Sprint 25/26 — 단면 분기 수정 + 다경간 + 피어 배치

Sprint 25: build_selectable_scene 의 SectionType::PscI 하드코딩 제거.
- p.section_type 에 따라 PscI / SteelBox 분기 (build_bridge_scene 과 동일 로직).
- 사용자가 단면 형식 전환 시 정상 반영.

Sprint 26: 다경간 + 교각 배치 (ParaWiki 교각 wiki Phase 1 MVP).
- SceneParams: span_count (1~5) + pier_type (SingleColumn/MultiColumn) 추가.
- span_m 의미 변경: 전체 교량 길이 → 경간당 길이. total = span_m × span_count.
- pier_ir_for_params() helper: 기본 사각 기둥·2m CSB·2.5m TB·5m column_height.
- build_bridge_scene / build_selectable_scene:
  · 거더: 경간마다 독립 세트 (span_count × girder_count 개)
  · 데크 슬래브: 전 구간 연속 1개
  · 받침: 모든 지점 (교대 2 + 교각 span_count-1)
  · 교각: 내부 지점 span_count-1 개 (새 기능)
  · 교대: 양 끝 (z=-800, z=total_mm)
  · 가로보: 경간마다 반복
  · 신축이음: 모든 지점 (선택적)
- build_background_scene + scene_extents: total_mm 기준으로 ground·alignment 길이 확장.
- project_file: version=2, span_count·pier_type 필드 추가 (v1 호환 default 값).
- UI ribbon: "경간 수" 슬라이더 + "교각 형식" T/π 선택.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cimery/crates/app/gen/schemas/capabilities.json

@@ -0,0 +1 @@
+{"default":{"identifier":"default","description":"Default cimery app capabilities","local":true,"windows":["main"],"permissions":["core:default","dialog:allow-open","dialog:allow-save","dialog:allow-message"]}}

cimery/crates/viewer/src/bridge_scene.rs

@@ -9,10 +9,13 @@
 //! Positions are in the same coordinate space as the girder mesh:
 //!   X = transverse (right = +), Y = vertical (up = +), Z = along span.
 
-use cimery_core::{AbutmentType, BearingType, CrossBeamSection, ExpansionJointType, MaterialGrade, SectionType};
+use cimery_core::{
+    AbutmentType, BearingType, ColumnShape, CrossBeamSection, ExpansionJointType,
+    MaterialGrade, PierType, SectionType,
+};
 use cimery_ir::{
-    AbutmentIR, BearingIR, CrossBeamIR, DeckSlabIR, ExpansionJointIR, FeatureId, GirderIR,
+    AbutmentIR, BearingIR, CapBeamIR, CrossBeamIR, DeckSlabIR, ExpansionJointIR, FeatureId,
-    PscISectionParams, SectionParams, WingWallIR,
+    GirderIR, PierIR, PscISectionParams, SectionParams, WingWallIR,
 };
 use cimery_kernel::{GeomKernel, KernelError, Mesh};
 
@@ -26,8 +29,13 @@ pub enum GirderSectionType { PscI, SteelBox }
 /// Changing any field and calling `build_bridge_scene` regenerates the mesh.
 #[derive(Debug, Clone)]
 pub struct SceneParams {
-    /// Girder span [m]. Range 20–80 m.
+    /// Length of ONE span [m]. Range 20–80 m. Sprint 26 의미 변경: 경간 = 교각·교대
+    /// 간 한 구간의 길이 (전체 교량 길이 = span_m × span_count).
     pub span_m:         f64,
+    /// 경간 수 (Sprint 26). 1 = 단경간(피어 없음), 2+ = 다경간(내부에 피어 배치).
+    pub span_count:     usize,
+    /// 교각 형식 (Sprint 26). SingleColumn=T형, MultiColumn=π형.
+    pub pier_type:      PierType,
     /// Number of girders (3–6).
     pub girder_count:   usize,
     /// Girder centre-to-centre spacing [mm].
@@ -52,6 +60,8 @@ impl Default for SceneParams {
     fn default() -> Self {
         Self {
             span_m:         40.0,
+            span_count:     1,
+            pier_type:      PierType::SingleColumn,
             girder_count:   5,
             girder_spacing: 2_500.0,
             girder_height:  1_800.0,
@@ -74,6 +84,48 @@ pub const COL_GROUND:        [f32; 3] = [0.35, 0.38, 0.30]; // dark olive ground
 pub const COL_ALIGNMENT:     [f32; 3] = [1.00, 0.60, 0.10]; // orange centreline
 pub const COL_CROSS_BEAM:    [f32; 3] = [0.75, 0.73, 0.65]; // slightly lighter concrete
 pub const COL_EXP_JOINT:     [f32; 3] = [0.20, 0.20, 0.25]; // dark steel
+pub const COL_PIER:          [f32; 3] = [0.68, 0.64, 0.55]; // pier concrete (Sprint 26)
+
+// ─── Pier helper (Sprint 26) ─────────────────────────────────────────────────
+
+/// 교각 IR 생성 — MVP Phase 1 (wiki 파라미터 카탈로그 30% 입력만 반영).
+/// 단면 직사각형 고정, CSB/CSL 은 기본값. 컬럼 수는 pier_type 으로 결정.
+pub fn pier_ir_for_params(
+    station_m:   f64,
+    n_girders:   usize,
+    spacing_mm:  f32,
+    girder_h_mm: f32,
+    pier_type:   PierType,
+) -> PierIR {
+    let n = n_girders as f64;
+    let total_trans = (n - 1.0) * spacing_mm as f64 + 2_000.0;
+    let column_count = match pier_type {
+        PierType::SingleColumn => 1,
+        PierType::MultiColumn  => 2,
+        _                      => 1,
+    };
+    let col_spacing = if column_count > 1 { total_trans / 2.0 } else { 0.0 };
+    PierIR {
+        id:              FeatureId::new(),
+        station:         station_m,
+        skew_angle:      0.0,
+        pier_type,
+        column_shape:    ColumnShape::Rectangular,
+        column_count:    column_count as u32,
+        column_spacing:  col_spacing,
+        column_diameter: 2_000.0,   // wiki CSB 매트릭스 (9-13k × ≤15k 영역)
+        column_depth:    2_000.0,
+        column_height:   girder_h_mm as f64 + 5_000.0,
+        cap_beam: CapBeamIR {
+            length:           total_trans,
+            width:            2_500.0,  // wiki TB ≥ 2500
+            depth:            1_500.0,
+            cantilever_left:  800.0,
+            cantilever_right: 800.0,
+        },
+        material: MaterialGrade::C40,
+    }
+}
 
 // ─── Helpers ─────────────────────────────────────────────────────────────────
 
@@ -93,9 +145,13 @@ fn merge(meshes: Vec<Mesh>) -> Mesh {
 // ─── Scene builder ────────────────────────────────────────────────────────────
 
 /// Build a complete bridge scene mesh using the provided kernel and parameters.
+/// Sprint 26: 다경간 + 피어 배치 지원 (span_count 로 제어).
 pub fn build_bridge_scene<K: GeomKernel>(kernel: &K, p: &SceneParams) -> Result<Mesh, KernelError> {
     let span_m      = p.span_m;
     let span_mm     = (p.span_m * 1_000.0) as f32;
+    let span_count  = p.span_count.max(1).min(5);
+    let total_m     = span_m * span_count as f64;
+    let total_mm    = span_mm * span_count as f32;
     let n_girders   = p.girder_count.max(1).min(10);
     let spacing     = p.girder_spacing;
     let girder_h    = p.girder_height;
@@ -132,32 +188,35 @@ pub fn build_bridge_scene<K: GeomKernel>(kernel: &K, p: &SceneParams) -> Result<
         GirderSectionType::SteelBox => SectionType::SteelBox,
     };
 
-    // ── Girders ────────────────────────────────────────────────────────────────
+    // ── Girders (경간마다 독립 세트) ───────────────────────────────────────────
-    for i in 0..n_girders {
+    for s in 0..span_count {
-        let x = (i as f32 - (n_girders as f32 - 1.0) * 0.5) * spacing;
+        let z_base = span_mm * s as f32;
-        let ir = GirderIR {
+        let s_start = span_m * s as f64;
-            id:                    FeatureId::new(),
+        for i in 0..n_girders {
-            station_start:         0.0,
+            let x = (i as f32 - (n_girders as f32 - 1.0) * 0.5) * spacing;
-            station_end:           span_m,
+            let ir = GirderIR {
-            offset_from_alignment: x as f64,
+                id:                    FeatureId::new(),
-            section_type:          section_type_enum,
+                station_start:         s_start,
-            section:               section_enum.clone(),
+                station_end:           s_start + span_m,
-            count:                 1,
+                offset_from_alignment: x as f64,
-            spacing:               0.0,
+                section_type:          section_type_enum,
-            material:              MaterialGrade::C50,
+                section:               section_enum.clone(),
-        };
+                count:                 1,
-        let mut mesh = kernel.girder_mesh(&ir)?;
+                spacing:               0.0,
-        mesh.recolor(COL_GIRDER);
+                material:              MaterialGrade::C50,
-        parts.push(translate(mesh, x, 0.0, 0.0));
+            };
+            let mut mesh = kernel.girder_mesh(&ir)?;
+            mesh.recolor(COL_GIRDER);
+            parts.push(translate(mesh, x, 0.0, z_base));
+        }
     }
 
-    // ── Deck Slab ──────────────────────────────────────────────────────────────
+    // ── Deck Slab (전 구간 연속) ───────────────────────────────────────────────
-    // KDS: min 220 mm, width = (N-1)*spacing + 2 × cantilever
+    let half_width = ((n_girders as f32 - 1.0) * spacing) * 0.5 + 1_000.0;
-    let half_width = ((n_girders as f32 - 1.0) * spacing) * 0.5 + 1_000.0; // 1 m cantilever
     let deck_ir = DeckSlabIR {
         id:            FeatureId::new(),
         station_start: 0.0,
-        station_end:   span_m,
+        station_end:   total_m,
         width_left:    half_width as f64,
         width_right:   half_width as f64,
         thickness:     p.slab_thickness as f64,
@@ -169,17 +228,16 @@ pub fn build_bridge_scene<K: GeomKernel>(kernel: &K, p: &SceneParams) -> Result<
     deck_mesh.recolor(COL_DECK);
     parts.push(translate(deck_mesh, 0.0, girder_h + p.slab_thickness, 0.0));
 
-    // ── Bearings ───────────────────────────────────────────────────────────────
+    // ── Bearings (모든 지점: 교대 2 + 교각 span_count-1) ──────────────────────
-    // 5 per abutment, one under each girder
-    // plan_length(350mm) = 경간 방향 → half = 175mm 으로 Z 센터링.
     const BEARING_PLAN_LEN: f32 = 350.0;
     const BEARING_PLAN_WID: f32 = 450.0;
-    for &z in &[0.0_f32, span_mm] {
+    let support_zs: Vec<f32> = (0..=span_count).map(|i| span_mm * i as f32).collect();
+    for &z in &support_zs {
         for i in 0..n_girders {
             let x = (i as f32 - (n_girders as f32 - 1.0) * 0.5) * spacing;
             let bearing_ir = BearingIR {
                 id:                FeatureId::new(),
-                station:           if z < 1.0 { 0.0 } else { span_m },
+                station:           z as f64 / 1_000.0,
                 bearing_type:      BearingType::Elastomeric,
                 plan_length:       BEARING_PLAN_LEN as f64,
                 plan_width:        BEARING_PLAN_WID as f64,
@@ -188,17 +246,30 @@ pub fn build_bridge_scene<K: GeomKernel>(kernel: &K, p: &SceneParams) -> Result<
             };
             let mut mesh = kernel.bearing_mesh(&bearing_ir)?;
             mesh.recolor(COL_BEARING);
-            // Z 중심 = 교대 위치(z). bearing mesh Z = [0, plan_length] → 오프셋 = z - plan_length/2.
             parts.push(translate(mesh, x, 0.0, z - BEARING_PLAN_LEN * 0.5));
         }
     }
 
-    // ── Abutments ──────────────────────────────────────────────────────────────
+    // ── Piers (내부 지점 span_count-1 개, Sprint 26) ──────────────────────────
+    for s in 1..span_count {
+        let pier_station_m = span_m * s as f64;
+        let pier_z = span_mm * s as f32;
+        let pier_ir = pier_ir_for_params(
+            pier_station_m, n_girders, spacing, girder_h, p.pier_type,
+        );
+        let mut mesh = kernel.pier_mesh(&pier_ir)?;
+        mesh.recolor(COL_PIER);
+        // pier_mesh 로컬 좌표: cap beam 상면이 Y=0 (거더 소핏 아래 bearing seat).
+        // Y 오프셋은 pier_mesh 자체가 정의하는 로컬 → 변환 불필요 (0).
+        parts.push(translate(mesh, 0.0, -BEARING_H, pier_z));
+    }
+
+    // ── Abutments (양 끝) ─────────────────────────────────────────────────────
     let wing = WingWallIR { length: 5_000.0, height: 2_500.0, thickness: 500.0 };
     let total_w = (n_girders as f64 - 1.0) * spacing as f64 + 3_000.0;
     let breast_wall_h = (girder_h + BEARING_H) as f64;
 
-    for &(station, z) in &[(0.0f64, -800.0_f32), (span_m, span_mm)] {
+    for &(station, z) in &[(0.0f64, -800.0_f32), (total_m, total_mm)] {
         let abut_ir = AbutmentIR {
             id:                      FeatureId::new(),
             station,
@@ -222,30 +293,30 @@ pub fn build_bridge_scene<K: GeomKernel>(kernel: &K, p: &SceneParams) -> Result<
 
     // ── Ground plane ───────────────────────────────────────────────────────────
     {
-        let ground_y  = -(BEARING_H + breast_wall_h as f32 + 1_000.0 + 200.0); // footing bottom - margin
+        let ground_y  = -(BEARING_H + breast_wall_h as f32 + 1_000.0 + 200.0);
-        let hw        = total_w as f32 * 0.5 + 8_000.0;   // wider than bridge
+        let hw        = total_w as f32 * 0.5 + 8_000.0;
-        let half_z    = span_mm * 0.5 + 8_000.0;
+        let half_z    = total_mm * 0.5 + 8_000.0;
         let thickness = 500.0_f32;
         let profile   = vec![
             [-hw, -thickness], [hw, -thickness], [hw, 0.0], [-hw, 0.0],
         ];
         let mut ground = cimery_kernel::sweep::sweep_profile_flat(&profile, half_z * 2.0);
         ground.recolor(COL_GROUND);
-        parts.push(translate(ground, 0.0, ground_y, -half_z));
+        parts.push(translate(ground, 0.0, ground_y, total_mm * 0.5 - half_z));
     }
 
     // ── Alignment centreline (optional) ───────────────────────────────────────
     if p.show_alignment {
         let radius = 80.0_f32;
-        let mut align = cimery_kernel::sweep::polygon_prism(0.0, 0.0, radius, 8, span_mm);
+        let mut align = cimery_kernel::sweep::polygon_prism(0.0, 0.0, radius, 8, total_mm);
         align.recolor(COL_ALIGNMENT);
         parts.push(translate(align, 0.0, girder_h * 0.5, 0.0));
     }
 
-    // ── Cross Beams (Sprint 19) ────────────────────────────────────────────────
+    // ── Cross Beams (경간마다) ────────────────────────────────────────────────
     if p.show_cross_beams {
         let interval_mm = (p.cross_beam_interval_m * 1_000.0) as f32;
-        let num_beams   = (span_mm / interval_mm).floor() as usize;
+        let num_per_span = (span_mm / interval_mm).floor() as usize;
         let cb_ir_base  = CrossBeamIR {
             id:               FeatureId::new(),
             station:          0.0,
@@ -258,26 +329,29 @@ pub fn build_bridge_scene<K: GeomKernel>(kernel: &K, p: &SceneParams) -> Result<
             girder_spacing:   spacing as f64,
             material:         MaterialGrade::C50,
         };
-        for i in 0..num_beams {
+        for s in 0..span_count {
-            let z = interval_mm * (i as f32 + 1.0);
+            let z_base = span_mm * s as f32;
-            let mut ir = cb_ir_base.clone();
+            for i in 0..num_per_span {
-            ir.id      = FeatureId::new();
+                let z = z_base + interval_mm * (i as f32 + 1.0);
-            ir.station = z as f64 / 1_000.0;
+                let mut ir = cb_ir_base.clone();
-            if let Ok(mut mesh) = kernel.cross_beam_mesh(&ir) {
+                ir.id      = FeatureId::new();
-                mesh.recolor(COL_CROSS_BEAM);
+                ir.station = z as f64 / 1_000.0;
-                parts.push(translate(mesh, 0.0, 0.0, z));
+                if let Ok(mut mesh) = kernel.cross_beam_mesh(&ir) {
+                    mesh.recolor(COL_CROSS_BEAM);
+                    parts.push(translate(mesh, 0.0, 0.0, z));
+                }
             }
         }
     }
 
-    // ── Expansion Joints (Sprint 19) ──────────────────────────────────────────
+    // ── Expansion Joints (양 교대 + 내부 피어 위치) ──────────────────────────
     if p.show_expansion_joints {
         let deck_w = ((n_girders as f32 - 1.0) * spacing + 2_000.0) as f64;
         let y_top  = girder_h + p.slab_thickness;
-        for &(station, z) in &[(0.0f64, 0.0_f32), (span_m, span_mm)] {
+        for &z in &support_zs {
             let ej_ir = ExpansionJointIR {
                 id:             FeatureId::new(),
-                station,
+                station:        z as f64 / 1_000.0,
                 joint_type:     ExpansionJointType::RubberType,
                 gap_width:      50.0,
                 total_width:    deck_w,
@@ -297,11 +371,14 @@ pub fn build_bridge_scene<K: GeomKernel>(kernel: &K, p: &SceneParams) -> Result<
 // ─── Background scene (ground + alignment only, no features) ─────────────────
 
 /// Returns only the non-selectable background elements: ground plane + alignment line.
+/// Sprint 26: 다경간 지원 — ground·alignment 가 전체 교량 길이 기준.
 pub fn build_background_scene(p: &SceneParams) -> Mesh {
-    let span_mm   = (p.span_m * 1_000.0) as f32;
+    let span_mm    = (p.span_m * 1_000.0) as f32;
-    let girder_h  = p.girder_height;
+    let span_count = p.span_count.max(1).min(5);
-    let n_girders = p.girder_count.max(1).min(10);
+    let total_mm   = span_mm * span_count as f32;
-    let spacing   = p.girder_spacing;
+    let girder_h   = p.girder_height;
+    let n_girders  = p.girder_count.max(1).min(10);
+    let spacing    = p.girder_spacing;
     const BEARING_H: f32 = 60.0;
     let breast_wall_h = (girder_h + BEARING_H) as f64;
     let total_w   = (n_girders as f64 - 1.0) * spacing as f64 + 3_000.0;
@@ -309,17 +386,17 @@ pub fn build_background_scene(p: &SceneParams) -> Mesh {
 
     let mut parts: Vec<Mesh> = Vec::new();
 
-    // Ground
+    // Ground — 전체 교량 길이 + 양끝 8m 여유
     let hw        = total_w as f32 * 0.5 + 8_000.0;
-    let half_z    = span_mm * 0.5 + 8_000.0;
+    let half_z    = total_mm * 0.5 + 8_000.0;
     let profile   = vec![[-hw, -500.0_f32], [hw, -500.0], [hw, 0.0], [-hw, 0.0]];
     let mut g = cimery_kernel::sweep::sweep_profile_flat(&profile, half_z * 2.0);
     g.recolor(COL_GROUND);
-    parts.push(translate(g, 0.0, ground_y, -half_z));
+    parts.push(translate(g, 0.0, ground_y, total_mm * 0.5 - half_z));
 
-    // Alignment
+    // Alignment — 전체 교량 길이
     if p.show_alignment {
-        let mut align = cimery_kernel::sweep::polygon_prism(0.0, 0.0, 80.0, 8, span_mm);
+        let mut align = cimery_kernel::sweep::polygon_prism(0.0, 0.0, 80.0, 8, total_mm);
         align.recolor(COL_ALIGNMENT);
         parts.push(translate(align, 0.0, girder_h * 0.5, 0.0));
     }
@@ -346,37 +423,71 @@ pub fn build_selectable_scene<K: GeomKernel>(
     let girder_h  = p.girder_height;
     const BEARING_H: f32 = 60.0;
 
-    let section = PscISectionParams {
+    // Sprint 25: 단면 타입 하드코딩 제거. p.section_type 에 따라 PscI / SteelBox 분기.
-        total_height:            girder_h as f64,
+    let (section_enum, section_type_enum) = match p.section_type {
-        top_flange_width:        600.0,
+        GirderSectionType::PscI => (
-        top_flange_thickness:    150.0,
+            SectionParams::PscI(PscISectionParams {
-        bottom_flange_width:     700.0,
+                total_height:            girder_h as f64,
-        bottom_flange_thickness: 180.0,
+                top_flange_width:        600.0,
-        web_thickness:           200.0,
+                top_flange_thickness:    150.0,
-        haunch:                  50.0,
+                bottom_flange_width:     700.0,
+                bottom_flange_thickness: 180.0,
+                web_thickness:           200.0,
+                haunch:                  50.0,
+            }),
+            SectionType::PscI,
+        ),
+        GirderSectionType::SteelBox => {
+            use cimery_ir::SteelBoxParams;
+            let h = girder_h as f64;
+            (
+                SectionParams::SteelBox(SteelBoxParams {
+                    total_height:            h,
+                    top_width:               h * 1.2,
+                    bottom_width:            h * 0.8,
+                    web_thickness:           20.0,
+                    top_flange_thickness:    25.0,
+                    bottom_flange_thickness: 22.0,
+                }),
+                SectionType::SteelBox,
+            )
+        }
     };
 
+    let span_count = p.span_count.max(1).min(5);
+    let total_m    = span_m * span_count as f64;
+    let total_mm   = span_mm * span_count as f32;
+
     let mut out: Vec<FeatureMesh> = Vec::new();
 
-    // Girders
+    // Girders (경간마다 독립 세트)
-    for i in 0..n_girders {
+    for s in 0..span_count {
-        let x = (i as f32 - (n_girders as f32 - 1.0) * 0.5) * spacing;
+        let z_base  = span_mm * s as f32;
-        let ir = GirderIR {
+        let s_start = span_m  * s as f64;
-            id: FeatureId::new(), station_start: 0.0, station_end: span_m,
+        for i in 0..n_girders {
-            offset_from_alignment: x as f64, section_type: SectionType::PscI,
+            let x = (i as f32 - (n_girders as f32 - 1.0) * 0.5) * spacing;
-            section: SectionParams::PscI(section.clone()),
+            let ir = GirderIR {
-            count: 1, spacing: 0.0, material: MaterialGrade::C50,
+                id: FeatureId::new(), station_start: s_start, station_end: s_start + span_m,
-        };
+                offset_from_alignment: x as f64, section_type: section_type_enum,
-        let mut mesh = kernel.girder_mesh(&ir)?;
+                section: section_enum.clone(),
-        mesh.recolor(COL_GIRDER);
+                count: 1, spacing: 0.0, material: MaterialGrade::C50,
-        for v in &mut mesh.vertices { v[0] += x; }
+            };
-        out.push(FeatureMesh { mesh, label: format!("거더 {}", i + 1) });
+            let mut mesh = kernel.girder_mesh(&ir)?;
+            mesh.recolor(COL_GIRDER);
+            for v in &mut mesh.vertices { v[0] += x; v[2] += z_base; }
+            let label = if span_count > 1 {
+                format!("거더 {}-{}", s + 1, i + 1)
+            } else {
+                format!("거더 {}", i + 1)
+            };
+            out.push(FeatureMesh { mesh, label });
+        }
     }
 
-    // Deck Slab (one unit)
+    // Deck Slab (전 구간 연속)
     let half_w = ((n_girders as f32 - 1.0) * spacing) * 0.5 + 1_000.0;
     let deck_ir = DeckSlabIR {
-        id: FeatureId::new(), station_start: 0.0, station_end: span_m,
+        id: FeatureId::new(), station_start: 0.0, station_end: total_m,
         width_left: half_w as f64, width_right: half_w as f64,
         thickness: p.slab_thickness as f64, haunch_depth: 0.0,
         cross_slope: 2.0, material: MaterialGrade::C40,
@@ -386,14 +497,14 @@ pub fn build_selectable_scene<K: GeomKernel>(
     for v in &mut deck.vertices { v[1] += girder_h + p.slab_thickness; }
     out.push(FeatureMesh { mesh: deck, label: "바닥판 슬래브".into() });
 
-    // Bearings
+    // Bearings (모든 지점)
-    // plan_length(350mm) = 경간 방향 → Z 센터링 오프셋 = z - 175.
     const SEL_BEARING_LEN: f32 = 350.0;
-    for &z in &[0.0_f32, span_mm] {
+    let support_zs: Vec<f32> = (0..=span_count).map(|i| span_mm * i as f32).collect();
+    for (sup_idx, &z) in support_zs.iter().enumerate() {
         for i in 0..n_girders {
             let x = (i as f32 - (n_girders as f32 - 1.0) * 0.5) * spacing;
             let bir = BearingIR {
-                id: FeatureId::new(), station: if z < 1.0 { 0.0 } else { span_m },
+                id: FeatureId::new(), station: z as f64 / 1_000.0,
                 bearing_type: BearingType::Elastomeric,
                 plan_length: SEL_BEARING_LEN as f64, plan_width: 450.0,
                 total_height: BEARING_H as f64, capacity_vertical: 1_500.0,
@@ -401,16 +512,31 @@ pub fn build_selectable_scene<K: GeomKernel>(
             let mut mesh = kernel.bearing_mesh(&bir)?;
             mesh.recolor(COL_BEARING);
             for v in &mut mesh.vertices { v[0] += x; v[2] += z - SEL_BEARING_LEN * 0.5; }
-            let side = if z < 1.0 { "시작" } else { "종점" };
+            let side = if sup_idx == 0 { "시작".to_string() }
+                       else if sup_idx == span_count { "종점".to_string() }
+                       else { format!("P{}", sup_idx) };
             out.push(FeatureMesh { mesh, label: format!("받침 {}-{}", side, i + 1) });
         }
     }
 
-    // Abutments
+    // Piers (내부 지점, Sprint 26)
+    for s in 1..span_count {
+        let pier_station_m = span_m * s as f64;
+        let pier_z = span_mm * s as f32;
+        let pier_ir = pier_ir_for_params(
+            pier_station_m, n_girders, spacing, girder_h, p.pier_type,
+        );
+        let mut mesh = kernel.pier_mesh(&pier_ir)?;
+        mesh.recolor(COL_PIER);
+        for v in &mut mesh.vertices { v[1] -= BEARING_H; v[2] += pier_z; }
+        out.push(FeatureMesh { mesh, label: format!("교각 P{}", s) });
+    }
+
+    // Abutments (양 끝)
     let total_w = (n_girders as f64 - 1.0) * spacing as f64 + 3_000.0;
     let bwh = (girder_h + BEARING_H) as f64;
     let wing = WingWallIR { length: 5_000.0, height: 2_500.0, thickness: 500.0 };
-    for &(station, z) in &[(0.0f64, -800.0_f32), (span_m, span_mm)] {
+    for &(station, z) in &[(0.0f64, -800.0_f32), (total_m, total_mm)] {
         let air = AbutmentIR {
             id: FeatureId::new(), station, skew_angle: 0.0,
             abutment_type: AbutmentType::ReverseT,
@@ -428,10 +554,10 @@ pub fn build_selectable_scene<K: GeomKernel>(
         out.push(FeatureMesh { mesh, label: format!("교대 ({})", side) });
     }
 
-    // ── Cross Beams (Sprint 19) ────────────────────────────────────────────
+    // Cross Beams (경간마다)
     if p.show_cross_beams {
-        let interval_mm = (p.cross_beam_interval_m * 1_000.0) as f32;
+        let interval_mm  = (p.cross_beam_interval_m * 1_000.0) as f32;
-        let num_beams   = (span_mm / interval_mm).floor() as usize;
+        let num_per_span = (span_mm / interval_mm).floor() as usize;
         let cb_ir_base  = CrossBeamIR {
             id:               FeatureId::new(),
             station:          0.0,
@@ -444,29 +570,28 @@ pub fn build_selectable_scene<K: GeomKernel>(
             girder_spacing:   spacing as f64,
             material:         MaterialGrade::C50,
         };
-        for i in 0..num_beams {
+        for s in 0..span_count {
-            let z = interval_mm * (i as f32 + 1.0);
+            let z_base = span_mm * s as f32;
-            let mut ir = cb_ir_base.clone();
+            for i in 0..num_per_span {
-            ir.id      = FeatureId::new();
+                let z = z_base + interval_mm * (i as f32 + 1.0);
-            ir.station = z as f64 / 1_000.0;
+                let mut ir = cb_ir_base.clone();
-            let mut mesh = kernel.cross_beam_mesh(&ir)?;
+                ir.id      = FeatureId::new();
-            mesh.recolor(COL_CROSS_BEAM);
+                ir.station = z as f64 / 1_000.0;
-            let half = ir.total_length_mm() as f32 * 0.5;
+                let mut mesh = kernel.cross_beam_mesh(&ir)?;
-            for v in &mut mesh.vertices {
+                mesh.recolor(COL_CROSS_BEAM);
-                v[2] += z;
+                for v in &mut mesh.vertices { v[2] += z; }
+                out.push(FeatureMesh { mesh, label: format!("가로보 @ {:.0}m", z / 1_000.0) });
             }
-            let _ = half; // translation already applied in cross_beam builder
-            out.push(FeatureMesh { mesh, label: format!("가로보 @ {:.0}m", z / 1_000.0) });
         }
     }
 
-    // ── Expansion Joints (Sprint 19) ───────────────────────────────────────
+    // ── Expansion Joints (모든 지점) ───────────────────────────────────────
     if p.show_expansion_joints {
         let deck_w = ((n_girders as f32 - 1.0) * spacing + 2_000.0) as f64;
-        for &(station, z) in &[(0.0f64, 0.0_f32), (span_m, span_mm)] {
+        for (sup_idx, &z) in support_zs.iter().enumerate() {
             let ej_ir = ExpansionJointIR {
                 id:             FeatureId::new(),
-                station,
+                station:        z as f64 / 1_000.0,
                 joint_type:     ExpansionJointType::RubberType,
                 gap_width:      50.0,
                 total_width:    deck_w,
@@ -480,7 +605,9 @@ pub fn build_selectable_scene<K: GeomKernel>(
                 v[1] += y_top;
                 v[2] += z;
             }
-            let side = if z < 1.0 { "시작" } else { "종점" };
+            let side = if sup_idx == 0 { "시작".to_string() }
+                       else if sup_idx == span_count { "종점".to_string() }
+                       else { format!("P{}", sup_idx) };
             out.push(FeatureMesh { mesh, label: format!("신축이음 ({})", side) });
         }
     }
@@ -489,10 +616,11 @@ pub fn build_selectable_scene<K: GeomKernel>(
 }
 
 /// Bounding box of the full bridge scene (for camera setup).
+/// Sprint 26: 다경간 지원 → Z 범위가 span_m × span_count.
 pub fn scene_extents(p: &SceneParams) -> ([f32; 3], [f32; 3]) {
-    let span_mm  = (p.span_m * 1_000.0) as f32;
+    let total_mm = (p.span_m * 1_000.0) as f32 * p.span_count.max(1) as f32;
     let half_w   = ((p.girder_count as f32 - 1.0) * p.girder_spacing * 0.5 + 2_000.0).max(5_000.0);
     let top_y    = p.girder_height + p.slab_thickness + 200.0;
     let bot_y    = -(p.girder_height + 3_000.0 + 1_000.0);
-    ([-half_w, bot_y, -2_000.0], [half_w, top_y, span_mm + 2_000.0])
+    ([-half_w, bot_y, -2_000.0], [half_w, top_y, total_mm + 2_000.0])
 }

cimery/crates/viewer/src/lib.rs

@@ -624,6 +624,15 @@ impl RenderState {
                             ps!("c/c 간격 (mm)",   &mut p.girder_spacing, 1_500.0..=4_000.0, 100.0);
                             ps!("거더 높이 (mm)",  &mut p.girder_height,  1_000.0..=3_000.0, 100.0);
                             ps!("슬래브 두께 (mm)",&mut p.slab_thickness, 150.0..=400.0,     10.0);
+                            // Sprint 26: 다경간 지원
+                            ps!("경간 수",          &mut p.span_count,     1..=5,             1.0);
+                            ui.label("교각 형식");
+                            let prev_pt = p.pier_type;
+                            ui.horizontal(|ui| {
+                                ui.selectable_value(&mut p.pier_type, cimery_core::PierType::SingleColumn, "T형(단주)");
+                                ui.selectable_value(&mut p.pier_type, cimery_core::PierType::MultiColumn,  "π형(다주)");
+                            });
+                            if p.pier_type != prev_pt { dirty = true; }
 
                             ui.label("단면 형식");
                             let prev_sec = p.section_type;

cimery/crates/viewer/src/project_file.rs

@@ -30,15 +30,22 @@ pub struct ProjectFile {
     pub cross_beam_interval_m: f64,
     #[serde(default = "default_true")]
     pub show_expansion_joints: bool,
+    /// Sprint 26: 다경간
+    #[serde(default = "default_span_count")]
+    pub span_count:            usize,
+    #[serde(default = "default_pier_type")]
+    pub pier_type:             String,   // "single" | "multi"
 }
 
 fn default_true() -> bool { true }
 fn default_cross_beam_interval() -> f64 { 5.0 }
+fn default_span_count() -> usize { 1 }
+fn default_pier_type() -> String { "single".into() }
 
 impl ProjectFile {
     pub fn from_params(name: &str, p: &SceneParams) -> Self {
         Self {
-            version:               1,
+            version:               2,
             name:                  name.to_owned(),
             span_m:                p.span_m,
             girder_count:          p.girder_count,
@@ -53,6 +60,11 @@ impl ProjectFile {
             show_cross_beams:      p.show_cross_beams,
             cross_beam_interval_m: p.cross_beam_interval_m,
             show_expansion_joints: p.show_expansion_joints,
+            span_count:            p.span_count,
+            pier_type:             match p.pier_type {
+                cimery_core::PierType::MultiColumn => "multi".into(),
+                _                                  => "single".into(),
+            },
         }
     }
 
@@ -71,6 +83,11 @@ impl ProjectFile {
             show_cross_beams:      self.show_cross_beams,
             cross_beam_interval_m: self.cross_beam_interval_m,
             show_expansion_joints: self.show_expansion_joints,
+            span_count:            self.span_count,
+            pier_type:             match self.pier_type.as_str() {
+                "multi" => cimery_core::PierType::MultiColumn,
+                _       => cimery_core::PierType::SingleColumn,
+            },
         }
     }