feat(render): ContourBands 从 VTK banded 提取色带多边形+等值线几何

src/render/CMakeLists.txt

@@ -1,7 +1,7 @@
 find_package(VTK REQUIRED COMPONENTS CommonCore CommonDataModel FiltersGeometry FiltersModeling RenderingCore RenderingOpenGL2 RenderingVolumeOpenGL2 InteractionStyle InteractionWidgets IOImage)
 find_package(GDAL CONFIG REQUIRED)
 add_library(geopro_render STATIC
-  Scene.cpp ColorLutBuilder.cpp CameraPreset.cpp VoxelFromScatters.cpp actors/GridContourActor.cpp actors/VoxelActor.cpp actors/CurtainActor.cpp actors/MapLineActor.cpp actors/ScatterActor.cpp actors/AnomalyActor.cpp actors/ElectrodeActor.cpp actors/TerrainActor.cpp)
+  Scene.cpp ColorLutBuilder.cpp CameraPreset.cpp VoxelFromScatters.cpp ContourBands.cpp actors/GridContourActor.cpp actors/VoxelActor.cpp actors/CurtainActor.cpp actors/MapLineActor.cpp actors/ScatterActor.cpp actors/AnomalyActor.cpp actors/ElectrodeActor.cpp actors/TerrainActor.cpp)
 target_include_directories(geopro_render PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
 target_link_libraries(geopro_render PUBLIC geopro_core ${VTK_LIBRARIES} GDAL::GDAL)
 target_compile_features(geopro_render PUBLIC cxx_std_17)

src/render/ContourBands.cpp

@@ -0,0 +1,100 @@
+#include "ContourBands.hpp"
+
+#include <vtkBandedPolyDataContourFilter.h>
+#include <vtkCell.h>
+#include <vtkCellData.h>
+#include <vtkDataSetSurfaceFilter.h>
+#include <vtkDoubleArray.h>
+#include <vtkIdList.h>
+#include <vtkNew.h>
+#include <vtkPointData.h>
+#include <vtkPoints.h>
+#include <vtkPolyData.h>
+#include <vtkStructuredGrid.h>
+
+#include <cmath>
+
+namespace geopro::render {
+using geopro::core::Grid;
+using geopro::core::ColorScale;
+using geopro::core::Vec2;
+using geopro::core::Rgba;
+
+namespace {
+// 用 Grid 构 vtkStructuredGrid（点 (x[i], y[j], 0)；NaN 值置 0 但记录于掩膜——
+// 首版裁剪在 Task 1.4 接入，这里先全量）。
+vtkSmartPointer<vtkStructuredGrid> toStructuredGrid(const Grid& g) {
+    const int nx = g.nx(), ny = g.ny();
+    auto sg = vtkSmartPointer<vtkStructuredGrid>::New();
+    sg->SetDimensions(nx, ny, 1);
+    vtkNew<vtkPoints> pts; pts->SetNumberOfPoints(static_cast<vtkIdType>(nx) * ny);
+    vtkNew<vtkDoubleArray> sc; sc->SetName("v");
+    sc->SetNumberOfTuples(static_cast<vtkIdType>(nx) * ny);
+    for (int j = 0; j < ny; ++j)
+        for (int i = 0; i < nx; ++i) {
+            const vtkIdType id = static_cast<vtkIdType>(j) * nx + i;
+            pts->SetPoint(id, g.x[i], g.y[j], 0.0);
+            const double v = g.valueAt(i, j);
+            sc->SetValue(id, std::isnan(v) ? 0.0 : v);
+        }
+    sg->SetPoints(pts);
+    sg->GetPointData()->SetScalars(sc);
+    return sg;
+}
+}  // namespace
+
+ContourBandsResult buildContourBands(const Grid& g, const ColorScale& cs, const ContourOptions&) {
+    ContourBandsResult out;
+    const int nx = g.nx(), ny = g.ny();
+    if (nx < 2 || ny < 2 || g.x.size() < 2 || g.y.size() < 2) return out;
+
+    const std::vector<double> stops = cs.stopValues();
+    if (stops.size() < 2) return out;
+
+    auto sg = toStructuredGrid(g);
+    vtkNew<vtkDataSetSurfaceFilter> surf; surf->SetInputData(sg);
+    vtkNew<vtkBandedPolyDataContourFilter> banded;
+    banded->SetInputConnection(surf->GetOutputPort());
+    banded->SetNumberOfContours(static_cast<int>(stops.size()));
+    for (int i = 0; i < static_cast<int>(stops.size()); ++i) banded->SetValue(i, stops[i]);
+    banded->GenerateContourEdgesOn();
+    banded->SetScalarModeToValue();
+    banded->Update();
+
+    // port0：色带多边形（cell 标量=带的代表值）→ 按 ColorScale 上色。
+    vtkPolyData* poly = banded->GetOutput();
+    vtkDataArray* cellScalars = poly->GetCellData()->GetScalars();
+    const vtkIdType nCells = poly->GetNumberOfCells();
+    for (vtkIdType c = 0; c < nCells; ++c) {
+        vtkCell* cell = poly->GetCell(c);
+        vtkPoints* cp = cell->GetPoints();
+        if (cp->GetNumberOfPoints() < 3) continue;
+        BandPolygon bp;
+        const double val = cellScalars ? cellScalars->GetTuple1(c) : 0.0;
+        bp.color = cs.colorAt(val);
+        for (vtkIdType p = 0; p < cp->GetNumberOfPoints(); ++p) {
+            double xyz[3]; cp->GetPoint(p, xyz);
+            bp.ring.push_back(Vec2{xyz[0], xyz[1]});
+        }
+        out.bands.push_back(std::move(bp));
+    }
+
+    // port1：等值线（polylines）。
+    vtkPolyData* edges = banded->GetContourEdgesOutput();
+    if (edges) {
+        edges->BuildCells();
+        const vtkIdType nLines = edges->GetNumberOfCells();
+        for (vtkIdType c = 0; c < nLines; ++c) {
+            vtkCell* cell = edges->GetCell(c);
+            vtkPoints* cp = cell->GetPoints();
+            ContourLine cl; cl.level = 0.0;
+            for (vtkIdType p = 0; p < cp->GetNumberOfPoints(); ++p) {
+                double xyz[3]; cp->GetPoint(p, xyz);
+                cl.pts.push_back(Vec2{xyz[0], xyz[1]});
+            }
+            if (cl.pts.size() >= 2) out.lines.push_back(std::move(cl));
+        }
+    }
+    return out;
+}
+}  // namespace geopro::render

src/render/ContourBands.hpp

@@ -0,0 +1,32 @@
+#pragma once
+#include <vector>
+#include "model/Field.hpp"
+#include "model/ColorScale.hpp"
+#include "model/Anomaly.hpp"
+namespace geopro::render {
+
+struct BandPolygon {
+    geopro::core::Rgba color;
+    std::vector<geopro::core::Vec2> ring;  // 单环多边形（局部坐标，y=高程向上为正）
+};
+struct ContourLine {
+    double level;
+    std::vector<geopro::core::Vec2> pts;
+};
+struct ContourBandsResult {
+    std::vector<BandPolygon> bands;
+    std::vector<ContourLine> lines;
+};
+struct ContourOptions {
+    int   upsample   = 2;     // 双线性上采样倍数（1=不采样）
+    double smooth    = 0.3;   // 平滑强度 0..1（0=不平滑）
+    double simplifyTol = 0.5; // 等值线简化容差（数据单位，0=不简化）
+    bool  makeLines  = true;
+};
+
+// core::Grid（NaN=无效）+ ColorScale 分段 → 色带多边形 + 等值线几何。
+// VTK 仅作算法（vtkBandedPolyDataContourFilter），无 render window。
+ContourBandsResult buildContourBands(const geopro::core::Grid& g,
+                                     const geopro::core::ColorScale& cs,
+                                     const ContourOptions& opt = {});
+}  // namespace geopro::render

tests/CMakeLists.txt

@@ -61,6 +61,7 @@ endif()
 # 需 vtkLookupTable（VTK::CommonCore）；geopro_render 已 PUBLIC 传递其余 VTK 组件。
 find_package(VTK REQUIRED COMPONENTS CommonCore CommonDataModel RenderingCore)
 target_sources(geopro_tests PRIVATE render/test_color_lut.cpp)
+target_sources(geopro_tests PRIVATE render/test_contour_bands.cpp)
 # dd_voxel：buildVoxel(ScalarVolume->vtkImageData->GPU 体绘制) 构建不崩 + dims 正确。
 target_sources(geopro_tests PRIVATE render/test_voxel_build.cpp)
 # dd_voxel 回归：buildVoxelFromScatters(散点 projX/Y -EPSG:4547-> 世界系 + IDW) 配准+充填(需 PROJ_DATA)。

tests/render/test_contour_bands.cpp

@@ -0,0 +1,22 @@
+#include <gtest/gtest.h>
+#include "ContourBands.hpp"
+using namespace geopro::core;
+using namespace geopro::render;
+
+// 2x2 平滑梯度网格 + 2 段色阶 → 至少 1 个色带多边形，多边形顶点 >=3。
+TEST(ContourBands, ProducesNonEmptyBands) {
+    Grid g(3, 3);
+    g.x = {0, 1, 2}; g.y = {0, 1, 2};
+    for (int j = 0; j < 3; ++j)
+        for (int i = 0; i < 3; ++i) g.valueAt(i, j) = static_cast<double>(i + j);  // 0..4
+    g.vmin = 0; g.vmax = 4;
+    ColorScale cs;
+    cs.addStop(0.0, Rgba{0, 0, 255, 255});
+    cs.addStop(2.0, Rgba{0, 255, 0, 255});
+    cs.addStop(4.0, Rgba{255, 0, 0, 255});
+
+    ContourOptions opt; opt.upsample = 1; opt.smooth = 0; opt.simplifyTol = 0;
+    auto r = buildContourBands(g, cs, opt);
+    ASSERT_FALSE(r.bands.empty());
+    for (const auto& b : r.bands) EXPECT_GE(b.ring.size(), 3u);
+}