4 ms·

Řrřola (a famous demoscene coder [1]) found a far better constant than the original (a 2.7-fold accuracy improvement) by using an optimisation algorithm over al

Řrřola (a famous demoscene coder [1]) found a far better constant than the original (a 2.7-fold accuracy improvement) by using an optimisation algorithm over all three constants present in the original inverse square hack. His algorithm and the result (along with a plot of relative error) can be found on his blog [2]. [1]: See, for example, this 256-byte raycaster https://www.youtube.com/watch?v=R35UuntQQF8 https://www.youtube.com/watch?v=R35UuntQQF8 [2]: http://rrrola.wz.cz/inv_sqrt.html http://rrrola.wz.cz/inv_sqrt.html

soravux 12y ago
This is really interesting. I'll be sure to include these references in my next blog post on the subject. The goal of the post was to find the equation from scratch, though. As it can be seen, the constant optimization was less the spotlight of the post.
- zo1 12y ago
  Not to mention your blog engine/site is broken. Please fix the fact that we can't click on the right scrollbar due to your fancy shmancy javascript side menu. Put it on the left hand side, or don't overlay it over the scrollbar. Damn #hipstercoders
  - nitrogen 12y ago
    The placement of any site elements on top of the scrollbar is indeed annoying. Is that a Blogspot thing, or is it due to a customization?
    - masklinn 12y ago
      It's blogspots "Dynamic Views". Complete dreck. I can only assume it's the default when you create a blog nowadays as I have no idea why anybody (least of all developers) would opt into that crap.
      - coldpie 12y ago
        Someone at blogspot needs a smack on the head. The site takes several seconds to load, which is absolutely ludicrous for displaying plain text, and when it finally does it's unusable as you've noted.
    - Sprint 12y ago
      It's a sadly commonly used theme that also does not display anything at all if you don't enable Javascript.
      - deleted 12y ago
        [deleted]
        coldpie 12y ago
        Requiring tons of javascript and seconds of load time to display plaintext? Yeah, that is pretty crazy.
        deleted 12y ago
        [deleted]
    - soravux 12y ago
      Everything is on default from Blogspot. I only put the Gist source code displayer and the LaTeX math javascript. If anyone is offering a new design, I would gladly take it... As long as I can concentrate on the content and not the container.
xellisx 12y ago
Has anyone gone in an plugged this into the Quake III / IOQuake 3 source and see if it's make a difference? Speed or better looking geometry?
- jheriko 12y ago
  its not faster and the accuracy improvement is more of a curiosity than of real value. infact on modern desktop/console hardware invsqrt hack is really bad. it causes type aliasing which is 'expensive' in native software terms. the x86(-64) chips underlying them all now has a dedicated instruction for this, as do the PPCs that came in the generation before... still of value on ARM though which is becoming more and more important.

soravux 12y ago

This is really interesting. I'll be sure to include these references in my next blog post on the subject. The goal of the post was to find the equation from scratch, though. As it can be seen, the constant optimization was less the spotlight of the post.

zo1 12y ago
Not to mention your blog engine/site is broken. Please fix the fact that we can't click on the right scrollbar due to your fancy shmancy javascript side menu. Put it on the left hand side, or don't overlay it over the scrollbar. Damn #hipstercoders
- nitrogen 12y ago
  The placement of any site elements on top of the scrollbar is indeed annoying. Is that a Blogspot thing, or is it due to a customization?
  - masklinn 12y ago
    It's blogspots "Dynamic Views". Complete dreck. I can only assume it's the default when you create a blog nowadays as I have no idea why anybody (least of all developers) would opt into that crap.
    - coldpie 12y ago
      Someone at blogspot needs a smack on the head. The site takes several seconds to load, which is absolutely ludicrous for displaying plain text, and when it finally does it's unusable as you've noted.
  - Sprint 12y ago
    It's a sadly commonly used theme that also does not display anything at all if you don't enable Javascript.
    - deleted 12y ago
      [deleted]
      - coldpie 12y ago
        Requiring tons of javascript and seconds of load time to display plaintext? Yeah, that is pretty crazy.
        deleted 12y ago
        [deleted]
  - soravux 12y ago
    Everything is on default from Blogspot. I only put the Gist source code displayer and the LaTeX math javascript. If anyone is offering a new design, I would gladly take it... As long as I can concentrate on the content and not the container.

xellisx 12y ago

Has anyone gone in an plugged this into the Quake III / IOQuake 3 source and see if it's make a difference? Speed or better looking geometry?

jheriko 12y ago
its not faster and the accuracy improvement is more of a curiosity than of real value. infact on modern desktop/console hardware invsqrt hack is really bad. it causes type aliasing which is 'expensive' in native software terms. the x86(-64) chips underlying them all now has a dedicated instruction for this, as do the PPCs that came in the generation before... still of value on ARM though which is becoming more and more important.