sdl12-compat: README: more details on building.

From 4ff7b6373339d74be2d78a2274f183e70767b1d8 Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Fri, 25 Feb 2022 15:22:29 -0500
Subject: [PATCH] README: more details on building.

--- | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/ b/
index afdfedd..a697059 100644
--- a/
+++ b/
@@ -47,6 +47,12 @@ You'll need to use CMake to build sdl12-compat. Download at
 Please refer to the [CMake documentation](
 for complete details, as platform and build tool details vary.
+You'll need a copy of SDL 2.0.x to build sdl12-compat, because we need the
+SDL2 headers. You can build this from source or install from a package
+manager. Windows and Mac users can download prebuilt binaries from
+[SDL's download page](; make sure you
+get the "development libraries" and not "runtime binaries" there.
 Now just point CMake at sdl12-compat's directory. Here's a command-line
@@ -58,8 +64,16 @@ cmake --build build
 On Windows or macOS, you might prefer to use CMake's GUI, but it's the same
 idea: give it the directory where sdl12-compat is located, click "Configure,"
-choose your favorite compiler, then click "Generate." Then you can build
-however you like with Visual Studio, Xcode, etc.
+choose your favorite compiler, then click "Generate." Now you have project
+files! Click "Open Project" to launch your development environment. Then you
+can build however you like with Visual Studio, Xcode, etc.
+If necessary, you might have to fill in the location of the SDL2 headers
+when using CMake. sdl12-compat does not need SDL2's library to _build_,
+just its headers (although it may complain about the missing library,
+you can ignore that). From the command line, add
+`-DSDL2_INCLUDE_DIR=/path/to/SDL2/include`, or find this in the CMake
+GUI and set it appropriately, click "Configure" again, and then "Generate."
 When the build is complete, you'll have a shared library you can drop in
 as a replacement for an existing SDL 1.2 build. This will also build