139 lines
4.6 KiB
C++
139 lines
4.6 KiB
C++
// =====================================================================================================================
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// fennec, a free and open source game engine
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// Copyright © 2025 Medusa Slockbower
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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// =====================================================================================================================
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#ifndef FENNEC_PLATFORM_INTERFACE_PLATFORM_H
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#define FENNEC_PLATFORM_INTERFACE_PLATFORM_H
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#include <fennec/containers/list.h>
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#include <fennec/fproc/strings/cstring.h>
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#include <fennec/fproc/strings/string.h>
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#include <fennec/platform/interface/fwd.h>
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/*
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* This class should resemble the target platform as a whole. By itself, it will represent the OS, i.e. Linux, Windows,
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* etc.
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*
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* We want everything to be type agnostic from the top level down
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*
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* The general structure is:
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* Platform -> Display Protocol -> GFX API -> GFX Context
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* -> Window -> GFX Surface
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* -> Input Protocol
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*
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* For example, let's say we are on Linux, using Wayland and OpenGL with EGL
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* EGL will know that we are using OpenGL, but won't know we are using Wayland
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* OpenGL won't know or care that Linux, EGL, or Wayland is being used
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* Wayland won't know or care that OpenGL or EGL is being used
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* Linux won't know or care that OpenGL, Wayland, or EGL are in use
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*
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* Why do we want everything to be type agnostic?
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* Let's say someone wants to add a DirectX extension for Windows. They shouldn't have to touch the
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* Windows platform class or Win32 display manager class at all to write the implementation. This
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* allows the extension to remain entirely independent of the engine which allows you to just drop
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* it into your project, and it will work as expected. This should also keep version compatibility
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* issues to the absolute minimum.
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*
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* We can allow this by notifying the platform of all available drivers at startup and give them priorities.
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* Then, the platform will load the highest priority first, only falling back when a driver fails to load or is
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* deemed incompatible for whatever reason.
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*
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*
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*/
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namespace fennec
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{
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class platform {
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public:
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using shared_object = struct shared_object;
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using symbol = void*;
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const string name;
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virtual ~platform() = default;
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// Dynamically linked objects
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virtual shared_object* load_object(const cstring& file) = 0;
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virtual void unload_object(shared_object* obj) = 0;
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virtual symbol find_symbol(shared_object* obj, const cstring& name) = 0;
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virtual void initialize(); // Initialize Drivers and Contexts
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virtual void shutdown(); // Close Drivers and Contexts
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display* get_display() { return _display; }
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protected:
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explicit platform(const cstring& name)
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: name(name) {
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auto& globals = _get_globals();
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assertf(globals.singleton == nullptr, "Conflicting Platform Definitions.");
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globals.singleton = this;
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}
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virtual void load_display();
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display* _display;
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private:
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platform(const platform&) = delete;
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// Static Stuff ========================================================================================================
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public:
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using display_ctor = display* (*)(platform*);
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using input_ctor = inputdevice* (*)(display*);
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using gfxctx_ctor = gfxcontext* (*)(display*);
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template<typename ctor>
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struct driver {
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int priority;
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ctor constructor;
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};
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static void add_driver(display_ctor ctor, int priority);
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static void add_driver(input_ctor ctor, int priority);
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static void add_driver(gfxctx_ctor ctor, int priority);
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private:
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struct global_context {
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platform* singleton;
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list<driver<display_ctor>> displays;
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list<driver<input_ctor>> inputs;
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list<driver<gfxctx_ctor>> graphics;
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global_context()
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: singleton(nullptr) {
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}
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};
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static global_context& _get_globals();
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public:
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static const global_context& get_globals() {
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return _get_globals();
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}
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static platform* instance() {
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return _get_globals().singleton;
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}
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};
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}
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#endif // FENNEC_PLATFORM_INTERFACE_PLATFORM_H
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