How to improve computer processing speed when using OpenSCAD

[KP Chiang]

I have spent a lot of time using OpenSCAD last year and wished my computer can process things faster.   However, not being a computer tech-savvy person I am not 100% sure how to improve.

It probably involves getting a computer with faster processor, bigger ram and better video card, but I want to talk this over with the forum first.

Question number one has to do with the "preview" button (F5) : If I load a model that is quite complex, the preview is actually fine until I started doing operations on it.   For example, I can load a car model with a lot of details.   I can pan and rotate the model alone in preview window just fine.   But if I use boolean operation to cut the car in half (make a big cube to cover half of the car, and then perform subtract, hit F5 key) the preview will show up pretty fast, but when I pan and rotate the model in preview window, it feels less smooth.   If the operation involves more operations(cut it in half, drill holes using cylinders, add a few more cubes here and there), the panning and rotating of resulting model gets choppier and choppier.   Why is this happening and how do I make it better?

Question number two has to do with the "render" button (F6) :   The most computer resource usage heavy operation I ever need to do is when I need to chop the model into many slices or slabs (say, a 20mm tall object sliced into 0.25mm thick slices), and then for each of those slices, a projection on XY plane is created, then a minkowski operation is done on the 2D projection, then an extrusion is made from the new 2D shape, then the extrusion is moved("translate") to a certain location, then all the new slices are merged into one object("union").   This series of operations are done to all slices with FOR loops.   I wrote down those codes, hit F6 and the computer goes into a near frozen state.   The operations eventually get finished, but it's incredi-slow and the computer cannot do anything during this time.   It's like asking an andriod maid the meaning of life and watch her roll her eyes into the back of the sockets for 15 mins.   If the operations are performed on a much taller model, say 200mm instead of 20mm then I just can't wait that long and eventually force abort with CTRL-ALT-DEL.   Why is this happening and how do I make it better ?

My computer spec is :

Windows Vista Home Premium

Intel(R) Core(TM)2 Duo CPU T6500 @2.10GHz

4GB RAM

64-bit

Graphics card is ATI Mobility Radeon HD4650

The computer was made by Sony.   One owner only, bought sometime around 2006 or 2007

when running OpenSCAD I usually have a browser(Google Chrome) open at the same time for looking up stuff.

Thank you

KP

[Jeremiah Timmins]

Your computer specs are the reason you're having issues.
I upgraded from an AMD 4 CORE 8Gb Ram, 1gb gpu (and some files were slow, the complex ones.  Forward thinking, I envisioned more grief) to an i7 32gb ram 8gb gpu.  It slows noticeably but I can tolerate that over the previous system.
Word of advice: If you plan to print complicated pieces, upgrade your rig...but don't cheap out on a new "vista ready" equivalent PC.  Pay for what really matters, clock, bus, and beef. 

---

From: 'KP Chiang' via 3D604
Sent: ‎2016-‎04-‎14 1:52 AM
To: 3D604
Subject: How to improve computer processing speed when using OpenSCAD

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[Nick Wimpney]

yes,  it is a combination of some operations just being very heavy to process,  and that being not the fastest computer.

I think the preview is using the video card to do a lit of its work,  where the f6 rendering is usually limited by the CPU.  That said,  I have a pretty top notch pc,  and it's still not too hard to overload it if you are silly in your drawings. in general I just use fairly low polygon counts on anything curved while I am still working on it,  and crank it up for the final render.

keep in mind that we re not talking orders of magnitude.   That 15 min render might still take 5 min,  where you could probably turn down the $fn and such,  and render in a minute instead.

also,  i don't know how CPU heavy booleans on imported stls are,  as i rarely do that, so others migh have better input on that.

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[KP Chiang]

Thanks for the replies. I have been wanting to get another computer for a while(desktop or laptop both fine)
How would this desktop improve the performance given the price:

http://vancouver.craigslist.ca/rds/sys/5523561935.html

It has an upgraded video card.
The spec of the computer itself is

Windows® 7 Professional
Intel® Core™ i3-4160 processor Dual-core 3.60 GHz
8 GB, DDR3 SDRAM
1 TB HDD


Thank you