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notes + optimization

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should only compile to one div instruction per path now
This commit is contained in:
Jaklyy 2024-03-17 10:42:52 -04:00
parent b6fa43b0cf
commit ee91d7f8f3
1 changed files with 8 additions and 7 deletions
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15
src/GPU3D_Soft.h
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@ -179,23 +179,24 @@ private:
else
{
// Z-buffering: linear interpolation
// still doesn't quite match hardware...
// not perfect, but close
if (dir)
{
// seems like y dir does different interpolation than x?
// this probably isn't right...
// interpolating along y uses a different algorithm than x
// this algo probably isn't quite right though...
if (z0 < z1)
return z0 + (z1-z0) * x / xdiff;
return z0 + (s64)(z1-z0) * x / xdiff;
else
return z1 + (z0-z1) * (xdiff-x) / xdiff;
return z1 + (s64)(z0-z1) * (xdiff-x) / xdiff;
}
else
{
// these algorithms are weiiird but i can't argue with the results
if (z0 < z1)
return z0 + (((z1-z0) / xdiff & ~0x1) * x);
return z0 + ((z1-z0 >> 1) / xdiff * x << 1);
else
return z1 + (((z0-z1) / xdiff & ~0x1) * (xdiff-x)) + ((z0-z1) % (xdiff << 1));
return z1 + (((z0-z1 >> 1) / xdiff * (xdiff-x)) + ((z0-z1 >> 1) % xdiff) << 1);
}
}
}