Improve allocation handling in cube map textures

While there isn't enough bits to track all face allocations, tracking
the base level per face is possible.  This allows mipmap generation to
work more sensibly.

diff --git a/source/texturecube.cpp b/source/texturecube.cpp
index 82447e65b8f91cb53f2170aa6e44617ccbbf8aff..14ddf43d41c2cdc076e4489a62e2ed2e7341dd36 100644 (file)
--- a/source/texturecube.cpp
+++ b/source/texturecube.cpp
@@ -71,7 +71,7 @@ void TextureCube::allocate(unsigned level)
                throw invalid_operation("TextureCube::allocate");
        if(level>=levels)
                throw invalid_argument("TextureCube::allocate");
-       if(allocated&(1<<level))
+       if(allocated&(64<<level))
                return;
 
        if(ARB_texture_storage)
@@ -107,13 +107,26 @@ void TextureCube::image(TextureCubeFace face, unsigned level, PixelFormat fmt, D
                glTexParameteri(target, GL_TEXTURE_MAX_LEVEL, levels-1);
        glTexImage2D(face, level, ifmt, s, s, 0, get_upload_format(fmt), type, data);
 
-       // XXX Allocation should be tracked per-face, but we'll run out of bits
-       allocated |= 1<<level;
-       if(auto_gen_mipmap && level==0)
+       if(level==0)
        {
-               // TODO Only do this once all faces are created
-               generate_mipmap();
-               allocated |= (1<<levels)-1;
+               allocated |= 1<<get_face_index(face);
+               if((allocated&63)==63)
+               {
+                       allocated |= 64;
+                       if(auto_gen_mipmap)
+                       {
+                               generate_mipmap();
+                               allocated |= (64<<levels)-1;
+                       }
+               }
+       }
+       else if(!(allocated&(64<<level)))
+       {
+               for(unsigned i=0; i<6; ++i)
+                       if(enumerate_faces(i)!=face)
+                               glTexImage2D(enumerate_faces(i), level, ifmt, s, s, 0, get_upload_format(fmt), type, 0);
+
+               allocated |= 64<<level;
        }
 }
 

diff --git a/source/texturecube.h b/source/texturecube.h
index f5a364047874aa10569e2fe1a4c727e69b47063b..dabf2b8883690228c9e12e9babe232a95326015e 100644 (file)
--- a/source/texturecube.h
+++ b/source/texturecube.h
@@ -51,6 +51,8 @@ public:
 private:
        unsigned size;
        unsigned levels;
+       /* Lowest six bits track allocation status of faces on the base level.  Bit
+       seven is set if the entire base level is allocated. */
        unsigned allocated;
 
        static TextureCubeFace face_order[6];