Thanks, Warp. It's a good summary, and it sounds like a procedure I dont' want to
explore, or I'll try to figure it out mathematically

Josh


Warp wrote:

>   The ideology in scanline rendering is completely different from raytracing.
>
>   In raytracing the program "shoots" rays from the camera towards the scene
> and sees what does it hit (this allows, among other things, the objects to
> be mathematical functions, not necessarily polygons).
>
>   In scanline rendering the process is completely different (this is a very
> simple explanation; the actual process used by current scanline renderers is
> a bit more complicated):
>   The scene consists entirely of polygons. Each polygon (that is, each vertex
> of each polygon) is projected on the viewing plane (the "screen"). That is,
> each 3D vertex is projected on the viewing plane thus getting 2D points
> (with depth information).
>   Then the polygons are drawn as if they were just 2D polygons on screen
> (of course texturing and lighting takes into account the depth information
> and normal vectors of the vertex points).
>   Hidden surface removal is (usually, but not necessarily) achieved with
> a z-buffering algorithm.
>
>   Drawing 2D polygons on screen (even taking into account the depth
> information) is a lot faster than raytracing.
>   Current 3D acceleration cards use purely scanline rendering.
>
>   If you have heard the term "perspective correct texture mapping", it's
> very closely related to scanline rendering. It's an algorithm which is
> necessary to use when drawing the polygons in order to get correct textures.
> Explaining its idea is beyond this short text.
>   Raytracing doesn't need this to get correct texturing, since the raytracing
> algorithm itself "automatically" gets the correct color in the texture.
>
> --
> char*i="b[7FK@`3NB6>B:b3O6>:B:b3O6><`3:;8:6f733:>::b?7B>:>^B>C73;S1";
> main(_,c,m){for(m=32;c=*i++-49;c&m?puts(""):m)for(_=(
> c/4)&7;putchar(m),_--?m:(_=(1<<(c&3))-1,(m^=3)&3););}    /*- Warp -*/

--
Josh English -- Lexiphanic Lethomaniac
eng### [at] spiritonecom
The POV-Ray Cyclopedia http://www.spiritone.com/~english/cyclopedia/

Post a reply to this message