world_to_ndc returns inf that triggers panic in bevy_ui layout

[tbillington]

Bevy version

0.15.2 (0.15.3 does not have commits related to this)

What you did

I'm creating worldspace UI using Camera::world_to_ndc to translate worldspace positions to screen space to position bevy_ui elements.

What went wrong

The below call to world_to_ndc outputs a Vec3::INFINITY.

Camera is the default Camera3d required component.

let cam_pos = GlobalTransform::from(Transform::default());
let target_pos = Vec3::new(5.0, 0.5, 0.0);
let ndc_pos = camera.world_to_ndc(&cam_pos, target_pos).unwrap();

println!("ndc_pos {ndc_pos}"); // ndc_pos [inf, inf, inf]

The inf ended up being used to position a Node, resulting in node.left = Val::Px(inf);.

This ended up triggering a panic in bevy_ui::layout because the layout code is not robust against this invalid value.

Additional information

Shifting the translation to be non-zero avoids the infinite values from world_to_ndc.

let cam_pos = GlobalTransform::from(Transform::from_xyz(-2.5, 4.5, 9.0));
let target_pos = Vec3::new(5.0, 0.5, 0.0);
let ndc_pos = camera.world_to_ndc(&cam_pos, target_pos).unwrap();

println!("ndc_pos {ndc_pos}"); // ndc_pos [1.1316626, -1.0729837, 0.011111111]

This seems to be 2 issues

1. world_to_ndc gives infinite values instead of returning None or some other result type or valid values
2. bevy_ui::layout panics on invalid position values, which can easily happen when multiplying floats around. I would feel much better if this was an error log

I initially thought this was related to #16765 but the UI node has no parent/hierarchy, focuses on the panic on inf, and doesn't mention world_to_ndc.

Backtraces from the panic:

RUST_BACKTRACE=1

thread 'Compute Task Pool (2)' panicked at /Users/choc/.rustup/toolchains/stable-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src/num/f32.rs:1406:9:
min > max, or either was NaN. min = 0.0, max = NaN
stack backtrace:
   0: _rust_begin_unwind
   1: core::panicking::panic_fmt
   2: bevy_ui::ui_node::BorderRadius::resolve_single_corner
   3: bevy_ui::layout::ui_layout_system::update_uinode_geometry_recursive
   4: bevy_ui::layout::ui_layout_system
   5: <bevy_ecs::system::function_system::FunctionSystem<Marker,F> as bevy_ecs::system::system::System>::run_unsafe

RUST_BACKTRACE=full

thread 'Compute Task Pool (1)' panicked at /Users/choc/.rustup/toolchains/stable-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src/num/f32.rs:1406:9:
min > max, or either was NaN. min = 0.0, max = NaN
stack backtrace:
   0:        0x103b692e4 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h7adefaad4a31afc0
   1:        0x103bad2a4 - core::fmt::write::h381c0b0ce6ab972a
   2:        0x103b5e610 - std::io::Write::write_fmt::h75af97148630d8d3
   3:        0x103b69198 - std::sys::backtrace::BacktraceLock::print::h8baf33e22611de71
   4:        0x103b6b504 - std::panicking::default_hook::{{closure}}::h369c7295ef58c5b1
   5:        0x103b6b348 - std::panicking::default_hook::h50746358288a9d6a
   6:        0x103b6bd50 - std::panicking::rust_panic_with_hook::h7d795911432661cb
   7:        0x103b6ba04 - std::panicking::begin_panic_handler::{{closure}}::h36f15310ecbde379
   8:        0x103b697a8 - std::sys::backtrace::__rust_end_short_backtrace::heed121414170e0c7
   9:        0x103b6b6bc - _rust_begin_unwind
  10:        0x103bcb658 - core::panicking::panic_fmt::h17b1b80ec02ffd19
  11:        0x10a35078c - bevy_ui::ui_node::BorderRadius::resolve_single_corner::h96e0353d5156373e
  12:        0x10a499244 - bevy_ui::layout::ui_layout_system::update_uinode_geometry_recursive::h9f6a40c905df7d90
  13:        0x10a49846c - bevy_ui::layout::ui_layout_system::h6edb8fb65ab422e7
  14:        0x10a4785dc - <bevy_ecs::system::function_system::FunctionSystem<Marker,F> as bevy_ecs::system::system::System>::run_unsafe::heafee9ceac417da3
  15:        0x10ccb8404 - bevy_ecs::schedule::executor::__rust_begin_short_backtrace::run_unsafe::haeaadbcd5fa25db3
  16:        0x10ccc6410 - <futures_lite::future::CatchUnwind<F> as core::future::future::Future>::poll::hd78e37e2bf3891b3
  17:        0x10cc8638c - async_executor::Executor::spawn_inner::{{closure}}::h3cba66f2fed0b69c
  18:        0x10cc84af0 - async_task::raw::RawTask<F,T,S,M>::run::hee81aae3c0549a93
  19:        0x10cccb74c - futures_lite::future::block_on::h43baf863f956827a
  20:        0x10ccd15b8 - std::sys::backtrace::__rust_begin_short_backtrace::h8c788a5f9414b8a6
  21:        0x10ccd09f0 - core::ops::function::FnOnce::call_once{{vtable.shim}}::ha7e3aec6aa0855b8
  22:        0x103b73eb0 - std::sys::pal::unix::thread::Thread::new::thread_start::h44ebc83f14222f58
  23:        0x18f0682e4 - __pthread_deallocate

[alice-i-cecile]

world_to_ndc gives infinite values instead of returning None or some other result type or valid values

IIRC I've pushed for this before: there are likely old PRs floating around to fix this that could be adopted.