Write text on the screen with LWJGL

Question

I want to write text on the screen for my game, for things like fps, random text for items and stuff. How can I write that text?

Is it possible without the Basic Game class? Isn't there a command like this g.drawString("Hello World", 100, 100);?

Ballance

LWJGL is really quite a thin wrapper around OpenGL - if you want to do things like this more simply I'd suggest something like JMonkey which provides a scenegraph API. – Aery

are you saying that its better move to a game engine if i want to write text? – Ballance

You say you're looking for a simple drawString() type method, which implies you want simplicity - JMonkey will make things simpler in this respect (and many others). – Aery

Answer 1

Update: this answer is now outdated, and does not work at all with the latest versions of LWJGL. Until I update this answer fully, I recommend that you look here: https://jvm-gaming.org/t/lwjgl-stb-bindings/54537

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You could use the TrueType fonts feature in the Slick-util library.

Using a common font is easy, just create the font like this:

TrueTypeFont font;
Font awtFont = new Font("Times New Roman", Font.BOLD, 24); //name, style (PLAIN, BOLD, or ITALIC), size
font = new TrueTypeFont(awtFont, false); //base Font, anti-aliasing true/false

If you want to load the font from a .ttf file, it's a little more tricky:

try {
    InputStream inputStream = ResourceLoader.getResourceAsStream("myfont.ttf");
    
    Font awtFont = Font.createFont(Font.TRUETYPE_FONT, inputStream);
    awtFont = awtFont.deriveFont(24f); // set font size
    font = new TrueTypeFont(awtFont, false);
        
} catch (Exception e) {
    e.printStackTrace();
}

After you have successfully created a TrueTypeFont, you can draw it like this:

font.drawString(100, 50, "ABC123", Color.yellow); //x, y, string to draw, color

For more information, you can look at the documentation for TrueTypeFont and java.awt.Font, and the Slick-Util tutorial I got most of this code from.

Disenthrone

Could you please update the links? They have already expired. Thank you in advance. – Radiocommunication

@IchHabsDrauf Thanks for letting me know; I'll get to it when I can. – Disenthrone

I tried both of your suggestions and none of them worked for me. The first one was printing just a yellow Rect at the specified location in the window. I tried the second option, by loading Consolas.ttf from my Control Panel into a directory in my project folder and used the inputStream just like in your example but it did not work. It still drew just a yellow Reck. What should I do? – Radiocommunication

Answer 2

Try Making a BufferedImage of required size. Then get its Graphics and draw a String. Then Convert it to a ByteBuffer and render it in OpenGL.

String text = "ABCD";
int s = 256; //Take whatever size suits you.
BufferedImage b = new BufferedImage(s, s, BufferedImage.TYPE_4BYTE_ABGR);
Graphics2D g = b.createGraphics();
g.drawString(text, 0, 0);

int co = b.getColorModel().getNumComponents();

byte[] data = new byte[co * s * s];
b.getRaster().getDataElements(0, 0, s, s, data);

ByteBuffer pixels = BufferUtils.createByteBuffer(data.length);
pixels.put(data);
pixels.rewind();

Now pixels contains the required Image data you need to draw. Use GL11.glTexImage2D() function to draw the byte buffer.

Stabler

could you please explain how we can use the glTexImage2D() in this case? – Radiocommunication

could you please explain how we can use the glTexImage2D() in this case? – Radiocommunication