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Fix aa being upside down on swapped y-major slopes (#1803)

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* fix aa being upside down on swapped y-major slopes

* further improvements to swapped aa

in addition to fixing swapped y-major slope aa, now fixes:
swapped x-major slope aa
swapped vertical slope aa

* use templates instead + style/comment tweaks

should force the compiler to precompile if statements like i want it to do, instead of just hoping it does so on its own
This commit is contained in:
Jaklyy
2023-08-27 07:28:44 -04:00
committed by GitHub
parent d7369857c3
commit dc8efb62b8
2 changed files with 42 additions and 22 deletions
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42
src/GPU3D_Soft.h
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@ -354,13 +354,19 @@ private:
else if (ret > xmax) ret = xmax;
return ret;
}
template<bool swapped>
void EdgeParams_XMajor(s32* length, s32* coverage)
{
if (side ^ Negative)
*length = (dx >> 18) - ((dx-Increment) >> 18);
else
*length = ((dx+Increment) >> 18) - (dx >> 18);
// only do length calc for right side when swapped as it's
// only needed for aa calcs, as actual line spans are broken
if constexpr (!swapped || side)
{
if (side ^ Negative)
*length = (dx >> 18) - ((dx-Increment) >> 18);
else
*length = ((dx+Increment) >> 18) - (dx >> 18);
}
// for X-major edges, we return the coverage
// for the first pixel, and the increment for
@ -371,33 +377,49 @@ private:
s32 startcov = (((startx << 10) + 0x1FF) * ylen) / xlen;
*coverage = (1<<31) | ((startcov & 0x3FF) << 12) | (xcov_incr & 0x3FF);
if constexpr (swapped) *length = 1;
}
template<bool swapped>
void EdgeParams_YMajor(s32* length, s32* coverage)
{
*length = 1;
if (Increment == 0)
{
*coverage = 31;
// for some reason vertical edges' aa values
// are inverted too when the edges are swapped
if constexpr (swapped)
*coverage = 0;
else
*coverage = 31;
}
else
{
s32 cov = ((dx >> 9) + (Increment >> 10)) >> 4;
if ((cov >> 5) != (dx >> 18)) cov = 31;
cov &= 0x1F;
if (!(side ^ Negative)) cov = 0x1F - cov;
if constexpr (swapped)
{
if (side ^ Negative) cov = 0x1F - cov;
}
else
{
if (!(side ^ Negative)) cov = 0x1F - cov;
}
*coverage = cov;
}
}
template<bool swapped>
void EdgeParams(s32* length, s32* coverage)
{
if (XMajor)
return EdgeParams_XMajor(length, coverage);
return EdgeParams_XMajor<swapped>(length, coverage);
else
return EdgeParams_YMajor(length, coverage);
return EdgeParams_YMajor<swapped>(length, coverage);
}
s32 Increment;