Integrate Dear ImGui with SDL to reduce code duplication.

Signed-off-by: Andrea Odetti <mariofutire@gmail.com>

source/frontends/common2/programoptions.cpp

@@ -24,6 +24,7 @@ bool getEmulatorOptions(int argc, const char * argv [], const std::string & edit
     ("multi-threaded,m", "Multi threaded")
     ("loose-mutex,l", "Loose mutex")
     ("sdl-driver", po::value<int>()->default_value(options.sdlDriver), "SDL driver")
+    ("imgui", "Render with Dear ImGui")
     ("timer-interval,i", po::value<int>()->default_value(options.timerInterval), "Timer interval in ms");
 
   po::options_description configDesc("configuration");
@@ -82,6 +83,7 @@ bool getEmulatorOptions(int argc, const char * argv [], const std::string & edit
     options.looseMutex = vm.count("loose-mutex");
     options.timerInterval = vm["timer-interval"].as<int>();
     options.sdlDriver = vm["sdl-driver"].as<int>();
+    options.imgui = vm.count("imgui");
 
     if (vm.count("config"))
     {

source/frontends/common2/programoptions.h

@@ -36,6 +36,7 @@ struct EmulatorOptions
   bool fixedSpeed = false; // default adaptive
 
   int sdlDriver = -1; // default = -1 to let SDL choose
+  bool imgui = false; // use imgui renderer
 
   std::vector<std::string> registryOptions;
 };

source/frontends/sdl/CMakeLists.txt

@@ -1,5 +1,7 @@
 include(FindPkgConfig)
 
+add_executable(sa2)
+
 set(SOURCE_FILES
   main.cpp
   emulator.cpp
@@ -7,7 +9,7 @@ set(SOURCE_FILES
   sdirectsound.cpp
   utils.cpp
   sdlframe.cpp
-  sdlrendererframe.cpp
+  renderer/sdlrendererframe.cpp
   )
 
 set(HEADER_FILES
@@ -16,12 +18,7 @@ set(HEADER_FILES
   sdirectsound.h
   utils.h
   sdlframe.h
-  sdlrendererframe.h
-  )
-
-add_executable(sa2
-  ${SOURCE_FILES}
-  ${HEADER_FILES}
+  renderer/sdlrendererframe.h
   )
 
 find_package(SDL2 REQUIRED)
@@ -41,5 +38,50 @@ target_link_libraries(sa2 PRIVATE
   common2
   )
 
+target_sources(sa2 PRIVATE
+  ${SOURCE_FILES}
+  ${HEADER_FILES}
+  )
+
+set(IMGUI_PATH NONE CACHE PATH "path to imgui")
+
+if (EXISTS ${IMGUI_PATH}/imgui.h)
+  message("Using IMGUI_PATH=${IMGUI_PATH}")
+
+  pkg_search_module(GLES2 REQUIRED glesv2)
+
+  target_sources(sa2 PRIVATE
+    imgui/sdlimguiframe.cpp
+    imgui/image.cpp
+    imgui/gles.h
+    imgui/image.h
+    imgui/sdlimguiframe.h
+    ${IMGUI_PATH}/imgui.cpp
+    ${IMGUI_PATH}/imgui_demo.cpp
+    ${IMGUI_PATH}/imgui_draw.cpp
+    ${IMGUI_PATH}/imgui_tables.cpp
+    ${IMGUI_PATH}/imgui_widgets.cpp
+    ${IMGUI_PATH}/backends/imgui_impl_sdl.cpp
+    ${IMGUI_PATH}/backends/imgui_impl_opengl3.cpp
+    )
+
+  target_include_directories(sa2 PRIVATE
+    ${IMGUI_PATH}
+    ${IMGUI_PATH}/backends
+    )
+
+  target_link_libraries(sa2 PRIVATE
+    ${GLES2_LIBRARIES}
+    )
+
+  target_compile_definitions(sa2 PRIVATE
+    SA2_IMGUI
+    IMGUI_IMPL_OPENGL_ES2
+    )
+else()
+  message("Bad IMGUI_PATH=${IMGUI_PATH}, skipping imgui code")
+endif()
+
+
 install(TARGETS sa2
   DESTINATION bin)

source/frontends/sdl/imgui/gles.h

@@ -0,0 +1,33 @@
+#pragma once
+
+#if defined(IMGUI_IMPL_OPENGL_ES2)
+
+// Pi3 with Fake KMS
+// "OpenGL ES 2.0 Mesa 19.3.2"
+// "Supported versions are: 1.00 ES"
+
+#include <GLES2/gl2.h>
+#define SDL_CONTEXT_MAJOR 2
+
+#elif defined(IMGUI_IMPL_OPENGL_ES3)
+
+// Pi4 with Fake KMS
+// "OpenGL ES 3.1 Mesa 19.3.2"
+// "Supported versions are: 1.00 ES, 3.00 ES, and 3.10 ES"
+
+// On my desktop
+// "OpenGL ES 3.1 Mesa 20.2.6"
+// "Supported versions are: 1.00 ES, 3.00 ES, and 3.10 ES"
+
+#include <GLES3/gl3.h>
+#define SDL_CONTEXT_MAJOR 3
+// "310 es" is accepted on a Pi4, but the imgui shaders do not compile
+
+#endif
+
+// this is used in all cases for GL_BGRA_EXT
+#include <GLES2/gl2ext.h>
+
+#include "imgui.h"
+#include "imgui_impl_sdl.h"
+#include "imgui_impl_opengl3.h"

source/frontends/sdl/imgui/image.cpp

@@ -0,0 +1,43 @@
+#include "frontends/sdl/imgui/image.h"
+
+#ifdef GL_UNPACK_ROW_LENGTH
+// GLES3: defined in gl3.h
+#define UGL_UNPACK_LENGTH GL_UNPACK_ROW_LENGTH
+#else
+// GLES2: defined in gl2ext.h as an extension GL_EXT_unpack_subimage
+#define UGL_UNPACK_LENGTH GL_UNPACK_ROW_LENGTH_EXT
+#endif
+
+/*
+2 extensions are used here
+
+ES2: GL_UNPACK_ROW_LENGTH_EXT and GL_BGRA_EXT
+ES3: GL_BGRA_EXT
+
+They both work on Pi3/4 and my Intel Haswell card.
+
+What does SDL do about it?
+
+GL_UNPACK_ROW_LENGTH_EXT: it uses instead texture coordinates
+GL_BGRA_EXT: it uses a shader to swap the color bytes
+
+For simplicity (and because it just works) here we are using these 2 extensions.
+ */
+
+void LoadTextureFromData(GLuint texture, const uint8_t * data, size_t width, size_t height, size_t pitch)
+{
+  glBindTexture(GL_TEXTURE_2D, texture);
+  glPixelStorei(UGL_UNPACK_LENGTH, pitch); // in pixels
+
+  // Setup filtering parameters for display
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+
+  const GLenum format = GL_BGRA_EXT; // this is defined in gl2ext.h and nowhere in gl3.h
+  const GLenum type = GL_UNSIGNED_BYTE;
+  glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, type, data);
+  // reset to default state
+  glPixelStorei(UGL_UNPACK_LENGTH, 0);
+}

source/frontends/sdl/imgui/image.h

@@ -0,0 +1,6 @@
+#pragma once
+
+#include <cstddef>
+#include "frontends/sdl/imgui/gles.h"
+
+void LoadTextureFromData(GLuint texture, const uint8_t * data, size_t width, size_t height, size_t pitch);

source/frontends/sdl/imgui/sdlimguiframe.cpp

@@ -0,0 +1,104 @@
+#include "StdAfx.h"
+#include "frontends/sdl/imgui/sdlimguiframe.h"
+#include "frontends/sdl/imgui/image.h"
+#include "frontends/sdl/utils.h"
+
+#include "Interface.h"
+#include "Core.h"
+
+#include <iostream>
+
+SDLImGuiFrame::SDLImGuiFrame()
+{
+  Video & video = GetVideo();
+
+  myBorderlessWidth = video.GetFrameBufferBorderlessWidth();
+  myBorderlessHeight = video.GetFrameBufferBorderlessHeight();
+
+  SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, 0);
+  SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
+  SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, SDL_CONTEXT_MAJOR); // from local gles.h
+  SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
+
+  // Create window with graphics context
+  SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
+  SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
+  SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);
+
+  SDL_WindowFlags windowFlags = (SDL_WindowFlags)(SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);
+  myWindow.reset(SDL_CreateWindow(g_pAppTitle.c_str(), SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, myBorderlessWidth, myBorderlessHeight, windowFlags), SDL_DestroyWindow);
+  if (!myWindow)
+  {
+    throw std::runtime_error(SDL_GetError());
+  }
+
+  myGLContext = SDL_GL_CreateContext(myWindow.get());
+  if (!myGLContext)
+  {
+    throw std::runtime_error(SDL_GetError());
+  }
+
+  SDL_GL_MakeCurrent(myWindow.get(), myGLContext);
+
+  // Setup Platform/Renderer backends
+  std::cerr << "GL_VENDOR: " << glGetString(GL_VENDOR) << std::endl;
+  std::cerr << "GL_RENDERER: " << glGetString(GL_RENDERER) << std::endl;
+  std::cerr << "GL_VERSION: " << glGetString(GL_VERSION) << std::endl;
+  std::cerr << "GL_SHADING_LANGUAGE_VERSION: " << glGetString(GL_SHADING_LANGUAGE_VERSION) << std::endl;
+  //  const char* runtime_gl_extensions = (const char*)glGetString(GL_EXTENSIONS);
+  //  std::cerr << "GL_EXTENSIONS: " << runtime_gl_extensions << std::endl;
+
+  // Setup Dear ImGui context
+  IMGUI_CHECKVERSION();
+  ImGui::CreateContext();
+  ImGuiIO& io = ImGui::GetIO(); (void)io;
+  //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
+  //io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+
+  ImGui::StyleColorsDark();
+
+  ImGui_ImplSDL2_InitForOpenGL(myWindow.get(), myGLContext);
+
+  ImGui_ImplOpenGL3_Init();
+
+  glGenTextures(1, &myTexture);
+
+  const int width = video.GetFrameBufferWidth();
+  const size_t borderWidth = video.GetFrameBufferBorderWidth();
+  const size_t borderHeight = video.GetFrameBufferBorderHeight();
+
+  myPitch = width;
+  myOffset = (width * borderHeight + borderWidth) * sizeof(bgra_t);
+}
+
+SDLImGuiFrame::~SDLImGuiFrame()
+{
+  glDeleteTextures(1, &myTexture);
+  ImGui_ImplOpenGL3_Shutdown();
+  ImGui_ImplSDL2_Shutdown();
+  ImGui::DestroyContext();
+  SDL_GL_DeleteContext(myGLContext);
+}
+
+void SDLImGuiFrame::UpdateTexture()
+{
+  LoadTextureFromData(myTexture, myFramebuffer.data() + myOffset, myBorderlessWidth, myBorderlessHeight, myPitch);
+}
+
+void SDLImGuiFrame::RenderPresent()
+{
+  ImGui_ImplOpenGL3_NewFrame();
+  ImGui_ImplSDL2_NewFrame(myWindow.get());
+  ImGui::NewFrame();
+
+  // need to flip the texture vertically
+  const ImVec2 uv0(0, 1);
+  const ImVec2 uv1(1, 0);
+  const ImVec2 zero(0, 0);
+  // draw on the background
+  ImGui::GetBackgroundDrawList()->AddImage((void*)(intptr_t)myTexture, zero, ImGui::GetIO().DisplaySize, uv0, uv1);
+
+  ImGui::Render();
+  ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
+  SDL_GL_SwapWindow(myWindow.get());
+}

source/frontends/sdl/imgui/sdlimguiframe.h

@@ -0,0 +1,24 @@
+#pragma once
+
+#include "frontends/sdl/sdlframe.h"
+#include "frontends/sdl/imgui/gles.h"
+
+class SDLImGuiFrame : public SDLFrame
+{
+public:
+  SDLImGuiFrame();
+
+  ~SDLImGuiFrame() override;
+
+  void UpdateTexture() override;
+  void RenderPresent() override;
+
+private:
+  size_t myPitch;
+  size_t myOffset;
+  size_t myBorderlessWidth;
+  size_t myBorderlessHeight;
+
+  SDL_GLContext myGLContext;
+  GLuint myTexture;
+};

source/frontends/sdl/main.cpp

@@ -17,7 +17,12 @@
 #include "frontends/sdl/gamepad.h"
 #include "frontends/sdl/sdirectsound.h"
 #include "frontends/sdl/utils.h"
-#include "frontends/sdl/sdlrendererframe.h"
+
+#include "frontends/sdl/renderer/sdlrendererframe.h"
+
+#ifdef SA2_IMGUI
+#include "frontends/sdl/imgui/sdlimguiframe.h"
+#endif
 
 #include "Core.h"
 #include "Log.h"
@@ -79,7 +84,21 @@ void run_sdl(int argc, const char * argv [])
   if (!run)
     return;
 
-  const std::shared_ptr<SDLFrame> frame(new SDLRendererFrame(options));
+  std::shared_ptr<SDLFrame> frame;
+
+#ifdef SA2_IMGUI
+  if (options.imgui)
+  {
+    frame.reset(new SDLImGuiFrame());
+  }
+  else
+  {
+    frame.reset(new SDLRendererFrame(options));
+  }
+#else
+  frame.reset(new SDLRendererFrame(options));
+#endif
+
   SetFrame(frame);
 
   if (options.log)

source/frontends/sdl/renderer/sdlrendererframe.cpp

@@ -1,5 +1,5 @@
 #include "StdAfx.h"
-#include "frontends/sdl/sdlrendererframe.h"
+#include "frontends/sdl/renderer/sdlrendererframe.h"
 #include "frontends/sdl/utils.h"
 #include "frontends/common2/programoptions.h"
 
@@ -20,8 +20,7 @@ SDLRendererFrame::SDLRendererFrame(const EmulatorOptions & options)
   myWindow.reset(SDL_CreateWindow(g_pAppTitle.c_str(), SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, sw, sh, SDL_WINDOW_SHOWN | SDL_WINDOW_RESIZABLE), SDL_DestroyWindow);
   if (!myWindow)
   {
-    std::cerr << "SDL_CreateWindow Error: " << SDL_GetError() << std::endl;
-    return;
+    throw std::runtime_error(SDL_GetError());
   }
 
   SetApplicationIcon();
@@ -29,8 +28,7 @@ SDLRendererFrame::SDLRendererFrame(const EmulatorOptions & options)
   myRenderer.reset(SDL_CreateRenderer(myWindow.get(), options.sdlDriver, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC), SDL_DestroyRenderer);
   if (!myRenderer)
   {
-    std::cerr << "SDL_CreateRenderer Error: " << SDL_GetError() << std::endl;
-    return;
+    throw std::runtime_error(SDL_GetError());
   }
 
   const Uint32 format = SDL_PIXELFORMAT_ARGB8888;

source/linux/raspbian.list.txt

@@ -10,3 +10,4 @@ libncurses-dev
 libevdev-dev
 libsdl2-image-dev
 libsdl2-dev
+libgles-dev