1a44ba1daa

adspartan: improve alphamap loading and conversion to big alpha format

src/noggit/Alphamap.cpp

@@ -95,16 +95,26 @@ void Alphamap::readBigAlpha(BlizzardArchive::ClientFile *f)
   f->seekRelative(0x1000);
 }
 
+namespace
+{
+    struct alpha_4_4
+    {
+        std::uint8_t lower : 4;
+        std::uint8_t upper : 4;
+    };
+}
+
+
 void Alphamap::readNotCompressed(BlizzardArchive::ClientFile *f, bool do_not_fix_alpha_map)
 {
-  char const* abuf = f->getPointer();
+  alpha_4_4 const* abuf = reinterpret_cast<alpha_4_4 const*>(f->getPointer());
 
   for (std::size_t x(0); x < 64; ++x)
   {
     for (std::size_t y(0); y < 64; y += 2)
     {
-      amap[x * 64 + y + 0] = ((*abuf & 0x0f) << 4) | (*abuf & 0x0f);
-      amap[x * 64 + y + 1] = ((*abuf & 0xf0) >> 4) | (*abuf & 0xf0);
+      amap[x * 64 + y + 0] = abuf->lower | abuf->lower << 4;
+      amap[x * 64 + y + 1] = abuf->upper | abuf->upper << 4;
       ++abuf;
     }
   }

src/noggit/texture_set.cpp

@@ -1133,9 +1133,12 @@ void TextureSet::alphas_to_big_alpha(uint8_t* dest)
 
     for (int k = static_cast<int>(nTextures - 2); k >= 0; --k)
     {
-      uint8_t val = misc::rounded_255_int_div(*alpha(k, i) * a);
+      // uint8_t val = misc::rounded_255_int_div(*alpha(k, i) * a);
+      uint8_t* value_ptr = alpha(k, i);
+      uint8_t val = alpha_convertion_lookup[*value_ptr * a];
       a -= val;
-      *alpha(k, i) = val;
+      // *alpha(k, i) = val;
+      *value_ptr = val;
     }
   }
 }
@@ -1148,14 +1151,14 @@ void TextureSet::convertToBigAlpha()
     return;
   }
 
-  uint8_t tab[4096 * 3];
+  std::array<std::uint8_t, 4096 * 3> tab;
 
   apply_alpha_changes();
-  alphas_to_big_alpha(tab);
+  alphas_to_big_alpha(tab.data());
 
   for (size_t k = 0; k < nTextures - 1; k++)
   {
-    alphamaps[k]->setAlpha(tab + 4096 * k);
+    alphamaps[k]->setAlpha(tab.data() + 4096 * k);
   }
 }
 
@@ -1639,3 +1642,5 @@ std::array<std::uint16_t, 8> TextureSet::lod_texture_map()
 
   return _doodadMapping;
 }
+
+std::array<std::uint8_t, 256 * 256> TextureSet::alpha_convertion_lookup = TextureSet::make_alpha_lookup_array();

src/noggit/texture_set.hpp

@@ -166,5 +166,19 @@ private:
 
   bool _do_not_convert_alphamaps;
 
+  static constexpr std::array<std::uint8_t, 256 * 256> make_alpha_lookup_array()
+  {
+      std::array<std::uint8_t, 256 * 256> array{};
+
+      for (int i = 0; i < 256 * 256; ++i)
+      {
+          array[i] = i / 255 + (i % 255 <= 127 ? 0 : 1);
+      }
+
+      return array;
+  }
+
+  static std::array<std::uint8_t, 256 * 256> alpha_convertion_lookup;
+
   Noggit::NoggitRenderContext _context;
 };