使用sass绘制三角形

用border生成三角形的@mixin：

// triangle
@mixin triangle($direction, $size, $borderColor ) {
  content:"";
  height: 0;
  width: 0;

  @if $direction == top {
    border-bottom:$size solid $borderColor;
    border-left:$size dashed transparent;
    border-right:$size dashed transparent;
  } 
  @else if $direction == right {
    border-left:$size solid $borderColor;
    border-top:$size dashed transparent;
    border-bottom:$size dashed transparent;
  } 
  @else if $direction == bottom {
    border-top:$size solid $borderColor;
    border-left:$size dashed transparent;
    border-right:$size dashed transparent;
  } 
  @else if $direction == left {
    border-right:$size solid $borderColor;
    border-top:$size dashed transparent;
    border-bottom:$size dashed transparent;
  }
}

这个@mixin主要有三个变量：第一个是方向的，由于三角形根据箭头朝向有四种方向，咱们对应经常使用的css属性top,right,bottom,left；第二个表示三角形的大小；第三个表示颜色。固然你能够挑你经常使用的那个设置为变量的默认值，那样调用经常使用的那个就比较简单了，直接@include triangle;就ok了。

编译以后的css代码：

/* line 192, ../sass/test1.scss */
.top {
  content: "";
  height: 0;
  width: 0;
  border-bottom: 20px solid #322222;
  border-left: 20px dashed transparent;
  border-right: 20px dashed transparent;
}

/* line 195, ../sass/test1.scss */
.bottom {
  content: "";
  height: 0;
  width: 0;
  border-top: 20px solid #322222;
  border-left: 20px dashed transparent;
  border-right: 20px dashed transparent;
}

/* line 198, ../sass/test1.scss */
.left {
  content: "";
  height: 0;
  width: 0;
  border-right: 20px solid #322222;
  border-top: 20px dashed transparent;
  border-bottom: 20px dashed transparent;
}

/* line 201, ../sass/test1.scss */
.right {
  content: "";
  height: 0;
  width: 0;
  border-left: 20px solid #322222;
  border-top: 20px dashed transparent;
  border-bottom: 20px dashed transparent;
}

页面html代码：

<div class="top"></div>
<div class="left"></div>
<div class="right"></div>
<div class="bottom"></div>

效果：