GetBoundingBox / Solar Pool Heating Coil

[john.uhden]

I had never noticed this until just now...

that vla-getboundingbox ignores the extra size of a polyline with widths > 0.

I was writing a routine to draw a coil of pipe that I will use to build a solar pool heater.

I needed to know if 100 ft. of 1 inch dia. black poly pipe would fit in a flat coil on a 4'x4' sheet of plywood with a 1/4" gap between pipes.  It will work just fine, but the actual overall height and width are greater than what getboundingbox returns.  Amazingly by one pipe diamter! <g>

I will face it towards the sun and pump water through it using my Little Giant cover pump so I don't have to mess with the pool filter piping.  I was going to sell the pump since I have acquired an Extreme Mesh winter cover from Dover Vinyl Products in Toms River, NJ (my only client left).  The cover is fantastic, but if I can heat my pool water with the pump, then I will keep it.

Does any of you wizards know a formula (and values) for computing what increase in temperature could be created?

I have attached the COIL.LSP program for your fun.

[Kent1Cooper]

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@john.uhden wrote:

.... vla-getboundingbox ignores the extra size of a polyline with widths > 0.

.....

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That's unfortunate.  But you could apply something like PLWtoOutline.lsp, with its PLWO command, available here, and then the bounding box should reflect the actual extent.

[john.uhden]

Thanks, Kent. I really don't need a solution for this situation. As long as the boundingbox height and width are around 3'10" then the coil will fit on the piece of plywood.

I was more interested in pointing out the limitation of the function, of which limitation I had not been aware.