On a flying elephant
Voxel - a volume pixel, is maximal
cue cube. On the ZX realizable not only to all
Voxel-known landscapes such as Mars, but
and voxel objects, which can rotate
on all axes. In the intro to the 5 th number you IG
saw an example of such an object. If the object
similar in complexity to that which was
in IG # 5 (and there was just a flying elephant)
to build a textured polygons, then
speed drawing heavily would have fallen.
In general terms, how the effect?
He works a simple brute force'om. Each
Therefore, the direction of view corresponds to a
direction vector of a certain length (y
I have it about 8 cells), we move
steps of this vector, until he met
non-empty voxel. Take the color of the voxel
and throw it on the screen (more precisely, chunkmap).
This simple algorithm I've used yet
in 1996 the first piece on Wolf 3d.
Then he, however, does not contain any uhisch
ments to speed up the scanning and scary
inhibited ...
The object is described by two cards. The first spacecraft
mouth (on it we scan) in the page does not
placed due to the fact that the envisaged
empty edge - to avoid off-scale.
This card is for each pair of coordinates X, Y
contains the thickness of the object (Z-coordinate).
The second map takes a page and stores
color voxel with coordinates X, Y (and higher
shown Z). Y corresponds to the senior buy
that addresses in a map, X corresponds to the younger
th byte of the address. In the second map all
addresses more to # 2000.
In another page is stack
vyvodilka chunks like the one
described in the Monster Born Dead # 5. In this
If implemented 16 colors, which codes
# C0, # c4 ,...,# fc.
Since the elephant is symmetric, requires
only one Z coordinate for each pair
coordinates X, Y. If you want to look at
elephant on the other hand, we just do (in
early scan a particular screen
pixel) transformation: Z0 =- Z0 (Z0 =
z-coordinate of the beginning of scanning),
dZ =- dZ (dZ = z-scanning step).
Both maps were drawn in Photoshop.
Drawing process occurred long before
writing koda.Poetomu to control the following I
drank little program in Delphi, makes it
that returns the view cuts the elephant. This gave
opportunity to see the "burr" in places with
low Z (ie, where poluslon osculating
tangent to with his reflection). Seen
"Burrs" Naturally, I wore out in fotosho
ne.
Scanning cycle is as follows:
LOOPout
EXX
ADD IX, BC
ADD HL, DE
LD A, H
EXX
LD E, A
LD D, HX
LD A, (DE)
ADD HL, BC
JR C / NC, LOOPzro
CP H
JR C, LOOPQ; DE = YX
DEC LY; do no more than 14 steps
JP NZ, LOOPout
LOOPzro LD DE, zro; found nothing
RET
Generally these cycles in the program 4 shtu
ki, under different situations (taking into account variables
progress with Z> 0 in Z <0 and vice versa). Address DE = zro
(There is a black pixel) is different from
All other scan results to those
that it is less than # 8000.
If we scan all directions
(44 * 44 = 1936 pieces), then the effect would give no
more than one frame per second. This problem
been solved by interpolation.
In the first place - fine interpolation
(Blur): blur obtained by scanning
derivations X, Y coordinates by 1 pixel. (She
comes to mind first, but you
holds, then it is in the least!)
To implement the interpolation results
The results of scanning (X, Y coordinates in the volume
KTA) we do not use immediately, and put in
array SCANS. The size of this array
((HEIGHT / 2) +1) * (WIDTH +1) words
where WIDTH - the width of the screen in the familiarity
(Pairs of chunks), and HEIGHT - its height in
chunk. Here, an order to be able to
to average the right and bottom
edges kartinki.Na these parts is always an array
contains the value zro, we did not scanning
em.Kak you might guess from the size, in this
array of pixels are having only odd
nye screen coordinates, while the remaining pixels
whether the computed blur in the process of filling
of chunkmap'a (cycle read0).
But realistically, scanning is not a
pixel, and by 3 pixels (the cycle scan0).
A rough interpolation (cycle ish0) interpolates
induces its rezultaty.Chtoby obtained from these
the results of the scan results ostensibly
through the pixel, has a simple nedostanochno
razmazyvaniya.Dlya some pixels to an
usual additional scan (cycle
fill0). Here the following scheme:
S1S
121
S1S
where S = SCAN, 1,2 = handling: if all neighbors
<> Zro or all = zro, then the cell is interpolated
is, or scanned. Sign "as well, ska
niruy this cage! "transferred from the cycle
ish0 cycle fill0 as the value of X =- 1.
If a rough interpolation is disabled, X =- 1
transmitted in all cases (on the button "S"
to tags MAYBEJP placed team unconditional
sition).
Source - as usual, in the appendix.
You can even accelerate, if we double step
scan. Then after crossing the boundary
boundary of the object should look, if not crossed
We object to a half-step ranshe.Esli so, in
zvraschaem as a result of scanning
of this zapolshagovuyu coordinate. So work
melts scanning Wolf2004. Lack of
a dual-scan is that it
can cut corners and fine detail. However,
texture in large parts it is imposing
em right.
Alone Coder
