v108.17

Enhanced perspective correction support [DerKoun]

bsnes/emulator/emulator.hpp

@@ -29,7 +29,7 @@ using namespace nall;
 
 namespace Emulator {
   static const string Name    = "bsnes";
-  static const string Version = "108.16";
+  static const string Version = "108.17";
   static const string Author  = "byuu";
   static const string License = "GPLv3";
   static const string Website = "https://byuu.org";

bsnes/sfc/ppu-fast/line.cpp

@@ -3,6 +3,7 @@ uint PPU::Line::count = 0;
 
 auto PPU::Line::flush() -> void {
   if(Line::count) {
+    if(ppu.hdScale() > 1) cacheMode7HD();
     #pragma omp parallel for if(Line::count >= 8)
     for(uint y = 0; y < Line::count; y++) {
       if(ppu.deinterlace()) {

bsnes/sfc/ppu-fast/mode7.cpp

@@ -16,8 +16,6 @@ auto PPU::Line::renderMode7(PPU::IO::Background& self, uint source) -> void {
   int hoffset = (int13)io.mode7.hoffset;
   int voffset = (int13)io.mode7.voffset;
 
-//if(source==Source::BG1&&y==1) print(a, " ", b, " ", c, " ", d, " ", hcenter, " ", vcenter, " ", hoffset, " ", voffset, "\n");
-
   uint mosaicCounter = 1;
   uint mosaicPalette = 0;
   uint mosaicPriority = 0;

bsnes/sfc/ppu-fast/mode7hd.cpp

@@ -1,3 +1,100 @@
+//determine mode 7 line groups for perspective correction
+auto PPU::Line::cacheMode7HD() -> void {
+  ppu.mode7LineGroups.count = 0;
+  if(ppu.hdPerspective()) {
+    #define isLineMode7(line) (line.io.bg1.tileMode == TileMode::Mode7 && !line.io.displayDisable && ( \
+      (line.io.bg1.aboveEnable || line.io.bg1.belowEnable) \
+    ))
+    bool state = false;
+    uint y;
+    //find the moe 7 groups
+    for(y = 0; y < Line::count; y++) {
+      if(state != isLineMode7(ppu.lines[Line::start + y])) {
+        state = !state;
+        if(state) {
+          ppu.mode7LineGroups.startLine[ppu.mode7LineGroups.count] = ppu.lines[Line::start + y].y;
+        } else {
+          ppu.mode7LineGroups.endLine[ppu.mode7LineGroups.count] = ppu.lines[Line::start + y].y - 1;
+          //the lines at the edges of mode 7 groups may be erroneous, so start and end lines for interpolation are moved inside
+          int offset = (ppu.mode7LineGroups.endLine[ppu.mode7LineGroups.count] - ppu.mode7LineGroups.startLine[ppu.mode7LineGroups.count]) / 8;
+          ppu.mode7LineGroups.startLerpLine[ppu.mode7LineGroups.count] = ppu.mode7LineGroups.startLine[ppu.mode7LineGroups.count] + offset;
+          ppu.mode7LineGroups.endLerpLine[ppu.mode7LineGroups.count] = ppu.mode7LineGroups.endLine[ppu.mode7LineGroups.count] - offset;
+          ppu.mode7LineGroups.count++;
+        }
+      }
+    }
+    #undef isLineMode7
+    if(state) {
+      //close the last group if necessary
+      ppu.mode7LineGroups.endLine[ppu.mode7LineGroups.count] = ppu.lines[Line::start + y].y - 1;
+      int offset = (ppu.mode7LineGroups.endLine[ppu.mode7LineGroups.count] - ppu.mode7LineGroups.startLine[ppu.mode7LineGroups.count]) / 8;
+      ppu.mode7LineGroups.startLerpLine[ppu.mode7LineGroups.count] = ppu.mode7LineGroups.startLine[ppu.mode7LineGroups.count] + offset;
+      ppu.mode7LineGroups.endLerpLine[ppu.mode7LineGroups.count] = ppu.mode7LineGroups.endLine[ppu.mode7LineGroups.count] - offset;
+      ppu.mode7LineGroups.count++;
+    }
+
+    //detect groups that do not have perspective
+    for(int i : range(ppu.mode7LineGroups.count)) {
+      int a = -1, b = -1, c = -1, d = -1;  //the mode 7 scale factors of the current line
+      int aPrev = -1, bPrev = -1, cPrev = -1, dPrev = -1;  //the mode 7 scale factors of the previous line
+      bool aVar = false, bVar = false, cVar = false, dVar = false;  //has a varying value been found for the factors?
+      bool aInc = false, bInc = false, cInc = false, dInc = false;  //has the variation been an increase or decrease?
+      for(y = ppu.mode7LineGroups.startLerpLine[i]; y <= ppu.mode7LineGroups.endLerpLine[i]; y++) {
+        a = ((int)((int16)(ppu.lines[y].io.mode7.a)));
+        b = ((int)((int16)(ppu.lines[y].io.mode7.b)));
+        c = ((int)((int16)(ppu.lines[y].io.mode7.c)));
+        d = ((int)((int16)(ppu.lines[y].io.mode7.d)));
+        //has the value of 'a' changed compared to the last line?
+        //(and is the factor larger than zero, which happens sometimes and seems to be game-specific, mostly at the edges of the screen)
+        if(aPrev > 0 && a > 0 && a != aPrev) {
+          if(!aVar) {
+            //if there has been no variation yet, store that there is one and store if it is an increase or decrease
+            aVar = true;
+            aInc = a > aPrev;
+          } else if(aInc != a > aPrev) {
+            //if there has been an increase and now we have a decrease, or vice versa, set the interpolation lines to -1
+            //to deactivate perspective correction for this group and stop analyzing it further
+            ppu.mode7LineGroups.startLerpLine[i] = -1;
+            ppu.mode7LineGroups.endLerpLine[i] = -1;
+            break;
+          }
+        }
+        if(bPrev > 0 && b > 0 && b != bPrev) {
+          if(!bVar) {
+            bVar = true;
+            bInc = b > bPrev;
+          } else if(bInc != b > bPrev) {
+            ppu.mode7LineGroups.startLerpLine[i] = -1;
+            ppu.mode7LineGroups.endLerpLine[i] = -1;
+            break;
+          }
+        }
+        if(cPrev > 0 && c > 0 && c != cPrev) {
+          if(!cVar) {
+            cVar = true;
+            cInc = c > cPrev;
+          } else if(cInc != c > cPrev) {
+            ppu.mode7LineGroups.startLerpLine[i] = -1;
+            ppu.mode7LineGroups.endLerpLine[i] = -1;
+            break;
+          }
+        }
+        if(dPrev > 0 && d > 0 && d != bPrev) {
+          if(!dVar) {
+            dVar = true;
+            dInc = d > dPrev;
+          } else if(dInc != d > dPrev) {
+            ppu.mode7LineGroups.startLerpLine[i] = -1;
+            ppu.mode7LineGroups.endLerpLine[i] = -1;
+            break;
+          }
+        }
+        aPrev = a, bPrev = b, cPrev = c, dPrev = d;
+      }
+    }
+  }
+}
+
 auto PPU::Line::renderMode7HD(PPU::IO::Background& self, uint source) -> void {
   const bool extbg = source == Source::BG2;
   const uint scale = ppu.hdScale();
@@ -7,15 +104,25 @@ auto PPU::Line::renderMode7HD(PPU::IO::Background& self, uint source) -> void {
   Pixel* below = &this->below[-1];
 
   //find the first and last scanline for interpolation
-  int y_a = y;
+  int y_a = -1;
-  int y_b = y;
+  int y_b = -1;
-  #define isLineMode7(n) (ppu.lines[n].io.bg1.tileMode == TileMode::Mode7 && ( \
+  #define isLineMode7(n) (ppu.lines[n].io.bg1.tileMode == TileMode::Mode7 && !ppu.lines[n].io.displayDisable && ( \
     (ppu.lines[n].io.bg1.aboveEnable || ppu.lines[n].io.bg1.belowEnable) \
   ))
   if(ppu.hdPerspective()) {
-    while(y_a >   1 && isLineMode7(y_a)) y_a--; y_a += 1;
+    //find the mode 7 line group this line is in and use its interpolation lines
-    while(y_b < 239 && isLineMode7(y_b)) y_b++; y_b -= 8;
+    for(int i : range(ppu.mode7LineGroups.count)) {
-  } else {
+      if(y >= ppu.mode7LineGroups.startLine[i] && y <= ppu.mode7LineGroups.endLine[i]) {
+        y_a = ppu.mode7LineGroups.startLerpLine[i];
+        y_b = ppu.mode7LineGroups.endLerpLine[i];
+        break;
+      }
+    }
+  }
+  if(y_a == -1 || y_b == -1) {
+    //if perspective correction is disabled or the group was detected as non-perspective, use the neighboring lines
+    y_a = y;
+    y_b = y;
     if(y_a >   1 && isLineMode7(y_a)) y_a--;
     if(y_b < 239 && isLineMode7(y_b)) y_b++;
   }

bsnes/sfc/ppu-fast/ppu.hpp

@@ -265,7 +265,7 @@ public:
   auto readObject(uint10 address) -> uint8;
   auto writeObject(uint10 address, uint8 data) -> void;
 
-  //[serialized]
+//serialized:
   Latch latch;
   IO io;
 
@@ -303,6 +303,7 @@ public:
     auto renderMode7(PPU::IO::Background&, uint source) -> void;
 
     //mode7hd.cpp
+    static auto cacheMode7HD() -> void;
     auto renderMode7HD(PPU::IO::Background&, uint source) -> void;
     alwaysinline auto lerp(float pa, float va, float pb, float vb, float pr) -> float;
 
@@ -313,7 +314,7 @@ public:
     auto renderWindow(PPU::IO::WindowLayer&, bool enable, bool output[256]) -> void;
     auto renderWindow(PPU::IO::WindowColor&, uint mask,   bool output[256]) -> void;
 
-    //[unserialized]
+  //unserialized:
     uint y;  //constant
     bool fieldID;
 
@@ -333,6 +334,8 @@ public:
     static uint start;
     static uint count;
   };
+
+//unserialized:
   Line lines[240];
 
   //used to help detect when the video output size changes between frames to clear overscan area.
@@ -341,6 +344,14 @@ public:
     uint width = 0;
     uint height = 0;
   } frame;
+
+  struct Mode7LineGroups {
+    int count = -1;
+    int startLine[32];
+    int endLine[32];
+    int startLerpLine[32];
+    int endLerpLine[32];
+  } mode7LineGroups;
 };
 
 extern PPU ppufast;