Tag: GameMaker

GameMaker Studio 2.0 officially released, no longer in Beta

Yesterday, YoYoGames announced that GameMaker Studio 2.0 is out of beta.

Perhaps not coincidentally, I’ve noticed a bit of an uptick in purchases of my assets on the GameMaker Marketplace in recent days.

I have not yet updated any of my Marketplace assets for GMS2, but I believe that most of them should still work, although they may require the use of compatibility scripts generated by GMS2 on import in order to run in GMS2.

If you happen to have downloaded any of my assets, and find an issue with it, I am easy to reach for technical support.

The best way to reach me would be to send a message through the asset page on the GameMaker Marketplace. My email address is also in the documentation for the asset. And you can also reach me via the Contact page on this website.

GameMaker data structures: a cautionary tale

When you work with data structures in GameMaker, you have to be very careful with references to a data structure that has been destroyed.

When you create a data structure in GMS, the ds_*_create() function returns an integer value which is the id of the data structure. You then use this id whenever working with that data structure.

When you destroy the data structure, this frees up the memory that the data structure used, and the data structure can no longer be accessed.

If you take that id that belonged to the destroyed data structure, and test to see if the data structure exists, using the ds_exists() function, it should return false.

The operative word being “should”. It might not.

Why not? Because, the GameMaker runtime reuses the ids of data structures, and if you create a new data structure, it will hand out that id that belonged to the data structure that was just destroyed.

To illustrate the example, we’ll use a ds_stack:

var a = ds_stack_create();
ds_stack_destroy(a);
 
var b = ds_stack_create();
show_message(string(ds_exists(a, ds_type_stack)));

You would think that ds_exists(a, ds_type_stack) would return false. But it doesn’t, because ds_stack b just reused ds_stack a‘s old id.

Apparently, the correct practice — which is not mentioned in the manual — is to immediately clear the value of a after destroying the ds_stack that it points to, like so:

ds_stack_destroy(a);
a = undefined;

If you do that, then a no longer points to an address that can potentially be assigned to new data structure, and so you’re safe, even if b has the same address as a once did.

Of course there’s still a problem if multiple variables all point to that same destroyed data structure. This is probably a somewhat rare circumstance, but could possibly by the case in some circumstances, for example if you have a global variable, or controller object, holding a data structure that is accessed by multiple instances of some common object. Keeping track of every variable that references the destroyed data structure and clearing all of them when the data structure is destroyed is not an easy thing to do.

Update: Thanks to @YellowAfterLife for the very clever tip!

In other words, do this:

//creation of stack:
a[0] = ds_stack_create();
//aliases to the stack
b = a[0]; //copy of stack id stored in a[0] -- don't do it this way!
c = a[@0]; //reference to stack id stored in a[0]
 
//destroy the data structure AND clear the variable
ds_stack_destroy(a[0]);
a = undefined; // this destroys the array a[], and therefore kills all references to the ds_stack.
 
//create a new stack, let's see what happens with our aliases
d[0] = ds_stack_create();
 
ds_exists(a[0], ds_type_stack); //returns false, because the array was destroyed.
ds_exists(b, ds_type_stack); //returns true, but misleadingly so, because when we created d[0], 
 //we re-used the same id that had been used by the stack referenced by a[0], 
 //and copied to b by value. 
ds_exists(c, ds_type_stack); //returns false, because c references a[0] rather than storing a copy of the id it had stored.
ds_exists(d[0], ds_type_stack); //returns true, because we created ds_stack d[0].

It’s debatable whether the re-use of handles like this is in fact a good practice, but at the moment it’s the way GameMaker works, and has worked, for years. But the discovery that they are re-used (and so soon after being destroyed) is a bit of a shocker.

More information.

GameMaker Tutorial: Instance Pooling for performance optimization

Instance pooling is a design pattern which can potentially help performance in games where you are creating and destroying a lot of instances.

If your program is spawning and destroying objects very frequently, calling the Create and Destroy Events many times per step, it’s potentially a lot of extra processing. Creating instances and destroying others constantly seems wasteful. Why destroy the instances that need to be destroyed when instead you can re-use them, and avoid having to call the Create event on a New instance every time you need one?

The Code

You can download my demo code here:

The GMS2 demo is an import of the 1.4 demo, cleaned up to remove the Compatibility scripts.

Looking at the project code, you will see that I have used inheritance to make the Control and Instance Pool test implementations as close to identical as possible. I have included telemetry code, which tracks the FPS of the game while it runs, so that performance is quantifiable. In the GMS1.4 version of the project, all of the telemetry code is neatly separated from the demo code into its own Execute Code action. This makes it easy to modify the project for your own use, and get rid of the telemetry code entirely if you don’t need to quantify runtime performance, and only want the code that actually implements the Instance Pool pattern.

How it works

The basic concept of the Instance Pool pattern is simple. The goal is to minimize the amount of times we create new instances of some object in large numbers during the game. A good candidate for objects to use Instance Pooling with would be bullets, bonuses, and enemies. Instance Pooling is particularly beneficial when the object in the pool is somewhat “heavy” — that is when the Create or Destroy events cause a lot of processing to happen.

The way we achieve this goal is by re-using already-existing instances of the object. This is done by deactivating the instance rather than destroying it. We add the id of all deactivated instances to our Pool. Then, when a new instance is needed, we first check the pool to see if an already-created but inactive instance exists, and if so, we remove it from the pool, activate it, and re-use it.

The most efficient way to create and manage our pool is with a stack. Stacks are elementary data structures in computer science. Imagine a stack of pancakes. The stack gets bigger as you add more pancakes to it. If someone orders a pancake, you take the top one off of the stack, and give it to them.

This is what’s known as Last In, First Out, or LIFO data access. This happens to be just what we need. The stack gives us an easy way to keep track of the id of all of our deactivated instances, and when we need to activate one, we just pop it off the top of the stack. This is very simple to do, and therefore very fast. In GameMaker, stacks are created by ds_stack functions. If you’ve never used them before, take a moment to read up on them. It will help you understand how the demo works.

The code at the heart of this is quite simple. It looks like this:

//First check the pool to see if it has any deactivated instances in it that we can use
 if ds_stack_empty(pool)
 {
 //If not, we need to create a new instance. No performance gain.
 instance_create(x,y,oInstancePoolBullet);
 }
 else
 {
 //If the pool has an instance we can use, take it out and activate it.
 var bullet = ds_stack_pop(pool);
 instance_activate_object(bullet);
 
 //Reset the state of the instance. 
 //**If** this is cheaper than a new instance, we gain performance.
 bullet.x = x;
 bullet.y = y;
 bullet.direction = direction + random_range(-20,20);
 bullet.alarm[0] = bullet.TTL;
 }

There’s only a little bit of other code that you need. You need to create the ds_stack, most likely this is best done in the Create Event, using ds_stack_create(). And when the pool is no longer needed, you need to destroy the ds_stack using ds_stack_destroy(), most likely in the Destroy Event.

Of course, we also need to push instances to the stack when they are no longer needed. To do that, we do this whenever we would ordinarily destroy the instance:

ds_stack_push(oInstancePoolPlayer.pool, id);
instance_deactivate_object(id);

So, don’t destroy instances that you want to pool; deactivate them instead. With our bullet demo, I do this by giving bullets a “time to live” and then setting an timer. When the alarm goes off, the instance’s id is added to the stack, and the instance is deactivated. Then it just waits for the game to need it. In a full game, you would need to look at other occasions where you need to deactivate the bullet, such as when it goes outside the room, off the screen, or when it hits an object.

That’s basically it. But you may need to think about some additional concerns, which I will cover in the Findings section of this tutorial.

Running The Demo

Open the project with GameMaker Studio, compile, and run.

The Demo consists of an Instance Pool demo and a Create-Destroy demo for comparison.

Press the Space bar to spawn bullets. Press Tab to switch from one demo to the other.

The FPS is displayed at the top-left of the screen. The first number is the minimum fps, the middle is the average fps over the last 30 steps, and the last number is the maximum fps. The minimum and maximum fps reset once per second. The average is a rolling average over the last second.

In the Instance Pool demo room, hold the space bar down until the first bullets to spawn reach the end of their life. At this point, the instance pool is filled, and no more instances will spawn; instead, deactivated instances will be re-used. At this point, you should notice the FPS dramatically shoots up and stays consistent.

Findings

To my surprise, I did not find that there was much benefit to creating an Instance Pool for bullets. Create and Destroy is about as fast as Instance Pooling with simple bullet objects in GameMaker. I expect the reason for this is that the GameMaker runtime engine is not particularly fast, but even when I did a YYC build, I still saw no real advantage to using an Instance Pool, at least in terms of fps.

Over a long game session, it may be that there is a reduction in memory fragmentation since we are updating values in RAM that has already been allocated, rather than rapidly allocating/de-allocating memory when we create new instances and destroy them constantly. But I haven’t tested that, so it’s merely speculation for now. Update: This benefit of reducing memory fragmentation is confirmed by Mike Dailly of YoYoGames.

In order to show a benefit to Instance Pooling, I had to weigh down the Create Event for my bullets. To do this, I ran a simple repeat loop to increment a variable. This is obviously inefficient and pretty pointless, but it serves the purpose of simulating a complicated object with an init script that takes some time to run. If that init script needs to be run only once, and not every time the instance is re-used, then there is a benefit and using the Instance Pool pattern will help.

When does it make sense to use the Instance Pool pattern? When there is a performance issue, and the Create or Destroy Events are more expensive than instance_activate_object() and instance_deactivate_object().

Setting up and managing the instance pool is pretty simple, but it does take some work, and incurs some overhead. It’s not worth it to incur this overhead unless there’s a tangible benefit in the form of noticeably improved performance.

Run the code profiler, and see where your code is spending the most time. If it’s heavy on Create and Destroy events, an instance pool might be just what the doctor ordered. Otherwise, you may want to look elsewhere for your low framerate fix.

Additional Considerations

As I mentioned, there are a few other considerations that you should think about when implementing an Instance Pool, which I will discuss here.

Should we Prime the pool?

In my demo, we only create new instances when there are none in the stack. This means that until we’ve deactivated our first instance, the stack is empty, and there is no performance gained by having it.

In fact, since we’re checking the stack before we create each new instance, there’s actually an infinitesimal hit to performance. When you run the Instance Pool room, we see pretty much the same fps performance as we did in the Create-Destroy room, until the first bullets start to be recycled. Only then do we see fps shoot up.

Well, what if we want the performance to be high from the very first bullet? We can do that, by priming the stack, by creating a bunch of bullets, and then immediately deactivating them and pop their id’s onto the stack.

We could create a special object that we might call oPoolPrimer, which lives for several steps, creates the instances we need and deactivates them, adds them to the Instance Pool stack, and then destroys itself when its work is done.

The best time to do this is when the performance hit won’t be noticed, such as when the game is in a menu screen. Alternately, we can create the instances gradually, over a longer time than would introduce a noticeable performance penalty.

To be effective, you will need to have a good way of calculating maximum the number of instances you need to have active in your game at any given time. Prime your pool with that many instances. That way, even when you have all of them active, you aren’t creating new ones, and your fps will stay high.

Trim the pool?

One of the downsides of the Instance Pool is that all those deactivated instances take up resources. Even though the CPU may not be spending as much time with those instances, they do incur some processing overhead to manage even when disabled, and as well they use some RAM.

Depending on your game, you might have a moment when you need a huge number of instances active, but in other parts of the game the action isn’t as intense, and you won’t need so many. For example, in my demo, I spawn 100 bullets per step, for 20 steps, resulting in some 2000 instances max if you hold the space bar down the entire time. But if you don’t need to shoot all the time, all those disabled bullets end up in the stack. Do you really need 2000 disabled instances? If there isn’t going to be as much shooting going on, you might not. We can free up resources by trimming the stack every so often.

One way to do this would be to set a recurring alarm so that every few seconds, the stack is trimmed if it goes over a certain size.

///Alarm0 Event:
while ds_stack_size(pool) > trim_limit
{
 //remove the top instance from the stack and destroy it
 with ds_stack_pop(pool) {instance_destroy();}
}
alarm[0] = reset;

This will keep the stack small when it doesn’t need to be so big.

Delete the pool?

If you delete the stack, you should realize that any disabled instances that we were tracking in the stack still exist. They will continue to do so until the game ends, or you change rooms. If you don’t change rooms right away for some reason, you may want to run through the stack before you destroy it, popping all the instances out of them so that they can be destroyed as well. Otherwise, those inactive instances will continue to take up resources.

while !ds_stack_empty(pool)
{
 //remove the top instance from the stack and destroy it
 with ds_stack_pop(pool) {instance_destroy();}
}
ds_stack_destroy(pool);

 

Benefits in network multiplayer games

This comes from GMC Forums user JuJu: There’s a nice implicit benefit of instance pooling: It makes handling multiplayer netcode for complicated scenes easier if you can refer to instances by a common index across all machines.

Fun enum ideas for game development

Most video games have a counting, ranking, or level system of some sort. It’s often good to have a thematic flavor to your counting systems. This way, rather than calling your level progression by boring old regular numbers, you can give each level number a meaningful, or flavorful, name. This can add character or meaning to your game world, or it can be used to help disguise the underlying math, resulting in a game where the underlying mechanics are masked away from the player, leading to a more mysterious experience where they need to experiment and discover. What’s cooler: a “level 3 sword?” Or “the sword of autumn?” What’s more powerful: the knight sword or the rook sword?

To that end, I thought I’d demonstrate a few example enums that you can use to spice up your game design.

ENUMerate all the things!

Alphabet {A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z}

Greek Alphabet {Alpha, Beta, Gamma, Delta, Epsilon, Zeta, Eta, Theta, Iota, Kappa, Iota, Kappa, Lambda, Mu, Nu, Xi, Omicron, Pi, Rho, Sigma, Tau, Upsilon, Phi, Chi, Psi, Omega}

Military Phonetic Alphabet {Alpha, Beta, Charlie, Delta, Echo, Foxtrot, Golf, Hotel, India, Juliett, Kilo, Lima, Mike, November, Oscar, Papa, Quebec, Romeo, Sierra, Tango, Uniform, Victor, Whiskey, Xray, Yankee, Zulu}

Army (simplified) {Private, Specialist, Corporal, Sergeant, Officer, Lieutenant, Captain, Major, Colonel, General}

Navy (simplified) {Seaman, Petty Officer, Ensign, Lieutenant, Commander, Captain, Admiral}

Chess {Pawn, Knight, Bishop, Rook, Queen, King}

Rainbow {Red, Orange, Yellow, Green, Blue, Indigo, Violet}

Elements {Earth, Air, Fire, Water}

CardRank {Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King, Ace, Joker}

CardSuit {Clubs, Diamonds, Hearts, Spades}

Zodiac {Aquarius, Pisces, Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn}

Seasons {Spring, Summer, Autumn, Winter}

Months {January, February, March, April, May, June, July, August, September, October, November, December}

Weekdays {Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday}

Lunar Cycle {New, WaxingCrescent, FirstQuarter, WaxingGibbous, Full, WaningGibbous, ThirdQuarter, WaningCresent}

Some of these may not necessarily have a natural order to them, but might just be a set of categories which you could use to organize something in your game. That something could be worlds, or items, or creature types, or powers, or anything else you can think of.

What else?

What else is there? Probably a whole lot! You could probably make a good basis for a game system out of gemstones, or metals, or barnyard animals, or anything, really!

If you know of a set of things that would make a good enum that I’ve left out, leave a comment below.

Using enums in GameMaker Studio

Enums are covered in the manual in the article on Data Types.

The basic syntax is as follows:

First, you have to declare the enum.

enum <variable>{<constant> [= <value>]}

You create the enum using the enum keyword, naming the enum <variable>. Then, in brackets, you list all the constants that make up the values in the enum. You can explicitly declare values for the enum constants, or you can leave them implied, in which case GameMaker will assign them integer values starting at 0, and increasing in order through the collection. You can even use expressions rather than a static value.

To access the enum constants, you use the syntax enum_variable.constant.

In your code, there are all kinds of situations where using an enum is potentially useful. Here’s a few things to look for in your code that might signal a good opportunity to use an enum:

Conditionals for checking state

Consider the following ways of checking the state of some object:

//check state using string matching
if state == "state_idle" {//do state actions}
//check state using literal numbers
if state == 0 {//do idle actions}
//check state using variable
state_idle = 0;
[...]
if state == state_idle {//do state0 actions}
//check state using enums
if state == enum.value {//do state actions}

Out of these, using enums is the best approach. Why are enums better?

Conditional checking by string matching is much slower than number matching. Your string value provides semantic meaning to the reader, making the code easier to understand when a human reads it. But when the program goes to check the conditional, it has to check every letter in both strings to see if they match.

As well, this approach is fairly error prone. It’s very easy to type the strings in slightly wrong. If you’re not careful, it’s easy to type one string where the state is assigned, and another string value where you’re checking state in order to do something state-specific. If you don’t catch the error, you’ll have a hard to diagnose bug because the conditional check won’t match what you’ve set the state variable to. One extra space, or misspelled word, or inconsistent use of capital letters, and the string match check will fail. The compiler won’t help you catch this sort of bug.

It’s a lot faster to do conditional checking via numbers. But naming your states with literal numbers: 0, 1, 2, etc. provides no meaning. Is 0 the idle state? is 1 running? is 2 jumping? Keeping track of this stuff in your head makes your work as a programmer harder, and makes the code hard to read, and brittle. You can do slightly better by creating a named variable and assigning the number value to it. The named variable can be expressive, e.g. state_idle = 0, state_running = 1, etc. But variables values can change, and storing each value takes a little bit of memory. By contrast, an enum value is constant — it cannot be changed once it is declared. And enums are global, so they are only declared and set in memory once, and thus require fewer resources. Even if you have ten thousand instances that use your enum, the memory used by them is the same as if there is only once instance.

Create an enum that provides expressive labels on these values, and you have the best of both worlds: expressive code that checks conditions fast, and uses computer resources efficiently.

Iteration over a set

Conventionally, programmers often rely on conventional looping variable names such as i or j to iterate over a collection of things, such as the members of an array, or other data structure. While this is OK, you can make your code more expressive by using enums to denote important numbers.

For example, it’s common for programmers to use a nested for loop iterating over the variables i and j to create a grid structure. Instead of using i and j, we can use variables named row and column instead. As we iterate over the range of rows and columns, we can use enums as flags to do something special at row (or column) == enum.constant.

Another example:

Say we want to implement an inventory equipping system for the player. The character has inventory slots for head, body, gloves, right hand, left hand, shoes. We decide to create an array, called inventory[], and assign the equipped item in each slot.

We could simply index the array with numbers:

inventory[0] = hat;
inventory[1] = armored_breastplate;
inventory[2] = iron_gauntlets;
inventory[3] = sword;
inventory[4] = empty;
inventory[5] = double_jump_boots;

Now, it’s not too hard to tell what each inventory slot is for. But it’s not as easy as it could be, either. Is the sword in the left hand or the right hand?

Let’s use an enum, and make the code easier understand.

enum inv_slots{head, body, gloves, right_hand, left_hand, shoes};
 
inventory[inv_slots.head] = hat;
inventory[inv_slots.body] = armored_breastplate;
inventory[inv_slots.gloves] = iron_gauntlets;
inventory[inv_slots.right_hand] = sword;
inventory[inv_slots.left_hand] = empty;
inventory[inv_slots.shoes] = double_jump_boots;

Now, it’s quite easy to see that the double_jump_boots are being worn on the player’s feet, rather than being carried in the player’s hands. It’s simple to keep track of which slot is which.

Creating a set of related, named values

Here’s a useful enum for direction angles for a top-down game:

enum compass {e = 0, ne = 45, n = 90, nw = 135, w = 180, sw = 225, s = 270, se = 315};

It’s much easier to remember and understand direction = compass.sw instead of direction = 225. You can use this enum for 4-direction and 8-direction movement or aiming, and you could even expand upon it if you wanted by adding constants for ene, nne, nnw, wnw, wsw, ssw, sse, and ese, like so:

enum compass {
 e = 0, 
 ene = 22.5, 
 ne = 45, 
 nne = 67.5, 
 n = 90, 
 nnw = 112.5
 nw = 135, 
 wnw = 157.5
 w = 180, 
 wsw = 202.5
 sw = 225, 
 ssw = 252.5
 s = 270, 
 sse = 292.5
 se = 315,
 ese = 337.5
 };

(I like to format my code like this; lining up the variable names, equals signs, and values makes it easy to scan down the file, and makes it clear that these values are all related.)

If I wanted, I could go a step further and use radians to make it clearer that these values are fractions of a circle:

enum compass {
 e = 0, 
 ene = radtodeg(pi * 0.125), 
 ne = radtodeg(pi * 0.25),
 nne = radtodeg(pi * 0.375), 
 n = radtodeg(pi * 0.5), 
 nnw = radtodeg(pi * 0.625),
 nw = radtodeg(pi * 0.75),
 wnw = radtodeg(pi * 0.875),
 w = radtodeg(pi), 
 wsw = radtodeg(pi * 1.125),
 sw = radtodeg(pi * 1.25),
 ssw = radtodeg(pi * 1.375),
 s = radtodeg(pi * 1.5),
 sse = radtodeg(pi * 1.625,
 se = radtodeg(pi * 1.75),
 ese = radtodeg(pi * 1.875)
 };

You can group together, and name other values that go together in a system using enums in this way, too.

Parting thoughts

Hopefully, these examples will help you see how enums can be useful to make your code more expressive, easier to read, and easier to maintain. Look for opportunities to use them in your code. They can really help!

Vote for GameMaker Studio 2 on Linux

I just created a Twitter poll to assess the interest in a Linux port of the GameMaker Studio 2 IDE.

One of my biggest wish list items for GameMaker Studio is to have the IDE on Linux, so I can stop being a Windows user. I’m on Windows 7 currently, and Microsoft will not support this version forever. Already they have stopped selling new computers with Windows 7. After the way Microsoft treated Windows users who were not interested in upgrading to Windows 10, using unethical, underhanded, and very likely illegal tactics to try to force Windows users to upgrade, I am not interested in ever purchasing another product from Microsoft, and my preferred platform to migrate to would be a popular Linux distro such as Ubuntu or Mint. GameMaker is the only Windows software that is holding me back.

I’ve asked on the GMC Forums if YYG intend to release a Linux port for GMS2, and currently there’s no plans to do so, but they are open to considering it if they see sufficient interest.

In 2014, then-YoYoGames CEO Sandy Duncan had teased us with the possibility that GMS2 would bring an IDE that ran on Windows, Mac OS X, and Linux. Obviously things can change, and a lot of things have changed with YoYoGames since then. Whether or not we see a native Linux IDE for GMS2, it’s still my #1 wish list item for GameMaker.

GameMaker Studio 2 nearing release

In the last couple of days, YoYoGames have released some teasers that seem to be signaling the immanent release of GameMaker: Studio 2.0. This long-awaited release will overhaul the GM:S GUI, which YoYo have been rewriting in modern C++, and usher in a new era for GameMaker. Beyond that, little is known, as YoYo have been pretty secretive about their plans for the future of GameMaker since being acquired by PlayTech in 2015.

My greatest hope is that GM:S2 will have builds for Mac OS X and Linux. Out of all the software I use today, GameMaker is the last product that runs only on Windows, and I am eager to move to Linux full-time.

It remains to be seen what the release will bring.

Recent purchases of GameMaker who picked it up through the Humble Bundle have been speculating about what GM:S2 will cost. Obviously, a major release isn’t going to be free. It’s typical practice for software companies to sell upgrades to existing users at a substantial discount, so I’m expecting no less.

If YYG do extend discounted upgrade pricing to Humble buyers, most of whom paid around $15, they’ll still be getting an incredible value.

iMprOVE_WRAP 2.0 released

My GameMaker extension iMprOVE_WRAP has been updated with a new release to 2.0.0.

iMproVE_WRAP is an extension for GameMaker: Studio that provides a number of new functions that improve upon the built-in GML function move_wrap().

iMproVE_WRAP is an extension for GameMaker: Studio that provides a number of new functions that improve upon the built-in GML function move_wrap(). It allows you to define the range in the room where the wrap takes place, and draw the instance on both edges of the wrap, as well as detect collisions on both edges of the wrap.

Version 2.0.0 adds two new functions:

  • draw_sprite_wrap()
  • draw_sprite_ext_wrap()

And makes improvements to the existing functions as follows:

  • boundary wrap drawing occurs at the corners of the wrap range (8 phantom drawings rather than 4) when do_wrap_h and do_wrap_v are both true.
  • the collision functions iw_collision_wrap() and iw_collision_wrap_map() incorporate do_wrap_h and do_wrap_v parameters, and only perform collision checks where they are needed. The functions still return all potential collision variables so that there is never an undefined value, even where collisions are not checked. (Unchecked collision locations return noone.)

You can get it at the YoYoGames Marketplace or Itch.io.

Full documentation.

GameMaker Humble Bundle – super cheap and source code too!

GameMaker Humble Bundle pay what you want, but for just $15 you can get licenses for GameMaker: Studio Professional and the ability to create games for HTML5, Android, iOS, and Windows UWP, which together normally cost several hundred dollars. The total value of the entire bundle is $1885, making this one of the best value bundles I’ve seen in the history of the Humble store.

Additionally, you can also get a number of commercially released indie games that were built in GameMaker, and for a few of those games, you even get the source code. It’s very exciting to be able to look at source code written by professionals to see how it’s done. Titles offering their source code include: Extreme Burger Defense, Freeway Mutant, Shep Hard, Angry Chicken, Galactic Missile Defense, Uncanny Valley, Ink, 10 Second Ninja X, Cook, Serve, Delicious!, Flop Rocket, Solstice, and Home.

The sheer cheapness of this giveaway leads me to wonder whether the release of GM:S 2.0 may be immanent. Time will tell. In the mean time, this is a spectacular value bundle and well worth buying for the project source alone.

GameMaker Marketplace new checkout system now allows direct downloads!

Yesterday, 9/7, I noticed a big spike in downloads of my GameMaker Marketplace assets. I also happened to notice when looking around on the Marketplace that they’ve changed the checkout so that you can download the .gmex files directly through your web browser, bypassing the My Library interface in the IDE.

As I’ve remarked several times in the past year, My Library is crippled by terrible performance when the user’s purchase manifest exceeds some number that is far too low. Allowing purchases to be downloaded directly through the browser makes a lot of sense, and is probably the simplest solution to the performance issues, which still plague GM:S as of 1.4.1760.

It remains to be seen whether this spike in downloads will be sustained as the new normal, or represents pent-up demand for users who were reluctant to buy due to the poor performance of My Library. Despite the seeming smallness of this change, I’m really excited that YoYoGames have made it, as it alleviates a significant pain point that I’ve been complaining about for well over a year, and means that I’ll likely be making more use of extensions in my projects.

Graph showing sales spike on 9/7/16. Could this be due to the change in delivery method?

On 9/7, 18 downloads. The other spike earlier in August was due to my Ludum Dare 36 sale, when I put my paid assets on sale for $FREE

Update: 9/8 saw another 18 download day.

Tutorial: GameMaker Object with multiple collision zones

GM Version: GameMaker:Studio 1.4 (concept should work in earlier versions)
Target Platform: ALL
Example Download: https://csanyk.com/cs/releases/games/LD48-36_AncientTechnologies/LD48_36_Ancient_Technologies_csanyk.gmz
Links: http://ludumdare.com/compo/ludum-dare-36/?action=preview&uid=10473

Summary:

How to make an object that handles multiple collision zones by using multiple sub-objects

Tutorial:

I used this technique in my recent Ludum Dare game, Ancient Technologies. The project has a TON of extraneous code in it, some of which is pretty messy, so I’ll replace the download link with a cleaner example project of just this technique in coming days.

If you look at the Atari 2600 console in this game, it is actually multiple objects, made to look like a single object. This enables each switch to have its own collision detection and mouse events.

I accomplished this with a few simple techniques that work really well:

The console itself is the main object. Then there are 6 objects for the 6 switches on the console.

I then took the image I wanted to use for the sprite, and cut out all the different clickable regions, putting each into its own subimage by itself. Then once all the subimages were created, I removed each subimage into its own sprite, and set the collision mask to cover just the pixels in the image

Atari 2600 clickmap sheet

As you can see, this approach results in a lot of “wasted” space in the sprite sheet in the form of transparent pixels, but if you’re concerned about this, you could always achieve the same effect by using sprite origin and sprite offset to position the images without all the whitespace in the sprite sheet. I skipped using sprite origin because I didn’t feel like bothering with counting pixels and setting each sprite origin differently. That would have been tedious, and if I had ever needed to change the sprites, could have thrown everything off and required extensive rework to recalculate again. If your sprites are tiny, it probably doesn’t matter too much, but if they’re quite large, then you should probably use sprite origin/offset.

(Note: With the small pieces, you’d need to use origin numbers that are larger than the dimensions of the sprite itself, or possibly negative values for the origin. You’d also need to carefully calculate the distance to set the origin so that the images all line up precisely. The goal is to make all the images align when each instance’s x and y are identical. This makes them easy to move around together as a group, without having to deal with offsets and so on. To make everything align easy, I created sprites that have the same height and width, so that getting them to align takes no extra effort or calculation at all.)

Next, use the “main” object to generate the collision zone objects, in the create event:

Note the example code below isn’t exactly the code in my project, but is cleaned up a bit for easier comprehension.

///oConsole Create Event:
power_switch = instance_create(x, y, oPowerSwitch);
tv_type_switch = instance_create(x, y, oTVTypeSwitch);
left_difficulty_switch = instance_create(x, y, oLeftDifficultySwitch);
right_difficulty_switch = instance_create(x, y, oRightDifficultySwitch);
select_switch = instance_create(x, y, oSelectSwitch);
reset_switch = instance_create(x, y, oResetSwitch);

Since these objects all use sprites that are the same size, they all line up together when their x,y position is the same. Now you have an easy way to place just the main object and have it create all of its collision zone objects, perfectly aligned.

If the main object needs to be able to move, you just need to update the x,y of all the objects whenever you need to.

Another great thing is that each of these instances can have its own animation which is completely separate from the rest of the collection of objects. This means you can do really sophisticated animation rigging.

Also, you can access the instance variables of the collision instances by using the main instance, like so:

oConsole.power_switch.position = UP;

is (essentially) equivalent to:

oPowerSwitch.position = UP;

This allows you to use the collision zone instances’ instance variables like you would use properties of a helper class in another language, which may make accessing these variables easier if you’re used to other programming languages.

As well, if each of these switch instances were of the same object, using the id returned by instance_create() would allow you to differentiate between them. This could be useful for, say, a battleship with multiple turrets that are all of the same object type.

Finally, you’ll want to be mindful that if you destroy the main object, you’ll likely want to destroy all the sub-objects. Perhaps not — maybe you’re doing a spaceship with an escape pod or a rocket with multiple stages that break away. But in that case you’ll wan to be sure that once the main object is gone, you are handling whatever remains somehow.