Print the text entered on keyboard onto GLUT window? - c++

Question

Trying to display the characters typed on keyboard, I am using the following code:
void myKey(unsigned char key, int x, int y)
{
if (key == 13) // enter key
{
return;
}
glRasterPos2f(xpos, 600);
glColor3f(0.0, 0.0, 1.0); // text color
glutBitmapCharacter(GLUT_BITMAP_TIMES_ROMAN_24, key); // print the color
glFlush();
xpos += 15;
player1[i] = key;
i += 1;
}
It prints the text entered onto the screen but, it doesn't exit as it is supposed to when I press enter. I want the the code to display the player name of the player1 and store it in an array then exit when I press enter and then continue to accept the second player name.

Answer 1

Only do OpenGL stuff in the display callback.
You need to break your text entry into two pieces:
Keyboard/array handling in the glutKeyboardFunc() callback. Once you're done modifying the name list post a redisplay event.
String rendering in the glutDisplayFunc() callback, where you iterate over the name vector and display each string.
Like so:
#include <GL/freeglut.h>
#include <sstream>
#include <string>
#include <vector>
using namespace std;
vector< string > names( 1 );
void keyboard( unsigned char key, int x, int y )
{
if( key == 13 )
{
// enter key
names.push_back( "" );
}
else if( key == 8 )
{
// backspace
names.back().pop_back();
}
else
{
// regular text
names.back().push_back( key );
}
glutPostRedisplay();
}
void display()
{
glClear( GL_COLOR_BUFFER_BIT );
glMatrixMode( GL_PROJECTION );
glLoadIdentity();
double w = glutGet( GLUT_WINDOW_WIDTH );
double h = glutGet( GLUT_WINDOW_HEIGHT );
glOrtho( 0, w, 0, h, -1, 1 );
glMatrixMode( GL_MODELVIEW );
glLoadIdentity();
for( size_t i = 0; i < names.size(); ++i )
{
ostringstream oss;
oss << ( i + 1 ) << ": " << names[i];
void* font = GLUT_BITMAP_9_BY_15;
const int fontHeight = glutBitmapHeight( font );
glRasterPos2i( 10, h - ( fontHeight * ( i + 1 ) ) );
glutBitmapString( font, (const unsigned char*)( oss.str().c_str() ) );
}
glutSwapBuffers();
}
int main( int argc, char **argv )
{
glutInit( &argc, argv );
glutInitDisplayMode( GLUT_RGBA | GLUT_DOUBLE );
glutInitWindowSize( 640, 480 );
glutCreateWindow( "GLUT" );
glutDisplayFunc( display );
glutKeyboardFunc( keyboard );
glutMainLoop();
return 0;
}