raylib-cpp-template/docs/MakefileExplanation.md
2020-12-25 15:43:26 +11:00

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# How the Makefile Works
This document attempts to explain how the project's build-system works, as well as general concepts in Makefile. It was created with the intention to help newcomers to C/C++ and Make understand how everything in the project is done, so that they can even dive in and make changes of their own if necessary.
### Contents
- [Macro Definitions](#macro-definitions)
- [Custom Functions](#custom-functions)
- [Global Macros](#global-macros)
- [Platform-Specific Macros](#platform-specific-macros)
- [Targets](#targets)
- [setup](#setup)
- [all](#all)
- [.PHONY](#phony)
## Macro Definitions
#### This section is still being written
### Custom Functions
Some text
```Makefile
rwildcard = $(wildcard $1$2) $(foreach d,$(wildcard $1*),$(call rwildcard,$d/,$2))
platformpth = $(subst /,$(PATHSEP),$1)
```
### Global Macros
Some text
```Makefile
buildDir := bin
executable := app
target := $(buildDir)/$(executable)
sources := $(call rwildcard,src/,*.cpp)
objects := $(patsubst src/%, $(buildDir)/%, $(patsubst %.cpp, %.o, $(sources)))
depends := $(patsubst %.o, %.d, $(objects))
compileFlags := -std=c++17 -I include
linkFlags = -L lib/$(platform) -l raylib
```
### Platform-Specific Macros
Some text
```Makefile
ifeq ($(OS), Windows_NT)
# Set Windows macros
platform := Windows
CXX ?= g++
linkFlags += -Wl,--allow-multiple-definition -pthread -lopengl32 -lgdi32 -lwinmm -mwindows
libGenDir := src
THEN := &&
PATHSEP := \$(BLANK)
MKDIR := -mkdir
RM := -del /q
COPY = -robocopy "$(call platformpth,$1)" "$(call platformpth,$2)" $3
else
# Check for MacOS/Linux
UNAMEOS := $(shell uname)
ifeq ($(UNAMEOS), Linux)
# Set Linux macros
platform := Linux
CXX ?= g++
linkFlags += -l GL -l m -l pthread -l dl -l rt -l X11
endif
ifeq ($(UNAMEOS), Darwin)
# Set macOS macros
platform := macOS
CXX ?= clang++
linkFlags += -framework CoreVideo -framework IOKit -framework Cocoa -framework GLUT -framework OpenGL
libGenDir := src
endif
# Set UNIX macros
THEN := ;
PATHSEP := /
MKDIR := mkdir -p
RM := rm -rf
COPY = cp $1$(PATHSEP)$3 $2
endif
```
## Targets
This section describes most of the Makefile's functionality target-by-target, where we explain how they each execute step-by-step.
### setup
The first target we get you to call before building the project is `setup`, which essentially pulls in all raylib and raylib-cpp dependencies, and then formats the project file structure.
As you can see below, the target simply depends on two sub-targets, `include` and `lib`:
```Makefile
setup: include lib
```
However, looking at `include`, we can see that it depends on `submodules`, so we'll look at that first.
```Makefile
include: submodules
...
```
`submodules` is a very simple target that will update the git submodules in the project recursively, pulling in the current raylib-cpp repository under the `/vendor` directory and then raylib itself under its own `/vendor` directory. The reason for this, is to make sure that the pulled versions of raylib and the bindings match in version. You can [read more about git submodules here](https://git-scm.com/book/en/v2/Git-Tools-Submodules).
```Makefile
submodules:
git submodule update --init --recursive
```
Having satisfied `submodules` and now returning to `include`, we can being to run its body (as can be seen below).
It begins by creating the `/include` directory (converting the directory path for Windows if necessary with the custom `platformpth` function) if it doesn't already exist.
Next, the target proceeds to call another custom function, `COPY` (a platform agnostic copy command), manually copying `raylib.h` and `raymath.h` from raylib's source code, and all files ending with `.hpp` from raylib-cpp's source code, into the newly created `/include` directory.
```Makefile
include: submodules
$(MKDIR) $(call platformpth, ./include)
$(call COPY,vendor/raylib-cpp/vendor/raylib/src,./include,raylib.h)
$(call COPY,vendor/raylib-cpp/vendor/raylib/src,./include,raymath.h)
$(call COPY,vendor/raylib-cpp/include,./include,*.hpp)
```
Finally, we move on to `lib`, which also depends on `submodules`, however because submodules has already run, it will not run again.
Next, we create the `/lib` directory (and a subdirectory for your current platform) if it doesn't already exist using the same method as above.
Moving on to the body of the target, we move into raylib's `/src` directory and immediately run Make on raylib. Once complete, this results in the creation of a static library file named `libraylib.a` (*which will appear in slightly different directories based on the platform you build it in for whatever reason...*).
To complete the target, it then copies that library file into the relevant directory for your platform under `/lib`.
```Makefile
lib: submodules
cd vendor/raylib-cpp/vendor/raylib/src $(THEN) "$(MAKE)" PLATFORM=PLATFORM_DESKTOP
$(MKDIR) $(call platformpth, lib/$(platform))
$(call COPY,vendor/raylib-cpp/vendor/raylib/$(libGenDir),lib/$(platform),libraylib.a)
```
Once all of these targets have been fulfilled, `setup` ends and your project should now contain a copy of the relevant static library for your platform in `/lib`, and all the necessary header files under `/include`.
### all
#### This section is still being written
### .PHONY
#### This section is still being written
```Makefile
.PHONY: all setup submodules execute clean
```