glTexImage2D(GL_TEXTURE_2D, 0, GL_R8, width, height, 0, GL_RED, GL_UNSIGNED_BYTE, NULL);
check_error();
glTexImage2D(GL_TEXTURE_2D, 0, GL_R8, width, height, 0, GL_RED, GL_UNSIGNED_BYTE, NULL);
check_error();
glTexImage2D(GL_TEXTURE_2D, 0, GL_RG8, width / 2, height, 0, GL_RG, GL_UNSIGNED_BYTE, NULL);
check_error();
glTexImage2D(GL_TEXTURE_2D, 0, GL_RG8, width / 2, height, 0, GL_RG, GL_UNSIGNED_BYTE, NULL);
check_error();