From 0502d2f82d93ec7ec324ceac2010c94a0a45daa1 Mon Sep 17 00:00:00 2001 From: Marco Arnulfo Date: Fri, 16 Oct 2026 16:06:15 +0200 Subject: [PATCH] Auto-orient: keep the last heading when an expression-driven Position stops (fixes #1650) --- crates/render/src/three_d/camera.rs | 47 +++++++++++++++++ crates/render/src/three_d/tests_orient.rs | 64 +++++++++++++++++++++++ 2 files changed, 111 insertions(+) diff --git a/crates/render/src/three_d/camera.rs b/crates/render/src/three_d/camera.rs index 5e1f983b2..553365e00 100644 --- a/crates/render/src/three_d/camera.rs +++ b/crates/render/src/three_d/camera.rs @@ -241,6 +241,53 @@ fn path_tangent(ctx: &EvalCtx, layer: &Layer) -> Option { .filter(|k| **k <= ctx.time) .find_map(|&k| dir(pos(k) - pos(k - dt))) .or_else(|| keys.iter().filter(|k| **k > ctx.time).find_map(|&k| dir(pos(k + dt) - pos(k)))) + .or_else(|| { + // An expression has no keys to fall back on: sample it instead. + let expr = dims.iter().any(|m| tr.get(m).is_some_and(|p| p.has_expression())); + expr.then(|| sampled_tangent(ctx, layer, &pos, dt, true).or_else(|| sampled_tangent(ctx, layer, &pos, dt, false))).flatten() + }) +} + +/// Samples spent on each phase of [`sampled_tangent`]: it runs per layer per frame. +const MOTION_SEARCH_STEPS: u32 = 12; + +/// Direction of the motion nearest to the context time, before it (`earlier`) or after it, for a +/// position with no keyframes to fall back on (an expression). Steps 1, 2, 4, ... frames away +/// (within the layer's in/out points) until the position differs from the current one, then +/// bisects down to `dt` the moment the motion stopped (or started), so the heading kept is the +/// one at the end of the motion whichever frame is shown. +fn sampled_tangent(ctx: &EvalCtx, layer: &Layer, pos: &dyn Fn(effectcraft_time::Tick) -> Vec3, dt: effectcraft_time::Tick, earlier: bool) -> Option { + let here = pos(ctx.time); + let moved = |t| (pos(t) - here).length() > 1e-9; + let limit = if earlier { layer.in_point.min(ctx.time) } else { layer.out_point.max(ctx.time) }; + let mut step = ctx.comp.frame_duration().max(dt); + let (mut still, mut away) = (ctx.time, None); + for _ in 0..MOTION_SEARCH_STEPS { + let t = if earlier { (ctx.time - step).max(limit) } else { (ctx.time + step).min(limit) }; + if moved(t) { + away = Some(t); + break; + } + still = t; + if t == limit { + break; + } + step = step + step; + } + let mut away = away?; + for _ in 0..MOTION_SEARCH_STEPS { + if (still - away).abs() <= dt { + break; + } + let mid = away + (still - away).mul_ratio(1, 2); + if moved(mid) { + away = mid; + } else { + still = mid; + } + } + let d = if earlier { here - pos(away) } else { pos(away) - here }; + (d.length() > 1e-9 && d.length().is_finite()).then(|| d.normalize()) } /// Auto-Orient ▸ Orient Along Path for 2D layers: extra Z rotation in degrees. diff --git a/crates/render/src/three_d/tests_orient.rs b/crates/render/src/three_d/tests_orient.rs index 06f2599dc..f9c72e296 100644 --- a/crates/render/src/three_d/tests_orient.rs +++ b/crates/render/src/three_d/tests_orient.rs @@ -8,6 +8,7 @@ use effectcraft_project::{AutoOrient, Comp, ItemId, ItemKind, Layer, LayerSource use effectcraft_time::{FrameRate, Tick}; use super::active_camera; +use super::camera::auto_orient_2d; use crate::EvalCtx; fn setup() -> (Project, ItemId, Comp) { @@ -78,6 +79,69 @@ fn orient_along_path_keeps_the_last_heading_at_and_after_the_end() { } } +/// #1650: the same end-of-path flip when Position has no keyframes of its own and is driven by +/// an expression (e.g. `pointOnPath()` fed by a keyframed slider on another layer): once the +/// motion stops there are no Position keys to fall back on, and the heading snapped to 0 degrees. +#[test] +fn orient_along_path_keeps_the_last_heading_when_position_is_an_expression() { + /// Stand-in for an expression: holds, moves 100 px left over 0.5..1 s, then holds again (like + /// a slider going from 0% to 100%). + struct LeftThenHold; + impl crate::ExprHost for LeftThenHold { + fn eval(&self, ctx: &EvalCtx, _: &Layer, prop: &effectcraft_project::Property, value: &Value) -> Result { + if prop.match_id != "position" { + return Ok(value.clone()); + } + let s = ((ctx.time.seconds() - 0.5) * 2.0).clamp(0.0, 1.0); + Ok(Value::Vec3([150.0 - 100.0 * s, 50.0, 0.0])) + } + } + for three_d in [false, true] { + let (mut p, cid, comp) = setup(); + let mut l = solid(&mut p, &comp, three_d, [150.0, 50.0, 0.0]); + l.auto_orient = AutoOrient::AlongPath; + let pos = l.props.prop_mut("transform/position").unwrap(); + assert!(pos.keys.is_empty(), "the fixture must have no Position keyframes"); + pos.expr = Some(effectcraft_project::Expression { text: "left then hold".into(), enabled: true }); + p.comp_mut(cid).unwrap().layers.push(l); + let c = p.comp(cid).unwrap(); + for secs in [0.2, 0.75, 1.0, 1.0 + 1.0 / 30.0, 1.2, 1.9] { + let ctx = EvalCtx { expr: Some(&LeftThenHold), ..EvalCtx::new(&p, cid, c, Tick::from_seconds_f64(secs)) }; + let x_axis = ctx.world_matrix(&c.layers[0]).apply_vec(vec3(1.0, 0.0, 0.0)); + // Moving left (-x): the layer's x axis points left before the motion starts and after it stops. + assert!((x_axis.x + 1.0).abs() < 1e-6 && x_axis.y.abs() < 1e-6 && x_axis.z.abs() < 1e-6, "3d={three_d} t={secs}: {x_axis:?}"); + } + } +} + +/// #1650 on a curved path: the heading kept once an expression stops moving is the one at the end +/// of the motion, the same on every later frame, not whatever earlier point a coarse search lands on. +#[test] +fn orient_along_a_curved_expression_path_keeps_the_end_heading() { + /// Quarter circle over 0..1 s: heading 0 degrees at the start, 90 degrees (down) at the end. + struct Arc; + impl crate::ExprHost for Arc { + fn eval(&self, ctx: &EvalCtx, _: &Layer, prop: &effectcraft_project::Property, value: &Value) -> Result { + if prop.match_id != "position" { + return Ok(value.clone()); + } + let a = ctx.time.seconds().clamp(0.0, 1.0) * std::f64::consts::FRAC_PI_2; + Ok(Value::Vec3([100.0 * a.sin(), 100.0 - 100.0 * a.cos(), 0.0])) + } + } + let (mut p, cid, comp) = setup(); + let mut l = solid(&mut p, &comp, false, [0.0, 0.0, 0.0]); + l.auto_orient = AutoOrient::AlongPath; + l.props.prop_mut("transform/position").unwrap().expr = Some(effectcraft_project::Expression { text: "arc".into(), enabled: true }); + p.comp_mut(cid).unwrap().layers.push(l); + let c = p.comp(cid).unwrap(); + for frame in [31, 33, 37, 45, 59] { + let ctx = EvalCtx { expr: Some(&Arc), ..EvalCtx::new(&p, cid, c, Tick::from_seconds_f64(frame as f64 / 30.0)) }; + let deg = auto_orient_2d(&ctx, &c.layers[0]); + assert!((deg - 90.0).abs() < 0.5, "frame {frame}: {deg}"); + } +} + #[test] fn layers_parented_to_a_camera_follow_its_rotation() { let (mut p, cid, comp) = setup();