All,
I am using the following snippets of code to create fixed width band regions at 90 degrees to a series of given straight lines. The lines contain numerical data which I can then thematically map. I also have a version that creates variable width bands but for the moment I'll assume all bands are the same width.
After a lot of tweaking I thought I had finished the tool...Unfortunately, after crudely holding the corner of a sheet of paper up to the screen it appears my bands aren't perfectly perpendicular to the original line though I am clueless as to what could have gone wrong…
Is there any error converting degrees to radians and then back again in MapInfo ? Also, I am the using British national grid co-ordinate set, could this where my slight discrepancy has come from multiplying ?
fFNodeX = ObjectNodeX(oLine, 1, 1) ' read longitude
fFNodeY = ObjectNodeY(oLine, 1, 1) ' read latitude
fTNodeX = ObjectNodeX(oLine, 1, k) ' read longitude
fTNodeY = ObjectNodeY(oLine, 1, k) ' read latitude
fA1 = fTNodeX - fFNodeX
fA2 = fTNodeY - fFNodeY
fLinkLength = SQR(fA1*fA1 + fA2*fA2)
fB1 = -fA2/fLinkLength
fB2 = fA1/fLinkLength
x1 = fFNodeX + (fB1 *(fWidth + fOffset))
y1 = fFNodeY + (fB2 *(fWidth + fOffset))
x2 = fTNodeX + (fB1 *(fWidth + fOffset))
y2 = fTNodeY + (fB2 *(fWidth + fOffset))
x3 = fTNodeX + (fB1 * fOffset)
y3 = fTNodeY + (fB2 * fOffset)
x4 = fFNodeX + (fB1 * fOffset)
y4 = fFNodeY + (fB2 * fOffset)
As always, any help would be greatly appreciated…
Many thanks
Stu
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