Pick a letter at random.
I wasn't checking that the destination values were not less than zero,
which let you click at the top/left edges of the screen and therefore
the carefree_alpha_blend_blit() would try to write to areas outside the
framebuffer. I started to see "zalgol" pixels in the letters, so I'm
guessing the pixel data is getting stored just above the framebuffer,
which makes sense (because that's the order they appear in the source
code and this is a simple system!) When you click at the top of the
screen it was writing pixels in the font data, eh? Then when you click
elsewhere on the screen you get extra pixels with your letterforms and
it looks like Unicode Lovecraft puns.
ooo that's a finicky parser tho
Early days. It's all good.
(But damn those Rust tracebacks, what a useless pile of text. i know
the problem is in the parser!? why is it showing me all the rust
internal crap and none of the actual stack trace of the ncc code? I
mean, look at this thing:
sforman@bock:~/src/Joypy/implementations/uvm-ncc % setenv RUST_BACKTRACE full
sforman@bock:~/src/Joypy/implementations/uvm-ncc % gmake
cd /home/sforman/src/uvm/ncc ; cargo run /home/sforman/src/Joypy/implementations/uvm-ncc/xerblin.c
Finished dev [unoptimized + debuginfo] target(s) in 0.01s
Running `target/debug/ncc /home/sforman/src/Joypy/implementations/uvm-ncc/xerblin.c`
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: ParseError { msg: "expected identifier", line_no: 139, col_no: 20 }', src/main.rs:98:43
stack backtrace:
0: 0x10d741f - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h919bef3d5abebde9
1: 0x10ee08e - core::fmt::write::h6413343c5226105f
2: 0x10bce85 - std::io::Write::write_fmt::had0ddcb25461208f
3: 0x10d71d5 - std::sys_common::backtrace::print::h5ed9962f90e9b258
4: 0x10c6eff - std::panicking::default_hook::{{closure}}::h3978a8a8f5c1f893
5: 0x10c6b91 - std::panicking::default_hook::h0cdbdd5201407347
6: 0x10c75bb - std::panicking::rust_panic_with_hook::h15bc8b6da20c2af3
7: 0x10d7777 - std::panicking::begin_panic_handler::{{closure}}::h082a693f9436206b
8: 0x10d756c - std::sys_common::backtrace::__rust_end_short_backtrace::h56343aa2331ff455
9: 0x10c7142 - rust_begin_unwind
10: 0x10ed3d3 - core::panicking::panic_fmt::hf18d1d226927e137
11: 0x10efa93 - core::result::unwrap_failed::ha5725a0b4539229c
12: 0x105b505 - core::result::Result<T,E>::unwrap::h0f336a18a308049e
at /wrkdirs/usr/ports/lang/rust/work/rustc-1.66.0-src/library/core/src/result.rs:1113:23
13: 0x1068314 - ncc::main::h189929cbc5450262
at /usr/home/sforman/src/uvm/ncc/src/main.rs:98:20
14: 0x10611cb - core::ops::function::FnOnce::call_once::h8146a3c8fa28ca14
at /wrkdirs/usr/ports/lang/rust/work/rustc-1.66.0-src/library/core/src/ops/function.rs:251:5
15: 0x106e13e - std::sys_common::backtrace::__rust_begin_short_backtrace::h4e9f285841c55b79
at /wrkdirs/usr/ports/lang/rust/work/rustc-1.66.0-src/library/std/src/sys_common/backtrace.rs:121:18
16: 0x1069fa1 - std::rt::lang_start::{{closure}}::h8ca60a785648e691
at /wrkdirs/usr/ports/lang/rust/work/rustc-1.66.0-src/library/std/src/rt.rs:166:18
17: 0x10c1514 - std::rt::lang_start_internal::hadf3843363799440
18: 0x1069f7a - std::rt::lang_start::h3ee6ffb894d9f1d3
at /wrkdirs/usr/ports/lang/rust/work/rustc-1.66.0-src/library/std/src/rt.rs:165:17
19: 0x10684ee - main
20: 0x104f472 - _start
at /usr/src/lib/csu/amd64/crt1.c:76:7
gmake: *** [GNUmakefile:11: /home/sforman/src/uvm/ncc/out.asm] Error 101
There's ONE LINE from the ncc source: uvm/ncc/src/main.rs:98:20 which is a call
to parse_unit, but it's the following unwrap that seems to be causing the error
message?
This is a compromise between updating the screen every frame (which
takes ~60% CPU on my old no-GPU hardware) and repairing damage from e.g.
dragging offscreen and back on, or covering and uncovering the window
with another window.
Simon Forman