Pure CSS to achieve wonderful and interesting background effects! !

This article will introduce you to some interesting background knowledge. Using some very small units and just a few lines of code, you can produce wonderful and interesting results. Background effect~

The impact of magnitude on background graphics

The protagonist of this article is mainly:

• Multiple radial gradients (repeating-radial -gradient)
• Multiple angular gradient (repeating-conic-gradient)

What is the order of magnitude for the background graphic? Let's take a look at such an interesting phenomenon:

We use repeating-conic-gradient to implement a graphic with multiple angular gradients. The code is very simple, as shown below:

div {
    width: 100vw;
    height: 100vh;
    background: repeating-conic-gradient(#fff, #000, #fff 30deg);
}

Replace 30deg with 0.1deg

Then, we use a very small value to replace the above code 30deg, similar to this:

{
    background: repeating-conic-gradient(#fff, #000, #fff 0.1deg);
}

What is this? Think about it, what will the graphics drawn by this line of code look like?

Look at the effect:

Wow, incredible. 0.1deg is very critical here. The smaller the angle here (preferably less than 1deg), the cooler the graphics will be, which is what we call the impact of the order of magnitude on the background graphics.

CodePen -- One Line CSS Pattern

Observe the change process with the help of CSS @property

Before, if we directly wrote the following transition code , it is impossible to get tween transition animation, only frame-by-frame animation:

div{
    background: repeating-conic-gradient(#fff, #000, #fff 0.1deg);
    transition: background 1s;
}

div:hover {
    background: repeating-conic-gradient(#fff, #000, #fff 30deg);
}

can only get this effect, the reason is that CSS does not support direct transition animation for such complex gradients ：

OK, next, use it in this article--CSS @property, making the impossible possible Introduction## With the knowledge of #CSS @property, we can use CSS @property to observe the process of their two status changes.

@property --angle {
  syntax: '';
  inherits: false;
  initial-value: 0.1deg;
}
div{
    background: repeating-conic-gradient(#fff, #000, #fff var(--angle));
    transition: --angle 2s;
}
html:hover {
    --angle: 30deg;
}

CodePen -- repeating-conic-gradient CSS Pattern Transition (Only Chrome 85)

CSS @property realizes the tween transition animation. Seeing the change process from 30deg to 0.1deg, we can roughly see that the small unit 0.1 How deg affects graphics.

Multiple radial gradients & multiple angular gradients with small units to achieve interesting backgrounds

div {
    background-image: repeating-radial-gradient(
        circle at center center,
        rgb(241, 43, 239),
        rgb(239, 246, 244) 3px
    );
}

div {
    background-image: repeating-radial-gradient(
        circle at 15% 30%,
        rgb(4, 4, 0),
        rgb(52, 72, 197),
        rgb(115, 252, 224),
        rgb(116, 71, 5),
        rgb(223, 46, 169),
        rgb(0, 160, 56),
        rgb(234, 255, 0) 2px
    );
}

div {
    background-image: repeating-radial-gradient(
        circle at center center,
        rgb(81, 9, 72),
        rgb(72, 90, 223),
        rgb(80, 0, 34),
        rgb(34, 134, 255),
        rgb(65, 217, 176),
        rgb(241, 15, 15),
        rgb(148, 213, 118) 0.1px
    );
}

div {
    background-image: repeating-radial-gradient(
        ellipse at center center,
        rgb(75, 154, 242),
        rgb(64, 135, 228),
        rgb(54, 117, 214),
        rgb(43, 98, 200),
        rgb(33, 79, 185),
        rgb(22, 60, 171),
        rgb(12, 42, 157),
        rgb(1, 23, 143) 0.01px
    );
}

CodePen Demo -- Magic Gradient Art

repeating-radial-gradient It is similar to radial-gradient() and takes the same arguments, but it repeats the color in all directions, overriding it the entire container.

1px, which is the focus of this article. How small can it be?

:root {
    --length: 1px
}
{
    background-image: repeating-radial-gradient(
        circle at 17% 32%,
        rgb(4, 4, 0),
        rgb(52, 72, 197),
        rgb(115, 252, 224),
        rgb(116, 71, 5),
        rgb(223, 46, 169),
        rgb(0, 160, 56),
        rgb(234, 255, 0) var(--length)
    );
}

100px to 0.00001px for comparison:

在 0.001px 到 0.0001px 这个区间段，基本上图形已经退化为粒子图形，见不到径向渐变的轮廓了，而到了 0.00001px 这个级别，居然退化为了一张纯色图片！

CodePen Demo -- 不同级别长度单位对 repeating-radial-gradient 图形的影响

使用 repeating-radial-gradient 实现电视雪花噪声动画

在上述 DEMO 中，我们发现，当在 0.001px 到 0.0001px 这个区间段，repeating-radial-gradient 基本退化为了粒子图形：

{
    background-image: repeating-radial-gradient(
        circle at 17% 32%,
        rgb(4, 4, 0),
        rgb(52, 72, 197),
        rgb(115, 252, 224),
        rgb(116, 71, 5),
        rgb(223, 46, 169),
        rgb(0, 160, 56),
        rgb(234, 255, 0) 0.0008px
    );
}

这不是非常类似电视雪花屏的效果么？微调 0.0008px 这个参数， 利用几帧不同的动画，我们就可以得到电视雪花噪声的动画了。

啊哈，非常的有意思，完整的源码你可以戳这里：

Copepen Demo -- PURE CSS TV NOISE EFFECT (Only Chrome 85+)

更多编程相关知识，请访问：编程视频！！

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