This _should_ only happen when we’re doing a partial PGO build, since
then the script is run in the parent terminal. In this case, the user
is expected to use --rows/--cols anyway.
This _should_ only happen when we’re doing a partial PGO build, since
then the script is run in the parent terminal. In this case, the user
is expected to use --rows/--cols anyway.
Using Python's own PRNG should make the code cleaner and allow for
reproducible stimulus files if that is desired via setting --seed (at
least for the same versions of the script, changing the kind and/or
order of the random calls will of course impact the output in the
future).
I did the following substitutions:
* rand.read(1)[0] % n and struct.unpack('@H', rand.read(2))[0] % n →
random.randrange(n)
* rand.read(1)[0] → random.randrange(256)
* rand.read(n) → [random.randrange(256) for _ in range(n)]
(better alternative would have been random.randbytes(n), but is only
available for Python >= 3.9, switching to this in the future will
impact output)
* list[rand.read(1) % len(list)] → random.choice(list)
We use pre-multiplied alpha color channels, but were having bad
rounding errors due to the alpha divider being truncated to an
integer.
The algorithm for pre-multiplying a color channel is:
alpha_divider = 0xffff / alpha
pre_mult_color = color / alpha_divider
In order to fix the rounding errors, we could turn ‘alpha_divider’
into a double.
That however would introduce a performance penalty since now we’d need
to do floating point math for each cell.
The algorithm can be trivially converted to:
pre_mult_color = color * alpha / 0xffff
Since both color and alpa values are < 65536, the multiplication is
“safe”; it will not overflow an uint32_t.
Closes#249
Dependency chains:
* pgolib -> terminal.c -> terminal.h -> wayland.h
* vtlib -> csi.c -> config.h -> wayland.h
wayland.h includes <primary-selection-unstable-v1.h>, which must be
generated by a custom_target() rule *before* any sources that require
it are built. Failure to fully specify these dependencies can otherwise
result in a race condition, where a dependent source file gets compiled
(and fails with a "header not found" error) before the header itself
has been generated.
Using Python's own PRNG should make the code cleaner and allow for
reproducible stimulus files if that is desired via setting --seed (at
least for the same versions of the script, changing the kind and/or
order of the random calls will of course impact the output in the
future).
I did the following substitutions:
* rand.read(1)[0] % n and struct.unpack('@H', rand.read(2))[0] % n →
random.randrange(n)
* rand.read(1)[0] → random.randrange(256)
* rand.read(n) → [random.randrange(256) for _ in range(n)]
(better alternative would have been random.randbytes(n), but is only
available for Python >= 3.9, switching to this in the future will
impact output)
* list[rand.read(1) % len(list)] → random.choice(list)
We use pre-multiplied alpha color channels, but were having bad
rounding errors due to the alpha divider being truncated to an
integer.
The algorithm for pre-multiplying a color channel is:
alpha_divider = 0xffff / alpha
pre_mult_color = color / alpha_divider
In order to fix the rounding errors, we could turn ‘alpha_divider’
into a double.
That however would introduce a performance penalty since now we’d need
to do floating point math for each cell.
The algorithm can be trivially converted to:
pre_mult_color = color * alpha / 0xffff
Since both color and alpa values are < 65536, the multiplication is
“safe”; it will not overflow an uint32_t.
Closes#249
Dependency chains:
* pgolib -> terminal.c -> terminal.h -> wayland.h
* vtlib -> csi.c -> config.h -> wayland.h
wayland.h includes <primary-selection-unstable-v1.h>, which must be
generated by a custom_target() rule *before* any sources that require
it are built. Failure to fully specify these dependencies can otherwise
result in a race condition, where a dependent source file gets compiled
(and fails with a "header not found" error) before the header itself
has been generated.
