1. A non-transitory computer-readable storage medium having stored therein a display control program to be executed by a computer of a display control apparatus which stereoscopically displays a predetermined two-dimensional object and a predetermined three-dimensional object positioned in a virtual three-dimensional space on a display device, the display control program causing the computer to execute: obtaining a depth value in accordance with a state of the virtual three-dimensional space captured by a virtual stereo camera; synthesizing an image for left eye and an image for right eye which are obtained by shifting the two-dimensional object, in order to generate parallax, by a shift amount in accordance with the obtained depth value, with an image for left eye and an image for right eye which are obtained by capturing the predetermined three-dimensional object by the virtual stereo camera, respectively, and rendering the respective synthesized images, thereby generating a stereoscopic image; stereoscopically displaying the generated stereoscopic image on the display device, obtaining the depth value repeatedly; re-setting the shift amount each time the depth value is obtained; synthesizing the image for left eye and the image for right eye, which are obtained by shifting the two-dimensional object by the re-set shift amount, with the image for left eye and the image for right eye which are obtained by capturing the three-dimensional object, respectively, and rendering the respective synthesized images, thereby regenerating the stereoscopic image; and replacing the stereoscopic image stereoscopically displayed on the display device with the regenerated stereoscopic image.