Re: DOOM style rendering - Need help

["Josiah Avery" <josiahavery@hotmail.com>]

*** Hello,

>   This is a question of what tricks did they use with the data to provide
> the necessary information. I do not have a complete edge list to use a
> generic affine texture mapper, and doing a ray casting style engine is a
>bit difficult with the data present. Since they obviously have a way of
doing
> it, I am obviously missing something. I am asking those persons who have
> gotten one to work to give me an idea of what I may be missing.

*** yea, raycasting isn't really what Doom used, so that's out of the
question. What do you mean you dont have a complete edge list to feed
to an affine mapper? I am assuming that for some reason when you are
scanning a quad ( ie floor/ceiling with 4 sides; not 2 triagles ), and
storing
the vector instances, and the list is incomplete??? Well, I would suggest
doing something as such:
                                    A __________________ B
                                     /
\
                                   /           typical quad            \
                                  /     of arbitrary dimensions    \
                                /    ( shown as projected           \
                               /   and prepped for rasterizer )     \
                              /
\
                            D___________________________C
1.Interpolate the view space coordinates of each segment AB,BC, CD,DA.

2. Map texture coordinates to each vertex.

3. Interpolate the 2d texture space coordinates in the number of steps == to
the change in values between corresponding, destination quad's segment's
lenght.

4. Feed the buffers created in step 3 to a *perspective correct* mapper.
Else you get the warping artifacts inherient with affine mappers ( which was
one
of Dooms claim to fame ).

    Now that I think about it, you can omitt step one.... Hope this helps.
Refer to Comp graph princ/pract is you dont know you to write a pc t-mapper.
Orrrr you can just  use OpenGL or DX and get accomplished in like 2 lines
of code ( at least in OGL )... I dunno, I still have a thing for software
rendering...

    Josiah


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