February 28, 2020

28 February, 2020 04:28PM · "Kim is not happy that we put them on another task with less pay. Let's hire an HR person who can "convince" Kim of the advantages of the new job."

grep evince /etc/mailcap >> $HOME/.mailcap

#!/bin/bash
# 

DESKTOP_BACKGROUND=$(gsettings get org.cinnamon.desktop.background picture-uri)
DESKTOP_SLIDESHOW=$(gsettings get org.cinnamon.desktop.background.slideshow slideshow-enabled)
LOCKSCREEN_BACKGROUND="/path/to/lock/screen/background/image"

# Check for existing instances and kill them leaving current instance running
for PID in $(pidof -o %PPID -x "${0##*/}"); do
    if [ "$PID" != $$ ]; then
        kill -9 "$PID"
    fi 
done

dbus-monitor --session "interface='org.cinnamon.ScreenSaver', member='ActiveChanged'" | while read -r msg
do
  # The profile mode does not contain the actual value of the state, while in
  # normal output mode the state is shown in the second line:
  #signal time=1582609490.461661 sender=:1.17859 -> destination=(null destination) serial=132 path=/org/cinnamon/ScreenSaver; interface=org.cinnamon.ScreenSaver; member=ActiveChanged
  #   boolean true
  #signal time=1582609495.138523 sender=:1.17859 -> destination=(null destination) serial=143 path=/org/cinnamon/ScreenSaver; interface=org.cinnamon.ScreenSaver; member=ActiveChanged
  #   boolean false
  case "$msg" in
    "boolean true")
      DESKTOP_BACKGROUND=$(gsettings get org.cinnamon.desktop.background picture-uri)
      DESKTOP_SLIDESHOW=$(gsettings get org.cinnamon.desktop.background.slideshow slideshow-enabled)
      gsettings set org.cinnamon.desktop.background.slideshow slideshow-enabled false
      gsettings set org.cinnamon.desktop.background picture-uri "file://$LOCKSCREEN_BACKGROUND"
      ;;
    "boolean false")
      gsettings set org.cinnamon.desktop.background picture-uri "$DESKTOP_BACKGROUND"
      gsettings set org.cinnamon.desktop.background.slideshow slideshow-enabled $DESKTOP_SLIDESHOW
      ;;
    *) ;;
  esac
done
[Desktop Entry]
Type=Application
Exec=/usr/local/bin/cinnamon-lockscreen-background.sh
X-GNOME-Autostart-enabled=true
NoDisplay=false
Hidden=false
Name=cinnamon-lockscreen-background.desktop
Comment=Change lockscreen background image
X-GNOME-Autostart-Delay=30
PERSON       →        PROBLEM

deb https://www.preining.info/debian unstable main
deb-src https://www.preining.info/debian unstable main
deb https://www.preining.info/debian buster main
deb-src https://www.preining.info/debian buster main
deb https://www.preining.info/debian unstable main
deb-src https://www.preining.info/debian unstable main
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. All permissions granted by this license must be passed on to all recipients of modified or unmodified versions of this work
2. This work may not be used in any way that impairs any individual's ability to exercise the permissions granted by this license, whether or not they have received a copy of the covered work
2. Your rights under this license terminate if you impair any individual's ability to exercise the permissions granted by this license, even if the covered work is not used to do so
t = 1.0f;

/* Iterate until s1 is flat */
do {
    t = t/2.0f;
    _de_casteljau(s, s1, s2, t);
} while (!_is_flat(s1));

flatness(t) = tolerance

float       hi = 1.0f;
float       lo = 0.0f;

/* Search for an initial section of the spline which
 * is flat, but not too flat
 */
for (;;) {

    /* Average the lo and hi values for our
     * next estimate
     */
    float t = (hi + lo) / 2.0f;

    /* Split the spline at the target location
     */
    _de_casteljau(s, s1, s2, t);

    /* Compute the flatness and see if s1 is flat
     * enough
     */
    float flat = _flatness(s1);

    if (flat <= SCALE_FLAT(SNEK_DRAW_TOLERANCE)) {

        /* Stop looking when s1 is close
         * enough to the target tolerance
         */
        if (flat >= SCALE_FLAT(SNEK_DRAW_TOLERANCE - SNEK_FLAT_TOLERANCE))
            break;

        /* Flat: t is the new lower interval bound */
        lo = t;
    } else {

        /* Not flat: t is the new upper interval bound */
        hi =  t;
    }
}

ux = (3×b.x - 2×a.x - d.x)²
uy = (3×b.y - 2×a.y - d.y)²
vx = (3×c.x - 2×d.x - a.x)²
vy = (3×c.y - 2×d.y - a.y)²

flat = max(ux, vx) + max(uy, vy)

/*
 * Copyright © 2020 Keith Packard <keithp@keithp.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
 */

#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <math.h>

typedef float point_t[2];
typedef point_t spline_t[4];

uint64_t num_flats;
uint64_t num_points;

#define SNEK_DRAW_TOLERANCE 0.5f
#define SNEK_FLAT_TOLERANCE 0.01f

/*
 * This actually returns flatness² * 16,
 * so we need to compare against scaled values
 * using the SCALE_FLAT macro
 */
static float
_flatness(spline_t spline)
{
    /*
     * This computes the maximum deviation of the spline from a
     * straight line between the end points.
     *
     * From https://hcklbrrfnn.files.wordpress.com/2012/08/bez.pdf
     */
    float ux = 3.0f * spline[1][0] - 2.0f * spline[0][0] - spline[3][0];
    float uy = 3.0f * spline[1][1] - 2.0f * spline[0][1] - spline[3][1];
    float vx = 3.0f * spline[2][0] - 2.0f * spline[3][0] - spline[0][0];
    float vy = 3.0f * spline[2][1] - 2.0f * spline[3][1] - spline[0][1];

    ux *= ux;
    uy *= uy;
    vx *= vx;
    vy *= vy;
    if (ux < vx)
        ux = vx;
    if (uy < vy)
        uy = vy;
    ++num_flats;

    /*
     *If we wanted to return the true flatness, we'd use:
     *
     * return sqrtf((ux + uy)/16.0f)
     */
    return ux + uy;
}

/* Convert constants to values usable with _flatness() */
#define SCALE_FLAT(f)   ((f) * (f) * 16.0f)

/*
 * Linear interpolate from a to b using distance t (0 <= t <= 1)
 */
static void
_lerp (point_t a, point_t b, point_t r, float t)
{
    int i;
    for (i = 0; i < 2; i++)
        r[i] = a[i]*(1.0f - t) + b[i]*t;
}

/*
 * Split 's' into two splines at distance t (0 <= t <= 1)
 */
static void
_de_casteljau(spline_t s, spline_t s1, spline_t s2, float t)
{
    point_t first[3];
    point_t second[2];
    int i;

    for (i = 0; i < 3; i++)
        _lerp(s[i], s[i+1], first[i], t);

    for (i = 0; i < 2; i++)
        _lerp(first[i], first[i+1], second[i], t);

    _lerp(second[0], second[1], s1[3], t);

    for (i = 0; i < 2; i++) {
        s1[0][i] = s[0][i];
        s1[1][i] = first[0][i];
        s1[2][i] = second[0][i];

        s2[0][i] = s1[3][i];
        s2[1][i] = second[1][i];
        s2[2][i] = first[2][i];
        s2[3][i] = s[3][i];
    }
}

/*
 * Decompose 's' into straight lines which are
 * within SNEK_DRAW_TOLERANCE of the spline
 */
static void
_spline_decompose(void (*draw)(float x, float y), spline_t s)
{
    /* Start at the beginning of the spline. */
    (*draw)(s[0][0], s[0][1]);

    /* Split the spline until it is flat enough */
    while (_flatness(s) > SCALE_FLAT(SNEK_DRAW_TOLERANCE)) {
        spline_t    s1, s2;
        float       hi = 1.0f;
        float       lo = 0.0f;

        /* Search for an initial section of the spline which
         * is flat, but not too flat
         */
        for (;;) {

            /* Average the lo and hi values for our
             * next estimate
             */
            float t = (hi + lo) / 2.0f;

            /* Split the spline at the target location
             */
            _de_casteljau(s, s1, s2, t);

            /* Compute the flatness and see if s1 is flat
             * enough
             */
            float flat = _flatness(s1);

            if (flat <= SCALE_FLAT(SNEK_DRAW_TOLERANCE)) {

                /* Stop looking when s1 is close
                 * enough to the target tolerance
                 */
                if (flat >= SCALE_FLAT(SNEK_DRAW_TOLERANCE - SNEK_FLAT_TOLERANCE))
                    break;

                /* Flat: t is the new lower interval bound */
                lo = t;
            } else {

                /* Not flat: t is the new upper interval bound */
                hi =  t;
            }
        }

        /* Draw to the end of s1 */
        (*draw)(s1[3][0], s1[3][1]);

        /* Replace s with s2 */
        memcpy(&s[0], &s2[0], sizeof (spline_t));
    }

    /* S is now flat enough, so draw to the end */
    (*draw)(s[3][0], s[3][1]);
}

void draw(float x, float y)
{
    ++num_points;
    printf("%8g, %8g\n", x, y);
}

int main(int argc, char **argv)
{
    spline_t spline = {
        { 0.0f, 0.0f },
        { 0.0f, 256.0f },
        { 256.0f, -256.0f },
        { 256.0f, 0.0f }
    };
    _spline_decompose(draw, spline);
    fprintf(stderr, "flats %lu points %lu\n", num_flats, num_points);
    return 0;
}

static void
_twin_spline_decompose (twin_path_t *path,
            twin_spline_t   *spline, 
            twin_dfixed_t   tolerance_squared)
{
    if (_twin_spline_error_squared (spline) <= tolerance_squared)
    {
    _twin_path_sdraw (path, spline->a.x, spline->a.y);
    }
    else
    {
    twin_spline_t s1, s2;
    _de_casteljau (spline, &s1, &s2);
    _twin_spline_decompose (path, &s1, tolerance_squared);
    _twin_spline_decompose (path, &s2, tolerance_squared);
    }
}

static void
_lerp_half (twin_spoint_t *a, twin_spoint_t *b, twin_spoint_t *result)
{
    result->x = a->x + ((b->x - a->x) >> 1);
    result->y = a->y + ((b->y - a->y) >> 1);
}

static void
_de_casteljau (twin_spline_t *spline, twin_spline_t *s1, twin_spline_t *s2)
{
    twin_spoint_t ab, bc, cd;
    twin_spoint_t abbc, bccd;
    twin_spoint_t final;

    _lerp_half (&spline->a, &spline->b, &ab);
    _lerp_half (&spline->b, &spline->c, &bc);
    _lerp_half (&spline->c, &spline->d, &cd);
    _lerp_half (&ab, &bc, &abbc);
    _lerp_half (&bc, &cd, &bccd);
    _lerp_half (&abbc, &bccd, &final);

    s1->a = spline->a;
    s1->b = ab;
    s1->c = abbc;
    s1->d = final;

    s2->a = final;
    s2->b = bccd;
    s2->c = cd;
    s2->d = spline->d;
}

S' = _de_casteljau(s, 1/2)

S[n] = _de_casteljau(s0, (1/2)ⁿ)

while S is not flat:
    n = 1
    do
        Sleft, Sright = _decasteljau(S, (1/2)ⁿ)
        n = n + 1
    until Sleft is flat
    result ← Sleft
    S = Sright
result ← S

/*
 * Copyright © 2020 Keith Packard <keithp@keithp.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
 */

#include <stdbool.h>
#include <stdio.h>
#include <string.h>

typedef float point_t[2];
typedef point_t spline_t[4];

#define SNEK_DRAW_TOLERANCE 0.5f

/* Is this spline flat within the defined tolerance */
static bool
_is_flat(spline_t spline)
{
    /*
     * This computes the maximum deviation of the spline from a
     * straight line between the end points.
     *
     * From https://hcklbrrfnn.files.wordpress.com/2012/08/bez.pdf
     */
    float ux = 3.0f * spline[1][0] - 2.0f * spline[0][0] - spline[3][0];
    float uy = 3.0f * spline[1][1] - 2.0f * spline[0][1] - spline[3][1];
    float vx = 3.0f * spline[2][0] - 2.0f * spline[3][0] - spline[0][0];
    float vy = 3.0f * spline[2][1] - 2.0f * spline[3][1] - spline[0][1];

    ux *= ux;
    uy *= uy;
    vx *= vx;
    vy *= vy;
    if (ux < vx)
        ux = vx;
    if (uy < vy)
        uy = vy;
    return (ux + uy <= 16.0f * SNEK_DRAW_TOLERANCE * SNEK_DRAW_TOLERANCE);
}

static void
_lerp (point_t a, point_t b, point_t r, float t)
{
    int i;
    for (i = 0; i < 2; i++)
        r[i] = a[i]*(1.0f - t) + b[i]*t;
}

static void
_de_casteljau(spline_t s, spline_t s1, spline_t s2, float t)
{
    point_t first[3];
    point_t second[2];
    int i;

    for (i = 0; i < 3; i++)
        _lerp(s[i], s[i+1], first[i], t);

    for (i = 0; i < 2; i++)
        _lerp(first[i], first[i+1], second[i], t);

    _lerp(second[0], second[1], s1[3], t);

    for (i = 0; i < 2; i++) {
        s1[0][i] = s[0][i];
        s1[1][i] = first[0][i];
        s1[2][i] = second[0][i];

        s2[0][i] = s1[3][i];
        s2[1][i] = second[1][i];
        s2[2][i] = first[2][i];
        s2[3][i] = s[3][i];
    }
}

static void
_spline_decompose(void (*draw)(float x, float y), spline_t s)
{
    float       t;
    spline_t    s1, s2;

    (*draw)(s[0][0], s[0][1]);

    /* If s is flat, we're done */
    while (!_is_flat(s)) {
        t = 1.0f;

        /* Iterate until s1 is flat */
        do {
            t = t/2.0f;
            _de_casteljau(s, s1, s2, t);
        } while (!_is_flat(s1));

        /* Draw to the end of s1 */
        (*draw)(s1[3][0], s1[3][1]);

        /* Replace s with s2 */
        memcpy(&s[0], &s2[0], sizeof (spline_t));
    }
    (*draw)(s[3][0], s[3][1]);
}

void draw(float x, float y)
{
    printf("%8g, %8g\n", x, y);
}

int main(int argc, char **argv)
{
    spline_t spline = {
        { 0.0f, 0.0f },
        { 0.0f, 256.0f },
        { 256.0f, -256.0f },
        { 256.0f, 0.0f }
    };
    _spline_decompose(draw, spline);
    return 0;
}

deb https://www.preining.info/debian unstable main
deb-src https://www.preining.info/debian unstable main
apt install lxc
echo "veth" >> /etc/modules
modprobe veth

net.ipv4.ip_forward=1

sysctl -p /etc/sysctl.d/local.conf

# LXC containers
-A FORWARD -d 10.0.3.0/24 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -s 10.0.3.0/24 -j ACCEPT
-A INPUT -d 224.0.0.251 -s 10.0.3.1 -j ACCEPT
-A INPUT -d 239.255.255.250 -s 10.0.3.1 -j ACCEPT
-A INPUT -d 10.0.3.255 -s 10.0.3.1 -j ACCEPT
-A INPUT -d 10.0.3.1 -s 10.0.3.0/24 -j ACCEPT

iptables-apply

systemctl restart lxc-net.service

lxc-create -n fedora31 -t download -- -d fedora -r 31 -a amd64

lxc-create -n foo --template=download -- --list

lxc.apparmor.profile = unconfined

lxc-start -n fedora31 -F

lxc-attach -n fedora31

passwd

$ dnf install openssh-server
Cannot create temporary file - mkstemp: No such file or directory

$ echo $TMPDIR
/tmp/user/0

TMPDIR=/tmp dnf install openssh-server

dnf install vim sudo man

adduser francois -G wheel
passwd francois

GSSAPIAuthentication no

mkdir .ssh
chmod 700 .ssh
echo "<your public key>" > .ssh/authorized_keys
chmod 644 .ssh/authorized_keys

lxc-ls --fancy

Publisher:	Porfolio/Penguin
Copyright:	2019
ISBN:	0-525-53654-X
Format:	Kindle
Pages:	256

Series:	Innkeeper Chronicles #5
Publisher:	NYLA
Copyright:	2020
ISBN:	1-64197-136-3
Format:	Kindle
Pages:	146

Series:	Murderbot Diaries #4
Publisher:	Tor.com
Copyright:	October 2018
ISBN:	1-250-18546-7
Format:	Kindle
Pages:	172

Publisher:	Subterranean
Copyright:	2011
ISBN:	1-59606-488-9
Format:	Kindle
Pages:	96

Search	Calls	Points
Simple	150	33
Bisect	229	25

February 28, 2020

February 27, 2020

Lomiri: New Name, Same Great Unity8

Change is never Easy

References

February 26, 2020

February 25, 2020

Visibility of conflicts

Layers of conflict solving

Conflict as process

Conclusion

February 24, 2020

February 23, 2020

February 22, 2020

Changes in version 0.0.2 (2020-02-21)

February 21, 2020

Individual reports

Evolution of the situation

Thanks to our sponsors

To FOSDEM…

… and back!

February 20, 2020

February 19, 2020

February 18, 2020

Credits

References

Slightly Better Iterative Spline Decomposition

The Initial Search

Bisection Method

A Closed Form Approach?

Update: Fancier Method Found!

Current Implementation

February 17, 2020

Factors increasing job burnout

What motivates people?

SnowCamp 2020

February 16, 2020

February 15, 2020

The Problem

What HDMI Can Do

HDMI Cables

What DisplayPort Can Do

Comparing HDMI and DisplayPort

The End Result

Decomposing Splines Without Recursion

The Usual Method

De Casteljau Splits At Any Point

Iterative Left-most Spline Decomposition

Final Code

Background Knowledge

What I’m Concerned About

Skills that Should be Easy to Compare

Conclusion

February 14, 2020