From c787a0759af94ecf1a344c259ce9f2081755f214 Mon Sep 17 00:00:00 2001
From: RSDuck <rsduck@users.noreply.github.com>
Date: Thu, 16 Jul 2020 02:26:54 +0200
Subject: [PATCH] don't render 3d again without a GX flush speedup in 30 FPS
 games

---
 src/GPU3D.cpp      | 20 ++++++++++++++++++++
 src/GPU3D.h        |  2 ++
 src/GPU3D_Soft.cpp | 14 +++++++++++---
 3 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/src/GPU3D.cpp b/src/GPU3D.cpp
index 4120fe7e4d..1e484790f7 100644
--- a/src/GPU3D.cpp
+++ b/src/GPU3D.cpp
@@ -174,6 +174,8 @@ u8 FogDensityTable[32];
 
 u32 ClearAttr1, ClearAttr2;
 
+bool RenderFrameIdentical;
+
 u32 RenderDispCnt;
 u8 RenderAlphaRef;
 
@@ -379,6 +381,8 @@ void Reset()
     NumPolygons = 0;
     NumOpaquePolygons = 0;
 
+    RenderFrameIdentical = false;
+
     // TODO: confirm initial polyid/color/fog values
     ClearAttr1 = 0x3F000000;
     ClearAttr2 = 0x00007FFF;
@@ -395,6 +399,8 @@ void Reset()
 
 void DoSavestate(Savestate* file)
 {
+    RenderFrameIdentical = false;
+
     file->Section("GP3D");
 
     CmdFIFO.DoSavestate(file);
@@ -2774,6 +2780,20 @@ void VBlank()
                 }
 
                 RenderNumPolygons = NumPolygons;
+
+                RenderFrameIdentical = false;
+            }
+            else
+            {
+                RenderFrameIdentical = RenderDispCnt == DispCnt
+                    && RenderAlphaRef == AlphaRef
+                    && RenderClearAttr1 == ClearAttr1
+                    && RenderClearAttr2 == ClearAttr2
+                    && RenderFogColor == FogColor
+                    && RenderFogOffset == FogOffset * 0x200
+                    && memcmp(RenderEdgeTable, EdgeTable, 8*2) == 0
+                    && memcmp(RenderFogDensityTable + 1, FogDensityTable, 32) == 0
+                    && memcmp(RenderToonTable, ToonTable, 32*2) == 0;
             }
 
             RenderDispCnt = DispCnt;
diff --git a/src/GPU3D.h b/src/GPU3D.h
index a7bc5c12b2..426a66353e 100644
--- a/src/GPU3D.h
+++ b/src/GPU3D.h
@@ -76,6 +76,8 @@ typedef struct
 
 } Polygon;
 
+extern bool RenderFrameIdentical;
+
 extern u32 RenderDispCnt;
 extern u8 RenderAlphaRef;
 
diff --git a/src/GPU3D_Soft.cpp b/src/GPU3D_Soft.cpp
index 8397898da3..547a52c0e5 100644
--- a/src/GPU3D_Soft.cpp
+++ b/src/GPU3D_Soft.cpp
@@ -2084,7 +2084,7 @@ void RenderFrame()
     {
         Platform::Semaphore_Post(Sema_RenderStart);
     }
-    else
+    else if (!RenderFrameIdentical)
     {
         ClearBuffers();
         RenderPolygons(false, &RenderPolygonRAM[0], RenderNumPolygons);
@@ -2099,8 +2099,16 @@ void RenderThreadFunc()
         if (!RenderThreadRunning) return;
 
         RenderThreadRendering = true;
-        ClearBuffers();
-        RenderPolygons(true, &RenderPolygonRAM[0], RenderNumPolygons);
+        if (!RenderFrameIdentical)
+        {
+            ClearBuffers();
+            RenderPolygons(true, &RenderPolygonRAM[0], RenderNumPolygons);
+        }
+        else
+        {
+            for (int i = 0; i < 192; i++)
+                Platform::Semaphore_Post(Sema_ScanlineCount);
+        }
 
         Platform::Semaphore_Post(Sema_RenderDone);
         RenderThreadRendering = false;