问在opengl中以单值纹理存储整数不起作用

EN

GLuint tex;
glGenTextures(1, &tex);

int time_horizon = 1000;
std::vector<decltype(time_horizon)> tex_vals(width * height * 4, time_horizon);
for (auto x: tex_vals)
  assert(x == time_horizon);


glBindTexture(GL_TEXTURE_2D, tex);
assert(glGetError() == 0);

glTexImage2D(GL_TEXTURE_2D, 0, GL_R32I, width, height, 0, GL_RED_INTEGER, GL_INT, tex_vals.data());

auto err = glGetError();
if (err) {
  std::cerr << "gl error is: " << err << '\n';
  exit(1);
}

decltype(time_horizon) test[static_cast<size_t>(width*height)];

glBindTexture(GL_TEXTURE_2D, tex);
glReadPixels(0, 0, width, height, GL_RED_INTEGER, GL_SHORT, test);

for (auto x: test) {
  std::cerr << x << '\n';
  assert(time_horizon == x);
}