OpenGL global variable changes

Next, we will need to update our OpenGL-related variables so that we can add three new global variables. We will need a new variable called glow_tex, which we will use to store a reference to the glow texture. We also need two new reference variables for our two new uniform variables in our shader, called u_time_location and u_glow_location. Here is what the new block of OpenGL variables will look like once we have added those three new lines:

GLuint program = 0;
GLuint texture;
GLuint glow_tex;

GLint a_texcoord_location = -1;
GLint a_position_location = -1;
GLint u_texture_location = -1;
GLint u_glow_location = -1;
GLint u_time_location = -1;

GLint u_translate_location = -1;
GLuint vertex_texture_buffer;