diff options
Diffstat (limited to 'src/GPU3D_Soft.cpp')
| -rw-r--r-- | src/GPU3D_Soft.cpp | 24 |
1 files changed, 12 insertions, 12 deletions
diff --git a/src/GPU3D_Soft.cpp b/src/GPU3D_Soft.cpp index 56660c1..89f191f 100644 --- a/src/GPU3D_Soft.cpp +++ b/src/GPU3D_Soft.cpp @@ -222,24 +222,24 @@ public: s32 InterpolateZ(s32 z0, s32 z1, bool wbuffer) { - if (xdiff == 0) return z0; + if (xdiff == 0 || z0 == z1) return z0; - s32 zbase, zdiff; - if (z1 < z0) + if ((wdiff != 0) && wbuffer) { - zbase = z0; - zdiff = z1 - z0 - 1; + // perspective-correct approx. interpolation + if (z0 < z1) + return z0 + (((s64)(z1-z0) * yfactor) >> shift); + else + return z1 + (((s64)(z0-z1) * ((1<<shift)-yfactor)) >> shift); } else { - zbase = z0; - zdiff = z1 - z0; + // linear interpolation + if (z0 < z1) + return z0 + (((s64)(z1-z0) * x) / xdiff); + else + return z1 + (((s64)(z0-z1) * (xdiff-x)) / xdiff); } - - if ((wdiff != 0) && wbuffer) - return zbase + (((s64)zdiff * yfactor) >> shift); - else - return zbase + (((s64)zdiff * x) / xdiff); } private: |