Well I am trying to learn openGL and want to make a triangle move one unit (0.1) everytime I press one of the keyboard arrows. However i want the triangle to turn first pointing the direction where i will move one unit. So if my triangle is pointing up and I press right the it should point right first and then move one unit in the x axis. I have implemented the code to move the object one unit in any direction, however I can not get it to turn pointing to the direction it is going. The initial position of the Triangle is pointing up.

#define LENGTH 0.05

float posX = -0.5, posY = -0.5, posZ = 0;
float inX = 0.0 ,inY = 0.0 ,inZ = 0.0; // what values????

void rect(){
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glPushMatrix();
    glTranslatef(posX,posY,posZ);
    glRotatef(rotate, inX, inY, inZ);
    glBegin(GL_TRIANGLES);
    glColor3f(0.0, 0.0, 1.0);
    glVertex2f(-LENGTH,-LENGTH);
    glVertex2f(LENGTH-LENGTH, LENGTH);
    glVertex2f(LENGTH, -LENGTH);
    glEnd();
    glPopMatrix();

}

void display(){
    //Clear Window
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    rect();
    glFlush();
}

void init(){
    glClearColor(0.0, 0.0, 0.0, 0.0);
    glColor3f(1.0, 1.0, 1.0);
}

float move_unit = 0.01;
bool change = false;
void keyboardown(int key, int x, int y)
{
    switch (key){
        case GLUT_KEY_UP:
            if(rotate = 0) posY += move_unit;
            else{
            inX = 1.0;
            rotate = 0;
            }
            break;

        case GLUT_KEY_RIGHT:
            if(rotate = -90) posX += move_unit;
            else{
            inX = 1.0; // is this value ok??
            rotate -= 90;
            }
            break;

        case GLUT_KEY_LEFT:
            if(rotate = 90) posX -= move_unit;
            else{
            inX = 1.0; // is this value ok???
            rotate += 90;
            }
            break;

        case GLUT_KEY_DOWN:
            if(rotate = 180) posY -= move_unit;
            else{
            inX = 1.0;
            rotate += 180;
            }
            break;
        case 27: // Escape button
            exit(0);
            break;
        default:
            break;
    }
    glutPostRedisplay();
}



int main(int argc, char** argv){
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize(500,500);
    glutInitWindowPosition(0, 0);
    glutCreateWindow("Triangle turn");
    glutSpecialFunc(keyboardown);
    glutDisplayFunc(display);
    init();
    glutMainLoop()