DraftangleAnalysis Colormapping Unsymmetric Interval (Bug)

[Tom_P]

Dear McNeel-Team
Referring to the help-file

DraftAngleAnalysis | Rhino 3-D modeling

_DraftAngleAnalysis the blue (left input field) value is the upper, the red value the lower value.

Either i do completely miss-understand the mapping of angles → color, or i would guess it s a bug:

see the follow series of pictures - i use a torus, part of a torus and two truncated-cone-like surfaces.
I would love to get more information about the two surfaces at the right and about their shared edge (kink) marked in the first picture:

Now i do a first Analysis from 80 (blue) 0(green) to - 80(red)
i interpret, that the surfaces are somewhere in the positiv sub-interval 0 to -80 / green to red.
i interpret that the edge that interests me is somewhere arround -40 (yellow)
this values also makes sense regarding the geometry:

In a next step i would like to have more precise info about the range, that is close to the shared edge entering a range from -10 as upper and -50 as lower, the entire surface is getting red.
i would interpret this as the entire surface is tilted more then -50 degree (what, of course is not true and does not make sense.

is it a bug ? or what did i miss-understand.
Thanks for your help.
Best Tom

[John_Brock]

I drew a torus on the Top viewport, then switched to the Perspective viewport, set a fairly low display angle, then turned on DraftAngleAnalysis.
I set the range from 44 to 46 degrees.
I see the color switch from red to blue centered around the 45 degree slope.
This seems right to me.

[Tom_P]

Dear @John_Brock

thanks for having a look at this.
Actually there is a difference in the mac and pc implementation - the colors are reversed.
PC
86-> blue, 88-> red for Pc

MAC
88-> blue, 86->red for Mac

to get the same result i have to map:

the second aspect is my mistake:
I always thought the angle is measured against the normal of the c-plane - but it is measured against the projected vector of the surface-Normal-Vector into the plane defined by the normal / pull direction. You might help others with a better explanation in the help ?

thanks - best tom

[Tom_P]

yeah this is the new rhino wip 7 interface
nice thanks

(solution)