# Optical illusions

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Two rectangular prongs at the top transform into three cylindrical prongs.

```100 call clear::call char(48,"01020408102040808040201008040201808080808080808080C0A09088848281")
110 call char(52,"814224181020408003020408F",54,"E01008040402020201020408081010101008080403")
120 for l=5 to 19::read c,s\$::display at(l,c):s\$; ::next l::for l=0 to 9^9::next l
130 data 17,01,16,0  1,15,0 03 1,14,0 0 21 1,13,0 0 010 02,12,0 0 0 0 0 2,11,0 0 0 0 0 0,10
140 data 0 0 0 0 0 0,9,0 0 0 0 0 0,8,760 0 0 0 0,8,85 0 0 0 0,10,760 0 0,10,85 0 0,12,760,12,85
run

```
Edited by sometimes99er

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Two rectangular prongs at the top transform into three cylindrical prongs.

```100 call clear::call char(48,"01020408102040808040201008040201808080808080808080C0A09088848281")
110 call char(52,"814224181020408003020408F",54,"E01008040402020201020408081010101008080403")
120 for l=5 to 19::read c,s\$::display at(l,c):s\$; ::next l::for l=0 to 9^9::next l
130 data 17,01,16,0  1,15,0 03 1,14,0 0 21 1,13,0 0 010 02,12,0 0 0 0 0 2,11,0 0 0 0 0 0,10
140 data 0 0 0 0 0 0,9,0 0 0 0 0 0,8,760 0 0 0 0,8,85 0 0 0 0,10,760 0 0,10,85 0 0,12,760,12,85
run

```

A classic, and very cool I loaded up in js99er to see what it'd look like.

i need to print some of these out to type in on my TI!

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Two rectangular prongs at the top transform into three cylindrical prongs.

```100 call clear::call char(48,"01020408102040808040201008040201808080808080808080C0A09088848281")
110 call char(52,"814224181020408003020408F",54,"E01008040402020201020408081010101008080403")
120 for l=5 to 19::read c,s\$::display at(l,c):s\$; ::next l::for l=0 to 9^9::next l
130 data 17,01,16,0  1,15,0 03 1,14,0 0 21 1,13,0 0 010 02,12,0 0 0 0 0 2,11,0 0 0 0 0 0,10
140 data 0 0 0 0 0 0,9,0 0 0 0 0 0,8,760 0 0 0 0,8,85 0 0 0 0,10,760 0 0,10,85 0 0,12,760,12,85
run

```

That is really cool. Now I have to figure out how you did it!

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Here is how I rendered it in Camel99 Forth

```\ classic pipe & bar illusion by sometimes99er on Atariage
GRAPHICS
HEX
CREATE SHAPES
0102 , 0408 , 1020 , 4080 ,
8040 , 2010 , 0804 , 0201 ,
8080 , 8080 , 8080 , 8080 ,
80C0 , A090 , 8884 , 8281 ,
8142 , 2418 , 1020 , 4080 ,
0302 , 0408 , F000 , 0000 ,
E010 , 0804 , 0402 , 0202 ,
0102 , 0408 , 0810 , 1010 ,
1008 , 0804 , 0300 , 0000 ,

\ write character definitions to VDP RAM all at once
: CHARACTERS ( 'pattern ascii# char-cnt   -- ) 8* SWAP ]PDT SWAP VWRITE ;

DECIMAL
SHAPES  CHAR 0   9 CHARACTERS

: RUN  PAGE
CR ."                01"
CR ."               0  1"
CR ."              0 03 1"
CR ."             0 0 21 1"
CR ."            0 0 010 02"
CR ."           0 0 0 0 0 2"
CR ."          0 0 0 0 0 0"
CR ."         0 0 0 0 0 0"
CR ."        0 0 0 0 0 0"
CR ."       760 0 0 0 0 "
CR ."       85 0 0 0 0"
CR ."         760 0 0"
CR ."         85 0 0"
CR ."           760"
CR ."           85"
BEGIN KEY? UNTIL ;
```

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...and here it is in fbForth 2.0 with slightly modified logistics:

```\ fbForth 2.0 port of Camel99 Forth version
\ of classic pipe & bar illusion by sometimes99er on Atariage
BASE @  \ current radix to stack
HEX
: SHAPES  ( --- addr cell-cnt )
DATA[
0102 0408 1020 4080
8040 2010 0804 0201
8080 8080 8080 8080
80C0 A090 8884 8281
8142 2418 1020 4080
0302 0408 F000 0000
E010 0804 0402 0202
0102 0408 0810 1010
1008 0804 0300 0000
]DATA  ;

: RUN  ( --- )
VDPMDE @       \ save current graphics mode to stack
GRAPHICS
SHAPES ASCII 0 DCHAR    \ redefine characters '0'..'8'
PAGE
CR ."                01"
CR ."               0  1"
CR ."              0 03 1"
CR ."             0 0 21 1"
CR ."            0 0 010 02"
CR ."           0 0 0 0 0 2"
CR ."          0 0 0 0 0 0"
CR ."         0 0 0 0 0 0"
CR ."        0 0 0 0 0 0"
CR ."       760 0 0 0 0 "
CR ."       85 0 0 0 0"
CR ."         760 0 0"
CR ."         85 0 0"
CR ."           760"
CR ."           85"
BEGIN ?KEY UNTIL
VMODE  ;       \ restore graphics mode ```

...lee

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Hey Lee,

When you post Forth code, what language do you select to make the colors look like that?

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Hey Lee,

When you post Forth code, what language do you select to make the colors look like that?

That is done by the code (<>) button in the editor.

I often indent a block of text in the “Courier New” font and bold/color it how I like. That procedure is more trouble and has greater line-spacing than the code button. I put long stretches of code formatted that way into spoilers.

...lee

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Curvature Blindness - all the curves are exactly the same shape. Source

```100 call clear::call screen(3)::call color(1,1,1,2,1,1,3,1,1,4,1,1,5,1,1,6,1,1,7,1,1,8,1,1)::call magnify(3)
110 c\$="00000000C038070000000000031CE000000738C000000000"::d\$="000738C00000000000E01C030000000000000000C0380700"
120 call char(32,"00000000000000000103070F1F3F7FFFFFFFFFFFFFFFFFFF",48,c\$,56,c\$,64,c\$,72,d\$,80,d\$,88,d\$)
130 call char(40,"0000000000000000FFFEFCF8F0E0C080")::e\$=rpt\$(" ",max(0,11))&"!"&rpt\$("""",22)&")"&rpt\$("(",14)
140 a\$=rpt\$("2IJ1",7)&rpt\$("HI01",7)::b\$=rpt\$(":QR9",7)&rpt\$("PQ89",7)::c\$=rpt\$("BYZA",7)&rpt\$("XY@A",7)
150 for i=0 to 7::read x,y,z::j=1+28*(i and 1)::d\$=seg\$(a\$,j,x)&seg\$(b\$,x+j,y)&seg\$(c\$,x+y+j,z)
160 display at(i*3+1,1):d\$;::display at(i*3+2,1):d\$;::display at(i*3+3,1):seg\$(e\$,i*3+1,28);::next i
170 for i=0 to 7::read c\$::call char(i*4+96,c\$)::next i
180 for i=0 to 4::call sprite(#i+1,96+(i and 3)*4,3,i*24+1,113-i*24)
190 call sprite(#i+6,112+(i and 3)*4,3,i*24+73,225-i*24)::next i
200 call color(1,3,16,2,3,2,3,4,16,4,4,3,5,4,2,6,13,16,7,13,3,8,13,2)::call screen(16)::for i=0 to 9^9::next i
210 data 14,14,0, 11,17,0, 8,20,0, 5,21,2, 2,21,5, 0,20,8, 0,17,11, 0,14,14
220 data "00000000000000000100070F1F3F7FFF0103030C1F3F7FFFFF1FE3FCFFFFFFFF"
230 data "00000000000000000103030C1F3F7FFF0103070F1F0778FFFFFFFFFF3FC7F8FF"
240 data "00000000000000000103070F1F0778FF0103070F1C231FFFFFFFFFFFFCE31FFF"
250 data "00000000000000000103070F1C231FFF0100070F1F3F7FFFFFF8C73FFFFFFFFF"
260 data "FFFFFFFF3FC7F8FFFFFEFCF830C0C080FFFEFCF8F0E000800000000000000000"
270 data "FFFFFFFFFCE31FFFFFFEFCF8F0E00080FFF8C438F0E0C0800000000000000000"
280 data "FFF8C73FFFFFFFFFFFF8C438F0E0C080FF1EE0F8F0E0C0800000000000000000"
290 data "FF1FE3FCFFFFFFFFFF1EE0F8F0E0C080FFFEFCF830C0C0800000000000000000"
run```
Edited by PeteE

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Two rectangular prongs at the top transform into three cylindrical prongs.

```100 call clear::call char(48,"01020408102040808040201008040201808080808080808080C0A09088848281")
110 call char(52,"814224181020408003020408F",54,"E01008040402020201020408081010101008080403")
120 for l=5 to 19::read c,s\$::display at(l,c):s\$; ::next l::for l=0 to 9^9::next l
130 data 17,01,16,0  1,15,0 03 1,14,0 0 21 1,13,0 0 010 02,12,0 0 0 0 0 2,11,0 0 0 0 0 0,10
140 data 0 0 0 0 0 0,9,0 0 0 0 0 0,8,760 0 0 0 0,8,85 0 0 0 0,10,760 0 0,10,85 0 0,12,760,12,85
run

```

MY EYES!!!!

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The boxes seem to tilt.

```100 call clear::call screen(6)::call char(33,"30C0030C30C0030C0C03C0300C03C03")
110 call box(4,9,29,11,33)::call box(10,13,23,18,34)::for i=0 to 9^9::next i
120 sub box(x1,y1,x2,y2,c)::for y=y1 to y2::call hchar(y,x1,c,x2-x1+1)::next y::subend
run
```
Edited by sometimes99er

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The boxes seem to tilt.

```100 call clear::call screen(6)::call char(33,"30C0030C30C0030C0C03C0300C03C03")
110 call box(4,9,29,11,33)::call box(10,13,23,18,34)::for i=0 to 9^9::next i
120 sub box(x1,y1,x2,y2,c)::for y=y1 to y2::call hchar(y,x1,c,x2-x1+1)::next y::subend
run

```

This is an amazing illusion. I can't believe my eyes lie to me like that.

I did this one in Forth because it was easier for me but I am sure you could crank this off in BASIC pretty easily.

It's called the Ternus Illusion. I found it on Wikipedia.

```HEX
CREATE SPOTDATA
071F , 3F7F , 7FFF , FFFF , \ upper left
E0F8 , FCFE , FEFF , FFFF , \ upper right
FFFF , FF7F , 7F3F , 1F07 , \ lower left
FFFF , FFFE , FEFC , F8E0 , \ lower right

DECIMAL
: AS_SPOT ( char -- ) SPOTDATA  SWAP ]PDT  32 VWRITE ;

: DRAW_SPOT ( 1stchar col row -- )
AT-XY                   \ Position cursor
DUP EMIT  1+ DUP EMIT   \ draw top 2 chars
1 VROW +!  -2 VCOL +!   \ goto next row, back 2 cols.
1+ DUP EMIT 1+ EMIT ;   \ draw bottom 2 chars

: FRAME1    16 1 1 COLOR   17 18 2 1 COLORS  ;
: FRAME2    16 18 1 1 COLORS  ;      \ blank frame
: FRAME3    16 17 2 1 COLORS   18 1 1 COLOR  ;

: TERNUS
GRAPHICS
PAGE
16 SCREEN
8 0 AT-XY ." Ternus Illusion"

128 AS_SPOT   16 2 1 COLOR
136 AS_SPOT   17 2 1 COLOR
144 AS_SPOT   18 1 1 COLOR

128  5 10 DRAW_SPOT
136 15 10 DRAW_SPOT
144 25 10 DRAW_SPOT

BEGIN
BEEP
0  23 BL 32 HCHAR
1 23 AT-XY ." Element Motion (press key)"
BEGIN
FRAME1 500 MS
FRAME2  15 MS
FRAME3 500 MS
FRAME2  15 MS
KEY?
UNTIL

BEEP
0  23 BL 32 HCHAR
10 23 AT-XY ." GROUP Motion"
BEGIN
FRAME1 500 MS
FRAME2 250 MS
FRAME3 500 MS
FRAME2 250 MS
KEY?
UNTIL
?BREAK
AGAIN ;
```

TERNUS.mp4

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This is an amazing illusion. I can't believe my eyes lie to me like that.

I did this one in Forth because it was easier for me but I am sure you could crank this off in BASIC pretty easily.

It's called the Ternus Illusion. I found it on Wikipedia.

<snip>

This code does not work correctly in Camel99 Forth v1.98 (latest?). I traced it to the definition of COLORS , which should have the address difference incremented by 1 to give VFILL the proper copy count.

```( *NEW*  change contiguous character sets at once)
: COLORS  ( set1 set2 fg bg  -- )
1 ?MODE
>COLR >R
SWAP ]CTAB SWAP ]CTAB OVER -
R> VFILL ;
```

should be

```( *NEW*  change contiguous character sets at once)
: COLORS  ( set1 set2 fg bg  -- )
1 ?MODE
>COLR >R
SWAP ]CTAB SWAP ]CTAB OVER -
1+      \ increment color-table-address difference to get proper count for VFILL
R> VFILL ;
```

...lee

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This code does not work correctly in Camel99 Forth v1.98 (latest?). I traced it to the definition of COLORS , which should have the address difference incremented by 1 to give VFILL the proper copy count.

```( *NEW*  change contiguous character sets at once)
: COLORS  ( set1 set2 fg bg  -- )
1 ?MODE
>COLR >R
SWAP ]CTAB SWAP ]CTAB OVER -
R> VFILL ;
```

should be

```( *NEW*  change contiguous character sets at once)
: COLORS  ( set1 set2 fg bg  -- )
1 ?MODE
>COLR >R
SWAP ]CTAB SWAP ]CTAB OVER -
1+      \ increment color-table-address difference to get proper count for VFILL
R> VFILL ;
```

...lee

You caught me Lee. In doing all this playing around I am finding bugs and or ways the words work that I like or dis-like.

I changed the COLORS word to increment the second colour set so you can state a range (from...too) of colour sets.

I am working on V1.99 as we speak so I will put it up there by end of day. So your change is correct.

Amazing. You must be the only user. :-)

B

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I put Version 1.99 up for you Lee.

Can't promise that it is bug-for-bug compatible, but I found a lot of little things that saved space.

Now I realize that the CAMEL Forth header takes 1 extra byte versus Fig-Forth so that is eating 300+ bytes alone.

More work on the cross-compiler will get me V2.0 with smaller headers and hopefully multiple binary file output for >8K programs.

See CAMEL Forth thread for a log of changes.

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...

Amazing. You must be the only user. :-)

B

Actually, I did not realize anything was wrong until I played your MP4 video. When I downloaded and ran the code, I had a “meh” moment because nothing looked different. That is when I played the video for comparison, showing the third spot, which was missing from the running code.

...lee

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It's been a while since I've done one of these

```100 call clear::call screen(15)::call color(5,2,15,6,16,15,7,2,4,8,16,4)
110 a\$="07030101010101010101010101010307E0C0808080808080808080808080C0E0"
120 b\$="FF80000000000000FF0100000000000000000000000080C00000000000000103"
130 call char(64,a\$,72,a\$,80,b\$,88,b\$)::for i=0 to 20 step 4
140 display at(i+1,1):seg\$(rpt\$("HXYB@XYJ",4),1,28);
150 display at(i+2,1):seg\$(rpt\$("IRSCARSK",4),1,28);
160 display at(i+3,1):seg\$(rpt\$("@PQJHPQB",4),1,28);
170 display at(i+4,1):seg\$(rpt\$("AZ[KIZ[C",4),1,28);
180 next i::for i=0 to 9^9::next i
run```

Edited by PeteE
changed to use display at
• 10

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Peripheral Drift

This one requires bitmap mode, so you'll need to use TI-BASIC with MiniMem cartridge, or RXB (or any with PEEKV and POKEV really)

```100 rem set reg 0 bitmap mode >02
101 call peekv(-32766,a)

110 rem set reg 3 color  table >9f  hybrid
111 call peekv(-31841,a)
120 rem set reg 4 pattern table >00  hybrid
121 call peekv(-31744,a)
130 rem background color tan
131 call peekv(-30966,a)

150 rem load character patterns and colors
151 for i=112 to 135
153 call char(i,a\$)
154 next i

160 rem copy data from pattern table >6C0..>738 to color table >2680..>26f8
161 for i=1728 to 1848 step 8
162 call peekv(i,a,b,c,d,e,f,g,h)
163 call pokev(i+8128,a,b,c,d,e,f,g,h)
164 next i

170 rem copy 2nd half of duplicate patterns
171 restore 210
172 for i=120 to 127
174 call char(i,a\$)
175 next i

180 rem screen image table is >0000
181 restore 240
183 k=32
184 for i=0 to 23*32 step 96
185 call pokev(i,a,a+1,k,b,b+1,k,c,c+1,k,d,d+1,k,e,e+1,k,f,f+1,k,g,g+1,k,h,h+1,k,a,a+1,k,b,b+1,k,c,c+1)
186 call pokev(i+32,a+4,a+5,k,b+4,b+5,k,c+4,c+5,k,d+4,d+5,k,e+4,e+5,k,f+4,f+5,k,g+4,g+5,k,h+4,h+5,k,a+4,a+5,k)
187 call pokev(i+59,b+4,b+5,k,c+4,c+5,k,k,k,k,k,k,k,k,k,k,k,k,k,k,k,k,k,k,k,k,k,k,k,k,k,k,k,k,k,k,k,k)
188 j=h
189 h=g
190 g=f
191 f=e
192 e=d
193 d=c
194 c=b
195 b=a
196 a=j
197 next i

200 goto 200

210 rem char patterns
211 data "FFFFC0C0C0C0C0C0","FEFC030303030303","7F3FC0C0C0C0C0C0","FFFF030303030303"
212 data "C0C0C0C0C0C08000","030303030303FFFF","C0C0C0C0C0C0FFFF","0303030303030100"

220 rem char colors
221 data "F0F0F4F4F4F4F4F4","F1F1141414141414","F1F1141414141414","F0F0F4F4F4F4F4F4"
222 data "F4F4F4F4F4F4F111","1414141414141010","1414141414141010","F4F4F4F4F4F4F1F1"
223 data "1010141414141414","1F1FF4F4F4F4F4F4","1F1FF4F4F4F4F4F4","1010141414141414"
224 data "1414141414141FFF","F4F4F4F4F4F4F0F0","F4F4F4F4F4F4F0F0","1414141414141F1F"

240 rem screen image patterns
241 data 208,210,210,216,216,218,218,208```

After breaking out the program, the bitmap mode will garble the screen, so blindly paste this to restore graphics mode

`call peekv(-32768,a)`

Edited by PeteE
• 8
• 1
• 1

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Wow!

The whole room feels very unstable...

My eyelids are getting very heavy...

Uhoh, I must leave you now...😵😵😵

P.S. Unreal!!!

• 1
• 4

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Primrose's Field

```100 call clear::call screen(15)::call color(5,14,13,6,16,4,7,14,4,8,16,13)
110 a\$="0000000103030D1F00000080C0C0B0F81F0D030301000000F8B0C0C080000000"
120 b\$="0000000000000000"::call char(64,b\$,65,a\$,72,b\$,73,a\$,81,a\$,89,a\$)
130 a\$=rpt\$("IZARIZARQBYJQBYJ",3)::b\$=rpt\$("[LSD[LSDCTK\CTK\",3)
140 display at(1,1):rpt\$("HH@@",7)::for i=0 to 20 step 4
150 display at(i+2,1):"H";seg\$(a\$,21-i,26);"@";"@";seg\$(b\$,21-i,26);"H"
160 if i<20 then display at(i+4,1):"@";seg\$(a\$,19-i,26);"H";"H";seg\$(b\$,19-i,26);"@"
170 next i::display at(24,1):rpt\$("@@HH",7);::for i=0 to 9^9::next i
run```

Edited by PeteE
changed to use display at

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On 10/26/2017 at 2:55 PM, RickyDean said:

Yes, but I can see them in a line too..

3 or 4 horizontally. 3 easy, 4th pops in and out.  Not vertical.. strange.

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6 hours ago, PeteE said:

Primrose's Field

I have been walked down such a path, before.

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On 11/21/2021 at 10:14 PM, PeteE said:

Primrose's Field

```
100 call clear::call screen(15)::call color(5,14,13,6,16,4,7,14,4,8,16,13)
110 a\$="0000000103030D1F00000080C0C0B0F81F0D030301000000F8B0C0C080000000"
120 b\$="0000000000000000"::call char(64,b\$,65,a\$,72,b\$,73,a\$,80,b\$,81,a\$,88,b\$,89,a\$)
130 a\$=rpt\$("IZARIZARQBYJQBYJ",3)::b\$=rpt\$("[LSD[LSDCTK\CTK\",3)
140 print rpt\$("HH@@",7)::for i=0 to 5
150 print "H";seg\$(a\$,21-i*4,26);"@";"@";seg\$(b\$,21-i*4,26);"H"
160 if i<5 then print "@";seg\$(a\$,19-i*4,26);"H";"H";seg\$(b\$,19-i*4,26);"@"
170 next i::print rpt\$("@@HH",7);::for i=0 to 9^9::next i
run```

Crazy and well done.

And PRINT may take up less space than a DISPLAY AT solution. The latter may execute slightly faster (not having to scroll).

Edited by sometimes99er

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11 hours ago, sometimes99er said:

Crazy and well done.

And PRINT may take up less space than a DISPLAY AT solution. The latter may execute slightly faster (not having to scroll).

Thanks.  I had backlog of Magellan files I wanted to implement in XB.  I will modify them to use "DISPLAY AT".

P.S. I'm happy to see you've edited your previous posts that were damaged by "8)" and ":d" getting removed.  I've also attempted to fix mine.

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