- From: Amelia Bellamy-Royds via GitHub <sysbot+gh@w3.org>
- Date: Fri, 07 Apr 2017 19:02:16 +0000
- To: public-fxtf-archive@w3.org
On the specific issue of the "neutral elements addition": that entire section needs to be re-written, as tracked in https://github.com/w3c/csswg-drafts/issues/932. The "neutral" perspective value is actually `perspective(Infinity)` (the same as no perspective modification at all), although I don't think we currently allow `perspective(Infinity)` to be specified directly. `perspective(0)` in general, however, suffers from the problem that it is logically sensible, but mathematically unfeasible as currently defined. The perspective distance is relative to the X-Y plane, so it is really a position, not an absolute distance. Even negative values are logical so long as the objects being viewed are also at (more) negative _z_ coordinates. In order to create useful matrices, however, you would need to normalize the entire scene relative to the viewer/perspective distance. Practical use cases of allowing zero and negative perspective distances would be to create a "zoom-in" effect of the viewer passing through a 3D scene. Currently, to make it work you have to instead treat the viewer's perspective as a fixed, finite, positive _z_ position, and then translate the entire scene along the _z_-axis towards the viewer. -- GitHub Notification of comment by AmeliaBR Please view or discuss this issue at https://github.com/w3c/fxtf-drafts/issues/126#issuecomment-292624418 using your GitHub account
Received on Friday, 7 April 2017 19:02:22 UTC