diff options
Diffstat (limited to 'src/GPU3D_Soft.cpp')
| -rw-r--r-- | src/GPU3D_Soft.cpp | 21 |
1 files changed, 13 insertions, 8 deletions
diff --git a/src/GPU3D_Soft.cpp b/src/GPU3D_Soft.cpp index cce5d70..3cbb71e 100644 --- a/src/GPU3D_Soft.cpp +++ b/src/GPU3D_Soft.cpp @@ -185,6 +185,8 @@ public: // TODO: hardware tests show that this method is too precise // I haven't yet figured out what the hardware does, though + if (w1factor==0 || w0factor==0) { yfactor = 0; return; } + s64 num = ((s64)x << (shift + 40)) / w1factor; s64 denw0 = ((s64)(xdiff-x) << 40) / w0factor; s64 denw1 = num >> shift; @@ -1590,25 +1592,28 @@ void ScanlineFinalPass(s32 y) } else { - // technically: Z difference is shifted left by fog shift - // then bit 0-18 are the fractional part and bit 19-23 are the density index - // things are a little different here to avoid overflow in 32-bit range + // technically: Z difference is shifted right by two, then shifted left by fog shift + // then bit 0-16 are the fractional part and bit 17-31 are the density index + // on hardware, the final value can overflow the 32-bit range with a shift big enough, + // causing fog to 'wrap around' and accidentally apply to larger Z ranges z -= fogoffset; - densityid = z >> (19-fogshift); + z = (z >> 2) << fogshift; + + densityid = z >> 17; if (densityid >= 32) { densityid = 32; densityfrac = 0; } else - densityfrac = (z << fogshift) & 0x7FFFF; + densityfrac = z & 0x1FFFF; } - // checkme + // checkme (may be too precise?) u32 density = - ((RenderFogDensityTable[densityid] * (0x80000-densityfrac)) + - (RenderFogDensityTable[densityid+1] * densityfrac)) >> 19; + ((RenderFogDensityTable[densityid] * (0x20000-densityfrac)) + + (RenderFogDensityTable[densityid+1] * densityfrac)) >> 17; if (density >= 127) density = 128; u32 srccolor = ColorBuffer[pixeladdr]; |