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3 ways to implement rounded triangles with pure CSS (skill sharing)

青灯夜游
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2021-07-15 19:15:564417browse

This article will introduce you to 3 methods of drawing rounded triangles using CSS. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to everyone.

3 ways to implement rounded triangles with pure CSS (skill sharing)

Previously in this article - "6 Techniques for Drawing Triangles with CSS (Sharing)", introduced 6 ways to use CSS to achieve Triangular way.

But a very important scene is missed. How to use pure CSS to implement a triangle with rounded corners? , like this:

3 ways to implement rounded triangles with pure CSS (skill sharing)

This article will introduce several ways to implement triangles with rounded corners.

Method 1. Fully Compatible SVG Method

If you want to generate a triangle with rounded corners, the least amount of code, the best way Generated using SVG.

Use SVG's polygon tag <polygon></polygon> to generate a trigonal shape, and use SVG's stroke-linejoin="round" to generate rounded corners at the connection.

The amount of code is very small, the core code is as follows:

<svg>
  <polygon></polygon>
</svg>
.triangle {
    fill: #0f0;
    stroke: #0f0;
    stroke-width: 10;
}

The actual graphics are as follows:

3 ways to implement rounded triangles with pure CSS (skill sharing)

Here, we actually use SVG polygons stroke-linejoin: round The rounded corners generated by the round attribute, what is stroke-linejoin

? It is used to control the space between two stroked line segments. It has three optional values:
  • miter
  • is the default value, which means using a square brush to form sharp corners at the connection
  • round
  • means connecting with rounded corners to achieve a smooth effect
  • bevel
  • The connection will form a miter

3 ways to implement rounded triangles with pure CSS (skill sharing)

We actually generate a rounded triangle through a polygon with a border and the border connection type is stroke-linejoin: round

.

If we separate the background color and border color, it actually looks like this:

.triangle {
    fill: #0f0;
    stroke: #000;
    stroke-width: 10;
}
3 ways to implement rounded triangles with pure CSS (skill sharing)

Control the fillet size through stroke-width

So how to control the size of the fillet? It is also very simple. By controlling the size of stroke-width

, you can change the size of the fillet.

Of course, to keep the size of the triangle consistent, while increasing/reducing the stroke-width, you need to reduce/increase the width/height of the graphic.

3 ways to implement rounded triangles with pure CSS (skill sharing)

For the complete DEMO, you can click here: CodePen Demo -- Using SVG to implement a triangle with rounded corners

https: //codepen.io/Chokcoco/pen/eYWZvKo

Method 2. Graphic splicing

However, as mentioned above,use pure CSS Implement a triangle with rounded corners

, but the first method above actually uses SVG. So is there a way to just use CSS?

Of course, divergent thinking, the interesting part of CSS is here, using a graphic, there can be many ingenious solutions!

Let’s take a look, a rounded triangle can actually be split into several parts:

3 ways to implement rounded triangles with pure CSS (skill sharing)

So, in fact, we only need to be able to draw For such a rhombus with rounded corners, by rotating and superposing three, you can get a rounded triangle:

3 ways to implement rounded triangles with pure CSS (skill sharing)

Drawing a rhombus with rounded corners

Then, our next goal becomes to draw a rhombus with rounded corners. There are many methods. This article gives one of the methods:

1. First, transform a square into Form a rhombus, use transform

There is a fixed formula:

<div></div>
div {
    width:  10em;
    height: 10em;
    transform: rotate(-60deg) skewX(-30deg) scale(1, 0.866);
}
3 ways to implement rounded triangles with pure CSS (skill sharing)

2. Transform one of the angles Rounded corners:

div {
 width:  10em;
 height: 10em;
 transform: rotate(-60deg) skewX(-30deg) scale(1, 0.866);
  + border-top-right-radius: 30%;
}
3 ways to implement rounded triangles with pure CSS (skill sharing)

At this point, we have successfully obtained a rhombus with rounded corners!

Splicing 3 rhombuses with rounded corners

The next step is very simple. We only need to use the other two pseudo-elements of the element to generate 2 more rhombuses with rounded corners. A rounded rhombus can be spliced ​​together with a total of 3 graphics rotation and displacement!

The complete code is as follows:###
<div></div>
div{
    position: relative;
    background-color: orange;
}
div:before,
div:after {
    content: &#39;&#39;;
    position: absolute;
    background-color: inherit;
}
div,
div:before,
div:after {
    width:  10em;
    height: 10em;
    border-top-right-radius: 30%;
}
div {
    transform: rotate(-60deg) skewX(-30deg) scale(1,.866);
}
div:before {
    transform: rotate(-135deg) skewX(-45deg) scale(1.414, .707) translate(0,-50%);
}
div:after {
    transform: rotate(135deg) skewY(-45deg) scale(.707, 1.414) translate(50%);
}

就可以得到一个圆角三角形了!效果如下:

13 ways to implement rounded triangles with pure CSS (skill sharing)

完整的代码你可以戳这里:CodePen Demo -- A triangle with rounded

https://codepen.io/Chokcoco/pen/vYmLVZr

法三. 图形拼接实现渐变色圆角三角形

完了吗?没有!

上述方案,虽然不算太复杂,但是有一点还不算太完美的。就是无法支持渐变色的圆角三角形。像是这样:

13 ways to implement rounded triangles with pure CSS (skill sharing)

如果需要实现渐变色圆角三角形,还是有点复杂的。但真就还有人鼓捣出来了,下述方法参考至 -- How to make 3-corner-rounded triangle in CSS。

同样也是利用了多块进行拼接,但是这次我们的基础图形,会非常的复杂。

首先,我们需要实现这样一个容器外框,和上述的方法比较类似,可以理解为是一个圆角菱形(画出 border 方便理解):

13 ways to implement rounded triangles with pure CSS (skill sharing)

<div></div>
div {
    width: 200px;
    height: 200px;
    transform: rotate(30deg) skewY(30deg) scaleX(0.866);
    border: 1px solid #000;
    border-radius: 20%;
}

接着,我们同样使用两个伪元素,实现两个稍显怪异的图形进行拼接,算是对 transform 的各种用法的合集:

div::before,
div::after {
    content: "";
    position: absolute;
    width: 200px;
    height: 200px;
}
div::before {
    border-radius: 20% 20% 20% 55%;
    transform: scaleX(1.155) skewY(-30deg) rotate(-30deg) translateY(-42.3%) skewX(30deg) scaleY(0.866) translateX(-24%);
    background: red;
}
div::after {
    border-radius: 20% 20% 55% 20%;
    background: blue;
    transform: scaleX(1.155) skewY(-30deg) rotate(-30deg) translateY(-42.3%) skewX(-30deg) scaleY(0.866) translateX(24%);
}

为了方便理解,制作了一个简单的变换动画:

3 ways to implement rounded triangles with pure CSS (skill sharing)

本质就是实现了这样一个图形:

13 ways to implement rounded triangles with pure CSS (skill sharing)

最后,给父元素添加一个 overflow: hidden 并且去掉父元素的 border 即可得到一个圆角三角形:

13 ways to implement rounded triangles with pure CSS (skill sharing)

由于这两个元素重叠空间的特殊结构,此时,给两个伪元素添加同一个渐变色,会完美的叠加在一起:

div::before,
div::after, {
    background: linear-gradient(#0f0, #03a9f4);
}

最终得到一个渐变圆角三角形:

13 ways to implement rounded triangles with pure CSS (skill sharing)

上述各个图形的完整代码,你可以戳这里:CodePen Demo -- A triangle with rounded and gradient background

https://codepen.io/Chokcoco/pen/LYyGRpV

最后

本文介绍了几种在 CSS 中实现带圆角三角形的方式,虽然部分有些繁琐,但是也体现了 CSS ”有趣且折磨人“ 的一面,具体应用的时候,还是要思考一下,对是否使用上述方式进行取舍,有的时候,切图也许是更好的方案。

好了,本文到此结束,希望对你有帮助 :)

原文地址:https://segmentfault.com/a/1190000040344317

作者:chokcoco

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