GPU: Improve batching by sampling a VRAM copy

src/pse/gpu.cpp

@@ -52,8 +52,8 @@ bool GPU::DoState(StateWrapper& sw)
 
   sw.Do(&m_GPUSTAT.bits);
 
-  sw.Do(&m_render_state.texture_base_x);
+  sw.Do(&m_render_state.texture_page_x);
-  sw.Do(&m_render_state.texture_base_y);
+  sw.Do(&m_render_state.texture_page_y);
   sw.Do(&m_render_state.texture_palette_x);
   sw.Do(&m_render_state.texture_palette_y);
   sw.Do(&m_render_state.texture_color_mode);
@@ -69,10 +69,10 @@ bool GPU::DoState(StateWrapper& sw)
   sw.Do(&m_render_state.texture_changed);
   sw.Do(&m_render_state.transparency_mode_changed);
 
-  sw.Do(&m_drawing_area.top_left_x);
+  sw.Do(&m_drawing_area.left);
-  sw.Do(&m_drawing_area.top_left_y);
+  sw.Do(&m_drawing_area.top);
-  sw.Do(&m_drawing_area.bottom_right_x);
+  sw.Do(&m_drawing_area.right);
-  sw.Do(&m_drawing_area.bottom_right_y);
+  sw.Do(&m_drawing_area.bottom);
   sw.Do(&m_drawing_offset.x);
   sw.Do(&m_drawing_offset.y);
   sw.Do(&m_drawing_offset.x);
@@ -429,18 +429,18 @@ void GPU::WriteGP0(u32 value)
 
       case 0xE3: // Set drawing area top left
       {
-        m_drawing_area.top_left_x = param & UINT32_C(0x3FF);
+        m_drawing_area.left = param & UINT32_C(0x3FF);
-        m_drawing_area.top_left_y = (param >> 10) & UINT32_C(0x1FF);
+        m_drawing_area.top = (param >> 10) & UINT32_C(0x1FF);
-        Log_DebugPrintf("Set drawing area top-left: (%u, %u)", m_drawing_area.top_left_x, m_drawing_area.top_left_y);
+        Log_DebugPrintf("Set drawing area top-left: (%u, %u)", m_drawing_area.left, m_drawing_area.top);
       }
       break;
 
       case 0xE4: // Set drawing area bottom right
       {
-        m_drawing_area.bottom_right_x = param & UINT32_C(0x3FF);
+        m_drawing_area.right = param & UINT32_C(0x3FF);
-        m_drawing_area.bottom_right_y = (param >> 10) & UINT32_C(0x1FF);
+        m_drawing_area.bottom = (param >> 10) & UINT32_C(0x1FF);
-        Log_DebugPrintf("Set drawing area bottom-right: (%u, %u)", m_drawing_area.bottom_right_x,
+        Log_DebugPrintf("Set drawing area bottom-right: (%u, %u)", m_drawing_area.right,
-                        m_drawing_area.bottom_right_y);
+                        m_drawing_area.bottom);
       }
       break;
 
@@ -785,8 +785,8 @@ void GPU::RenderState::SetFromPageAttribute(u16 value)
   if (texpage_attribute == value)
     return;
 
-  texture_base_x = static_cast<s32>(ZeroExtend32(value & UINT16_C(0x0F)) * UINT32_C(64));
+  texture_page_x = static_cast<s32>(ZeroExtend32(value & UINT16_C(0x0F)) * UINT32_C(64));
-  texture_base_y = static_cast<s32>(ZeroExtend32((value >> 4) & UINT16_C(1)) * UINT32_C(256));
+  texture_page_y = static_cast<s32>(ZeroExtend32((value >> 4) & UINT16_C(1)) * UINT32_C(256));
   texture_color_mode = (static_cast<TextureColorMode>((value >> 7) & UINT16_C(0x03)));
   if (texture_color_mode == TextureColorMode::Reserved_Direct16Bit)
     texture_color_mode = TextureColorMode::Direct16Bit;

src/pse/gpu.h

@@ -228,8 +228,8 @@ protected:
     static constexpr u16 PALETTE_ATTRIBUTE_MASK = UINT16_C(0b0111111111111111);
 
     // decoded values
-    s32 texture_base_x;
+    s32 texture_page_x;
-    s32 texture_base_y;
+    s32 texture_page_y;
     s32 texture_palette_x;
     s32 texture_palette_y;
     TextureColorMode texture_color_mode;
@@ -265,8 +265,8 @@ protected:
 
   struct DrawingArea
   {
-    u32 top_left_x, top_left_y;
+    u32 left, top;
-    u32 bottom_right_x, bottom_right_y;
+    u32 right, bottom;
   } m_drawing_area = {};
 
   struct DrawingOffset

src/pse/gpu_hw.cpp

@@ -1,6 +1,8 @@
 #include "gpu_hw.h"
 #include "YBaseLib/Assert.h"
+#include "YBaseLib/Log.h"
 #include <sstream>
+Log_SetChannel(GPU_HW);
 
 GPU_HW::GPU_HW() = default;
 
@@ -110,10 +112,10 @@ void GPU_HW::LoadVertices(RenderCommand rc, u32 num_vertices)
 
 void GPU_HW::CalcScissorRect(int* left, int* top, int* right, int* bottom)
 {
-  *left = m_drawing_area.top_left_x;
+  *left = m_drawing_area.left;
-  *right = m_drawing_area.bottom_right_x + 1;
+  *right = m_drawing_area.right + 1;
-  *top = m_drawing_area.top_left_y;
+  *top = m_drawing_area.top;
-  *bottom = m_drawing_area.bottom_right_y + 1;
+  *bottom = m_drawing_area.bottom + 1;
 }
 
 static void DefineMacro(std::stringstream& ss, const char* name, bool enabled)
@@ -176,7 +178,6 @@ in vec2 a_tex0;
 
 out vec4 v_col0;
 #if TEXTURED
-  uniform vec2 u_tex_scale;
   out vec2 v_tex0;
 #endif
 
@@ -199,26 +200,75 @@ void main()
   return ss.str();
 }
 
-std::string GPU_HW::GenerateFragmentShader(bool textured, bool blending)
+std::string GPU_HW::GenerateFragmentShader(bool textured, bool blending, TextureColorMode texture_color_mode)
 {
   std::stringstream ss;
   GenerateShaderHeader(ss);
   DefineMacro(ss, "TEXTURED", textured);
   DefineMacro(ss, "BLENDING", blending);
+  DefineMacro(ss, "PALETTE",
+              textured && (texture_color_mode == GPU::TextureColorMode::Palette4Bit ||
+                           texture_color_mode == GPU::TextureColorMode::Palette8Bit));
+  DefineMacro(ss, "PALETTE_4_BIT", textured && texture_color_mode == GPU::TextureColorMode::Palette4Bit);
+  DefineMacro(ss, "PALETTE_8_BIT", textured && texture_color_mode == GPU::TextureColorMode::Palette8Bit);
 
   ss << R"(
 in vec4 v_col0;
 #if TEXTURED
   in vec2 v_tex0;
   uniform sampler2D samp0;
+  uniform ivec2 u_texture_page_base;
+  #if PALETTE
+    uniform ivec2 u_texture_palette_base;
+  #endif
 #endif
 
 out vec4 o_col0;
 
+#if TEXTURED
+vec4 SampleFromVRAM(vec2 coord)
+{
+  // from 0..1 to 0..255
+  ivec2 icoord = ivec2(coord * vec2(255.0));
+
+  // adjust for tightly packed palette formats
+  ivec2 index_coord = icoord;
+  #if PALETTE_4_BIT
+    index_coord.x /= 4;
+  #elif PALETTE_8_BIT
+    index_coord.x /= 2;
+  #endif
+
+  // fixup coords
+  ivec2 vicoord = ivec2(u_texture_page_base.x + index_coord.x,
+                        fixYCoord(u_texture_page_base.y + index_coord.y));
+
+  // load colour/palette
+  vec4 color = texelFetch(samp0, vicoord & VRAM_COORD_MASK, 0);
+
+  // apply palette
+  #if PALETTE
+    #if PALETTE_4_BIT
+      int subpixel = int(icoord.x) & 3;
+      uint vram_value = RGBA8ToRGBA5551(color);
+      int palette_index = int((vram_value >> (subpixel * 4)) & 0x0Fu);
+    #elif PALETTE_8_BIT
+      int subpixel = int(icoord.x) & 1;
+      uint vram_value = RGBA8ToRGBA5551(color);
+      int palette_index = int((vram_value >> (subpixel * 8)) & 0xFFu);
+    #endif
+    ivec2 palette_icoord = ivec2(u_texture_palette_base.x + palette_index, fixYCoord(u_texture_palette_base.y));
+    color = texelFetch(samp0, palette_icoord & VRAM_COORD_MASK, 0);
+  #endif
+
+  return color;
+}
+#endif
+
 void main()
 {
   #if TEXTURED
-    vec4 texcol = texture(samp0, v_tex0);
+    vec4 texcol = SampleFromVRAM(v_tex0);
     if (texcol == vec4(0.0, 0.0, 0.0, 0.0))
       discard;
 
@@ -255,64 +305,6 @@ void main()
   return ss.str();
 }
 
-std::string GPU_HW::GenerateTexturePageFragmentShader(TextureColorMode mode)
-{
-  const bool is_palette = (mode == GPU::TextureColorMode::Palette4Bit || mode == GPU::TextureColorMode::Palette8Bit);
-
-  std::stringstream ss;
-  GenerateShaderHeader(ss);
-  DefineMacro(ss, "PALETTE", is_palette);
-  DefineMacro(ss, "PALETTE_4_BIT", mode == GPU::TextureColorMode::Palette4Bit);
-  DefineMacro(ss, "PALETTE_8_BIT", mode == GPU::TextureColorMode::Palette8Bit);
-
-  ss << R"(
-uniform sampler2D samp0;
-uniform ivec2 base_offset;
-
-#if PALETTE
-uniform ivec2 palette_offset;
-#endif
-
-in vec2 v_tex0;
-out vec4 o_col0;
-
-void main()
-{
-  ivec2 local_coords = ivec2(gl_FragCoord.xy);
-  #if PALETTE_4_BIT
-    local_coords.x /= 4;
-  #elif PALETTE_8_BIT
-    local_coords.x /= 2;
-  #endif
-
-  // fixup coords
-  ivec2 coords = ivec2(base_offset.x + local_coords.x, fixYCoord(base_offset.y + local_coords.y));
-
-  // load colour/palette
-  vec4 color = texelFetch(samp0, coords & VRAM_COORD_MASK, 0);
-
-  // apply palette
-  #if PALETTE
-    #if PALETTE_4_BIT
-      int subpixel = int(gl_FragCoord.x) & 3;
-      uint vram_value = RGBA8ToRGBA5551(color);
-      int palette_index = int((vram_value >> (subpixel * 4)) & 0x0Fu);
-    #elif PALETTE_8_BIT
-      int subpixel = int(gl_FragCoord.x) & 1;
-      uint vram_value = RGBA8ToRGBA5551(color);
-      int palette_index = int((vram_value >> (subpixel * 8)) & 0xFFu);
-    #endif
-    ivec2 palette_coords = ivec2(palette_offset.x + palette_index, fixYCoord(palette_offset.y));
-    color = texelFetch(samp0, palette_coords & VRAM_COORD_MASK, 0);
-  #endif
-
-  o_col0 = color;
-}
-)";
-
-  return ss.str();
-}
-
 std::string GPU_HW::GenerateFillFragmentShader()
 {
   std::stringstream ss;
@@ -331,8 +323,6 @@ void main()
   return ss.str();
 }
 
-void GPU_HW::UpdateTexturePageTexture() {}
-
 GPU_HW::HWRenderBatch::Primitive GPU_HW::GetPrimitiveForCommand(RenderCommand rc)
 {
   if (rc.primitive == Primitive::Line)
@@ -343,6 +333,8 @@ GPU_HW::HWRenderBatch::Primitive GPU_HW::GetPrimitiveForCommand(RenderCommand rc
     return HWRenderBatch::Primitive::Triangles;
 }
 
+void GPU_HW::InvalidateVRAMReadCache() {}
+
 void GPU_HW::DispatchRenderCommand(RenderCommand rc, u32 num_vertices)
 {
   if (rc.texture_enable)
@@ -375,20 +367,46 @@ void GPU_HW::DispatchRenderCommand(RenderCommand rc, u32 num_vertices)
       if (m_render_state.IsTextureChanged())
       {
         if (!IsFlushed())
+        {
+          // we only need to update the copy texture if the render area intersects with the texture page
+          const u32 texture_page_left = m_render_state.texture_page_x;
+          const u32 texture_page_right = m_render_state.texture_page_y + TEXTURE_PAGE_WIDTH;
+          const u32 texture_page_top = m_render_state.texture_page_y;
+          const u32 texture_page_bottom = texture_page_top + TEXTURE_PAGE_HEIGHT;
+          const bool texture_page_overlaps =
+            (texture_page_left < m_drawing_area.right && texture_page_right > m_drawing_area.left &&
+             texture_page_top > m_drawing_area.bottom && texture_page_bottom < m_drawing_area.top);
+
+          // TODO: Check palette too.
+          if (texture_page_overlaps)
+          {
+            Log_DebugPrintf("Invalidating VRAM read cache due to drawing area overlap");
+            InvalidateVRAMReadCache();
+          }
+
+          // texture page changed?
+          // TODO: Move this to the shader...
           FlushRender();
-        UpdateTexturePageTexture();
+        }
+
         m_render_state.ClearTextureChangedFlag();
       }
 
       if (m_batch.transparency_enable && m_render_state.IsTransparencyModeChanged() && !IsFlushed())
         FlushRender();
-
-      m_batch.transparency_mode = m_render_state.transparency_mode;
       m_render_state.ClearTransparencyModeChangedFlag();
+
+      m_batch.texture_color_mode = m_render_state.texture_color_mode;
+      m_batch.texture_page_x = m_render_state.texture_page_x;
+      m_batch.texture_page_y = m_render_state.texture_page_y;
+      m_batch.texture_palette_x = m_render_state.texture_palette_x;
+      m_batch.texture_palette_y = m_render_state.texture_palette_y;
+      m_batch.transparency_mode = m_render_state.transparency_mode;
     }
   }
 
   // extract state
+  const bool rc_transparency_enable = rc.transparency_enable;
   const bool rc_texture_enable = rc.texture_enable;
   const bool rc_texture_blend_enable = !rc.texture_blend_disable;
   const HWRenderBatch::Primitive rc_primitive = GetPrimitiveForCommand(rc);
@@ -399,14 +417,15 @@ void GPU_HW::DispatchRenderCommand(RenderCommand rc, u32 num_vertices)
     // including the degenerate triangles for strips
     const u32 max_added_vertices = num_vertices + 2;
     const bool params_changed =
-      (m_batch.texture_enable != rc_texture_enable || m_batch.texture_blending_enable != rc_texture_blend_enable ||
+      (m_batch.transparency_enable != rc_transparency_enable || m_batch.texture_enable != rc_texture_enable ||
-       m_batch.primitive != rc_primitive);
+       m_batch.texture_blending_enable != rc_texture_blend_enable || m_batch.primitive != rc_primitive);
     if ((m_batch.vertices.size() + max_added_vertices) >= MAX_BATCH_VERTEX_COUNT || params_changed)
       FlushRender();
   }
 
+  m_batch.primitive = rc_primitive;
+  m_batch.transparency_enable = rc_transparency_enable;
   m_batch.texture_enable = rc_texture_enable;
   m_batch.texture_blending_enable = rc_texture_blend_enable;
-  m_batch.primitive = rc_primitive;
   LoadVertices(rc, num_vertices);
 }

src/pse/gpu_hw.h

@@ -39,6 +39,11 @@ protected:
     bool transparency_enable;
     bool texture_enable;
     bool texture_blending_enable;
+    TextureColorMode texture_color_mode;
+    u32 texture_page_x;
+    u32 texture_page_y;
+    u32 texture_palette_x;
+    u32 texture_palette_y;
     TransparencyMode transparency_mode;
 
     std::vector<HWVertex> vertices;
@@ -46,6 +51,10 @@ protected:
 
   static constexpr u32 VERTEX_BUFFER_SIZE = 1 * 1024 * 1024;
   static constexpr u32 MAX_BATCH_VERTEX_COUNT = VERTEX_BUFFER_SIZE / sizeof(HWVertex);
+  static constexpr u32 TEXTURE_TILE_SIZE = 256;
+  static constexpr u32 TEXTURE_TILE_X_COUNT = VRAM_WIDTH / TEXTURE_TILE_SIZE;
+  static constexpr u32 TEXTURE_TILE_Y_COUNT = VRAM_HEIGHT / TEXTURE_TILE_SIZE;
+  static constexpr u32 TEXTURE_TILE_COUNT = TEXTURE_TILE_X_COUNT * TEXTURE_TILE_Y_COUNT;
 
   static constexpr std::tuple<float, float, float, float> RGBA8ToFloat(u32 rgba)
   {
@@ -55,7 +64,7 @@ protected:
                            static_cast<float>(rgba >> 24) * (1.0f / 255.0f));
   }
 
-  virtual void UpdateTexturePageTexture();
+  virtual void InvalidateVRAMReadCache();
 
   bool IsFlushed() const { return m_batch.vertices.empty(); }
 
@@ -64,9 +73,8 @@ protected:
   void CalcScissorRect(int* left, int* top, int* right, int* bottom);
 
   std::string GenerateVertexShader(bool textured);
-  std::string GenerateFragmentShader(bool textured, bool blending);
+  std::string GenerateFragmentShader(bool textured, bool blending, TextureColorMode texture_color_mode);
   std::string GenerateScreenQuadVertexShader();
-  std::string GenerateTexturePageFragmentShader(TextureColorMode mode);
   std::string GenerateFillFragmentShader();
 
   HWRenderBatch m_batch = {};

src/pse/gpu_hw_opengl.cpp

@@ -43,7 +43,7 @@ void GPU_HW_OpenGL::RenderUI()
 
     ImGui::TextUnformatted("Texture Page Updates:");
     ImGui::NextColumn();
-    ImGui::Text("%u", m_stats.num_texture_page_updates);
+    ImGui::Text("%u", m_stats.num_vram_read_texture_updates);
     ImGui::NextColumn();
 
     ImGui::TextUnformatted("Batches Drawn:");
@@ -64,6 +64,11 @@ void GPU_HW_OpenGL::RenderUI()
   m_stats = {};
 }
 
+void GPU_HW_OpenGL::InvalidateVRAMReadCache()
+{
+  m_vram_read_texture_dirty = true;
+}
+
 std::tuple<s32, s32> GPU_HW_OpenGL::ConvertToFramebufferCoordinates(s32 x, s32 y)
 {
   return std::make_tuple(x, static_cast<s32>(static_cast<s32>(VRAM_HEIGHT) - y));
@@ -79,11 +84,11 @@ void GPU_HW_OpenGL::CreateFramebuffer()
   glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, m_framebuffer_texture->GetGLId(), 0);
   Assert(glCheckFramebufferStatus(GL_FRAMEBUFFER) == GL_FRAMEBUFFER_COMPLETE);
 
-  m_texture_page_texture =
+  m_vram_read_texture =
-    std::make_unique<GL::Texture>(TEXTURE_PAGE_WIDTH, TEXTURE_PAGE_HEIGHT, GL_RGBA, GL_UNSIGNED_BYTE, nullptr, false);
+    std::make_unique<GL::Texture>(VRAM_WIDTH, VRAM_HEIGHT, GL_RGBA, GL_UNSIGNED_BYTE, nullptr, false);
-  glGenFramebuffers(1, &m_texture_page_fbo_id);
+  glGenFramebuffers(1, &m_vram_read_fbo_id);
-  glBindFramebuffer(GL_FRAMEBUFFER, m_texture_page_fbo_id);
+  glBindFramebuffer(GL_FRAMEBUFFER, m_vram_read_fbo_id);
-  glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, m_texture_page_texture->GetGLId(), 0);
+  glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, m_vram_read_texture->GetGLId(), 0);
   Assert(glCheckFramebufferStatus(GL_FRAMEBUFFER) == GL_FRAMEBUFFER_COMPLETE);
 }
 
@@ -100,9 +105,9 @@ void GPU_HW_OpenGL::ClearFramebuffer()
 
 void GPU_HW_OpenGL::DestroyFramebuffer()
 {
-  glDeleteFramebuffers(1, &m_texture_page_fbo_id);
+  glDeleteFramebuffers(1, &m_vram_read_fbo_id);
-  m_texture_page_fbo_id = 0;
+  m_vram_read_fbo_id = 0;
-  m_texture_page_texture.reset();
+  m_vram_read_texture.reset();
 
   glDeleteFramebuffers(1, &m_framebuffer_fbo_id);
   m_framebuffer_fbo_id = 0;
@@ -132,41 +137,29 @@ void GPU_HW_OpenGL::CreateVertexBuffer()
 
 bool GPU_HW_OpenGL::CompilePrograms()
 {
-  bool result = true;
+  for (u32 textured = 0; textured < 2; textured++)
-  result &= CompileProgram(m_color_program, false, false);
+  {
-  result &= CompileProgram(m_texture_program, true, false);
+    for (u32 blending = 0; blending < 2; blending++)
-  result &= CompileProgram(m_blended_texture_program, true, true);
+    {
-  if (!result)
+      for (u32 format = 0; format < 3; format++)
-    return false;
+      {
-
+        // TODO: eliminate duplicate shaders here
-  const std::string screen_quad_vs = GenerateScreenQuadVertexShader();
+        if (!CompileProgram(m_render_programs[textured][blending][format], ConvertToBoolUnchecked(textured),
-  for (u32 palette_size = 0; palette_size < static_cast<u32>(m_texture_page_programs.size()); palette_size++)
+                            ConvertToBoolUnchecked(blending), static_cast<TextureColorMode>(format)))
         {
-    const std::string fs = GenerateTexturePageFragmentShader(static_cast<TextureColorMode>(palette_size));
-
-    GL::Program& prog = m_texture_page_programs[palette_size];
-    if (!prog.Compile(screen_quad_vs.c_str(), fs.c_str()))
           return false;
-
+        }
-    prog.BindFragData(0, "o_col0");
+      }
-
+    }
-    if (!prog.Link())
-      return false;
-
-    prog.RegisterUniform("samp0");
-    prog.RegisterUniform("base_offset");
-    prog.RegisterUniform("palette_offset");
-    prog.Bind();
-    prog.Uniform1i(0, 0);
   }
 
   return true;
 }
 
-bool GPU_HW_OpenGL::CompileProgram(GL::Program& prog, bool textured, bool blending)
+bool GPU_HW_OpenGL::CompileProgram(GL::Program& prog, bool textured, bool blending, TextureColorMode texture_color_mode)
 {
   const std::string vs = GenerateVertexShader(textured);
-  const std::string fs = GenerateFragmentShader(textured, blending);
+  const std::string fs = GenerateFragmentShader(textured, blending, texture_color_mode);
   if (!prog.Compile(vs.c_str(), fs.c_str()))
     return false;
 
@@ -187,21 +180,29 @@ bool GPU_HW_OpenGL::CompileProgram(GL::Program& prog, bool textured, bool blendi
   if (textured)
   {
     prog.RegisterUniform("samp0");
+    prog.RegisterUniform("u_texture_page_base");
+    prog.RegisterUniform("u_texture_palette_base");
     prog.Uniform1i(1, 0);
   }
 
   return true;
 }
 
-void GPU_HW_OpenGL::SetProgram(bool textured, bool blending)
+void GPU_HW_OpenGL::SetProgram()
 {
-  const GL::Program& prog = textured ? (blending ? m_blended_texture_program : m_texture_program) : m_color_program;
+  const GL::Program& prog =
+    m_render_programs[BoolToUInt32(m_batch.texture_enable)][BoolToUInt32(m_batch.texture_blending_enable)]
+                     [static_cast<u32>(m_batch.texture_color_mode)];
   prog.Bind();
 
-  if (textured)
-    m_texture_page_texture->Bind();
-
   prog.Uniform2i(0, m_drawing_offset.x, m_drawing_offset.y);
+
+  if (m_batch.texture_enable)
+  {
+    m_vram_read_texture->Bind();
+    prog.Uniform2i(2, m_batch.texture_page_x, m_batch.texture_page_y);
+    prog.Uniform2i(3, m_batch.texture_palette_x, m_batch.texture_palette_y);
+  }
 }
 
 void GPU_HW_OpenGL::SetViewport()
@@ -302,6 +303,8 @@ void GPU_HW_OpenGL::FillVRAM(u32 x, u32 y, u32 width, u32 height, u16 color)
   const auto [r, g, b, a] = RGBA8ToFloat(RGBA5551ToRGBA8888(color));
   glClearColor(r, g, b, a);
   glClear(GL_COLOR_BUFFER_BIT);
+
+  InvalidateVRAMReadCache();
 }
 
 void GPU_HW_OpenGL::UpdateVRAM(u32 x, u32 y, u32 width, u32 height, const void* data)
@@ -334,6 +337,8 @@ void GPU_HW_OpenGL::UpdateVRAM(u32 x, u32 y, u32 width, u32 height, const void*
   // lower-left origin flip happens here
   glTexSubImage2D(GL_TEXTURE_2D, 0, x, VRAM_HEIGHT - y - height, width, height, GL_RGBA, GL_UNSIGNED_BYTE,
                   rgba_data.data());
+
+  InvalidateVRAMReadCache();
 }
 
 void GPU_HW_OpenGL::CopyVRAM(u32 src_x, u32 src_y, u32 dst_x, u32 dst_y, u32 width, u32 height)
@@ -347,31 +352,18 @@ void GPU_HW_OpenGL::CopyVRAM(u32 src_x, u32 src_y, u32 dst_x, u32 dst_y, u32 wid
   glBindFramebuffer(GL_FRAMEBUFFER, m_framebuffer_fbo_id);
   glBlitFramebuffer(src_x, src_y, src_x + width, src_y + height, dst_x, dst_y, dst_x + width, dst_y + height,
                     GL_COLOR_BUFFER_BIT, GL_NEAREST);
+
+  InvalidateVRAMReadCache();
 }
 
-void GPU_HW_OpenGL::UpdateTexturePageTexture()
+void GPU_HW_OpenGL::UpdateVRAMReadTexture()
 {
-  m_stats.num_texture_page_updates++;
+  m_stats.num_vram_read_texture_updates++;
+  m_vram_read_texture_dirty = false;
 
-  glBindFramebuffer(GL_FRAMEBUFFER, m_texture_page_fbo_id);
+  // TODO: Fallback blit path, and partial updates.
-  m_framebuffer_texture->Bind();
+  glCopyImageSubData(m_framebuffer_texture->GetGLId(), GL_TEXTURE_2D, 0, 0, 0, 0, m_vram_read_texture->GetGLId(),
-
+                     GL_TEXTURE_2D, 0, 0, 0, 0, VRAM_WIDTH, VRAM_HEIGHT, 1);
-  glDisable(GL_BLEND);
-  glDisable(GL_SCISSOR_TEST);
-  glViewport(0, 0, TEXTURE_PAGE_WIDTH, TEXTURE_PAGE_HEIGHT);
-  glBindVertexArray(m_attributeless_vao_id);
-
-  const GL::Program& prog = m_texture_page_programs[static_cast<u8>(m_render_state.texture_color_mode)];
-  prog.Bind();
-
-  prog.Uniform2i(1, m_render_state.texture_base_x, m_render_state.texture_base_y);
-  if (m_render_state.texture_color_mode >= GPU::TextureColorMode::Palette4Bit)
-    prog.Uniform2i(2, m_render_state.texture_palette_x, m_render_state.texture_palette_y);
-
-  glDrawArrays(GL_TRIANGLES, 0, 3);
-
-  m_framebuffer_texture->Unbind();
-  glBindFramebuffer(GL_FRAMEBUFFER, m_framebuffer_fbo_id);
 }
 
 void GPU_HW_OpenGL::FlushRender()
@@ -379,6 +371,9 @@ void GPU_HW_OpenGL::FlushRender()
   if (m_batch.vertices.empty())
     return;
 
+  if (m_vram_read_texture_dirty)
+    UpdateVRAMReadTexture();
+
   m_stats.num_batches++;
   m_stats.num_vertices += static_cast<u32>(m_batch.vertices.size());
 
@@ -386,7 +381,7 @@ void GPU_HW_OpenGL::FlushRender()
   glDisable(GL_DEPTH_TEST);
   glEnable(GL_SCISSOR_TEST);
   glDepthMask(GL_FALSE);
-  SetProgram(m_batch.texture_enable, m_batch.texture_blending_enable);
+  SetProgram();
   SetViewport();
   SetScissor();
   SetBlendState();

src/pse/gpu_hw_opengl.h

@@ -23,13 +23,13 @@ protected:
   void FillVRAM(u32 x, u32 y, u32 width, u32 height, u16 color) override;
   void UpdateVRAM(u32 x, u32 y, u32 width, u32 height, const void* data) override;
   void CopyVRAM(u32 src_x, u32 src_y, u32 dst_x, u32 dst_y, u32 width, u32 height) override;
-  void UpdateTexturePageTexture() override;
   void FlushRender() override;
+  void InvalidateVRAMReadCache() override;
 
 private:
   struct GLStats
   {
-    u32 num_texture_page_updates;
+    u32 num_vram_read_texture_updates;
     u32 num_batches;
     u32 num_vertices;
   };
@@ -39,13 +39,14 @@ private:
   void CreateFramebuffer();
   void ClearFramebuffer();
   void DestroyFramebuffer();
+  void UpdateVRAMReadTexture();
 
   void CreateVertexBuffer();
 
   bool CompilePrograms();
-  bool CompileProgram(GL::Program& prog, bool textured, bool blending);
+  bool CompileProgram(GL::Program& prog, bool textured, bool blending, TextureColorMode texture_color_mode);
 
-  void SetProgram(bool textured, bool blending);
+  void SetProgram();
   void SetViewport();
   void SetScissor();
   void SetBlendState();
@@ -53,16 +54,15 @@ private:
   std::unique_ptr<GL::Texture> m_framebuffer_texture;
   GLuint m_framebuffer_fbo_id = 0;
 
-  std::unique_ptr<GL::Texture> m_texture_page_texture;
+  std::unique_ptr<GL::Texture> m_vram_read_texture;
-  GLuint m_texture_page_fbo_id = 0;
+  GLuint m_vram_read_fbo_id = 0;
+  bool m_vram_read_texture_dirty = true;
 
   GLuint m_vertex_buffer = 0;
   GLuint m_vao_id = 0;
   GLuint m_attributeless_vao_id = 0;
 
-  GL::Program m_texture_program;
+  std::array<std::array<std::array<GL::Program, 3>, 2>, 2> m_render_programs;
-  GL::Program m_color_program;
-  GL::Program m_blended_texture_program;
   std::array<GL::Program, 3> m_texture_page_programs;
 
   GLStats m_stats = {};