VolumeMapperBlendModes

Live example

Source

import '@kitware/vtk.js/favicon';

// Load the rendering pieces we want to use (for both WebGL and WebGPU)
import '@kitware/vtk.js/Rendering/Profiles/Volume';

// Force DataAccessHelper to have access to various data source
import '@kitware/vtk.js/IO/Core/DataAccessHelper/HtmlDataAccessHelper';
import '@kitware/vtk.js/IO/Core/DataAccessHelper/HttpDataAccessHelper';
import '@kitware/vtk.js/IO/Core/DataAccessHelper/JSZipDataAccessHelper';

import vtkFullScreenRenderWindow from '@kitware/vtk.js/Rendering/Misc/FullScreenRenderWindow';
import vtkHttpDataSetReader from '@kitware/vtk.js/IO/Core/HttpDataSetReader';
import vtkPiecewiseFunction from '@kitware/vtk.js/Common/DataModel/PiecewiseFunction';
import vtkColorTransferFunction from '@kitware/vtk.js/Rendering/Core/ColorTransferFunction';
import vtkVolume from '@kitware/vtk.js/Rendering/Core/Volume';
import vtkVolumeMapper from '@kitware/vtk.js/Rendering/Core/VolumeMapper';
import controlPanel from './controller.html';

// ----------------------------------------------------------------------------
// Standard rendering code setup
// ----------------------------------------------------------------------------

const fullScreenRenderer = vtkFullScreenRenderWindow.newInstance({
background: [0.3, 0.3, 0.3],
});
const renderer = fullScreenRenderer.getRenderer();
const renderWindow = fullScreenRenderer.getRenderWindow();

fullScreenRenderer.addController(controlPanel);

// ----------------------------------------------------------------------------
// Example code
// ----------------------------------------------------------------------------
const minHounsfieldLabel = document.querySelector('#minHounsfieldLabel');
const maxHounsfieldLabel = document.querySelector('#maxHounsfieldLabel');
const maxAbsorptionLabel = document.querySelector('#maxAbsorptionLabel');
const minAbsorptionLabel = document.querySelector('#minAbsorptionLabel');
const sampleDistanceLabel = document.querySelector('#sampleDistanceLabel');
const reader = vtkHttpDataSetReader.newInstance({ fetchGzip: true });
const initialSampleDistance = 1.3;

const actor = vtkVolume.newInstance();
const mapper = vtkVolumeMapper.newInstance();
mapper.setSampleDistance(initialSampleDistance);
mapper.setPreferSizeOverAccuracy(true);
actor.setMapper(mapper);

const radonParameters = {
minHounsfield: 1000, // water HU for headsq (normally 0)
minAbsorption: 0.01,
maxHounsfield: 2500, // bone HU for headsq
maxAbsorption: 0.03,
};
let sampleDistance = initialSampleDistance;
sampleDistanceLabel.innerHTML = sampleDistance.toFixed(1);

function updatePiecewiseFunction() {
minHounsfieldLabel.innerHTML = radonParameters.minHounsfield.toFixed(0);
minAbsorptionLabel.innerHTML = radonParameters.minAbsorption.toFixed(3);
maxHounsfieldLabel.innerHTML = radonParameters.maxHounsfield.toFixed(0);
maxAbsorptionLabel.innerHTML = radonParameters.maxAbsorption.toFixed(3);

const currentBlendMode = mapper.getBlendMode();
let opacityFunction;

if (currentBlendMode === 5) {
opacityFunction = vtkVolumeMapper.createRadonTransferFunction(
radonParameters.minHounsfield,
radonParameters.minAbsorption,
radonParameters.maxHounsfield,
radonParameters.maxAbsorption
);
} else {
opacityFunction = vtkPiecewiseFunction.newInstance();
opacityFunction.addPoint(-3024, 0.1);
opacityFunction.addPoint(-637.62, 0.1);
opacityFunction.addPoint(700, 0.5);
opacityFunction.addPoint(3071, 0.9);
}
actor.getProperty().setScalarOpacity(0, opacityFunction);
}

actor.getProperty().setScalarOpacityUnitDistance(0, 3.0);
actor.getProperty().setInterpolationTypeToLinear();
actor.getProperty().setShade(true);
actor.getProperty().setAmbient(0.1);
actor.getProperty().setDiffuse(0.9);
actor.getProperty().setSpecular(0.2);
actor.getProperty().setSpecularPower(10.0);

mapper.setInputConnection(reader.getOutputPort());

function updateMin(event) {
radonParameters.minHounsfield = event.target.valueAsNumber;
updatePiecewiseFunction();
renderWindow.render();
}

function updateMax(event) {
radonParameters.maxHounsfield = event.target.valueAsNumber;
updatePiecewiseFunction();
renderWindow.render();
}

function updateScalarValue(event) {
radonParameters.maxAbsorption = event.target.valueAsNumber;
updatePiecewiseFunction();
renderWindow.render();
}

function updateScalarValue2(event) {
radonParameters.minAbsorption = event.target.valueAsNumber;
updatePiecewiseFunction();
renderWindow.render();
}

function updateSampleDistance(event) {
sampleDistance = event.target.valueAsNumber;
sampleDistanceLabel.innerHTML = sampleDistance.toFixed(3);
mapper.setSampleDistance(sampleDistance);
renderWindow.render();
}

function updateScalarMin(event) {
mapper.setIpScalarRange(
event.target.valueAsNumber,
mapper.getIpScalarRange()[1]
);
renderWindow.render();
}

function updateScalarMax(event) {
mapper.setIpScalarRange(
mapper.getIpScalarRange()[0],
event.target.valueAsNumber
);
renderWindow.render();
}

function updateBlendMode(event) {
const currentBlendMode = parseInt(event.target.value, 10);
const ipScalarEls = document.querySelectorAll('.ipScalar');
const radonScalars = document.querySelectorAll('.radonScalar');

mapper.setBlendMode(currentBlendMode);
mapper.setIpScalarRange(0.0, 1.0);

// if average or additive blend mode
for (let i = 0; i < ipScalarEls.length; i += 1) {
const el = ipScalarEls[i];
el.style.display =
currentBlendMode === 3 || currentBlendMode === 4 ? 'table-row' : 'none';
}

// Radon
for (let i = 0; i < radonScalars.length; i += 1) {
const el = radonScalars[i];
el.style.display = currentBlendMode === 5 ? 'table-row' : 'none';
}

const colorTransferFunction = vtkColorTransferFunction.newInstance();
if (currentBlendMode === 5) {
colorTransferFunction.addRGBPoint(0, 0, 0, 0);
colorTransferFunction.addRGBPoint(1, 1, 1, 1);
} else {
colorTransferFunction.addRGBPoint(-3024, 0, 0, 0);
colorTransferFunction.addRGBPoint(-637.62, 0, 0, 0);
colorTransferFunction.addRGBPoint(700, 1, 1, 1);
colorTransferFunction.addRGBPoint(3071, 1, 1, 1);
}
actor.getProperty().setRGBTransferFunction(0, colorTransferFunction);
updatePiecewiseFunction();

renderWindow.render();
}

reader.setUrl(`${__BASE_PATH__}/data/volume/headsq.vti`).then(() => {
reader.loadData().then(() => {
renderer.addVolume(actor);
const interactor = renderWindow.getInteractor();
interactor.setDesiredUpdateRate(15.0);
renderer.resetCamera();
renderer.getActiveCamera().elevation(-70);
updatePiecewiseFunction();

const el = document.querySelector('.blendMode');
el.addEventListener('change', updateBlendMode);

const scalarMinEl = document.querySelector('.scalarMin');
scalarMinEl.addEventListener('input', updateScalarMin);
const scalarMaxEl = document.querySelector('.scalarMax');
scalarMaxEl.addEventListener('input', updateScalarMax);

const minInput = document.querySelector('.minHounsfield');
minInput.addEventListener('input', updateMin);
const maxInput = document.querySelector('.maxHounsfield');
maxInput.addEventListener('input', updateMax);
const maxAbsorptionInput = document.querySelector('.maxAbsorption');
maxAbsorptionInput.addEventListener('input', updateScalarValue);
const minAbsorptionInput = document.querySelector('.minAbsorption');
minAbsorptionInput.addEventListener('input', updateScalarValue2);
const unitV = document.querySelector('.sampleDistance');
unitV.addEventListener('input', updateSampleDistance);

minInput.value = radonParameters.minHounsfield;
maxInput.value = radonParameters.maxHounsfield;
maxAbsorptionInput.value = radonParameters.maxAbsorption;
minAbsorptionInput.value = radonParameters.minAbsorption;
unitV.value = sampleDistance;

el.value = 5;
const evt = document.createEvent('HTMLEvents');
evt.initEvent('change', false, true);
el.dispatchEvent(evt);
});
});

// -----------------------------------------------------------
// Make some variables global so that you can inspect and
// modify objects in your browser's developer console:
// -----------------------------------------------------------

global.source = reader;
global.mapper = mapper;
global.actor = actor;
global.renderer = renderer;
global.renderWindow = renderWindow;