Making a Clock with the New CSS sin() and cos() Trigonometry Capabilities | CSS-Methods

CSS trigonometry capabilities are right here! Effectively, they’re when you’re utilizing the most recent variations of Firefox and Safari, that’s. Having this form of mathematical energy in CSS opens up an entire bunch of potentialities. On this tutorial, I assumed we’d dip our toes within the water to get a really feel for a few the newer capabilities: sin() and cos().

There are different trigonometry capabilities within the pipeline — together with tan() — so why focus simply on sin() and cos()? They occur to be excellent for the thought I take into account, which is to put textual content alongside the sting of a circle. That’s been coated right here on CSS-Methods when Chris shared an method that makes use of a Sass mixin. That was six years in the past, so let’s give it the bleeding edge therapy.

Right here’s what I take into account. Once more, it’s solely supported in Firefox and Safari in the meanwhile:

So, it’s not precisely like phrases forming a round form, however we’re inserting textual content characters alongside the circle to kind a clock face. Right here’s some markup we will use to kick issues off:

<div class="clock">
  <div class="clock-face">
    <time datetime="12:00">12</time>
    <time datetime="1:00">1</time>
    <time datetime="2:00">2</time>
    <time datetime="3:00">3</time>
    <time datetime="4:00">4</time>
    <time datetime="5:00">5</time>
    <time datetime="6:00">6</time>
    <time datetime="7:00">7</time>
    <time datetime="8:00">8</time>
    <time datetime="9:00">9</time>
    <time datetime="10:00">10</time>
    <time datetime="11:00">11</time>
  </div>
</div>

Subsequent, listed below are some tremendous primary kinds for the .clock-face container. I made a decision to make use of the <time> tag with a datetime attribute. 

.clock {
  --_ow: clamp(5rem, 60vw, 40rem);
  --_w: 88cqi;
  aspect-ratio: 1;
  background-color: tomato;
  border-radius: 50%;
  container-type: inline;
  show: grid;
  top: var(--_ow);
  place-content: middle;
  place: relative;
  width var(--_ow);
}

I adorned issues a bit in there, however solely to get the fundamental form and background colour to assist us see what we’re doing. Discover how we save the width worth in a CSS variable. We’ll use that later. Not a lot to have a look at to this point:

It appears to be like like some form of trendy artwork experiment, proper? Let’s introduce a brand new variable, --_r, to retailer the circle’s radius, which is the same as half of the circle’s width. This fashion, if the width (--_w) modifications, the radius worth (--_r) may also replace — thanks to a different CSS math perform, calc():

.clock {
  --_w: 300px;
  --_r: calc(var(--_w) / 2);
  /* remainder of kinds */
}

Now, a little bit of math. A circle is 360 levels. Now we have 12 labels on our clock, so wish to place the numbers each 30 levels (360 / 12). In math-land, a circle begins at 3 o’clock, so midday is definitely minus 90 levels from that, which is 270 levels (360 - 90).

Let’s add one other variable, --_d, that we will use to set a diploma worth for every quantity on the clock face. We’re going to increment the values by 30 levels to finish our circle:

.clock time:nth-child(1) { --_d: 270deg; }
.clock time:nth-child(2) { --_d: 300deg; }
.clock time:nth-child(3) { --_d: 330deg; }
.clock time:nth-child(4) { --_d: 0deg; }
.clock time:nth-child(5) { --_d: 30deg; }
.clock time:nth-child(6) { --_d: 60deg; }
.clock time:nth-child(7) { --_d: 90deg; }
.clock time:nth-child(8) { --_d: 120deg; }
.clock time:nth-child(9) { --_d: 150deg; }
.clock time:nth-child(10) { --_d: 180deg; }
.clock time:nth-child(11) { --_d: 210deg; }
.clock time:nth-child(12) { --_d: 240deg; }

OK, now’s the time to get our fingers soiled with the sin() and cos() capabilities! What we wish to do is use them to get the X and Y coordinates for every quantity so we will place them correctly across the clock face.

The method for the X coordinate is radius + (radius * cos(diploma)). Let’s plug that into our new --_x variable:

--_x: calc(var(--_r) + (var(--_r) * cos(var(--_d))));

The method for the Y coordinate is radius + (radius * sin(diploma)). Now we have what we have to calculate that:

--_y: calc(var(--_r) + (var(--_r) * sin(var(--_d))));

There are a number of housekeeping issues we have to do to arrange the numbers, so let’s put some primary styling on them to ensure they’re completely positioned and positioned with our coordinates:

.clock-face time {
  --_x: calc(var(--_r) + (var(--_r) * cos(var(--_d))));
  --_y: calc(var(--_r) + (var(--_r) * sin(var(--_d))));
  --_sz: 12cqi;
  show: grid;
  top: var(--_sz);
  left: var(--_x);
  place-content: middle;
  place: absolute;
  prime: var(--_y);
  width: var(--_sz);
}

Discover --_sz, which we’ll use for the width and top of the numbers in a second. Let’s see what we’ve got to this point.

This positively appears to be like extra like a clock! See how the top-left nook of every quantity is positioned on the appropriate place across the circle? We have to “shrink” the radius when calculating the positions for every quantity. We will deduct the scale of a quantity (--_sz) from the scale of the circle (--_w), earlier than we calculate the radius:

--_r: calc((var(--_w) - var(--_sz)) / 2);

Significantly better! Let’s change the colours, so it appears to be like extra elegant:

We may cease proper right here! We completed the aim of inserting textual content round a circle, proper? However what’s a clock with out arms to indicate hours, minutes, and seconds?

Let’s use a single CSS animation for that. First, let’s add three extra parts to our markup,

<div class="clock">
  <!-- after <time>-tags -->
  <span class="arm seconds"></span>
  <span class="arm minutes"></span>
  <span class="arm hours"></span>
  <span class="arm middle"></span>
</div>

Then some widespread markup for all three arms. Once more, most of that is simply make certain the arms are completely positioned and positioned accordingly:

.arm {
  background-color: var(--_abg);
  border-radius: calc(var(--_aw) * 2);
  show: block;
  top: var(--_ah);
  left: calc((var(--_w) - var(--_aw)) / 2);
  place: absolute;
  prime: calc((var(--_w) / 2) - var(--_ah));
  rework: rotate(0deg);
  transform-origin: backside;
  width: var(--_aw);
}

We’ll use the similar animation for all three arms:

@keyframes flip {
  to {
    rework: rotate(1turn);
  }
}

The one distinction is the time the person arms take to make a full flip. For the hours arm, it takes 12 hours to make a full flip. The animation-duration property solely accepts values in milliseconds and seconds. Let’s follow seconds, which is 43,200 seconds (60 seconds * 60 minutes * 12 hours).

animation: flip 43200s infinite;

It takes 1 hour for the minutes arm to make a full flip. However we wish this to be a multi-step animation so the motion between the arms is staggered reasonably than linear. We’ll want 60 steps, one for every minute:

animation: flip 3600s steps(60, finish) infinite;

The seconds arm is virtually the identical because the minutes arm, however the length is 60 seconds as a substitute of 60 minutes:

animation: flip 60s steps(60, finish) infinite;

Let’s replace the properties we created within the widespread kinds:

.seconds {
  --_abg: hsl(0, 5%, 40%);
  --_ah: 145px;
  --_aw: 2px;
  animation: flip 60s steps(60, finish) infinite;
}
.minutes {
  --_abg: #333;
  --_ah: 145px;
  --_aw: 6px;
  animation: flip 3600s steps(60, finish) infinite;
}
.hours {
  --_abg: #333;
  --_ah: 110px;
  --_aw: 6px;
  animation: flip 43200s linear infinite;
}

What if we wish to begin on the present time? We’d like just a little little bit of JavaScript:

const time = new Date();
const hour = -3600 * (time.getHours() % 12);
const minutes = -60 * time.getMinutes();
app.fashion.setProperty('--_dm', `${minutes}s`);
app.fashion.setProperty('--_dh', `${(hour+minutes)}s`);

I’ve added id="app" to the clockface and set two new customized properties on it that set a destructive animation-delay, as Mate Marschalko did when he shared a CSS-only clock. The getHours() technique of JavaScipt’s Date object is utilizing the 24-hour format, so we use the the rest operator to transform it into 12-hour format.

Within the CSS, we have to add the animation-delay as nicely:

.minutes {
  animation-delay: var(--_dm, 0s);
  /* different kinds */
}

.hours {
  animation-delay: var(--_dh, 0s);
  /* different kinds */
}

Only one other thing. Utilizing CSS @helps and the properties we’ve already created, we will present a fallback to browsers that don’t supprt sin() and cos(). (Thanks, Temani Afif!):

@helps not (left: calc(1px * cos(45deg))) {
  time {
    left: 50% !vital;
    prime: 50% !vital;
    rework: translate(-50%,-50%) rotate(var(--_d)) translate(var(--_r)) rotate(calc(-1*var(--_d)))
  }
}

And, voilà! Our clock is finished! Right here’s the ultimate demo yet one more time. Once more, it’s solely supported in Firefox and Safari in the meanwhile.

What else can we do?

Simply messing round right here, however we will shortly flip our clock right into a round picture gallery by changing the <time> tags with <img> then updating the width (--_w) and radius (--_r) values:

Let’s strive yet one more. I discussed earlier how the clock appeared form of like a contemporary artwork experiment. We will lean into that and re-create a sample I noticed on a poster (that I sadly didn’t purchase) in an artwork gallery the opposite day. As I recall, it was known as “Moon” and consisted of a bunch of dots forming a circle.

We’ll use an unordered record this time because the circles don’t observe a selected order. We’re not even going to place all of the record gadgets within the markup. As a substitute, let’s inject them with JavaScript and add a number of controls we will use to govern the ultimate consequence.

The controls are vary inputs (<enter kind="vary">) which we’ll wrap in a <kind> and hear for the enter occasion.

<kind id="controls">
  <fieldset>
    <label>Variety of rings
      <enter kind="vary" min="2" max="12" worth="10" id="rings" />
    </label>
    <label>Dots per ring
      <enter kind="vary" min="5" max="12" worth="7" id="dots" />
    </label>
    <label>Unfold
      <enter kind="vary" min="10" max="40" worth="40" id="unfold" />
    </label>
  </fieldset>
</kind>

We’ll run this technique on “enter”, which can create a bunch of <li> parts with the diploma (--_d) variable we used earlier utilized to every one. We will additionally repurpose our radius variable (--_r) .

I additionally need the dots to be totally different colours. So, let’s randomize (nicely, not fully randomized) the HSL colour worth for every record merchandise and retailer it as a brand new CSS variable, --_bgc:

const replace = () => {
  let s = "";
  for (let i = 1; i <= rings.valueAsNumber; i++) {
    const r = unfold.valueAsNumber * i;
    const theta = coords(dots.valueAsNumber * i);
    for (let j = 0; j < theta.size; j++) {
      s += `<li fashion="--_d:${theta[j]};--_r:${r}px;--_bgc:hsl(${random(
        50,
        25
      )},${random(90, 50)}%,${random(90, 60)}%)"></li>`;
    }
  }
  app.innerHTML = s;
}

The random() technique picks a price inside an outlined vary of numbers:

const random = (max, min = 0, f = true) => f ? Math.ground(Math.random() * (max - min) + min) : Math.random() * max;

And that’s it. We use JavaScript to render the markup, however as quickly because it’s rendered, we don’t actually need it. The sin() and cos() capabilities assist us place all of the dots in the fitting spots.

Last ideas

Inserting issues round a circle is a reasonably primary instance to reveal the powers of trigonometry capabilities like sin() and cos(). Nevertheless it’s actually cool that we’re getting trendy CSS options that present new options for previous workarounds I’m positive we’ll see far more fascinating, advanced, and inventive use circumstances, particularly as browser assist involves Chrome and Edge.