Source code for Xiaolin Wu's line algorithm in C?

Question

I'm looking for a nice and efficient implementation of Xiaolin Wu's anti-aliased line drawing algorithm in C, does anyone have this code they could share with me?

Thanks

Answer 1

Wikipedia has pseudo code.

Google has many examples like this one or this one. And your question reminded me this nice article on antialiasing.

EDIT: It's time to discover Hugo Helias's website if you don't know it already.

Answer 2

Wondering if implementation here is correct, because in

ErrorAdj = ((unsigned long) DeltaX << 16) / (unsigned long) DeltaY;
      /* Draw all pixels other than the first and last */
while (--DeltaY) {
         ErrorAccTemp = ErrorAcc;   /* remember current accumulated error */
         ErrorAcc += ErrorAdj;      /* calculate error for next pixel */
         if (ErrorAcc <= ErrorAccTemp) {
            /* The error accumulator turned over, so advance the X coord */
            X0 += XDir;
         }
         Y0++; /* Y-major, so always advance Y */
         /* The IntensityBits most significant bits of ErrorAcc give us the
            intensity weighting for this pixel, and the complement of the
            weighting for the paired pixel */
         Weighting = ErrorAcc >> IntensityShift;
         DrawPixel(pDC,X0, Y0, BaseColor + Weighting);
         DrawPixel(pDC,X0 + XDir, Y0,
               BaseColor + (Weighting ^ WeightingComplementMask));
      }

condition if (ErrorAcc <= ErrorAccTemp) is always false.