 'Click me'

-- Add a handler to the GameReady event.
GameReady.handler.add( onGameReady )

function Cleanup()
    -- Script is about to be unloaded, so cleanup here.
    Windows.destroyWindow( Win ) -- Destroy the UI window.
    GameReady.handler.remove( onGameReady ) -- Remove the event handler.

And here’s the result when you run the script in game:


OK that’s it, thanks for reading if you made it this far!  Right now I’m starting to rough out some tutorial scenarios, and I’ll continue to extend the Lua scripting functionality as required for this, hopefully I’ll have another progress update on this soon.

Building a new map

Hi everyone, it’s been a while, so time for a dev update I think.

Over the past couple of months I’ve been working on making a new map for the full game.  Currently in the demo there’s a procedurally generated “desert” map that’s a bit boring as it doesn’t have much variation.  So I decided to hand craft another map that would be more fun for testing wheeled vehicles, with various road and race track layouts.

At some point I’d like to have other maps tailored towards different kinds of creations, but those will have to wait until some time in the future.

The race track layout

The map sizes in the game are 12x12km, with an 8x8km playable area, which is a huge area to create a map for, especially by hand.  So for now I’ve been focusing on one 2x2km region to try and get that up to a decent quality level.

The first step was to design a race track layout, which I did by piecing together corners inspired by some of my favourite real world tracks.  I wanted to have a good mix of corner types, elevation change, and a nice flow.  The track also has multiple routes, for more variety.

The next stage was to build the race track in Unity, for this I used EasyRoads3D (  This is a node based tool for creating road layouts that generates the road meshes, matches the terrain height to the road, and can generate other associated objects such as tunnels, bridges, kerbs, and walls.  This tool isn’t without its problems, it has quite a few bugs that I struggled with initially, especially when using the flex connectors to create road intersections.  However once I got used to working around these issues, I found this tool to be quite powerful and flexible, and it can produce some great results.

Here’s the initial race track layout, you can see where I’ve used intersections to create alternate routes and a pit lane, and where the flat terrain has been automatically raised up to match the elevation changes in the track:-

Following on from this I sculpted the terrain around the track to match it, and added a tunnel for the bit where it crosses over:-

Terrain texturing

Before painting textures onto the race track terrain, I first wanted to make some improvements over the terrain texturing that has been in the game so far.  The textures themselves didn’t really fit the visual style of the game, they weren’t varied enough, and I’m not a huge fan of “cross fade” blending between the textures either.

So I created a set of new terrain textures with a more stylised look (a mix of adapting some pre-made textures and making my own).

I implemented height-based blending into my terrain shaders (also with gloss, occlusion, and metallic maps), this was based on the mask map support in Unity’s URP (I’m using the built-in RP).  I’ll skip the details here for brevity, but here’s a comparison between conventional and height-based blending:-

And now here’s the terrain with the textures painted onto it (and also with some tweaks to the pit lane area):-

Terrain details and trees

The next job was to add some terrain details (grass & rocks) and trees.  I implemented custom shaders for all these, in order to have deferred lighting support, and translucency on the tree leaves.  I created tree models using Unity’s old tree editor, which is somewhat flawed (I think it might be abandoned nowadays?), but it did the job, and besides I couldn’t justify spending money on a third party tree creator tool!

I implemented a simple tool in Unity to procedurally place the grass and rocks based on the underlying terrain textures (e.g. so I could quickly place the grass details on top of wherever the grass terrain texture is painted).  The trees I just placed by hand.

Here are some images of the final result:-

Desert map

I also worked on the old desert map to bring it in line with the new one, by switching over to the new stylised textures, adding grass & rock details, and adding trees.  The desert map was created procedurally using TerrainComposer (, so it was fairly simple to set up and automatically place the details and trees.  They definitely add a bit more life to the old map:-

Next steps

Overall I’m reasonably happy with how the race track map turned out so far, the track itself is a lot of fun to drive on, although visually I feel the map is still lacking something in some places.  I’d like to tweak the terrain and tree textures some more, improve the pit / paddock area, and maybe place more objects (such as large rocks) around the map.  Hopefully that’ll help.

More importantly, I need to finish laying out the rest of the map, by adding an oval track (I’ve made a start on this already), a go kart track, and an off-road track.  Beyond that, I’ll probably fill out the remaining outer regions of the map with more generic elements (hills, mountains, etc.) which should be less time consuming to make.

GearBlocks on Steam

GearBlocks on Steam

GearBlocks on Steam

GearBlocks on Steam