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C1 intersecting curves

davide ciarloni's picture

I made some tests on the "intersector".
I always get C1 curves. I get C1 curves also when the involved surfaces are Ck
Is there a way to get C2 (or higher) intersecting curves?

Below, my basic test on Draw

# create 2 shapes (surfaces) and intersect them
pload ALL
# 1st shape: sphere
sphere ss 0 0 0 1000
# 2nd shape: cylinder
cylinder cc 500 0 0 500
# compute intersection
intersect ii ss cc
# iges out
brepiges ii_1 c:/temp/ii_1.igs
brepiges ii_2 c:/temp/ii_2.igs
brepiges ii_3 c:/temp/ii_3.igs
brepiges ii_4 c:/temp/ii_4.igs

jelle's picture

hello Davide,

surprising indeed that you only get C1 continuity...
however, I do think [ suspect ] that the TCL commands give you less control than the std OCC API.
are you specifically interested in the cases of analytic forms?
since there are specialized analytic interesection algo's perhaps you are interested in those...

davide ciarloni's picture

thank you for your prompt reply

as you have well understood, I am testing the system using Draw only

in case you can use specialized algos, please do that.
You might replicate my case (sphere 0 0 0 1000 Vs cilynder 500 0 0 500)
I need back iges format of the intersecting curves.



davide ciarloni's picture

In the mean time I tried with solids
I get C1 curves and a mistake in the intersection.

# create 2 shapes (SOLIDS) and intersect them
pload ALL
# 1st shape: SOLID sphere
psphere SS 1000
# 2nd shape: SOLID cylinder
pcylinder C 500 4000
ttranslate C 500 0 -2000
# compute intersection
bop C S
bopsection R
# iges out
brepiges R c:/temp/R.igs

If you can use a specialized algo, please do that



davide ciarloni's picture

waiting for a specialized algo from you, I noticed that the intersection works fine if I come back from solids into surfaces (despite it is always C1 and C2 is highly desirable).

# remove wrong intersection
erase R
# explode solids into faces
explode S F
explode C F
donly S_1 C_1
# make surfaces from faces
mksurface SS S_1
mksurface CC C_1
# intersect surfaces
intersect AA SS CC
# igesout
brepiges AA_1 c:/temp/AA_1.igs
brepiges AA_2 c:/temp/AA_2.igs
brepiges AA_3 c:/temp/AA_3.igs
brepiges AA_4 c:/temp/AA_4.igs

jelle's picture

if you go through the OCC API docs you'll see that with [ShapeUpgrade?] you can also "upgrade" the continuity with this API.
please don't keep waiting for me Davide...

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