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- Understanding transition basics
- Working with 2D and 3D transforms
- Animating color changes
- Fading objects
- Changing the size of page elements and fonts
- Transitioning multiple properties at the same time
- Understanding keyframes and animations
- Working in the z-index
- Crafting transitions in Dreamweaver
Skill Level Intermediate
Although we're still in its infancy, 3D Transforms take the next logical step in Transitions and Transforms. The W3C 3D Transforms working group starts with a very straightforward definition: "CSS 3D Transforms extends CSS Transforms to allow elements rendered by CSS to be transform in three-dimensional space." Again, the devil is in the details. To represent 3D in a 2D medium like a computer screen, you have to first establish a perspective. Typically in a 3D transform, a CSS rule for the containing element like a div tag is established that defines both the perspective and perspective origin.
Perspective is essentially the distance from the viewer to the object. Lower numbers bring you closer to the object and distorted more. If you're a photographer, you can think of it as changing the focal length. Let me show you what I mean with a demo that changes the perspective dynamically, going from a value of 1000 to 100 in about 6 seconds. As you can see, the distortion begins to take effect as you get closer to the object with the lower perspective values.
If you've done any perspective drawing, you'll be familiar with a concept of the vanishing point. Perspective-origin establishes the vanishing point which by default is 50%, 50%, or the center. Use values from 0% to 100% in both X and Y axes to change the perspective origin. Here is that same perspective demo with a prospective origin set to 50%, 100% the bottom center, which shows the ugly truth about my seemingly 3D boxes.
Transformed 3D functions are, for the most part, the same as their 2D counterpart but include the Z axis. For example, translate adds translateZ to translateX, and translateY. You can also use the shorthand function translate3d. Use negative values for translateZ to move the object further away and positive for closer. Now let's add a translateZ function to our perspective demo, moving in 75 pixels.
Scary, eh? There's also a transformed 3D version of scale, where negative Z values make the objects smaller and positive larger. This page shows you the test that the Webkit Engineers came up with to verify that scale 3D was working. When I hover over the area, the scale 3D property is applied to the blue box. Now it scales up enough to stretch outside of the box, and there is also rotate. If you use the shorthand property rotate3d, you need to include four values.
The first three define the axis of rotation and the fourth is the degree of movement, or angle of rotation. Positive angles move the object clockwise and negative counterclockwise. To demonstrate this, let me show you a great showcase for 3D rotation. This example was created by webkit.org, Let me move down a little bit so you can appreciate the rotation of the cube, and I can also click on the Toggle Shape button to see a different kind of rotation.
Not only it is a terrific showcase for 3D rotation, but it also demonstrates one of the other properties available to you in the 3D space, Backface Visibility. So let me toggle off that option and toggle it back on, and then let's bring the cubes back, and I'll toggle off Backface Visibility one more time. Now there is one more 3D-related property you should be familiar with, Transform Style.
This property determines how the child elements in a perspective space are rendered. If transform-style is set to preserve 3D, all the transforms are applied to the children, but if transform-style is flat, the elements appear to be in the 2D plane of the parent element. This is far easier demoed than explained. So now you see three objects rotating with the transform-style set to preserve-3d, but watch what happens when I hover over them and the transform-style is changed from preserve-3d to flat.
The object continues to rotate, but now the children collapsed into the parent element. I'll hover out, and we're back to 3D. Originally, only Safari browsers handle 3D transforms, but in the last year browser support has really expanded with Firefox and Chrome coming onboard, as this shot from caniuse shows. At this stage you'll definitely need to use render prefixes to get any effects, but include the generic property to future-proof your code.
So that's an overview of 3D transforms. You'll have an opportunity to explore the various functions in depth in Chapter 4.