SDL: Emscripten works well using the normal CMake workflow

From 74536243dde05fb033d8079bfe8fae2c037e41e6 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Wed, 22 Jan 2025 12:56:32 -0800
Subject: [PATCH] Emscripten works well using the normal CMake workflow

---
 docs/INTRO-emscripten.md | 45 +++++++++++++++++++++++++---------------
 1 file changed, 28 insertions(+), 17 deletions(-)

diff --git a/docs/INTRO-emscripten.md b/docs/INTRO-emscripten.md
index 89831248cc823..a3f3572cf1bbc 100644
--- a/docs/INTRO-emscripten.md
+++ b/docs/INTRO-emscripten.md
@@ -1,35 +1,46 @@
 
 # Introduction to SDL with Emscripten
 
+The easiest way to use SDL is to include it as a subproject in your project.
+
+We'll start by creating a simple project to build and run [hello.c](hello.c)
+
 First, you should have the Emscripten SDK installed from:
 
 https://emscripten.org/docs/getting_started/downloads.html
 
-We'll start by creating a simple project to build and run [hello.c](hello.c)
+Create the file CMakeLists.txt
+```cmake
+cmake_minimum_required(VERSION 3.16)
+project(hello)
 
-## Building SDL
+# set the output directory for built objects.
+# This makes sure that the dynamic library goes into the build directory automatically.
+set(CMAKE_RUNTIME_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/$<CONFIGURATION>")
+set(CMAKE_LIBRARY_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/$<CONFIGURATION>")
 
-Once you have a command line interface with the Emscripten SDK set up and you've changed directory to the SDL directory, you can build SDL like this:
+# This assumes the SDL source is available in vendored/SDL
+add_subdirectory(vendored/SDL EXCLUDE_FROM_ALL)
 
-```sh
-mkdir hello
-cd hello
-emcmake cmake ..
-emmake make
-```
+# on Web targets, we need CMake to generate a HTML webpage. 
+if(EMSCRIPTEN)
+  set(CMAKE_EXECUTABLE_SUFFIX ".html" CACHE INTERNAL "")
+endif()
 
-## Building your app
+# Create your game executable target as usual
+add_executable(hello WIN32 hello.c)
 
-In this case we'll just run a simple command to compile our source with the SDL library we just built:
-```sh
-emcc -o index.html ../docs/hello.c -I../include -L. -lSDL3
+# Link to the actual SDL3 library.
+target_link_libraries(hello PRIVATE SDL3::SDL3)

-## Running your app

-You can now run your app by pointing a webserver at your build directory and connecting a web browser to it.
+sh +emcmake cmake -S . -B build +cd build +emmake make +

-## More information
+You can now run your app by pointing a webserver at your build directory and connecting a web browser to it, opening hello.html.

A more complete example is available at: