Move a Triangle through glTranslated

Good morning dear friends, I apologize for my ignorance, but what is happening in my code, because I can only move once in my triangle, by pressing the key, I need to always move to the left side …
I’m a rookie myself, please help me …


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

typedef struct {
    GLint x,y;
}ponto;

void desenha();
void inicializacao();
void GerenciaTeclado(unsigned char key, int x, int y);
void desenha_triangulo();
int main(int argc, char **argv){

    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGBA);
    glutInitWindowSize(800,600);
    glutInitWindowPosition(0,0);
    glutCreateWindow("Trabalho 1");
    glutKeyboardFunc(GerenciaTeclado);
    inicializacao();
    glutDisplayFunc(desenha);
    glutMainLoop();
    return 0;
}

void inicializacao(void){

    glClearColor(1.0f,1.0f,1.0f,1.0f); // cor de fundo branca
    glPointSize(8.0); // tamanho dos pontos de cada pixels
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(0,800,0,600);
    glLineWidth(4.0);
}

void desenha(){
    glClear(GL_COLOR_BUFFER_BIT);
    glColor3f(1.0,0.1,0.1);
    desenha_triangulo();
}

void desenha_triangulo(){

    //desenha um retangulo vermelho
    glBegin(GL_TRIANGLES);
        glVertex2i(100,100);
        glVertex2i(200,200);
        glVertex2i(300,100);
    glEnd();
    glFlush();   //envia toda a saída para a exibição
}


void GerenciaTeclado(unsigned char key, int x, int y){
    printf("Tecla Pressionada %d
",key);
    if ((key == 97) || (key ==65)){ // tecla A mover para a esquerda

        glPushMatrix();
        glTranslated(-20,0,1.0); // translação de -10 para mover para a esquerda
        desenha();
        glPopMatrix();
       // glutPostRedisplay();
    }
}


It won’t be storing the value of the matrix, you’ll need to store the translation in a float and increment it and then use that.