[GDNative] Creating Example library

README.md

@@ -1,2 +1,108 @@
 # cpp_bindings
 C++ bindings for the Godot script API
+
+# Creating a GDNative library (Linux)
+Create a director named `SimpleLibrary` with subdirector `lib, src`
+
+Getting latest `cpp_bindings` and `godot_headers`
+```
+$ cd SimpleLibrary
+$ git clone https://github.com/GodotNativeTools/cpp_bindings
+$ git clone https://github.com/GodotNativeTools/godot_headers
+```
+right now our file structure should look like this
+```
+[SimpleLibrary]
+	├── cpp_bindings/
+	├── godot_headers/
+	├── lib/
+	└── src/
+```
+
+Now to generate cpp bindings
+```
+$ cd cpp_bindings
+```
+
+Edit `SConstruct` file and assign your godot executable path at line:7 `godot_bin_path = "../godot_fork/bin/"`,
+
+Building core/bindings, (`libgodot_cpp_core.so` , `libgodot_cpp_bindings.so`)
+```
+$ scons p=linux
+$ scons p=linux target=bindings generate_bindings=yes
+```
+resulting libraries will be placed under `bin/` and generated bindings will be found under `includes/*`
+
+Note: Use `use_llvm=yes` to use clang.
+
+copy Core && Bindings librarys into `SimpleLibrary/lib` folder
+```
+$ cd ..
+$ cp cpp_bindings/bin/libgodot_cpp_core.so lib/
+$ cp cpp_bindings/bin/libgodot_cpp_bindings.so lib/
+```
+And our file structure will be
+```
+[SimpleLibrary]
+  ├── cpp_bindings/
+  ├── godot_headers/
+  ├── lib/
+  │       ├── libgodot_cpp_core.so
+  │       ├── libgodot_cpp_bindings.so
+  └── src/
+```
+
+# Creating simple class
+
+Create `init.cpp` under `SimpleLibrary/src/` and add the following code
+```
+#include <godot.h>
+
+#include <core/Godot.hpp>
+#include <core/GodotGlobal.hpp>
+#include <Reference.hpp>
+
+using namespace godot;
+
+class SimpleClass : public GodotScript<Reference> {
+        GODOT_CLASS(SimpleClass);
+public:
+        SimpleClass() { }
+
+        void test_void_method() {
+                Godot::print("This is test");
+        }
+
+        Variant method(Variant arg) {
+            Variant ret;
+            ret = arg;
+
+            return ret;
+        }
+
+        static void _register_methods() {
+           register_method("method", &SimpleClass::method);
+        }
+};
+
+GODOT_NATIVE_INIT(godot_native_init_options *options) {
+        register_class<SimpleClass>();
+}
+```
+
+# Compiling
+```
+$ cd ..
+$ clang -fPIC -o src/init.os -c src/init.cpp -g -O3 -std=c++14 -Icpp_bindings/include -Igodot_headers -Icpp_bindings/include/core
+$ clang -o lib/libtest.so -shared src/init.os -Llib -lgodot_cpp_core -lgodot_cpp_bindings
+```
+This creates the file `libtest.so` in your `SimpleLibrary/lib` directory. For windows you need to find out what compiler flags need to be used.
+
+# Creating `.gdn` file
+follow [godot_header/README.md](https://github.com/GodotNativeTools/godot_headers/blob/master/README.md) file to create the `.gdn`
+
+# Implementing with gdscript
+```
+var simpleclass = load("res://simpleclass.gdn").new();
+simpleclass.method("Test argument");
+```