add plugin mini-HOWTO

plugin_mini_howto.md

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+
+# Plugin Mini-HowTo
+
+
+## How to add new modules to VeeSeeVSTRack via dynamically loaded plugin DLLs
+
+( $(PLUGINNAME) refers to the plugin's name, e.g. "my_unique_plugin_name". $(MODULENAME) refers to the respective module name, e.g. "my_lfo" )
+
+1. Either clone the GitHub repo OR download the [precompiled plugin SDK](README.md#dynamically-loaded-plugins-via-plugin-sdk)
+
+2. Study the [template_shared](plugins/community/repos/Template_shared) example plugin (also included in the plugin SDK) (you may also want to take a look at my `bsp` plugin, which is also loaded dynamically). Also take a look at `include/plugin.hpp`.
+
+3. Develop your module (!). Don't forget to pick a suitable license, e.g. [MIT](https://opensource.org/licenses/MIT)
+
+4. Compile the plugin DLL using Microsoft Visual Studio (on Windows), or GCC (on Linux)
+
+5. Create a folder for your plugin, i.e. `vst2_bin/plugins/$(PLUGINNAME)/`
+
+6. Duplicate the plugin DLL file and name them `plugin.dll.fx` and `plugin.dll.instr`
+
+7. Copy the DLLs to `vst2_bin/plugins/$(PLUGINNAME)/`
+
+8. Copy the plugin's assets (.svg files, readme, license, example patches) to `vst2_bin/plugins/$(PLUGINNAME)/`
+
+9. Test and debug :-)
+
+
+## Porting modules written for Rack v0.6
+
+The steps are similar, here are some porting hints:
+
+1. Do _not_ use static variables or members in your plugin. (Never ever !)
+
+2. Use the `RACK_PLUGIN_MODEL_DECLARE`, `RACK_PLUGIN_INIT`, `RACK_PLUGIN_INIT_ID`, `RACK_PLUGIN_INIT_VERSION`, `RACK_PLUGIN_INIT_WEBSITE`, `RACK_PLUGIN_MODEL_ADD` macros (see example code for details)
+
+3. Remove the `extern Plugin *plugin;` and `extern Model *modelXYZ;` declarations from the plugin's global include file
+
+4. Add the following to your global plugin include file:
+~~~
+RACK_PLUGIN_DECLARE($(PLUGINNAME));
+
+#if defined(USE_VST2) && !defined(RACK_PLUGIN_SHARED)
+#define plugin "$(PLUGINNAME)"
+#endif // USE_VST2
+~~~
+
+(the "plugin" define is mainly used to build asset path names, i.e. in `assetPlugin()` calls)
+
+5. Rewrite the static modules initializations (`Model *model$(MODULENAME)> = Model::create<..>(..);`) as functions:
+~~~
+RACK_PLUGIN_MODEL_INIT($(PLUGINNAME), $(MODULENAME)) {
+   Model *model = Model::create<$(MODULENAME), $(MODULENAME)Widget>("cf", "$(MODULENAME)", "$(MODULEDISPLAYNAME)", ..);
+   return model;
+}
+~~~
+
+6. Replace all references to Rack internal global vars with macro calls:
+     - `gRackScene` => `RACK_PLUGIN_UI_RACKSCENE`
+     - `gRackWidget` => `RACK_PLUGIN_UI_RACKWIDGET`
+     - `gToolbar` => `RACK_PLUGIN_UI_TOOLBAR`
+     - `gDraggedWidget` => `RACK_PLUGIN_UI_DRAGGED_WIDGET`
+     - `gHoveredWidget` => `RACK_PLUGIN_UI_HOVERED_WIDGET`
+     - `gDragHoveredWidget` => `RACK_PLUGIN_UI_DRAGHOVERED_WIDGET`
+     - `gFocusedWidget` => `RACK_PLUGIN_UI_FOCUSED_WIDGET` / `RACK_PLUGIN_UI_FOCUSED_WIDGET_SET`
+
+7. On Windows: Fix any remaining MSVC compile errors (Rack modules were originally written for GCC and some use GCC-specific features like dynamically sized local arrays).
+
+
+## Statically linked plugins
+
+Statically linking a plugin to the VSVR VST is a bit trickier. You need to make sure that all linker symbols are unique, i.e. you may need to place the plugin code in its own namespace.
+There are dozens of examples for this in the GitHub repo so please study them if you want to do that.
+
+Otherwise stick to dynamically loaded plugins. They are much easier to handle and do not require the entire GitHub repo to be checked out / built. They also do _not_ require the VST2.4 SDK.
+
+
+Happy Hacking !