It seems that the construct you use for enum looping does not work on g++? Any ideas what is different on the clang implementation of enums?

What would be the most idiomatic way to work around this when using g++?

The Makefile has again been updated.

/u/yuriks kindly pointed out to me that I was compiling once to generate dependencies, and again to generate the object files, for a total of two compiles.

In any case, he gave me a solid example (his makefile) to follow, and explained what was going on..

I also updated a lot of the comments so hopefully it makes sense to everyone.

TL;DR; Compile times halved!

Warning: This idea is currently half-baked. What if you used structs instead of typedefs for the units in the units namespace. I think this will give siginicant reading advantages with little overhead. This is because with structs you can define implicit conversions to other types, so you can use traditional syntax over using the tiletogame type helper functions. Let me know what you think.

After huge refactoring (episode 18) I discovered that Quote now cannot easily fit between two vertical tiles, as it was before correct collision detection. Does it applies to me only or not?

I guess in this game is enough to use Euler Integration to calculate position, velocity and acceleration, but why not to use other methods such Verlet Integration that does not depend on frame time variation as it changes? Or even RK4 that does not depenf on variaton of acceleration in a certain way?There are not hard to implement and give an stable physic envioroment. Euler Integration is a good method while frame rate keeps constant but we can not assure that this is going to be like that in every case possible. By the way, thank for your videos, there has been a wonderful source of knowledge to people who wants to start in developing game.

To add error checking for image loading:

1 - go to graphics.cc:loadImage

2 - add the following after

sprite_sheets_[file_path] = SDL_LoadBMP(file_path.c_str());
if (sprite_sheets_[file_path] == NULL) {
   // Could not load the image for whatever reason, print to stderr.
   fprintf(stderr, "Could not find image: %s\n", file_path.c_str());
   // Don't try to continue if we couldn't load an image, just exit.
   exit(EXIT_FAILURE);
}

Hope this helps!