I had a similar issue recently, but the symptom was memory consumption,
not CPU.  The solution was code optimization.  The pre-optimization code
was the union of ten intersections, post-optimization was an intersection
of 10 unions.  The common shape to the intersections was a cone, so there
were a lot of edges being created in the intersection command.
Dan

On Sun, Aug 4, 2024 at 5:43 PM Todd Allen via Discuss <
discuss@lists.openscad.org> wrote:

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F5, F6 and F7 do preview, render and export but I think F7 is STL only.

On Sun, 4 Aug 2024 at 17:44, Todd Allen via Discuss <
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I use the render key but the other two are no longer of much use.  If I
can I'll rewrite the <export STL> key to do a render with $export=true
which I can test in script to go higher res and then export an OBJ.

On Sun, Aug 4, 2024 at 11:57 AM nop head via Discuss <
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What is the openscad version, as well as OS and hardware spec? Nightly
version is using a different preview pipeline. And this somehow makes me
wonder if you are using software rendering instead of GPU rendering.
On 5/8/2024 07:05, Sanjeev Prabhakar via Discuss wrote:

Can you share a picture of your model?

On Mon, 5 Aug, 2024, 2:20 am Todd Allen via Discuss, <
discuss@lists.openscad.org> wrote:

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Ryzen 9 6900HX w/ AMD Radeon 680M graphics, 32 GB ram
OS is a fully updated Arch linux virtual machine running under Qubes
OS 4.2 with pvh virtualization and seamless integration enabled.
I get the same behavior with both a week old unstable release and the
last stable release 2024.01.06 of OpenSCAD, both are .appimage files.

I think the issue may be a graphics driver as the problem got much
worse after switching from a 1080p monitor to a 2560x1440 monitor.

I have a Windows VM which I rarely use to run Fusion360 which is a
much more graphically demanding app and it runs well.  I should try
OpenSCAD there to help isolate if the problem is with the linux
graphics driver.  Curiously though when I render the video is smooth
and fairly responsive under linux and it is only when looking at a
preview the system chokes.

Here's a sample script which causes this:

include <BOSL2/std.scad>
include <BOSL2/rounding.scad>

$fn= $preview ? 32 : 256;
eps = 0.002;

module setenv_RodFrame(rod_d=10, wall_t=2.5, corner_size=26,
chamfer=0.5, inner_chamfer, outer_chamfer) {
    $rod_d = rod_d;
    $wall_t = wall_t;
    $corner_size = corner_size;
    $inner_chamfer = is_undef(inner_chamfer) ? chamfer : inner_chamfer;
    $outer_chamfer = is_undef(outer_chamfer) ? chamfer : outer_chamfer;
    $pipe_d = $rod_d+2*$wall_t;
    $flange_t = $wall_t;
    $flange_fillet = 1.25*$wall_t;
    $corner_cut = $rod_d0.5+$wall_t0.8;
    children();
}

module leg(h, d, cb, ct) {
    joined_shape = rect([h-$flange_fillet0.6,$flange_t]);
    union() {
        zcyl(h=h, d=d, chamfer1=cb, chamfer2=ct, circum=true);
        for(a = [-45,-135]) zrot(a) right($pipe_d0.5) yrot(90)
down($pipe_d0.5)
join_prism(joined_shape,base="cylinder",base_d=$pipe_d, length=h0.6,
fillet=$flange_fillet, n=24);
        }
}

module leg_core(h, d, cb, ct) {
    down(eps) zcyl(h=h+10*eps, d=d, chamfer1=cb, chamfer2=ct,
circum=true);
}

module corner() {
    ang = acos(1/sqrt(3));
    h = $corner_size-$corner_cut;
    top_half(s=200) up(h1.04) {
        difference() {
            zrot_copies(n=3) xrot(ang) down(h0.5+$corner_cut) leg(h,
$pipe_d, $outer_chamfer, $inner_chamfer);
            zrot_copies(n=3) xrot(ang) down(h*0.5+$corner_cut)
leg_core(h, $rod_d, -$outer_chamfer,0);
            // trim bottom outer edge of flange
            // figuring out a formula too hard for now so if
parameters change this will need tweaking, probably make these values
enviroment vars
            zrot_copies(n=3) fwd(14) down(h) xrot(45)
cuboid([26,3,7],anchor=BACK);
            }
        }
}

// EXAMPLE invocation
setenv_RodFrame() corner();

On Sun, Aug 4, 2024 at 7:07 PM Chun Kit LAM via Discuss
discuss@lists.openscad.org wrote:

 What is the openscad version, as well as OS and hardware spec?
 Nightly version is using a different preview pipeline. And this
 somehow makes me wonder if you are using software rendering
 instead of GPU rendering.

 On 5/8/2024 07:05, Sanjeev Prabhakar via Discuss wrote:

 _______________________________________________
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 To unsubscribe send an email to discuss-leave@lists.openscad.org

Do you have GPU passthrough for your VM? When running under
virtualization, it may run under software rendering. And I doubt if
Fusion360 is much more graphically demanding, openscad preview render is
kind of like unoptimized ray-tracing (from my understanding) which is quite
heavy even for good GPUs, and it will definitely stress your CPU when run
under software rendering.
On 5/8/2024 10:43, Todd Allen wrote:

Ryzen 9 6900HX w/ AMD Radeon 680M graphics, 32 GB ram
OS is a fully updated Arch linux virtual machine running under Qubes OS
4.2 with pvh virtualization and seamless integration enabled.
I get the same behavior with both a week old unstable release and the last
stable release 2024.01.06 of OpenSCAD, both are .appimage files.

I think the issue may be a graphics driver as the problem got much worse
after switching from a 1080p monitor to a 2560x1440 monitor.

I have a Windows VM which I rarely use to run Fusion360 which is a much
more graphically demanding app and it runs well.  I should try OpenSCAD
there to help isolate if the problem is with the linux graphics driver.
Curiously though when I render the video is smooth and fairly responsive
under linux and it is only when looking at a preview the system chokes.

Here's a sample script which causes this:

include <BOSL2/std.scad>
include <BOSL2/rounding.scad>

$fn= $preview ? 32 : 256;
eps = 0.002;

module setenv_RodFrame(rod_d=10, wall_t=2.5, corner_size=26, chamfer=0.5,
inner_chamfer, outer_chamfer) {
$rod_d = rod_d;
$wall_t = wall_t;
$corner_size = corner_size;
$inner_chamfer = is_undef(inner_chamfer) ? chamfer : inner_chamfer;
$outer_chamfer = is_undef(outer_chamfer) ? chamfer : outer_chamfer;
$pipe_d = $rod_d+2*$wall_t;
$flange_t = $wall_t;
$flange_fillet = 1.25*$wall_t;
$corner_cut = $rod_d0.5+$wall_t0.8;
children();
}

module leg(h, d, cb, ct) {
joined_shape = rect([h-$flange_fillet0.6,$flange_t]);
union() {
zcyl(h=h, d=d, chamfer1=cb, chamfer2=ct, circum=true);
for(a = [-45,-135]) zrot(a) right($pipe_d0.5) yrot(90)
down($pipe_d0.5) join_prism(joined_shape,base="cylinder",base_d=$pipe_d,
length=h0.6, fillet=$flange_fillet, n=24);
}
}

module leg_core(h, d, cb, ct) {
down(eps) zcyl(h=h+10*eps, d=d, chamfer1=cb, chamfer2=ct, circum=true);
}

module corner() {
ang = acos(1/sqrt(3));
h = $corner_size-$corner_cut;
top_half(s=200) up(h1.04) {
difference() {
zrot_copies(n=3) xrot(ang) down(h0.5+$corner_cut) leg(h,
$pipe_d, $outer_chamfer, $inner_chamfer);
zrot_copies(n=3) xrot(ang) down(h*0.5+$corner_cut) leg_core(h,
$rod_d, -$outer_chamfer,0);
// trim bottom outer edge of flange
// figuring out a formula too hard for now so if parameters
change this will need tweaking, probably make these values enviroment vars
zrot_copies(n=3) fwd(14) down(h) xrot(45)
cuboid([26,3,7],anchor=BACK);
}
}
}

// EXAMPLE invocation
setenv_RodFrame() corner();

On Sun, Aug 4, 2024 at 7:07 PM Chun Kit LAM via Discuss <
discuss@lists.openscad.org> wrote: