Talk:Ray casting

What's with all the CSG?

It appears that this page has recently been taken in a completely different direction. Most of the page now focuses on use of ray tracing for rendering constructive solid geometry. It appears that the page is practically a reprint of Scott Roth's original CSG rendering paper, which first coined the term "ray casting".

While it's worthwhile to mention this original introduction of the term, and while this paper establishes that CSG rendering is one definition of "ray casting" I think this overwhelming focus on CSG hides the much more prevalent meaning of the term "ray casting", which was well represented by the article as it stood before the recent rewrite by SRoth222. When people want to learn about ray casting they will mostly want to learn about primary ray rendering, especially as used in games during the last twenty years. If they want to learn about CSG rendering I think that information ought to be found on the solid modeling page of the constructive solid geometry.

I propose to rewrite the page to mention this second definition of "ray casting" in the lead paragraph, but then move all of the CSG stuff to a single section down below.

Another option would be to make a new CSG rendering page containing all of the material that is basically a copy of Scott Roth's paper, and simply link to that from the Ray Casting page. Thoughts?

I should add that, while the shaded rendering of a CSG universal joint is nice (especially for 1982!) and fits Scott Roth's paper's definition of "ray casting" it contradicts the prevalent use of the term "ray casting" because it clearly uses secondary rays, while the essential characteristic of ray casting is that it is primary rays only.

Ray casting in DOOM

This page doesn't describe ray casting - it describes an application of ray casting used in old video games (DOOM specifically). Should be rewritten to describe ray casting in general.

There's already a good article on ray casting in general, so I've tried to alter this article to reflect the situations where the term ray casting is more common. I hope I've made a significant advancement. ThomasHarte 21:04, 12 August 2005 (UTC)

New edit 11/18/2005

This page incorrectly defines ray casting as a synonym for ray tracing and cites extremely outdated examples of its implementation. While the old implementation might be useful as a foray into the beginnings of real-time video games, it gives the wrong impression of the current state of rendering technologies used in real-time games. I added the ray casting info from the ray tracing definition, because I come to Wikipedia for definitions, not examples - so hopefully I am not alone! It would be nice to add some links and data about the current uses of Ray tracing.

K.C. Murphy

I agree. This article also needs restructuring. Ray casting is activly used e.g. in direct volume visualisation (medical/scientific visualisation).

Flash raycasting

At first, I was going to edit this because it was non-neutral, but, considering it......

• was non-notable
• violates copyright (I believe Wolfenstein's engine is free for use, its graphics aren't)
• is a thinly veiled advertisement for a "consolidation loan"
• is probably a vanity edit

.....I removed it altogether. The sections above it talk about major engines' use of raycasting. This, however, was just some dude's little flash project. It doesn't follow from the other sections, it's not useful, it's not even interesting: There are a million raycasting engines, this makes it a million and one. Now that Flash 8 allows pixel-level manipulation of images, it's practically trivial task, no more difficult than any other implementation and therefore not more significant than any other: congratulations on your mediocrity.

With the above reasons, then, it needs to go. so it did. TheBilly 13:19, 23 April 2006 (UTC)

While I agree with the removal, I think the snark is completely unnecessary.... 86.130.110.101 (talk) 22:55, 2 September 2015 (UTC)

Origin of term "ray casting"

I'm certain that I first used the term "ray casting" in my published paper:

Roth, S. D. "Ray Casting for Modeling Solids." Computer Graphics and Image Processing, 18 (February 1982), 109-144.

"Computer Graphics" by Foley, et al, references my paper. The paper describes the use of rays to model solids and to generate images of solid compositions using shadows, transparancy, etc. The paper includes numerous computer-generated examples.

I guess it would ve vain of me to edit aritcle.

-- Scott Roth

Origin of the algorithms

Not discussing origins of "term" ray casting, just the note that algorithms of ray casting were probably first described in: APPEL, A. Some techniques for shading machine renderings of solids. Proc. AFIPS 1968 Spring Joint Comput. Conf., Vol. 32, MDI Publications, Wayne, Pa., pp. 37-49, at least it looks like according to http://en.wiki.x.io/wiki/Rendering_(computer_graphics)

-- Jan Pečiva —Preceding unsigned comment added by Pcjohn (talk • contribs) 09:22, 17 February 2010 (UTC)

Duke3D

The section on how duke nukem 3D is made is wrong, commented by the engine devloper: http://jonof.edgenetwork.org/forum/viewtopic.php?p=7012#7012

I propose that the section be either removed or corrected. I'll remove it for now.

-I corrected it --24.56.241.134 21:21, 6 March 2007 (UTC)

I have removed the Duke3D/Build Engine section, as it doesn't use raycasting at all. The algorithm described is in fact a portal-traversal algorithm, which renders entire polygons at a time. Kayamon (talk) 07:41, 14 December 2008 (UTC)

Doom uses "trigonometric multiply" instead of division??

So Doom has a BSP that is used to reduce the number of walls available for raycasting and speed up the process. According to the article, "This has the advantage of replacing thousands of expensive divide operations with trigonometric multiplies." But what is a trigonometric multiply? —Preceding unsigned comment added by 136.176.8.18 (talk) 15:10, 4 September 2007 (UTC)

• I want to know, too. I think it has to do with multiplying x*z and y*z instead of dividing x/z and y/z for 3d to 2d projection. This also enables the use of integers instead of floating points. The integer can then be split up into levels of accuracy (like in a fixed point). Is there an article specifically on this topic of multiply vs. division for projection, or even a more proper term than "trigonometric multiply"? Each choice has its advantage, and (as far as I know) division wins out. Erudecorp ? * 23:11, 22 October 2007 (UTC)
• I removed the Doom section since I couldn't find any evidence that Doom used ray casting at all. JustinTalbot (talk) 00:36, 22 November 2007 (UTC)

I'm having difficulty using Ray Casting..... I'm using it to determine paths for a path finder, but the method I use is too slow. (I'm coding in lua) I determine the direction and distance between the two points, and then count up with the distance form the start, until it either reaches the destination, or hits a block. Is there a faster, mathematical way of determining where the firs tintersection with a series of boxes will occur? The method I use freezes the window. —Preceding unsigned comment added by 74.199.8.90 (talk) 23:07, 11 December 2009 (UTC)

merge suggestion

• Oppose. These are two fairly different topics. Basically, in computer graphics, ray casting is a step of ray tracing. Also, the ray casting problem is used in other contexts as well.

Don't most hitscan implimentations use this?

Maybe that should be mentioned, as lots of shooters have been made since Wolfenstein... —Preceding unsigned comment added by 207.159.180.169 (talk) 13:58, 26 April 2011 (UTC)

Fix Concept section

The "Concept" section mentions both ray tracing and ray casting but isn't very clear in its explanations of the two or how they differ — Preceding unsigned comment added by 184.16.136.97 (talk) 18:27, 12 May 2018 (UTC)

Brain explosion time

just a reminder,that we've technically gone from THIS to S&Box or Half-life: Alyx Aperksoriginal (talk) 15:41, 9 May 2023 (UTC)