glutBitmapCharacter() doesn't display anything?

Question

I am trying to make a simple text output with OpenGL, FreeGlut using glutBitmapCharacter(). My problem is, that i do not get any text shown. The triangle works fine. I guess the problem is not the displayText() function itself but maybe i call it at the wrong place or redraw/clear the text? I compile with gcc main.c -lGL -lglut -o filename

#include <stdio.h>
#include <string.h>
#include <GL/freeglut.h>


int WindowHeight = 500;
int WindowWidth = 500;

void displayText(float x, float y, int r, int g, int b, const char *string) {

    int j = strlen(string);
    glColor3f(r, g, b);
    glRasterPos2f(x, y);
    for (int i = 0; i < j; i++) {
        glutBitmapCharacter(GLUT_BITMAP_HELVETICA_18, string[i]);
    }
    printf("Lange: %i - Raster: %f %f", j, x, y);

}

void keyboard(unsigned char key, int x, int y) {
    if (key == 27)
        exit(0);
    else
        printf("Sie haben %c gedruckt.\n", key);
}

void display(void) {


    glClearColor(1.0, 1.0, 1.0, 0);
    glClear(GL_COLOR_BUFFER_BIT);

    glLoadIdentity();

    glBegin(GL_LINE_LOOP);
    glVertex3f(-0.3, -0.3, 0);
    glVertex3f(0, 0.3, 0);
    glVertex3f(0.3, -0.3, 0);
    glEnd();

    displayText(200, 200, 0, 0, 255, "test");

    glFlush();
}

int main(int argc, char **argv) {


    glutInit(&argc, argv);
    glutInitWindowSize(WindowWidth, WindowHeight);
    glutInitWindowPosition(0, 0);
    glutCreateWindow("Test");

    glutDisplayFunc(display);
    glutKeyboardFunc(keyboard);

    glutMainLoop();
    return 0;
}

Answer 1

glRasterPos2f() takes the current matrix stack into account, either switch to glWindowPos() (which works directly in window coordinates, bypassing the matrix stacks and viewport transform) or change your modelview/projection matrices to make a transform where (200, 200) isn't off-screen.