fix: Spline snap points and TextStyle backward/upside-down rendering

Spline entities now expose fit_points (or control_points when no fit
points are defined) as key_vertices, enabling Endpoint and Midpoint
snap to reach spline construction points.

TextStyle is_backward flag is applied by negating the width_factor,
producing horizontally mirrored text. is_upside_down rotates the text
180°. Both tessellate_text_ex and text_local_bounds now handle negative
width_factor without clamping it to zero.

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

src/entities/spline.rs

@@ -37,11 +37,24 @@ fn to_truck(spl: &Spline) -> TruckEntity {
     let v_start = builder::vertex(p_start);
     let v_end = builder::vertex(p_end);
     let edge = Edge::new(&v_start, &v_end, Curve::BSplineCurve(bspline));
+
+    // Expose fit_points (preferred) or control_points as key_vertices so that
+    // Endpoint/Midpoint snap can reach spline construction points.
+    let snap_source = if !spl.fit_points.is_empty() {
+        &spl.fit_points
+    } else {
+        &spl.control_points
+    };
+    let key_vertices: Vec<[f32; 3]> = snap_source
+        .iter()
+        .map(|p| [p.x as f32, p.y as f32, p.z as f32])
+        .collect();
+
     TruckEntity {
         object: TruckObject::Curve(edge),
         snap_pts: vec![],
         tangent_geoms: vec![],
-        key_vertices: vec![],
+        key_vertices,
     }
 }
 

src/entities/text.rs

@@ -54,12 +54,17 @@ fn to_truck(t: &Text, document: &acadrust::CadDocument) -> TruckEntity {
     );
     let resolved_style = resolve_text_style(&t.style, document);
     let font_name = resolved_style.font_name;
-    let width_factor = (if t.width_factor > 0.0 {
-        t.width_factor as f32
-    } else {
-        1.0
-    } * resolved_style.width_factor.max(0.01))
+    let base_wf = (if t.width_factor > 0.0 { t.width_factor as f32 } else { 1.0 }
+        * resolved_style.width_factor.max(0.01))
     .clamp(0.01, 100.0);
+    // is_backward mirrors text left-right via negative width factor.
+    let width_factor = if resolved_style.is_backward { -base_wf } else { base_wf };
+    // is_upside_down rotates 180° around the insertion point.
+    let rotation = if resolved_style.is_upside_down {
+        t.rotation as f32 + std::f32::consts::PI
+    } else {
+        t.rotation as f32
+    };
     let oblique_angle = t.oblique_angle as f32 + resolved_style.oblique_angle;
     let anchor = match (
         &t.horizontal_alignment,
@@ -96,7 +101,7 @@ fn to_truck(t: &Text, document: &acadrust::CadDocument) -> TruckEntity {
     } else {
         (0.0, 0.0)
     };
-    let (cos_r, sin_r) = ((t.rotation as f32).cos(), (t.rotation as f32).sin());
+    let (cos_r, sin_r) = (rotation.cos(), rotation.sin());
     let origin = [
         anchor[0] - (anchor_local_x * cos_r - anchor_local_y * sin_r),
         anchor[1] - (anchor_local_x * sin_r + anchor_local_y * cos_r),
@@ -105,7 +110,7 @@ fn to_truck(t: &Text, document: &acadrust::CadDocument) -> TruckEntity {
     let strokes_2d = cxf::tessellate_text_ex(
         origin,
         t.height as f32,
-        t.rotation as f32,
+        rotation,
         width_factor,
         oblique_angle,
         &font_name,

src/entities/text_support.rs

@@ -6,6 +6,8 @@ pub struct ResolvedTextStyle {
     pub font_name: String,
     pub width_factor: f32,
     pub oblique_angle: f32,
+    pub is_backward: bool,
+    pub is_upside_down: bool,
 }
 
 pub fn resolve_text_style(style_name: &str, document: &CadDocument) -> ResolvedTextStyle {
@@ -45,6 +47,8 @@ pub fn resolve_text_style(style_name: &str, document: &CadDocument) -> ResolvedT
         font_name,
         width_factor: style.map(|s| s.width_factor as f32).unwrap_or(1.0),
         oblique_angle: style.map(|s| s.oblique_angle as f32).unwrap_or(0.0),
+        is_backward: style.map(|s| s.is_backward()).unwrap_or(false),
+        is_upside_down: style.map(|s| s.is_upside_down()).unwrap_or(false),
     }
 }
 
@@ -61,7 +65,7 @@ pub fn text_local_bounds(
 
     let font = cxf::get_font(font_name);
     let scale = height / 9.0;
-    let wf = width_factor.clamp(0.01, 100.0);
+    let wf = width_factor.abs().clamp(0.01, 100.0);
     let ob = oblique_angle.tan();
     let mut cursor_x = 0.0_f32;
     let mut min_x = f32::INFINITY;

src/scene/cxf.rs

@@ -215,7 +215,12 @@ pub fn tessellate_text_ex(
 
     let font = get_font(font_name);
     let scale = height / 9.0;
-    let wf = width_factor.clamp(0.01, 100.0);
+    // Negative width_factor produces mirrored (backward) text.
+    let wf = if width_factor < 0.0 {
+        width_factor.clamp(-100.0, -0.01)
+    } else {
+        width_factor.clamp(0.01, 100.0)
+    };
     let ob = oblique_angle.tan();
     let (cos_r, sin_r) = (rotation.cos(), rotation.sin());