Am 03.06.2022 um 17:30 schrieb Paul B Mahol:
On Fri, Jun 3, 2022 at 5:05 PM Michael Koch <astroelectro...@t-online.de>
wrote:
Hello,
I'd like to ask if the number of variables in expressions could be
increased from 10 to 25 please. I mean the st() and ld() functions. I'm
just programming a realtime wormhole simulation and the limitation to 10
variables is becoming nasty. I did already begin to re-use the same
variables for different things, but that makes debugging complicated. It
would be so much easier to have more variables and use each one only for
one thing.
What you see below is only a small part of the code.
Why you doing that way, this is the most inefficient way to do it.
How would you do it instead? Sure, it's possible to generate the mapping
files with C or C# code.
Pro C code:
+ No limit for the number of variables.
+ The code can be commented in the same line.
+ It's very helpful to get error messages for division by zero,
sqrt(-1), asin(2), log(0), log(-1).
Pro FFmpeg code in batch file:
+ A whole project can be written in one batch file and executed with
just one double-click. No compiler required.
+ The mapping files are automatically generated in the correct working
folder, no problems with files in wrong folder.
In the meantime I got the code for a realtime wormhole (with fisheye
projection in a planetarium) running with just 10 variables (see below).
I had to re-use some of the variables, which is error-prone. I also had
to use many if/ifnot functions to avoid overwriting of variables. With
12 variables the code would have been simpler.
I have some ideas for even more complex transformations, but with the
limitation to just 10 variables they are impossible to implement.
Michael
ffmpeg -f lavfi -i nullsrc=size=%OUT_W%x%OUT_H% -vf
format=pix_fmts=gray16le,geq='^
st(0,%OUT_H_FOV%/180*((2*X+1)/%OUT_W%-1));^
st(1,%OUT_V_FOV%/180*((2*Y+1)/%OUT_H%-1));^
st(2,atan2(ld(1),ld(0)));^
st(3,PI/2*hypot(ld(0),ld(1)));^
st(4,sin(ld(3))*cos(ld(2)));^
st(5,sin(ld(3))*sin(ld(2)));^
st(6,cos(ld(3)));^
st(1,if(lt(ld(6),cos(%OUT_H_FOV%/360*PI)),32767,0));^
st(0,ld(5)*cos(%PITCH2%/180*PI)-ld(6)*sin(%PITCH2%/180*PI));^
st(6,ld(6)*cos(%PITCH2%/180*PI)+ld(5)*sin(%PITCH2%/180*PI));^
st(5,ld(0));^
st(7,atan2(ld(5),ld(4)));^
st(8,acos(ld(6)));^
st(9,if(lte(ld(8),%RS%/180*PI),1));^
if(ld(9),st(7,ld(8)*cos(ld(7))));^
ifnot(ld(9),st(8,ld(8)-%S%*(2*%RS%/180*PI/(ld(8)-%RS%/180*PI))));^
ifnot(ld(9),st(4,sin(ld(8))*cos(ld(7))));^
ifnot(ld(9),st(5,sin(ld(8))*sin(ld(7))));^
ifnot(ld(9),st(6,cos(ld(8))));^
ifnot(ld(9),st(0,ld(5)*cos(%PITCH1%/180*PI)-ld(6)*sin(%PITCH1%/180*PI)));^
ifnot(ld(9),st(6,ld(6)*cos(%PITCH1%/180*PI)+ld(5)*sin(%PITCH1%/180*PI)));^
ifnot(ld(9),st(5,ld(0)));^
ifnot(ld(9),st(7,atan2(ld(5),ld(4))));^
ifnot(ld(9),st(8,acos(ld(6))));^
ifnot(ld(9),st(7,atan2(sin(ld(8))*cos(ld(7)),cos(ld(8)))));^
if(ld(9),0.5*%IN_W2%*(1+180/PI/%RS%*ld(7)),ld(1)+0.5*%IN_W%*(1+ld(7)/PI))'
-frames 1 -y xmap.pgm
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