CODEWITHSUNDEEP
c++opengltextglut
tysonsmiths
tysonsmiths

Reputation: 493

Drawing large text with GLUT?

I have created a tic-tac-toe game for school, and I am basically finished. The only thing I have left is that when someone wins, I want a box to pop up on the screen and to say in big text "X Wins" or "O Wins" depending on who one.

I've found that drawing text in openGL is very complicated. Since this isn't crucial to the assignment, I'm not looking for something complicated or and don't need it to look super nice. Also, I would most likely just want to change my code. Also, I want the size of the text to be variable driven for when I re-size the window.

This is what my text drawing function currently looks like. It draws it really small.

Note: mText is an int [2] data member that holds where I want to draw the text

void FullGame::DrawText(const char *string) const
{
    glColor3d(1, 1, 1);

    void *font = GLUT_BITMAP_TIMES_ROMAN_24;

    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    glEnable(GL_BLEND);

    int len, i;
    glRasterPos2d(mText[0], mText[1]);
    len = (int)strlen(string);
    for (i = 0; i < len; i++)
    {
        glutBitmapCharacter(font, string[i]);
    }

    glDisable(GL_BLEND);
}

Upvotes: 3

Views: 7049

Answers (2)

erol yeniaras
erol yeniaras

Reputation: 3797

Short answer:

You are drawing bitmap characters which cannot be resized since they are given in pixels. Try using a stroke character or string with one of the following functions: glutStrokeCharacter, glutStrokeString. Stroke fonts can be resized using glscalef.

Long answer:

Actually, instead of printing the text character by character you could have used:

glutBitmapString(GLUT_BITMAP_TIMES_ROMAN_24, "Text to appear!");

Here the font size is in pixel so scaling will not work in direct usage.

Please note that glutBitmapString is introduced in FreeGLUT, which is an open source alternative to the OpenGL Utility Toolkit (GLUT) library. For more details in font rendering: http://freeglut.sourceforge.net/docs/api.php#FontRendering

I strongly advice using FreeGlut rather than the original Glut.

1 - Glut`s last release was before the year 2000 so it has some missing features: http://www.lighthouse3d.com/cg-topics/glut-and-freeglut/

2 - Two of the most common GLUT replacements are OpenGLUT and freeGLUT, both of which are open source projects.

If you decide using FreeGlut you should have the following include:

#include < GL/freeglut.h>

Having said that all you need is scaling the text, therefore you can use glutStrokeString which is more flexible than bitmap string,e.g., it can be resized visually. You can try:

glScalef(0.005,0.005,1);
glutStrokeString(GLUT_STROKE_ROMAN, (unsigned char*)"The game over!");

Hope that helps!

Upvotes: 3

beaker
beaker

Reputation: 16791

The easiest way is to generate a texture for each "Win" screen and render it on a quad. It sounds like you're not concerned about printing arbitrary strings, only 2 possible messages. You can draw the textures in Paint or whatever, and if you're not that worried about quality, the textures don't even have to be that big. Easy to implement and totally resizable.

Upvotes: 1

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