Fixed OpenGL detection issues

- Removed an assumption that application will always run using OpenGL 3
- Added support for ES 2/3
- MacOS builds should now be compatible with lower OS versions (Starting with 10.13, High Sierra)

.ci/build.py

@@ -2,11 +2,18 @@
 
 import os
 from subprocess import run
+from sys import platform
 
 if not os.path.exists('_build'):
     os.makedirs('_build')
 
 kwargs = {'cwd': '_build', 'check': True}
-run(['conan', 'install', '..', '-b', 'missing', '-s', 'compiler.cppstd=17'], **kwargs)
+install_args = ['conan', 'install', '..', '-b', 'missing', '-s', 'compiler.cppstd=17']
+
+if platform == 'darwin':
+    # Build for High Sierra and x64
+    install_args.extend(['-s', 'os.version=10.13', '-s', 'arch=x86_64'])
+
+run(install_args, **kwargs)
 run(['conan', 'build', '..'], **kwargs)
 run(['cpack', '-G', 'ZIP'], **kwargs)

CMakeLists.txt

@@ -51,6 +51,15 @@ target_sources(serial-plotter PRIVATE
 
    src/inputs/serial.cpp
    src/inputs/data.cpp
+
+   src/render/backend.cpp
+   src/render/frontend.cpp
+   src/render/opengl2.cpp
+   src/render/opengl3.cpp
+   src/render/gles2.cpp
+   src/render/gles3.cpp
+   src/render/detail/imgui_impl_sdl_es2.cpp
+   src/render/detail/imgui_impl_sdl_es3.cpp
 )
 
 set_target_properties(serial-plotter
@@ -63,9 +72,11 @@ set_target_properties(serial-plotter
        SOVERSION 0
 )
 
+find_package(OpenGL REQUIRED)
 target_link_libraries(serial-plotter PUBLIC
    ${CONAN_LIBS_SDL2} ${CONAN_LIBS_GLAD}
-   imgui::opengl3 imgui::sdl implot::implot Boost::program_options
+   imgui::opengl2 imgui::opengl3
+   OpenGL::GL imgui::sdl implot::implot Boost::program_options
 )
 
 target_include_directories(serial-plotter SYSTEM

conanfile.py

@@ -26,7 +26,4 @@ def build(self):
     def configure(self):
         self.options['glad'].spec = 'gl'
         self.options['glad'].gl_profile = 'core'
-        if self.settings.os in ['Android', 'iOS']:
-            self.options['glad'].gles2_version = '3.0'
-        else:
-            self.options['glad'].gl_version = '3.2'
+        self.options['glad'].gl_version = '3.2'

include/asp/render/backend.h

@@ -0,0 +1,38 @@
+/**
+ * @file   backend.h
+ * @author Dennis Sitelew
+ * @date   Sep. 14, 2021
+ */
+#ifndef INCLUDE_ASP_RENDER_BACKEND_H
+#define INCLUDE_ASP_RENDER_BACKEND_H
+
+#include <memory>
+
+namespace asp::render {
+
+enum class version { opengl2 = 2, opengl3 = 3, gles2 = 20, gles3 = 30 };
+
+class frontend;
+
+class backend {
+public:
+   backend(frontend &v)
+      : frontend_{&v} {}
+
+   virtual ~backend() = default;
+
+public:
+   virtual void init() = 0;
+   virtual void new_frame() = 0;
+   virtual void render() = 0;
+   virtual version get_version() = 0;
+
+   static std::unique_ptr<backend> make(version v, frontend &f);
+
+protected:
+   frontend *frontend_;
+};
+
+} // namespace asp::render
+
+#endif /* INCLUDE_ASP_RENDER_BACKEND_H */

include/asp/render/detail/imgui_impl_sdl_es2.h

@@ -0,0 +1,26 @@
+// ImGui SDL2 binding with OpenGL2
+// In this binding, ImTextureID is used to store an OpenGL 'GLuint' texture identifier. Read the FAQ about ImTextureID in imgui.cpp.
+
+// You can copy and use unmodified imgui_impl_* files in your project. See main.cpp for an example of using this.
+// If you use this binding you'll need to call 4 functions: ImGui_ImplXXXX_Init(), ImGui_ImplXXXX_NewFrame(), ImGui::Render() and ImGui_ImplXXXX_Shutdown().
+// If you are new to ImGui, see examples/README.txt and documentation at the top of imgui.cpp.
+// https://github.com/ocornut/imgui
+
+#ifndef IMGUI_IMPL_SDL_ES2
+#define IMGUI_IMPL_SDL_ES2
+
+#include <imgui.h>
+
+struct SDL_Window;
+typedef union SDL_Event SDL_Event;
+
+IMGUI_API bool        ImGui_ImplSdlGLES2_Init();
+IMGUI_API void        ImGui_ImplSdlGLES2_Shutdown();
+IMGUI_API void        ImGui_ImplSdlGLES2_NewFrame(SDL_Window* window);
+IMGUI_API void        ImGui_ImplSdlGLES2_RenderDrawLists(ImDrawData* draw_data);
+
+// Use if you want to reset your rendering device without losing ImGui state.
+IMGUI_API void        ImGui_ImplSdlGLES2_InvalidateDeviceObjects();
+IMGUI_API bool        ImGui_ImplSdlGLES2_CreateDeviceObjects();
+
+#endif // IMGUI_IMPL_SDL_ES2

include/asp/render/detail/imgui_impl_sdl_es3.h

@@ -0,0 +1,26 @@
+// ImGui SDL2 binding with OpenGL3
+// In this binding, ImTextureID is used to store an OpenGL 'GLuint' texture identifier. Read the FAQ about ImTextureID in imgui.cpp.
+
+// You can copy and use unmodified imgui_impl_* files in your project. See main.cpp for an example of using this.
+// If you use this binding you'll need to call 4 functions: ImGui_ImplXXXX_Init(), ImGui_ImplXXXX_NewFrame(), ImGui::Render() and ImGui_ImplXXXX_Shutdown().
+// If you are new to ImGui, see examples/README.txt and documentation at the top of imgui.cpp.
+// https://github.com/ocornut/imgui
+
+#ifndef IMGUI_IMPL_SDL_ES3
+#define IMGUI_IMPL_SDL_ES3
+
+#include <imgui.h>
+
+struct SDL_Window;
+typedef union SDL_Event SDL_Event;
+
+IMGUI_API bool        ImGui_ImplSdlGLES3_Init();
+IMGUI_API void        ImGui_ImplSdlGLES3_Shutdown();
+IMGUI_API void        ImGui_ImplSdlGLES3_NewFrame(SDL_Window* window);
+IMGUI_API void        ImGui_ImplSdlGLES3_RenderDrawLists(ImDrawData* draw_data);
+
+// Use if you want to reset your rendering device without losing ImGui state.
+IMGUI_API void        ImGui_ImplSdlGLES3_InvalidateDeviceObjects();
+IMGUI_API bool        ImGui_ImplSdlGLES3_CreateDeviceObjects();
+
+#endif // IMGUI_IMPL_SDL_ES3

include/asp/render/frontend.h

@@ -0,0 +1,40 @@
+/**
+ * @file   frontend.h
+ * @author Dennis Sitelew
+ * @date   Sep. 14, 2021
+ */
+#ifndef INCLUDE_ASP_RENDER_FRONTEND_H
+#define INCLUDE_ASP_RENDER_FRONTEND_H
+
+#include <SDL2/SDL.h>
+
+#include <memory>
+#include <string>
+
+namespace asp::render {
+
+class backend;
+
+class frontend {
+public:
+   frontend(SDL_Window &window, SDL_GLContext context);
+   ~frontend();
+
+public:
+   void new_frame();
+   void render();
+   void process_event(const SDL_Event &event);
+
+   const std::string &shader_version() const { return shader_version_; }
+
+   SDL_Window &window() { return *window_; }
+
+private:
+   SDL_Window *window_;
+   std::unique_ptr<backend> backend_;
+   std::string shader_version_;
+};
+
+} // namespace asp::render
+
+#endif /* INCLUDE_ASP_RENDER_FRONTEND_H */

include/asp/render/gles2.h

@@ -0,0 +1,28 @@
+/**
+ * @file   gles2.h
+ * @author Dennis Sitelew
+ * @date   Sep. 14, 2021
+ */
+#ifndef INCLUDE_ASP_RENDER_GLES2_H
+#define INCLUDE_ASP_RENDER_GLES2_H
+
+#include <asp/render/backend.h>
+
+namespace asp::render {
+
+class GLES2 : public backend {
+public:
+   using backend::backend;
+   ~GLES2();
+
+public:
+   void init() override;
+   void new_frame() override;
+   void render() override;
+
+   version get_version() override { return version::gles2; }
+};
+
+} // namespace asp::render
+
+#endif /* INCLUDE_ASP_RENDER_GLES2_H */

include/asp/render/gles3.h

@@ -0,0 +1,28 @@
+/**
+ * @file   gles3.h
+ * @author Dennis Sitelew
+ * @date   Sep. 14, 2021
+ */
+#ifndef INCLUDE_ASP_RENDER_GLES3_H
+#define INCLUDE_ASP_RENDER_GLES3_H
+
+#include <asp/render/backend.h>
+
+namespace asp::render {
+
+class GLES3 : public backend {
+public:
+   using backend::backend;
+   ~GLES3();
+
+public:
+   void init() override;
+   void new_frame() override;
+   void render() override;
+
+   version get_version() override { return version::gles3; }
+};
+
+} // namespace asp::render
+
+#endif /* INCLUDE_ASP_RENDER_GLES3_H */

include/asp/render/opengl2.h

@@ -0,0 +1,28 @@
+/**
+ * @file   opengl2.h
+ * @author Dennis Sitelew
+ * @date   Sep. 14, 2021
+ */
+#ifndef INCLUDE_ASP_RENDER_OPENGL2_H
+#define INCLUDE_ASP_RENDER_OPENGL2_H
+
+#include <asp/render/backend.h>
+
+namespace asp::render {
+
+class OpenGL2 : public backend {
+public:
+   using backend::backend;
+   ~OpenGL2();
+
+public:
+   void init() override;
+   void new_frame() override;
+   void render() override;
+
+   version get_version() override { return version::opengl2; }
+};
+
+} // namespace asp::render
+
+#endif /* INCLUDE_ASP_RENDER_OPENGL2_H */

include/asp/render/opengl3.h

@@ -0,0 +1,28 @@
+/**
+ * @file   opengl3.h
+ * @author Dennis Sitelew
+ * @date   Sep. 14, 2021
+ */
+#ifndef INCLUDE_ASP_RENDER_OPENGL3_H
+#define INCLUDE_ASP_RENDER_OPENGL3_H
+
+#include <asp/render/backend.h>
+
+namespace asp::render {
+
+class OpenGL3 : public backend {
+public:
+   using backend::backend;
+   ~OpenGL3();
+
+public:
+   void init() override;
+   void new_frame() override;
+   void render() override;
+
+   version get_version() override { return version::opengl3; }
+};
+
+} // namespace asp::render
+
+#endif /* INCLUDE_ASP_RENDER_OPENGL3_H */

include/asp/ui/window.h

@@ -10,11 +10,13 @@
 
 #include <asp/inputs/data.h>
 #include <asp/inputs/serial.h>
+#include <asp/render/frontend.h>
 
 #include <SDL2/SDL.h>
 #include <imgui.h>
 #include <implot.h>
 #include <vector>
+#include <memory>
 
 namespace asp {
 
@@ -56,7 +58,9 @@ class window {
    bool stop_{false};
 
    SDL_Window *window_{nullptr};
+   SDL_GLContext context_;
    SDL_Event event_{};
+   std::unique_ptr<render::frontend> frontend_;
    ImVec4 clear_color_{0.45f, 0.55f, 0.60f, 1.00f};
 
    std::vector<drawable *> drawables_;

src/render/backend.cpp

@@ -0,0 +1,35 @@
+/**
+ * @file   backend.cpp
+ * @author Dennis Sitelew
+ * @date   Sep. 14, 2021
+ */
+
+#include <asp/render/backend.h>
+#include <asp/render/opengl2.h>
+#include <asp/render/opengl3.h>
+#include <asp/render/gles2.h>
+#include <asp/render/gles3.h>
+
+#include <string>
+#include <stdexcept>
+
+using namespace asp::render;
+
+std::unique_ptr<backend> backend::make(version v, frontend &f) {
+   switch (v) {
+      case version::opengl2:
+         return std::make_unique<OpenGL2>(f);
+
+      case version::opengl3:
+         return std::make_unique<OpenGL3>(f);
+
+      case version::gles2:
+         return std::make_unique<GLES2>(f);
+
+      case version::gles3:
+         return std::make_unique<GLES3>(f);
+   }
+
+   throw std::runtime_error("Unexpected GL Version: " +
+                            std::to_string(static_cast<int>(v)));
+}