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

* 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
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2 changed files with 42 additions and 22 deletions
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22
src/GPU3D_Soft.cpp
View File

@ -753,8 +753,8 @@ void SoftRenderer::RenderShadowMaskScanline(RendererPolygon* rp, s32 y)
interp_start = &rp->SlopeR.Interp;
interp_end = &rp->SlopeL.Interp;
rp->SlopeR.EdgeParams_YMajor(&l_edgelen, &l_edgecov);
rp->SlopeL.EdgeParams_YMajor(&r_edgelen, &r_edgecov);
rp->SlopeR.EdgeParams<true>(&l_edgelen, &l_edgecov);
rp->SlopeL.EdgeParams<true>(&r_edgelen, &r_edgecov);
std::swap(xstart, xend);
std::swap(wl, wr);
@ -771,8 +771,8 @@ void SoftRenderer::RenderShadowMaskScanline(RendererPolygon* rp, s32 y)
interp_start = &rp->SlopeL.Interp;
interp_end = &rp->SlopeR.Interp;
rp->SlopeL.EdgeParams(&l_edgelen, &l_edgecov);
rp->SlopeR.EdgeParams(&r_edgelen, &r_edgecov);
rp->SlopeL.EdgeParams<false>(&l_edgelen, &l_edgecov);
rp->SlopeR.EdgeParams<false>(&r_edgelen, &r_edgecov);
}
// color/texcoord attributes aren't needed for shadow masks
@ -958,10 +958,8 @@ void SoftRenderer::RenderPolygonScanline(RendererPolygon* rp, s32 y)
// if the left and right edges are swapped, render backwards.
// on hardware, swapped edges seem to break edge length calculation,
// causing X-major edges to be rendered wrong when
// wireframe/edgemarking/antialiasing are used
// it also causes bad antialiasing, but not sure what's going on (TODO)
// most probable explanation is that such slopes are considered to be Y-major
// causing X-major edges to be rendered wrong when filled,
// and resulting in buggy looking anti-aliasing on X-major edges
if (xstart > xend)
{
@ -973,8 +971,8 @@ void SoftRenderer::RenderPolygonScanline(RendererPolygon* rp, s32 y)
interp_start = &rp->SlopeR.Interp;
interp_end = &rp->SlopeL.Interp;
rp->SlopeR.EdgeParams_YMajor(&l_edgelen, &l_edgecov);
rp->SlopeL.EdgeParams_YMajor(&r_edgelen, &r_edgecov);
rp->SlopeR.EdgeParams<true>(&l_edgelen, &l_edgecov);
rp->SlopeL.EdgeParams<true>(&r_edgelen, &r_edgecov);
std::swap(xstart, xend);
std::swap(wl, wr);
@ -991,8 +989,8 @@ void SoftRenderer::RenderPolygonScanline(RendererPolygon* rp, s32 y)
interp_start = &rp->SlopeL.Interp;
interp_end = &rp->SlopeR.Interp;
rp->SlopeL.EdgeParams(&l_edgelen, &l_edgecov);
rp->SlopeR.EdgeParams(&r_edgelen, &r_edgecov);
rp->SlopeL.EdgeParams<false>(&l_edgelen, &l_edgecov);
rp->SlopeR.EdgeParams<false>(&r_edgelen, &r_edgecov);
}
// interpolate attributes along Y

42
src/GPU3D_Soft.h
View File

@ -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;