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GameMaker Tutorial: String handling and Drawing Text

[Editor’s note: This article was written primarily with GameMaker: Studio 1.x in mind. There have been some changes to the way GameMaker Studio 2 handles strings, mainly dealing with escaping codes, and this article has not yet been updated to reflect that. Refer to the official manual chapter on Strings for all the details.]

Drawing text to the screen is a basic part of most videogames. There are a huge number of useful applications for text. Just a few of the more common applications:

  1. Score
  2. HUD/Dashboard
  3. Menus
  4. Special effects
  5. Messages and dialogs
  6. Instructions/Story
  7. Debugging/diagnostics/benchmarking — it can be incredibly useful to draw the current value of variables to the screen when debugging, or performance metrics.

Things to know about drawing stuff in GameMaker

  1. Draw functions only work in two places: In the Draw or Draw GUI Events, or when drawing to a Surface. If you try to use them anywhere else, nothing happens. If you’re drawing in the Draw GUI Event, you’ll want to be familiar with the draw_set_gui_size() function so your Draw GUI stuff will be drawn to the proper scale if you’re using Views.
  2. Drawing directly to the screen (especially text) is slow. Draw a lot of text and performance will suffer.
  3. There are ways to improve performance when drawing text. The most important of these is to use Surfaces. Surfaces are not available in the free edition of GameMaker, and not all hardware may support them. Using surfaces properly is not that difficult once you understand them, but is generally considered to be an “advanced” concept in GameMaker, and is less straightforward than drawing directly to the screen in the “normal” way.
  4. But there are challenges. Setting up a Surface for optimizing text performance is tricky because it can be hard to know in advance how large the surface needs to be to contain the text you are drawing. Fortunately, GameMaker provides some useful functions which can enable you to get the dimensions needed for the surface: string_width() and string_height(), which give you the width and height, respectively, in pixels of a string drawn with draw_text() in the current font. If you’re using draw_text_ext() string_width_ext() and string_height_ext() are the functions to use instead. These functions allow you to create a drawing surface of proper dimensions, provided you know the string and font and can decide on a width prior to creating the surface. Keep in mind that the dimensions of a string depend on the font used to display it, so always use draw_set_font() to set the font to the correct one that you intend to draw the string with before using the measurement functions.
  5. Draw settings (for things such as color, alpha transparency, and font alignment) are global in GameMaker. That means that if you have multiple objects which draw functions, and if any of them changes the color, alpha, or font alignment, all objects will be drawn using those same settings. For this reason, if you are using draw functions in your objects, it’s best to set all the draw settings in the object in order to make sure they are what they need to be. If you never change color, or alpha, or font alignment, then you don’t need to set that property before you use draw functions — but if you do need to change them for one object, it’s best to set them to what they need in the Draw event of every object, immediately before calling the drawing routines.
  6. For serious performance optimization, you need to learn how GameMaker “batches” drawing operations, and organize your code to have the least number of drawing batches as possible.

Fonts

Everyone these days knows what fonts are, right? Fonts are like the clothes that text dresses up in when it wants to go out and be seen. In GameMaker, fonts are game resources, just like sprites, or objects, or other resources, and need to be added to the project — you don’t simply have direct access to the same fonts that are installed on the system, you have to explicitly add a font to your project. If your project has no font resources set up, text drawn to the screen will still render, but oddly and probably not consistently across platforms. So, always define a font resource and make sure that it’s used if you’re drawing text.

To save space, you can define a font resource to include only certain character ranges, such as number digits only, or alphabet characters only, or only the upper case or lower case letters in the alphabet. If you know you won’t be needing certain characters, and are concerned about the size of the game when it is built, go ahead and constrain the range. Otherwise, the default range of 37-128, covering A-z, 0-9, and special characters, is good.

For legal reasons, it’s important to note that fonts are copyrighted, and most need to be licensed for commercial use. There are free fonts out there (google for them) with liberal licensing terms that you may be able to use in your project, if the terms of the license allow.

Of course, you can create your own fonts. Creating your own font is outside the scope of this article, but there are tools you can use to produce your own fonts if you’re crazy enough. It’s probably easier to simply purchase a license for a professionally designed font.

Formatting issues

Alignment

Text alignment is set using the and draw_set_valign() functions. Use GameMaker’s built-in font align constants {fa_left, fa_center, fa_right, fa_top, fa_middle, fa_bottom} as arguments to these functions to keep the code readable.

New Lines

To signify a new line in a GML string, use the pound character (#). The GML code

draw_text(x, y, "Hello#World");

would be drawn like so:

Hello
World

You can also use a literal return in your string, but it’ll make your source code look yucky.

draw_text(x, y, "Hello
World");

Would draw to the screen exactly the same as “Hello#World”.

Escape characters

If you’re familiar with strings in programming languages, you know that it gets tricky when using certain characters that are reserved for program syntax or markup. Most languages allow you to “escape” the markup syntax so that you can still use characters normally reserved for markup purposes as literal characters in a string. GML is no exception.

#

What if you want to use a # in a string, and you don’t want it to signify a new line? Use the “\#” escape character.

The string "We're \#1!" would be drawn like so:

We’re #1!

Quotes

A matched pair of quotes, single or double, can be used in GML to begin and end a string. If you want quotes to appear as text within a string, you can use the other type of quote to encapsulate them, like so:

my_string = 'This is a single-quoted string.';
my_string = "This is a double-quoted string.";
my string = 'This is "an example" of a string including double quotes-as-text.';
my string = "This is 'an example' of a string including single quotes-as-text.";

It gets tricky when you need to have BOTH types of quotes in the same sentence:

my_string = 'Bob said " We shouldn' + "'" + "t."+ '"' ; // Bob said "We shouldn't."

It looks like a mess, but you just have to do a lot of concatenation and quote your quotes with the other type of quote marks.

String concatenation

As with many languages, you can combine two strings together by adding them with the + operator. With number values + adds them; with strings, + concatenates the two strings together, creating a longer string made of the first one and second one stitched together. You can do this with literal string values, or with variables containing strings:

concatenated_string = string1 + string2;
concatenated_string = "Hello " + "World";

But if you try to add a string and a number, you need to tell the program to convert the number into a string. The string() function will convert numeric values to strings, which allows them to be incorporated into a larger string.

health = 100;
draw_string(x, y, "Player1 Health: " + string(health));

GML String functions

We’ve already introduced a few of the more commonly useful ones, but there are many other useful GML string functions. I’m not going to go into each one in depth, but review the official documentation and keep in mind that they’re out there, and can be useful.

One important thing to be aware of with GML strings is that, unlike most other languages, GML strings are 1-indexed, not 0-indexed. This means that when counting the characters that make up the string, the first character is character 1, not character 0.

GML text drawing functions

Mostly I have used draw_text() and draw_text_ext(), but it’s good to know that there are a few more variations on these basic text drawing functions.

  • draw_text
  • draw_text_color
  • draw_text_ext
  • draw_text_ext_color
  • draw_text_ext_transformed
  • draw_text_ext_transformed_color
  • draw_text_transformed
  • draw_text_transformed_color

It might seem like a lot to keep track of, but it’s pretty easy if you remember the following:

draw_text: basic draw text function.

_ext: allows you control over the line spacing and width of the draw area. This means you don’t have to manually handle line breaks by inserting # or return characters in your text.

_transformed: allows you to scale and rotate the drawn text.

_color: allows you to set a color gradient and alpha to the text.

Again, text is always drawn using the current global drawing color, alpha, halign and valign properties. It’s best to set these before drawing to ensure that they are the expected values, using draw_set_color, draw_set_alpha, draw_set_halign, and draw_set_valign functions.

Keep code clean by storing strings in variables

This is perhaps obvious, but it’s often useful to store a string value in a variable, to keep your code neater and easier to read.

draw_string(x, y, "Four score and seven years ago our fathers brought forth on this continent a new nation, conceived in liberty, and dedicated to the proposition that all men are created equal.##Now we are engaged in a great civil war, testing whether that nation, or any nation so conceived and so dedicated, can long endure. We are met on a great battlefield of that war. We have come to dedicate a portion of that field, as a final resting place for those who here gave their lives that that nation might live. It is altogether fitting and proper that we should do this.##But, in a larger sense, we can not dedicate, we can not consecrate, we can not hallow this ground. The brave men, living and dead, who struggled here, have consecrated it, far above our poor power to add or detract. The world will little note, nor long remember what we say here, but it can never forget what they did here. It is for us the living, rather, to be dedicated here to the unfinished work which they who fought here have thus far so nobly advanced. It is rather for us to be here dedicated to the great task remaining before us—that from these honored dead we take increased devotion to that cause for which they gave the last full measure of devotion—that we here highly resolve that these dead shall not have died in vain—that this nation, under God, shall have a new birth of freedom—and that government of the people, by the people, for the people, shall not perish from the earth.");

— is a lot harder to read than:

draw_string(x, y, gettysburg_address);

— and moreover, all that text gets in the way of comprehension of what your code is doing. So use variables to store strings, and keep your code looking clean.

draw_text_ext()

While we’re dealing with a very long string, it’s a good opportunity to talk about a function that makes drawing them much easier.

You could manually set line breaks in a long string by sprinkling #’s every N characters or so, but that is laborious and inflexible. It’s better to use the draw_text_ext() function, which allows you to specify a width for the line, and (optionally) also how many pixels should separate lines.

draw_text_ext(x, y, string, vertical_separation, width);

When drawn, the line will automatically break when it reaches the width provided to the function.

Formatting

GameMaker is rather limited in its typographical capability when drawing text to the screen. GameMaker Font resources, unlike an installed font on the system, are a specific size and style only. There’s no bold or italic or other style options available that you can use to modify the font resource. If you want bold or italic, you have to create a new font resource, and use draw_set_font(font) to that resource in order to use it.

This means that if you want to use bold text in a sentence, you need to create a second font resource for the bold font, draw your normal text, then switch fonts to the bold font, and draw the bold text, *somehow* positioning the two different drawings so that they look like they’re a single block of text. You have to leave a hole in your normal text where the bold word will appear. This is *not* easy, nor is it generally recommended. If you really want it, and are masochistic enough to put yourself through the trial and error to do it, go ahead. But before too long you’ll probably realize that it’s not worth the effort.

See this script draw_text_rtf which allows you to draw rich text format, originally written by Miah_84 and improved by me.

Special Effects

Scrolling text

Scrolling text is extremely easy to do. The draw_text function must be called by some object, and includes arguments for the x and y where the text will be drawn. Simply change the x and y over time, add you have moving text. The easiest thing to do is to set the instance that is drawing the text in motion.

Typewriter text

Another easy to implement technique is “typewriter text” — that is, displaying a string one character at a time as though it were being typed out.

First, let’s take a string stored in a variable, my_string.

string_length(my_string) will give you the length of my_string.

draw_text(x, y, my_string) would draw the entire string at once. But we want to draw it one letter at a time.

The GML function string_copy(string, index, length) comes in handy here. We can use this instead of string in our draw_text function:

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//In the Create Event
typed_letters = 0;
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//In the Draw Event
draw_text(x, y, string_copy(my_string, 0, typed_letters);
if (typed_letters < string_length(my_string)) {typed_letters++};

Note that this will type at room_speed characters per second, which at 30 fps is extremely fast. You may want to type slower, in which case you can slow down the function in one of several ways. You can use an alarm to increment typed_letters every N steps, rather than increment it in the Draw event. Or you don’t want to bother with an Alarm event, you could do something like this:

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//In the Draw Event
if typed_letters < length {typed_letters+=0.1;}
draw_text(x, y, string_copy(my_string, 0, ceil(typed_letters)));

This would give a typing speed of room_speed/10, or 1 character roughly every 0.33 seconds for a 30 fps room, or 3 characters/second, which is a bit more reasonable. You can adjust this rate to taste.

If you want the text to reset and type over again when the message is completed, you can do this:

if typed_letters < length {typed_letters+=0.1;} else {typed_letters = 0;}

Additionally, you can optionally add code to play a sound with each letter, or start a sound when the typing starts and stop the sound with the full length string has been reached.

Marquee text

The Typewriter Text technique can be modified slightly to draw a scrolling marquee:

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//In the Create Event
/*Hint: you may want to pad the end of your marquee string with extra spaces so it 
will scroll all the way off your marquee.*/
my_string = "Some text for your marquee "
start_letter = 0;
marquee_length = 10; // or however many letters in your marquee
type_rate = 3/room_speed; // 3 char per second
marquee_scrolling = true;
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//In the Draw Event
if marquee_scrolling{
 draw_text(x, y, string_copy(my_string, start_letter, ceil(start_letter + marquee_length)));
 start_letter += type_rate;
 if (start_letter > string_length(my_string)) start_letter = 0;
}

Blinking text

Blinking is annoying in web pages, but can be a very useful effect in games. Blinking attracts the eye, and can get attention where it’s needed. Of course, blinking can be done with any graphical element, not just text.

Blinking is just turning on the drawing and then turning it off on a cycle, using a timer, such as an Alarm Event.

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//In the Create Event
blink = true; //(or false, if you want the initial state to be off)
blink_steps = room_speed/2; //for a 1 second blink cycle. Set this value to suit.
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//In the Alarm[0] Event
blink = !blink; //toggles the blink from on to off or vice versa.
alarm[0] = blink_steps; //re-sets the alarm so it keeps blinking
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//In the Draw Event
if blink {/*do the draw stuff*/}

The above code gives a 50% “duty cycle” (the blink is “on” 50% of the time, “off” 50% of the time). It’s possible to vary the duty cycle in a variety of interesting ways…

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//In the Create Event
blink = true; //(or false, if you want the initial state to be off)
blink_on_steps = room_speed/2;
blink_off_steps = room_speed/4;
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//In Alarm[0]
if blink {alarm[0] = on_steps;} else {alarm[0] = off_steps;}
blink = !blink;

This blink code will result in a blink that stays on for 0.5 seconds, and blinks off for 0.25 seconds.

Even more sophisticated blink periods can be achieved using math functions rather than a static value. Setting alarm[0] = irandom(10) would result in a random flicker. Think of creative ways to use other math functions to create interesting effects. If you come up with a good one, share your code by posting a comment to this article.

Yet another way to flicker or blink text is through varying alpha. Or by switching colors. Or even size.

One last way to blink is to toggle the state of the visible boolean in the instance.

visible = !visible;

One thing to keep in mind, though, is that an instance that is not visible will not be checked for collisions. Also visible applies to the entire object’s Draw event, so it is all or nothing. Still it is a simple way to draw or not draw an object.

What next?

If you’re familiar with other programming languages, you may be disappointed at the limits of the built-in functions for manipulating strings. There are a lot of things you can do more easily in other languages than in GML, unfortunately. Since GML only has two data types, strings are extremely important, but because games tend to focus more on graphics, sound, and interface, the average GameMaker developer can get by with the string functions that do exist, for the most part.

There are a number of useful GML scripts for doing more advanced things with strings that have been collected at gmlscripts.com. Many of the functions built in to more mainstream programming languages can be found there.

3 Comments

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  1. Another way to make text blink is to toggle the ‘visible’ variable of whatever object it’s attached to. Of course this makes the entire object visible/invisible, so if you have a single object that’s drawing text and something else, that’s not always practical. But it is simple and requires no additional code or variable space on the object to store its blink state.

      

    1. Thanks for the tip!

        

  2. how can i use special characters like ¿,á,ó,é

      

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