101 lines
3.7 KiB
C++
101 lines
3.7 KiB
C++
#include "actors/VoxelActor.hpp"
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#include <cmath>
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#include <limits>
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#include <vtkColorTransferFunction.h>
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#include <vtkDoubleArray.h>
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#include <vtkNew.h>
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#include <vtkSmartVolumeMapper.h>
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#include <vtkPiecewiseFunction.h>
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#include <vtkPointData.h>
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#include <vtkVolumeProperty.h>
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namespace geopro::render {
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namespace {
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// 颜色/不透明度传递函数采样级数。
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constexpr int kTransferSamples = 64;
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// 体绘制最大不透明度（[vmin,vmax] 线性 0→kMaxOpacity）。
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constexpr double kMaxOpacity = 0.15;
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// NaN/留空格的哨兵：落在 [vmin,vmax] 之外，传递函数把它映射为完全透明。
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double sentinel(double vmin) { return vmin - 1.0; }
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} // namespace
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vtkSmartPointer<vtkVolume> buildVoxel(const geopro::core::ScalarVolume& vol,
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const geopro::core::ColorScale& cs,
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double ox, double oy, double oz,
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double dx, double dy, double dz,
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double vmin, double vmax,
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vtkSmartPointer<vtkImageData>& outImage)
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{
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const int nx = vol.nx(), ny = vol.ny(), nz = vol.nz();
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// vmin/vmax 退化兜底，避免传递函数区间为零。
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if (vmin >= vmax) vmax = vmin + 1.0;
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const double blank = sentinel(vmin);
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auto img = vtkSmartPointer<vtkImageData>::New();
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img->SetDimensions(nx, ny, nz);
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img->SetOrigin(ox, oy, oz);
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img->SetSpacing(dx, dy, dz);
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vtkNew<vtkDoubleArray> sc;
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sc->SetName("v");
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sc->SetNumberOfTuples(static_cast<vtkIdType>(nx) * ny * nz);
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// 点序 i 最快、j 次之、k 最慢（匹配 vtkImageData 与 ScalarVolume::idx）。
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for (int k = 0; k < nz; ++k)
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for (int j = 0; j < ny; ++j)
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for (int i = 0; i < nx; ++i) {
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const double v = vol.at(i, j, k);
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const vtkIdType id = (static_cast<vtkIdType>(k) * ny + j) * nx + i;
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sc->SetValue(id, std::isnan(v) ? blank : v); // NaN → 哨兵
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}
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img->GetPointData()->SetScalars(sc);
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outImage = img;
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// 颜色传递函数：在 [vmin,vmax] 按 ColorScale 采样若干 RGB 点。
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vtkNew<vtkColorTransferFunction> color;
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for (int t = 0; t < kTransferSamples; ++t) {
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const double val = vmin + (vmax - vmin) * t / (kTransferSamples - 1);
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const auto c = cs.colorAt(val);
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color->AddRGBPoint(val, c.r / 255.0, c.g / 255.0, c.b / 255.0);
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}
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// 不透明度传递函数：哨兵 → 0（透明）；[vmin,vmax] 线性递增到 kMaxOpacity。
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vtkNew<vtkPiecewiseFunction> opacity;
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opacity->AddPoint(blank, 0.0);
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opacity->AddPoint(vmin, 0.0);
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opacity->AddPoint(vmax, kMaxOpacity);
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// SmartVolumeMapper：有 GPU 走 GPU ray cast，否则自动回退 CPU，避免无 GPU 时卡死/失败。
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vtkNew<vtkSmartVolumeMapper> mapper;
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mapper->SetInputData(img);
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vtkNew<vtkVolumeProperty> prop;
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prop->SetColor(color);
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prop->SetScalarOpacity(opacity);
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prop->SetInterpolationTypeToLinear();
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prop->ShadeOff();
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auto volume = vtkSmartPointer<vtkVolume>::New();
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volume->SetMapper(mapper);
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volume->SetProperty(prop);
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return volume;
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}
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vtkSmartPointer<vtkVolume> buildVoxel(const geopro::core::ScalarVolume& vol,
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const geopro::core::ColorScale& cs,
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double ox, double oy, double oz,
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double dx, double dy, double dz,
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double vmin, double vmax)
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{
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vtkSmartPointer<vtkImageData> ignored;
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return buildVoxel(vol, cs, ox, oy, oz, dx, dy, dz, vmin, vmax, ignored);
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}
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} // namespace geopro::render
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