SGI Developer Toolbox 6.1/SGI Developer Toolbox 6.1 - Disc 1.iso/toolbox/src/tutorials/custEducation/opengl1/examples/text/fineClip.c

C/C++ Source or Header | 1996-11-11 | 5.3 KB | 248 lines

/*
 * Copyright 1993, 1996, Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This is UNPUBLISHED PROPRIETARY SOURCE CODE of Silicon Graphics, Inc.;
 * the contents of this file may not be disclosed to third parties, copied or
 * duplicated in any form, in whole or in part, without the prior written
 * permission of Silicon Graphics, Inc.
 *
 * RESTRICTED RIGHTS LEGEND:
 * Use, duplication or disclosure by the Government is subject to restrictions
 * as set forth in subdivision (c)(1)(ii) of the Rights in Technical Data
 * and Computer Software clause at DFARS 252.227-7013, and/or in similar or
 * successor clauses in the FAR, DOD or NASA FAR Supplement. Unpublished -
 * rights reserved under the Copyright Laws of the United States.
 */

/* fineClip.c - render a bitmap font string using X Window System fonts;
 *    adjust the viewport so the text is not prematurely clipped.
 *
 *    Escape key     - exit the program
 */

#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>

#include <stdio.h>

/*  Function Prototypes  */

GLvoid  initgfx( GLvoid );
GLvoid  drawScene( GLvoid );
GLvoid  animate( GLvoid );
GLvoid  visibility( int );
GLvoid  reshape( GLsizei, GLsizei );
GLvoid  keyboard( GLubyte, GLint, GLint );

int getBitmapStringLength( void *, char * );

void printHelp( char * );

/* Global Definitions */

#define KEY_ESC    27    /* ascii value for the escape key */

/* Global Variables */

static GLdouble    left, right, bottom, top;
static GLint       strLength;
static void       *fixedFont, *strokeFont;
static char        *charStr = "A text string.";

GLvoid
main( int argc, char *argv[] )
{
    GLsizei width, height;

    glutInit( &argc, argv );

    width = glutGet( GLUT_SCREEN_WIDTH );
    height = glutGet( GLUT_SCREEN_HEIGHT );
    glutInitWindowPosition( (width / 2), height / 4 );
    glutInitWindowSize( (width / 2) - 4, height / 2 );
    glutInitDisplayMode( GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH );
    glutCreateWindow( argv[0] );

    initgfx();

    glutIdleFunc( animate );
    glutVisibilityFunc( visibility );
    glutKeyboardFunc( keyboard );
    glutReshapeFunc( reshape );
    glutDisplayFunc( drawScene );

    printHelp( argv[0] );

    glutMainLoop();
}

void
printHelp( char *progname )
{
    fprintf(stdout,
        "\n%s - render a bitmap font string; adjust the viewport "
        "so the text is\nnot prematurely clipped.\n\n"
        "Escape Key        - exit the program\n\n",
        progname);
}

GLvoid
initgfx( GLvoid )
{
    GLdouble    aspect;

    glClearColor( 0.0, 0.0, 0.0, 1.0 );
    glShadeModel( GL_FLAT );

    /* Set up two fonts to use for rendering */
    fixedFont = GLUT_BITMAP_TIMES_ROMAN_24;
    strokeFont = GLUT_STROKE_ROMAN;

    strLength = getBitmapStringLength( fixedFont, charStr );
}

GLvoid
keyboard( GLubyte key, GLint x, GLint y )
{
    switch (key) {
    case KEY_ESC:    /* Exit whenever the Escape key is pressed */
        exit(0);
    }
}

GLvoid
reshape( GLsizei width, GLsizei height )
{
    GLdouble    aspect;

    glViewport( -strLength, 0, width + strLength, height );

    aspect = (GLdouble) (width + strLength) / (GLdouble) height;
    if ( aspect < 1.0 ) {
        left = -2.0;
        right = 2.0;
        bottom = -2.0 * ( 1.0 / aspect );
        top = 2.0 * ( 1.0 / aspect );
    } else {
        left = -2.0 * aspect;
        right = 2.0 * aspect;
        bottom = -2.0;
        top = 2.0;
    }

    glMatrixMode( GL_PROJECTION );
    glLoadIdentity();
    glOrtho( left, right, bottom, top, -1.0, 1.0 );
    glMatrixMode( GL_MODELVIEW );
}

GLvoid
animate( GLvoid )
{
    /* Tell GLUT to redraw the scene */
    glutPostRedisplay();
}

GLvoid
visibility( int state )
{
    if (state == GLUT_VISIBLE) {
        glutIdleFunc( animate );
    } else {
        glutIdleFunc( NULL );
    }
}

GLvoid
renderBitmapString( void *font, char *string )
{
        int i;
        int len = (int) strlen(string);
        for (i = 0; i < len; i++) {
                glutBitmapCharacter(font, string[i]);
        }
}

/* Compute the length of a bitmap string ( in pixels ) */
int
getBitmapStringLength( void *font, char *string )
{
    int width = 0;

#if GLUT_API_VERSION >= 3
    int i, len = strlen(string);

    for (i = 0; i < len; i++) {
        width += glutBitmapWidth(font, string[i]);
    }
#else
    width += strlen(string) * 9;
#endif
    return width;
}

GLvoid
renderStrokeString( void *font, char *string )
{
        int i;
        int len = (int) strlen(string);
        for (i = 0; i < len; i++) {
                glutStrokeCharacter(font, string[i]);
        }
}

GLvoid
drawScene( GLvoid )
{
    char              str[16];
    static GLfloat    whiteColor[] = { 1.0, 1.0, 1.0 };
    static GLfloat    x = 3.0;

    glClear( GL_COLOR_BUFFER_BIT );

    XYaxes();

    /* update the x position each time we're called;
     * wrap when we go off the screen */
    x -= 0.02;
    if ( x <= left )
        x = right ;

    glColor3fv( whiteColor );

    glPushMatrix();
        /* Bitmap characters ARE NOT affected by
         * modeling transformations
         */
        glRotatef( 15.0, 0.0, 0.0, 1.0 );
        glScalef( 2.0, 2.0, 2.0 );

        /* Set position for the left end of the baseline for
         *  our text string */
        glRasterPos2f( x, 0.0 );
        renderBitmapString( fixedFont, charStr );

        /* show the baseline */
        glBegin( GL_LINES );
               glVertex2f( x, 0.0 );
               glVertex2f( x+1.0, 0.0 );
        glEnd();
    glPopMatrix();

    glPushMatrix();
        /* Stroke characters ARE affected by
         * modeling transformations
         */
        glTranslatef( -1.0, 0.0, 0.0 );
        glRotatef( 15.0, 0.0, 0.0, 1.0 );
        glScalef(0.003, 0.003, 0.003);
        sprintf( str, "x = %5.2f", x );
        renderStrokeString( strokeFont, str );
    glPopMatrix();


    glutSwapBuffers();
}