Could reproduce the seam in the negative area (when coordinate is less 0). This should fix it:
https://www.dropbox.com/s/apiw469qp7gfue4/MatrixInitial.cs?dl=0
https://www.dropbox.com/s/5wf1f0oyqytej8a/MatrixOps.cs?dl=0
Not sure if it will work without other changes, though.
I get an error on MatrixInitial.cs
Line 120 CoordRect rect = CoordRect.WorldToPixel((Vector2D)matrixPos, (Vector2D)matrixSize, (Vector2D)cellSize); //will convert to cells as well
Says Assets\MapMagic\Generators\Matrix\Runtime\MatrixInitial.cs(120,40): error CS0117: 'CoordRect' does not contain a definition for 'WorldToPixel'
Hi Wright, i've added a post regarding this topic in the unity forum describing what I did to run across the same issue. Not sure what you mean with negative area, but maybe you could have another look.