//! Coordinate conversion helpers for viewport interactions.
//!
//! Conventions:
//! - egui screen space: +Y is down.
//! - Viewport space: +Y is up, origin at viewport center.
//!
//! Use these helpers to keep Y inversion consistent across viewport input.
use egui;
/// Flip Y for a 2D vector.
/// Convert screen-space pos to centered viewport space (+Y up).
/// Convert screen-space delta to viewport delta (+Y up).