Seite 6: Diskussion Kirk vs. Slusallek

Weiter mit GameStar Plus

---

Wenn dir gute Spiele wichtig sind.

Besondere Reportagen, Analysen und Hintergründe für Rollenspiel-Helden, Hobbygeneräle und Singleplayer-Fans – von Experten, die wissen, was gespielt wird. Deine Vorteile:

Alle Artikel, Videos & Podcasts von GameStar

Frei von Banner- und Video-Werbung

Einfach online kündbar

Jetzt weiter

Inhaltsverzeichnis

1

Einleitung
Ray tracing or rasterization?

2

Weiter

3

Perfect effects

4

Weiter

5

Game development

6

Weiter

7

Ray tracing in today GPUs

8

Weiter

---

Weiter

Kirk:
I'll stick with my original comment - the rendering framework is essentially a solved problem. The real work in game authoring is model (scene) creation, character creation and animation, and lighting and shader creation for specific effects.

Ray tracing does not eliminate any of that work - even in ray tracing, the material shaders still have to be written to create any material appearance that is desired. In rasterization, the shader is applied when the triangle is rendered. In ray tracing, intersections are determined, and the shader is applied to determine which additional rays should be generated for lighting and reflection. In either case, it's essentially the same shader.

Slusallek:
I am a bit surprised about your comment on shading in rasterization versus ray tracing. You are right, as long as purely local effects are concerned (e.g. computing the color or normal procedurally or via textures). But the difference shows up when you want to do anything more advanced that also requires global effects.

Let's take again reflection as a very simple example to show the difference: Yes, where a ray tracer shader simply shoot a ray in the reflected direction and is done, a CG shader running on a rasterizer could just look up the reflected color from a reflection map. So it is similar on this level.

But how do you get the reflection map in the first place? What resolution do you use? Where to you place the camera? What do you do if the reflected geometry is too close or the reflective surface is curved, such that the reflection map would produce clearly visible artifacts? Or what if the reflected objects need special processing as well because they are reflective too, or receive shadows, or should show nice global illumination effects.

The problem is that all of this needs to be worked out by the application outside of the graphics hardware. With ray tracing the shader running on the graphics hardware simply shoots one or more rays that get handled within the same hardware, and the application does not even care about these details.

I sometime have the feeling that with the dominance of rasterization hardware today, too many of us are simply not aware any more of the many limitations that rasterization actually has.