Creating a 2D lighting demo app

We can start our lighting app by creating a new C file called lighting.c. The macros at the beginning of lighting.c are the same macros we used in glow.c, but we can remove the #define TWOPI macro because it is no longer needed. Here are the macros we will have in our lighting.c file:

#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>
#include <SDL_opengl.h>

#include <GLES3/gl3.h>
#include <stdlib.h>
#include <emscripten.h>

#define CANVAS_WIDTH 800
#define CANVAS_HEIGHT 600
#define FLOAT32_BYTE_SIZE 4
#define STRIDE FLOAT32_BYTE_SIZE*4

The vertex shader code in this file will be very similar to the vertex shader code we had in our glow.c file. The one change we will make is done by removing the u_translate uniform variable. We are doing this because we will be centering our shaded sprite image, and we will allow the user...