Amazon Is Developing Smartphone With 3-D Screen Inc.’s  Hardware ambitions are broadening.

The Seattle e-commerce giant has recently been developing a wide-ranging lineup of gadgets—including two smartphones and an audio-only streaming device—to expand its reach beyond its Kindle Fire line of tablet computers, said people familiar with the company’s plans.

One of the devices is a high-end smartphone featuring a screen that allows for 3-D images without glasses, these people said. Using retina-tracking technology, images on the smartphone would seem to float above the screen like a hologram and appear three-dimensional at all angles, they said. Users may be able to navigate through content using just their eyes, two of the people said.

Some elements of Amazon’s hardware push have previously become public. Last year, news surfaced that Amazon was developing one smartphone. And last month, The Wall Street Journal and other media outlets reported that Amazon also was developing a set-top box for streaming movies and TV shows.

But the people familiar with Amazon’s plans said the smartphone and set-top box are just two elements of a broader foray into hardware that also includes the audio-streaming device and the high-end smartphone with the 3-D screen. Inside Amazon’s Lab126 facility in Cupertino, Calif., where each of the devices have been under development, the efforts are known as Project A, B, C and D, or collectively as the Alphabet Projects, the people said.

Though Amazon has goals of releasing some of these devices in coming months, these people cautioned that some or all of the devices could be shelved because of performance, financial or other concerns.

An Amazon spokesman declined to comment.

In recent years Amazon has been diving deeper into hardware manufacturing to expand its presence in the gadget market and compete more directly with Apple Inc. and its tremendously popular iPad. The array of planned devices is part of a strategy to widen Amazon’s influence beyond its core e-commerce website and broadly into content distribution.

Write to Greg Bensinger at [email protected]