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Lock segment molding to an axis with Shift #4325

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Lock segment molding to an axis with Shift #4325

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59fe147
Add Shift to lock segment molding to horizontal/vertical
Chetansahney Jul 10, 2026
0199339
Draw axis guides while molding and lock relative to the grab point
Chetansahney Jul 18, 2026
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27 changes: 26 additions & 1 deletion editor/src/messages/tool/tool_messages/path_tool.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2125,16 +2125,37 @@ impl Fsm for PathToolFsmState {
}

let break_molding = input.keyboard.get(break_colinear_molding as usize);
let lock_direction = input.keyboard.get(snap_angle as usize);

// Logic for molding segment
if let Some(segment) = &mut tool_data.segment
&& let Some(molding_segment_handles) = tool_data.molding_info
{
// While the lock direction modifier is held, constrain the drag to whichever screen axis it has travelled
// further along. The axis is stored in `snapping_axis` so the drag overlay draws the same X/Y guide lines
// through the grab point as it does when dragging points.
let mouse_position = match lock_direction {
true => {
let delta = input.mouse.position - tool_data.drag_start_pos;

@cubic-dev-ai cubic-dev-ai Bot Jul 18, 2026

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P2: Shift molding does not fully constrain the segment when click position differs from the curve's closest point: mold_handle_positions subtracts the Bezier grab point, but this projection uses cursor-down position. Project around segment.closest_point_to_viewport() (and use that same origin for the guide) so the constrained delta's perpendicular component is zero.

Prompt for AI agents 
Check if this issue is valid — if so, understand the root cause and fix it. At editor/src/messages/tool/tool_messages/path_tool.rs, line 2139:

<comment>Shift molding does not fully constrain the segment when click position differs from the curve's closest point: `mold_handle_positions` subtracts the Bezier grab point, but this projection uses cursor-down position. Project around `segment.closest_point_to_viewport()` (and use that same origin for the guide) so the constrained delta's perpendicular component is zero.</comment>

<file context>
@@ -2131,13 +2131,32 @@ impl Fsm for PathToolFsmState {
+					// through the grab point as it does when dragging points.
+					let mouse_position = match lock_direction {
+						true => {
+							let delta = input.mouse.position - tool_data.drag_start_pos;
+							let axis = if delta.x.abs() >= delta.y.abs() { Axis::X } else { Axis::Y };
+							tool_data.snapping_axis = Some(axis);
</file context>

let axis = if delta.x.abs() >= delta.y.abs() { Axis::X } else { Axis::Y };
tool_data.snapping_axis = Some(axis);

match axis {
Axis::Y => DVec2::new(tool_data.drag_start_pos.x, input.mouse.position.y),
Axis::X | Axis::Both => DVec2::new(input.mouse.position.x, tool_data.drag_start_pos.y),
}
}
false => {
tool_data.snapping_axis = None;
input.mouse.position
}
};

tool_data.temporary_adjacent_handles_while_molding = segment.mold_handle_positions(
document,
responses,
molding_segment_handles,
input.mouse.position,
mouse_position,
break_molding,
tool_data.temporary_adjacent_handles_while_molding,
);
Expand Down Expand Up @@ -2389,6 +2410,7 @@ impl Fsm for PathToolFsmState {
tool_data.molding_segment = false;
tool_data.temporary_adjacent_handles_while_molding = None;
tool_data.angle_locked = false;
tool_data.snapping_axis = None;
responses.add(DocumentMessage::AbortTransaction);
tool_data.snap_manager.cleanup(responses);
PathToolFsmState::Ready
Expand Down Expand Up @@ -2511,6 +2533,7 @@ impl Fsm for PathToolFsmState {
tool_data.molding_info = None;
tool_data.molding_segment = false;
tool_data.temporary_adjacent_handles_while_molding = None;
tool_data.snapping_axis = None;

if segment_dissolved || point_inserted {
responses.add(DocumentMessage::EndTransaction);
Expand Down Expand Up @@ -3639,6 +3662,8 @@ fn update_dynamic_hints(

let mut molding_hints = vec![HintGroup(vec![HintInfo::mouse(MouseMotion::Rmb, ""), HintInfo::keys([Key::Escape], "Cancel").prepend_slash()])];

molding_hints.push(HintGroup(vec![HintInfo::keys([Key::Shift], "Lock Direction")]));

if molding_disable_possible {
molding_hints.push(HintGroup(vec![HintInfo::keys([Key::Alt], "Break Colinear Handles")]));
}
Expand Down