GPU/SDL: Correct aspect ratio when displaying

src/pse-sdl/sdl_interface.cpp

@@ -371,12 +371,38 @@ void SDLInterface::Render()
   ImGui::NewFrame();
 }
 
+static std::tuple<int, int, int, int> CalculateDrawRect(int window_width, int window_height, float display_ratio)
+{
+  const float window_ratio = float(window_width) / float(window_height);
+  int left, top, width, height;
+  if (window_ratio >= display_ratio)
+  {
+    width = static_cast<int>(float(window_height) * display_ratio);
+    height = static_cast<int>(window_height);
+    left = (window_width - width) / 2;
+    top = 0;
+  }
+  else
+  {
+    width = static_cast<int>(window_width);
+    height = static_cast<int>(float(window_width) / display_ratio);
+    left = 0;
+    top = (window_height - height) / 2;
+  }
+
+  return std::tie(left, top, width, height);
+}
+
 void SDLInterface::RenderDisplay()
 {
   if (!m_display_texture)
     return;
 
-  glViewport(0, 0, m_window_width, m_window_height - 20);
+  // - 20 for main menu padding
+  const auto [vp_left, vp_top, vp_width, vp_height] =
+    CalculateDrawRect(m_window_width, std::max(m_window_height - 20, 1), m_display_aspect_ratio);
+
+  glViewport(vp_left, m_window_height - (20 + vp_top) - vp_height, vp_width, vp_height);
   glDisable(GL_BLEND);
   glDisable(GL_CULL_FACE);
   glDisable(GL_DEPTH_TEST);
@@ -473,13 +499,15 @@ void SDLInterface::AddOSDMessage(const char* message, float duration /*= 2.0f*/)
   m_osd_messages.push_back(std::move(msg));
 }
 
-void SDLInterface::SetDisplayTexture(GL::Texture* texture, u32 offset_x, u32 offset_y, u32 width, u32 height)
+void SDLInterface::SetDisplayTexture(GL::Texture* texture, u32 offset_x, u32 offset_y, u32 width, u32 height,
+                                     float aspect_ratio)
 {
   m_display_texture = texture;
-  m_display_texture_offset_x = 0;
-  m_display_texture_offset_y = 0;
+  m_display_texture_offset_x = offset_x;
+  m_display_texture_offset_y = offset_y;
   m_display_texture_width = width;
   m_display_texture_height = height;
+  m_display_aspect_ratio = aspect_ratio;
   m_display_texture_changed = true;
 }
 

src/pse-sdl/sdl_interface.h

@@ -23,7 +23,7 @@ public:
 
   static TinyString GetSaveStateFilename(u32 index);
 
-  void SetDisplayTexture(GL::Texture* texture, u32 offset_x, u32 offset_y, u32 width, u32 height) override;
+  void SetDisplayTexture(GL::Texture* texture, u32 offset_x, u32 offset_y, u32 width, u32 height, float aspect_ratio) override;
 
   void ReportMessage(const char* message) override;
 
@@ -70,6 +70,7 @@ private:
   u32 m_display_texture_offset_y = 0;
   u32 m_display_texture_width = 0;
   u32 m_display_texture_height = 0;
+  float m_display_aspect_ratio = 1.0f;
   bool m_display_texture_changed = false;
 
   std::deque<OSDMessage> m_osd_messages;

src/pse/gpu.h

@@ -37,6 +37,7 @@ public:
   void Execute(TickCount ticks);
 
 protected:
+  static constexpr float DISPLAY_ASPECT_RATIO = 4.0f / 3.0f;
   static constexpr u32 VRAM_WIDTH = 1024;
   static constexpr u32 VRAM_HEIGHT = 512;
   static constexpr u32 VRAM_SIZE = VRAM_WIDTH * VRAM_HEIGHT * sizeof(u16);

src/pse/gpu_hw_opengl.cpp

@@ -23,6 +23,7 @@ bool GPU_HW_OpenGL::Initialize(System* system, DMA* dma, InterruptController* in
   if (!CompilePrograms())
     return false;
 
+  m_system->GetHostInterface()->SetDisplayTexture(m_display_texture.get(), 0, 0, VRAM_WIDTH, VRAM_HEIGHT, 1.0f);
   return true;
 }
 
@@ -123,8 +124,6 @@ void GPU_HW_OpenGL::ClearFramebuffer()
   glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
   glClear(GL_COLOR_BUFFER_BIT);
   glBindFramebuffer(GL_FRAMEBUFFER, 0);
-
-  m_system->GetHostInterface()->SetDisplayTexture(m_framebuffer_texture.get(), 0, 0, VRAM_WIDTH, VRAM_HEIGHT);
 }
 
 void GPU_HW_OpenGL::DestroyFramebuffer()
@@ -287,7 +286,7 @@ void GPU_HW_OpenGL::UpdateDisplay()
   // TODO: 24-bit support.
   if (m_show_vram)
   {
-    m_system->GetHostInterface()->SetDisplayTexture(m_framebuffer_texture.get(), 0, 0, VRAM_WIDTH, VRAM_HEIGHT);
+    m_system->GetHostInterface()->SetDisplayTexture(m_framebuffer_texture.get(), 0, 0, VRAM_WIDTH, VRAM_HEIGHT, 1.0f);
   }
   else
   {
@@ -303,7 +302,8 @@ void GPU_HW_OpenGL::UpdateDisplay()
                        VRAM_HEIGHT - vram_offset_y - copy_height, 0, m_display_texture->GetGLId(), GL_TEXTURE_2D, 0, 0,
                        0, 0, copy_width, copy_height, 1);
 
-    m_system->GetHostInterface()->SetDisplayTexture(m_display_texture.get(), 0, 0, copy_width, copy_height);
+    m_system->GetHostInterface()->SetDisplayTexture(m_display_texture.get(), 0, 0, copy_width, copy_height,
+                                                    DISPLAY_ASPECT_RATIO);
   }
 }
 

src/pse/host_interface.h

@@ -16,7 +16,7 @@ public:
 
   bool InitializeSystem(const char* filename, const char* exp1_filename, const char* save_state_filename);
 
-  virtual void SetDisplayTexture(GL::Texture* texture, u32 offset_x, u32 offset_y, u32 width, u32 height) = 0;
+  virtual void SetDisplayTexture(GL::Texture* texture, u32 offset_x, u32 offset_y, u32 width, u32 height, float aspect_ratio) = 0;
   virtual void ReportMessage(const char* message) = 0;
 
   // Adds OSD messages, duration is in seconds.