Bug 344 - Serious TextRenderer problems involving large fonts & unicode characters
Summary: Serious TextRenderer problems involving large fonts & unicode characters
Alias: None
Product: Jogl
Classification: JogAmp
Component: core (show other bugs)
Version: 1
Hardware: All all
: P3 normal
Assignee: Sven Gothel
Depends on:
Reported: 2008-02-15 07:55 CET by Sven Gothel
Modified: 2010-03-24 07:51 CET (History)
0 users

See Also:
SCM Refs:
Workaround: ---


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Description Sven Gothel 2010-03-24 07:51:17 CET

---- Reported by qwerty999 2008-02-15 19:55:39 ----

There are issues with the TextRenderer utility class which causes problems
involving large fonts and/or long strings of text.

issue 1) Artifacts appear which distort/obscure the text, and cause the text to
flip back and forth.

issue 2) Unicode characters cause the program the crash.

For a screenshot of issue one, check out this thread:
(note that this isn't a screen shot of the test code below, but it also exhibits
the strange behavior).

Here is some test code (modified from TextCube.java in the JOGL demos). There
are two cases (uncomment one or the other in the constructor). The first case
shows that unicode characters crash JOGL if large fonts are used. The second
case shows the weird artifacts that flip back and forth when using large fonts
(and no unicode characters).

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Font;
import java.awt.Frame;
import java.awt.event.*;
import java.awt.geom.*;

import javax.media.opengl.*;
import javax.media.opengl.glu.*;
import com.sun.opengl.util.*;
import com.sun.opengl.util.j2d.*;

/** Test Code adapted from TextCube.java (in JOGL demos) */

public class WeirdFontTest implements GLEventListener
	GLU glu = new GLU();
	TextRenderer renderer;

	float textScaleFactor;
	String text;
	Font font;
	boolean useMipMaps;

	public WeirdFontTest()
		//test 1 - unicode hangs program with a large font & long string
		//font = new Font("default", Font.PLAIN, 200);
		//text = "\u201Cabcdefghijklmnopqrstuvwxyz\u201D";

		//test 2 - weird artifacts appear with a large font & long string 
		font = new Font("default", Font.PLAIN, 200);
		text = "abcdefghijklmnopqrstuvwxyz1234567890";

		useMipMaps = true; //false

	public static void main(String[] args)
		Frame frame = new Frame("WeirdFontTest");
		frame.setLayout(new BorderLayout());

		GLCanvas canvas = new GLCanvas();
		final WeirdFontTest demo = new WeirdFontTest();

		frame.add(canvas, BorderLayout.CENTER);

		frame.setSize(512, 512);
		final Animator animator = new Animator(canvas);
		frame.addWindowListener(new WindowAdapter()
				  public void windowClosing(WindowEvent e)
				    new Thread(new Runnable()
				      public void run()

	public void init(GLAutoDrawable drawable)
		GL gl = drawable.getGL();


		renderer = new TextRenderer(font, useMipMaps);

		Rectangle2D bounds = renderer.getBounds(text);
		float w = (float) bounds.getWidth();
		float h = (float) bounds.getHeight();
		textScaleFactor = 2.0f / (w * 1.1f);

	public void display(GLAutoDrawable drawable)
		GL gl = drawable.getGL();

		glu.gluLookAt(0, 0, 10,
			0, 0, 0,
			0, 1, 0);

		Rectangle2D bounds = renderer.getBounds(text);
		float w = (float) bounds.getWidth();
		float h = (float) bounds.getHeight();
		    w / -2.0f * textScaleFactor,
	            h / -2.0f * textScaleFactor,

	public void reshape(GLAutoDrawable drawable, int x, int y, int width, int height)
		GL gl = drawable.getGL();
		glu.gluPerspective(15, (float) width / (float) height, 5, 15);

	public void displayChanged(GLAutoDrawable drawable, boolean modeChanged,
boolean deviceChanged)

---- Additional Comments From qwerty999 2008-02-15 19:59:52 ----

(changed description slightly)

---- Additional Comments From kbr 2008-02-16 09:24:56 ----

Thanks for the test case. Fixing this is going to require a large reorganization
of the code in the TextRenderer. I will promote 1.1.1-rc7 with the current code
and fix this for 1.1.1-rc8.

---- Additional Comments From kbr 2008-02-17 23:59:16 ----

The glyph-based rendering algorithm for the TextRenderer was
performing rendering in two steps: glyph preparation and upload, and
rendering. This structure doesn't work in the context of the
RectanglePacker, which can reorganize the backing store during any

Restructured the glyph cache in the TextRenderer in terms of flyweight
Glyph objects which know how to upload and render themselves. During
any upload, the outstanding glyphs not yet rendered to the screen may
thereby be flushed. Improved the code path which falls back to the
string-by-string algorithm for complex Unicode characters so that
incoming strings can be segmented into multiple parts which are
rendered either using the glyph cache or the string-by-string

Also tinkered with the bounds of glyphs and strings on the backing
store to try to more definitively eliminate bleed-over between
adjacent characters on the backing store, and to ensure that all of
the pixels of glyphs are drawn. Some heuristics are unfortunately
involved but the new code appears to work well with both very large
and very small fonts.

Added a few more test cases for the TextRenderer based on the bug
report. Tested with the previous test cases as well.

This fix will be in tomorrow's nightly build as well as the forthcoming
JOGL 1.1.1-rc8.

--- Bug imported by sgothel@jausoft.com 2010-03-24 07:51 EDT  ---

This bug was previously known as _bug_ 344 at https://jogl.dev.java.net/bugs/show_bug.cgi?id=344