Transforms

Transform Syntax

The actual syntax for the transform property is quite simple, including the transform property followed by the value. The value specifies the transform type followed by a specific amount inside parentheses.

2D Transforms

Elements may be distorted, or transformed, on both a two-dimensional plane or a three-dimensional plane. Two-dimensional transforms work on the x and y axes, known as horizontal and vertical axes. Three-dimensional transforms work on both the x and y axes, as well as the z axis. These three-dimensional transforms help define not only the length and width of an element.

2D Rotate

The transform property accepts a handful of different values. The rotate value provides the ability to rotate an element from 0 to 360 degrees. Using a positive value will rotate an element clockwise, and using a negative value will rotate the element counterclockwise. The default point of rotation is the center of the element, 50% 50%, both horizontally and vertically.

2D Scale

Using the scale value within the transform property allows you to change the appeared size of an element. The default scale value is 1, therefore any value between .99 and .01 makes an element appear smaller while any value greater than or equal to 1.01 makes an element appear larger.

It is possible to scale only the height or width of an element using the scaleX and scaleY values. The scaleX value will scale the width of an element while the scaleY value will scale the height of an element. To scale both the height and width of an element but at different sizes, the x and y axis values may be set simultaneously. To do so, use the scale transform declaring the x axis value first, followed by a comma, and then the y axis value.

2D Translate

The translate value works a bit like that of relative positioning, pushing and pulling an element in different directions without interrupting the normal flow of the document. Using the translateX value will change the position of an element on the horizontal axis while using the translateY value will change the position of an element on the vertical axis.As with the scale value, to set both the x and y axis values at once, use the translate value and declare the x axis value first, followed by a comma, and then the y axis value.

2D Skew

The last transform value in the group, skew, is used to distort elements on the horizontal axis, vertical axis, or both. The syntax is very similar to that of the scale and translate values. Using the skewX value distorts an element on the horizontal axis while the skewY value distorts an element on the vertical axis. To distort an element on both axes the skew value is used, declaring the x axis value first, followed by a comma, and then the y axis value.

Combining Transforms

It is common for multiple transforms to be used at once, rotating and scaling the size of an element at the same time for example. In this event multiple transforms can be combined together. To combine transforms, list the transform values within the transform property one after the other without the use of commas.

Transform Origin

The transform-origin property can accept one or two values. When only one value is specified, that value is used for both the horizontal and vertical axes. If two values are specified, the first is used for the horizontal axis and the second is used for the vertical axis. Individually the values are treated like that of a background image position, using either a length or keyword value. That said, 0 0 is the same value as top left, and 100% 100% is the same value as bottom right. More specific values can also be set, for example 20px 50px would set the origin to 20 pixels across and 50 pixels down the element.

Perspective

The perspective of an element can be set in two different ways. One way includes using the perspective value within the transform property on individual elements, while the other includes using the perspective property on the parent element residing over child elements being transformed.

Perspective Depth Value

The perspective value can be set as none or a length measurement. The none value turns off any perspective, while the length value will set the depth of the perspective. The higher the value, the further away the perspective appears, thus creating a fairly low intensity perspective and a small three-dimensional change. The lower the value the closer the perspective appears, thus creating a high intensity perspective and a large three-dimensional change.

3D Transforms

Working with two-dimensional transforms we are able to alter elements on the horizontal and vertical axes, however there is another axis along which we can transform elements. Using three-dimensional transforms we can change elements on the z axis, giving us control of depth as well as length and width.

3D Rotate

So far we’ve discussed how to rotate an object either clockwise or counterclockwise on a flat plane. With three-dimensional transforms we can rotate an element around any axes. To do so, we use three new transform values, including rotateX, rotateY, and rotateZ.

3D Scale

By using the scaleZ three-dimensional transform elements may be scaled on the z axis. This isn’t extremely exciting when no other three-dimensional transforms are in place, as there is nothing in particular to scale. In the demonstration below the elements are being scaled up and down on the z axis, however the rotateX value is added in order to see the behavior of the scaleZ value. When removing the rotateX in this case, the elements will appear to be unchanged.

Transform Style

On occasion three-dimensional transforms will be applied on an element that is nested within a parent element which is also being transformed. In this event, the nested, transformed elements will not appear in their own three-dimensional space. To allow nested elements to transform in their own three-dimensional plane use the transform-style property with the preserve-3d value.The transform-style property needs to be placed on the parent element, above any nested transforms. The preserve-3d value allows the transformed children elements to appear in their own three-dimensional plane while the flat value forces the transformed children elements to lie flat on the two-dimensional plane.

Backface Visibility

When working with three-dimensional transforms, elements will occasionally be transformed in a way that causes them to face away from the screen. This may be caused by setting the rotateY(180deg) value for example. By default these elements are shown from the back. So if you prefer not to see these elements at all, set the backface-visibility property to hidden, and you will hide the element whenever it is facing away from the screen. The other value to backface-visibility is visible which is the default value, always displaying an element, no matter which direction it faces.