Finding Roof valleys

[Andrew Mac]

Is there a relatively easy way to have VW find the roof valleys when drawing individual roof faces that die into each other

[Chad McNeely]

For planar surfaces, top view, convert copy to lines, hidden line render. Where the eave and ridge lines stop are the end points of the valley, generally.

But you should (IMO) have already drawn these lines in 2d before starting to build roof faces. You then have a guide for creating the roof face polys, a reality check on the VW output, and a way of keeping your head in the game, so to speek. I believe I can actually draw a roof faster this way, too, not counting the simple roofs where "Create roof" actually works.

The goal is actively and accurately placing the valleys and such, versus throwing up geometry and letting VW mash it together for you, and then passively using the results to try again, and again.

[CS1]

Dont know anyone can help here. When you have two roof faces that of the same roof pitch running at 90? to each other the valley is 45? to the direction of the two roofs. Does anyone know the math for how to work out the angle of this valley when the roof pitchs are at different pitches?

[mike m oz]

http://books.whitcoulls.co.nz/carpenters-metric-roofing-ready-reckoner/ISBN9780854420049

http://www.bookmarki.com/A-Roof-Cutter-s-Secrets-to-Framing-the-Custom-Home-p/9781928580324.htm

[mike m oz]

Or use the Roof object to create it for you.

[Chad McNeely]

Dont know anyone can help here. When you have two roof faces that of the same roof pitch running at 90? to each other the valley is 45? to the direction of the two roofs. Does anyone know the math for how to work out the angle of this valley when the roof pitchs are at different pitches?

Measuring a roof as a rise/run instead of as an angle is the key. The valley will be a line whose x:y dimensions are proportional to the roof faces' rise:rise. So in your example, two same-pitched roof faces each have the same rise, and a line with equal x and y happens to be a 45 degree angle (between 90 degree bearing lines). If a 6:12 roof runs into a 12:12 roof, it takes the 6:12 roof half as far to match the height of the 12:12 slope, so the valley will have x:y dimensions that are 2:1 or 1:2 depending on which way things meet.

Another way to skin the cat is to draw (just 2d) lines parallel to the bearing line, such that they are, say, one foot above the bearing height. So at 3:12, this line is 4 feet in, at 6:12 it is 2 feet in, etc. When you connect a line from the intersection of the bearing lines to the intersection of these lines of equal height, you have an accurate hip or valley angle. This works for any pitch, and at any intersection angle.