GPU: Add force true color setting

src/core/gpu.cpp

@@ -26,7 +26,7 @@ bool GPU::Initialize(System* system, DMA* dma, InterruptController* interrupt_co
   return true;
 }
 
-void GPU::UpdateResolutionScale()
+void GPU::UpdateSettings()
 {
   m_resolution_scale = std::clamp<u32>(m_system->GetSettings().gpu_resolution_scale, 1, m_max_resolution_scale);
 }

src/core/gpu.h

@@ -55,7 +55,7 @@ public:
   // Resolution scaling.
   u32 GetResolutionScale() const { return m_resolution_scale; }
   u32 GetMaxResolutionScale() const { return m_max_resolution_scale; }
-  virtual void UpdateResolutionScale();
+  virtual void UpdateSettings();
 
   // Ticks for hblank/vblank.
   void Execute(TickCount ticks);

src/core/gpu_hw.cpp

@@ -1,6 +1,8 @@
 #include "gpu_hw.h"
 #include "YBaseLib/Assert.h"
 #include "YBaseLib/Log.h"
+#include "settings.h"
+#include "system.h"
 #include <sstream>
 Log_SetChannel(GPU_HW);
 
@@ -15,6 +17,13 @@ void GPU_HW::Reset()
   m_batch = {};
 }
 
+void GPU_HW::UpdateSettings()
+{
+  GPU::UpdateSettings();
+
+  m_true_color = m_system->GetSettings().gpu_true_color;
+}
+
 void GPU_HW::LoadVertices(RenderCommand rc, u32 num_vertices, const u32* command_ptr)
 {
   const u32 texpage =
@@ -259,6 +268,7 @@ std::string GPU_HW::GenerateFragmentShader(HWBatchRenderMode transparency, Textu
   DefineMacro(ss, "PALETTE_8_BIT", actual_texture_mode == GPU::TextureMode::Palette8Bit);
   DefineMacro(ss, "RAW_TEXTURE", raw_texture);
   DefineMacro(ss, "DITHERING", dithering);
+  DefineMacro(ss, "TRUE_COLOR", m_true_color);
 
   ss << "const int[16] s_dither_values = int[16]( ";
   for (u32 i = 0; i < 16; i++)
@@ -384,7 +394,9 @@ void main()
   #endif
 
   // Clip to 15-bit range
-  icolor = TruncateTo15Bit(icolor);
+  #if !TRUE_COLOR
+    icolor = TruncateTo15Bit(icolor);
+  #endif
 
   // Normalize
   vec3 color = vec3(icolor) / vec3(255.0, 255.0, 255.0);
@@ -585,7 +597,7 @@ void GPU_HW::DispatchRenderCommand(RenderCommand rc, u32 num_vertices, const u32
   const TransparencyMode transparency_mode =
     rc.transparency_enable ? m_render_state.transparency_mode : TransparencyMode::Disabled;
   const HWPrimitive rc_primitive = GetPrimitiveForCommand(rc);
-  const bool dithering_enable = rc.IsDitheringEnabled() ? m_GPUSTAT.dither_enable : false;
+  const bool dithering_enable = (!m_true_color && rc.IsDitheringEnabled()) ? m_GPUSTAT.dither_enable : false;
   if (!IsFlushed())
   {
     const u32 max_added_vertices = num_vertices + 2;

src/core/gpu_hw.h

@@ -12,6 +12,7 @@ public:
   virtual ~GPU_HW();
 
   virtual void Reset() override;
+  virtual void UpdateSettings() override;
 
 protected:
   enum class HWPrimitive : u8
@@ -107,6 +108,7 @@ protected:
   std::string GenerateDisplayFragmentShader(bool depth_24bit, bool interlaced);
 
   HWRenderBatch m_batch = {};
+  bool m_true_color = false;
 
 private:
   static HWPrimitive GetPrimitiveForCommand(RenderCommand rc);

src/core/gpu_hw_opengl.cpp

@@ -65,9 +65,9 @@ void GPU_HW_OpenGL::RestoreGraphicsAPIState()
   glBindVertexArray(m_vao_id);
 }
 
-void GPU_HW_OpenGL::UpdateResolutionScale()
+void GPU_HW_OpenGL::UpdateSettings()
 {
-  GPU_HW::UpdateResolutionScale();
+  GPU_HW::UpdateSettings();
 
   CreateFramebuffer();
   CompilePrograms();
@@ -322,8 +322,8 @@ bool GPU_HW_OpenGL::CompileProgram(GL::Program& prog, HWBatchRenderMode render_m
 
 void GPU_HW_OpenGL::SetDrawState(HWBatchRenderMode render_mode)
 {
-  const GL::Program& prog =
-    m_render_programs[static_cast<u32>(render_mode)][static_cast<u32>(m_batch.texture_mode)][m_batch.dithering];
+  const GL::Program& prog = m_render_programs[static_cast<u8>(render_mode)][static_cast<u8>(m_batch.texture_mode)]
+                                             [BoolToUInt8(m_batch.dithering)];
   prog.Bind();
 
   prog.Uniform2i(0, m_drawing_offset.x, m_drawing_offset.y);

src/core/gpu_hw_opengl.h

@@ -18,7 +18,7 @@ public:
 
   void ResetGraphicsAPIState() override;
   void RestoreGraphicsAPIState() override;
-  void UpdateResolutionScale() override;
+  void UpdateSettings() override;
 
   void DrawRendererStatsWindow() override;
 

src/core/settings.h

@@ -17,6 +17,7 @@ struct Settings
   u32 gpu_resolution_scale = 1;
   u32 max_gpu_resolution_scale = 1;
   bool gpu_vsync = true;
+  bool gpu_true_color = false;
   bool display_linear_filtering = true;
 
   struct DebugSettings

src/duckstation/sdl_interface.cpp

@@ -862,7 +862,7 @@ void SDLInterface::DrawMainMenuBar()
                 nullptr, current_internal_resolution == scale))
           {
             m_system->GetSettings().gpu_resolution_scale = scale;
-            m_system->GetGPU()->UpdateResolutionScale();
+            m_system->GetGPU()->UpdateSettings();
           }
         }
 
@@ -872,10 +872,13 @@ void SDLInterface::DrawMainMenuBar()
       if (ImGui::MenuItem("VSync", nullptr, &m_system->GetSettings().gpu_vsync))
         UpdateAudioVisualSync();
 
+      if (ImGui::MenuItem("True (24-Bit) Color", nullptr, &m_system->GetSettings().gpu_true_color))
+        m_system->GetGPU()->UpdateSettings();
+
       if (ImGui::MenuItem("Display Linear Filtering", nullptr, &m_system->GetSettings().display_linear_filtering))
       {
         // this has to update the display texture for now..
-        m_system->GetGPU()->UpdateResolutionScale();
+        m_system->GetGPU()->UpdateSettings();
       }
 
       ImGui::EndMenu();
@@ -1300,7 +1303,7 @@ void SDLInterface::DoModifyInternalResolution(s32 increment)
     return;
 
   settings.gpu_resolution_scale = new_resolution_scale;
-  m_system->GetGPU()->UpdateResolutionScale();
+  m_system->GetGPU()->UpdateSettings();
 
   AddOSDMessage(TinyString::FromFormat("Resolution scale set to %ux (%ux%u)", settings.gpu_resolution_scale,
                                        GPU::VRAM_WIDTH * settings.gpu_resolution_scale,