OpenGLEAN 0.6 development - OpenGLEAN: fonts.c File Reference

The old OpenGLUT fonts "demo" was a test program to verify the font bitmaps and to compare pixel-for-pixel with old GLUT. That program now resides as a test program in the "tests" directory.
#include <stdlib.h>

#include <GL/openglean.h>

#define NUMBEROF(a)   ((sizeof (a)) / sizeof (a [0]))

/*
 * Some lighting and material values.  Not particularly
 * of interest since this is not a lighting or material
 * demo.  If you must know, though: l0 refers to Light 0;
 * plan refers to the planet,  and pole refers to the flagpole.
 */
GLfloat l0_pos [] = {0, 0, 0, 1};
GLfloat l0_amb [] = {.05, .05, .1, 1};
GLfloat l0_diff [] = {.95, .95, .8, 1};

GLfloat plan_diff [] = {.15, .5, .7, 1};
GLfloat plan_spec [] = {.8, .9, 1, 1};

GLfloat pole_diff [] = {.8, .4, .4, 1};
GLfloat pole_spec [] = {1, 1, 1, 1};

/*
 * A handle on the main window.
 */
int main_window;

/*
 * The current font.  Can be any of the builtin fonts.
 */
GLUTfont font;

/*
 * Our text message is displayed at the top of a flag.  This
 * symbolic constant is the distance from the core of the planet
 * to the top of the flagpole.
 */
#ifndef FLAG_HEIGHT
#define FLAG_HEIGHT 5
#endif

/*
 * This structure is used to simplify associating a GLUT font
 * with a GLUT menu item.
 */
struct font_map
{
    GLUTfont   id;
    const char *const name;
};

struct font_map font_map [] =
{
    {GLUT_BITMAP_8_BY_13, "Fixed 8x13"},
    {GLUT_BITMAP_9_BY_15, "Fixed 9x15"},
    {GLUT_BITMAP_TIMES_ROMAN_10, "Times Roman 10"},
    {GLUT_BITMAP_TIMES_ROMAN_24, "Times Roman 24"},
    {GLUT_BITMAP_HELVETICA_10, "Helvetica 10"},
    {GLUT_BITMAP_HELVETICA_12, "Helvetica 12"},
    {GLUT_BITMAP_HELVETICA_18, "Helvetica 18"},
    {GLUT_STROKE_ROMAN, "Stroked Roman"},
    {GLUT_STROKE_MONO_ROMAN, "Stroked Mono Roman"}
};

/*
 * Writes a given string in the current( global ){font}.
 * The string is drawn at the location corresponding to the modelspace
 * origin, providing a somewhat unified interface for the 2 classes
 * of fonts.
 */
void write_string (const char *s)
{
    glDisable (GL_LIGHTING);
    glColor3d (1, 1, 1);

    if ((GLUT_STROKE_ROMAN == font) || (GLUT_STROKE_MONO_ROMAN == font))
    {
        /*
         * Stroked fonts are about 100 model units tall.
         * This scales the font down to something usable in the current
         * context.
         */
        static GLfloat  f = 1.0 / 64;

        glScalef (f, f, f);
        glutStrokeString (font, (const GLubyte *) s);
        glScalef (1 / f, 1 / f, 1 / f);
    }
    else
    {
        glRasterPos3f (0, 0, 0);
        glutBitmapString (font, (const GLubyte *) s);
    }
    glEnable (GL_LIGHTING);
}


/*
 * The main window's display callback renders a small bluish world
 * with a flagpole, flying an eerily familiar banner.
 */
void cb_display (void)
{
    int msec = glutGet (GLUT_ELAPSED_TIME);

    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glPushMatrix ();
    glRotated (msec / 50.0, 0, 1, 0);
    glMaterialfv (GL_FRONT, GL_AMBIENT_AND_DIFFUSE, plan_diff);
    glMateriali (GL_FRONT, GL_SHININESS, 100);
    glMaterialfv (GL_FRONT, GL_SPECULAR, plan_spec);
    glutSolidSphere (3, 20, 20);
    glMaterialfv (GL_FRONT, GL_AMBIENT_AND_DIFFUSE, pole_diff);
    glMaterialfv (GL_FRONT, GL_SPECULAR, pole_spec);
    glutSolidCylinder (.1, FLAG_HEIGHT, 6, 3);
    glTranslated (0, 0, FLAG_HEIGHT);
    write_string ("Hello\nWorld!");
    glPopMatrix ();

    glutSwapBuffers ();
}

/*
 * All your shape belong to us.
 *
 * Err, sorry.  Nothing especially font-oriented here.
 */
void cb_reshape (int w, int h)
{
    GLdouble        r = w * 1.0 / h;

    glViewport (0, 0, w, h);
    glMatrixMode (GL_PROJECTION);
    glLoadIdentity ();
    if (r < 1)
        glFrustum (-1, 1, -1 / r, 1 / r, 3, 100);
    else
        glFrustum (-r, r, -1, 1, 3, 100);

    glMatrixMode (GL_MODELVIEW);
    glLoadIdentity ();

    glEnable (GL_CULL_FACE);
    glEnable (GL_DEPTH_TEST);
    glEnable (GL_LIGHTING);
    glEnable (GL_LIGHT0);
    glLightfv (GL_LIGHT0, GL_POSITION, l0_pos);
    glLightfv (GL_LIGHT0, GL_AMBIENT, l0_amb);
    glLightfv (GL_LIGHT0, GL_DIFFUSE, l0_pos);
    glTranslated (0, 0, -30);

    glutPostRedisplay ();
}

/*
 * Idle functions are covered elsewhere.  We just use this one
 * to keep the window updating when nothing else is happening.
 */
void cb_idle (void)
{
    glutSetWindow (main_window);
    glutPostRedisplay ();
}

/*
 * A bit fragile against changes, but maps menu
 * selections to a global {font} setting.
 */
void cb_menu (int item)
{
    if (NUMBEROF (font_map) == item)
        exit (EXIT_SUCCESS);
    else
        font = font_map [item].id;
}

int main (int argc, char **argv)
{
    unsigned int i;

    glutInit (&argc, argv);
    glutInitDisplayMode (GLUT_DEPTH | GLUT_DOUBLE);
    main_window = glutCreateWindow ("OpenGLEAN fonts");
    glutDisplayFunc (cb_display);
    glutReshapeFunc (cb_reshape);
    glutIdleFunc (cb_idle);

    glutCreateMenu (cb_menu);
    for (i = 0; i < NUMBEROF (font_map); ++i)
        glutAddMenuEntry (font_map [i].name, i);
    glutAddMenuEntry ("Quit", i);
    glutAttachMenu (2);

    font = GLUT_BITMAP_8_BY_13;
    glutMainLoop ();

    return EXIT_SUCCESS;
}
fonts.c File Reference

Detailed Description
