void initSkybox(){


    //skybox top
    glGenTextures(1, &skybox[1]);
    glBindTexture(GL_TEXTURE_2D, skybox[1]);
    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
    imag.LoadBmpFile("skybox/skyrender0002.bmp");
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB,
                 imag.GetNumCols(),
                 imag.GetNumRows(), 0, GL_RGB, GL_UNSIGNED_BYTE,
                 imag.ImageData());

    //skybox right
    glGenTextures(1, &skybox[2]);
    glBindTexture(GL_TEXTURE_2D, skybox[2]);
    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
    imag.LoadBmpFile("skybox/skyrender0003.bmp");
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB,
                 imag.GetNumCols(),
                 imag.GetNumRows(), 0, GL_RGB, GL_UNSIGNED_BYTE,
                 imag.ImageData());

    //skybox left
    glGenTextures(1, &skybox[3]);
    glBindTexture(GL_TEXTURE_2D, skybox[3]);
    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
    imag.LoadBmpFile("skybox/skyrender0005.bmp");
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB,
                 imag.GetNumCols(),
                 imag.GetNumRows(), 0, GL_RGB, GL_UNSIGNED_BYTE,
                 imag.ImageData());

    //skybox front
    glGenTextures(1, &skybox[4]);
    glBindTexture(GL_TEXTURE_2D, skybox[4]);
    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
    imag.LoadBmpFile("skybox/skyrender0001.bmp");
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB,
                 imag.GetNumCols(),
                 imag.GetNumRows(), 0, GL_RGB, GL_UNSIGNED_BYTE,
                 imag.ImageData());

    //skybox back
    glGenTextures(1, &skybox[5]);
    glBindTexture(GL_TEXTURE_2D, skybox[5]);
    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
    imag.LoadBmpFile("skybox/skyrender0004.bmp");
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB,
                 imag.GetNumCols(),
                 imag.GetNumRows(), 0, GL_RGB, GL_UNSIGNED_BYTE,
                 imag.ImageData());

}

//================================================================================
//================== OBJECTOS
//================================================================================

void drawSkybox(){
    glPushMatrix();
    glTranslatef (0, 0, 100);

    glEnable(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D,skybox[4]);
    glColor3f(1.0,1.0,1.0);

    glBegin(GL_POLYGON);//back
    glTexCoord2f(1.0f,0.0f);  glVertex3f(200, 0, 0);
    glTexCoord2f(0.0f,0.0f);  glVertex3f(-200, 0, 0);
    glTexCoord2f(0.0f,1.0f);  glVertex3f(-200, 200, 0);
    glTexCoord2f(1.0f,1.0f);  glVertex3f(200, 200, 0);
    glEnd();

    glDisable(GL_TEXTURE_2D);
    glEnable(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D,skybox[2]);

    glBegin(GL_POLYGON);//top
    glTexCoord2f(0.0f,0.0f);glVertex3f(200, 200, 0);
    glTexCoord2f(0.0f,1.0f);glVertex3f(-200, 200, 0);
    glTexCoord2f(1.0,1.0f);glVertex3f(-200, 200, -200);
    glTexCoord2f(1.0,0.0);glVertex3f(200, 200, -200);
    glEnd();

    glDisable(GL_TEXTURE_2D);
    glEnable(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D,skybox[3]);

    glBegin(GL_POLYGON);
    glTexCoord2f(0.0f,0.0f);  glVertex3f(-200, 0, -200);
    glTexCoord2f(1.0f,0.0f);  glVertex3f(-200, 0, 0);
    glTexCoord2f(1.0f,1.0f);  glVertex3f(-200, 200, 0);
    glTexCoord2f(0.0f,1.0f);  glVertex3f(-200, 200, -200);
    glEnd();

    glDisable(GL_TEXTURE_2D);
    glEnable(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D,skybox[1]);

    glBegin(GL_POLYGON);
    glTexCoord2f(1.0f,0.0f);glVertex3f(200, 0, -200);
    glTexCoord2f(0.0f,0.0f);glVertex3f(200, 0, 0);
    glTexCoord2f(0.0f,1.0f);glVertex3f(200, 200, 0);
    glTexCoord2f(1.0f,1.0f);glVertex3f(200, 200, -200);
    glEnd();

    glDisable(GL_TEXTURE_2D);
    glEnable(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D,skybox[5]);

    glBegin(GL_POLYGON);
    glTexCoord2f(0.0f,0.0f);  glVertex3f(200, 0, -200);
    glTexCoord2f(1.0f,0.0f);  glVertex3f(-200, 0, -200);
    glTexCoord2f(1.0f,1.0f);  glVertex3f(-200, 200, -200);
    glTexCoord2f(0.0f,1.0f);  glVertex3f(200, 200, -200);
    glEnd();
    glDisable(GL_TEXTURE_2D);

    glPopMatrix();
}