Not sure if the formulas you've set out do this, but couldn't the rainbow tool treat the difference between y coordinates as depth, the way that the grass tool does? When y1 == y2, you get a semi-circle with the height == 1/2 * abs(x2 - x1), i.e. the radius. Otherwise you get a rainbow with a wider base at the point closer to the bottom of the screen that arcs back to the other point.
On Tue, Mar 31, 2009 at 10:12 PM, Bill Broadley <[email protected]>wrote: > Bill Kendrick wrote: > > On Tue, Mar 31, 2009 at 07:21:36PM -0700, Bill Broadley wrote: > >> Some. Not sure what you are getting at though. You want to draw 180 > degrees > >> of a circle with the end points defined by p1 and p2? What if you want > to > >> make an upside down rainbow? Or 1/2 of one? > > > > I only want to draw all 180 degress if y1==y2. Otherwise, it'd be > > less of the arc. (See my ASCII diagrams) > > Hrm, I don't think ascii is going to help, at least for me. Ah, ok, I have > an > idea of what you think you want to do. I think you do need 3 points. A > center, radius, range of angles. Basically there are an infinite number of > 180 degree curves that go through 2 points, and there's no way to know how > high the peak should be, nor which exact fraction of a circle to display. > > So for your diagrams how do you decide that in case 1 you do 1/2 a circle > and > the circle doesn't go above P2, but in case #3 you get 60% of a circle. > _______________________________________________ > vox-tech mailing list > [email protected] > http://lists.lugod.org/mailman/listinfo/vox-tech >
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