SphereMapper

Source

index.js
import * as macro from 'vtk.js/Sources/macros';
import * as vtkMath from 'vtk.js/Sources/Common/Core/Math';
import vtkWebGPUPolyDataMapper from 'vtk.js/Sources/Rendering/WebGPU/PolyDataMapper';
import vtkWebGPUBufferManager from 'vtk.js/Sources/Rendering/WebGPU/BufferManager';
import vtkWebGPUShaderCache from 'vtk.js/Sources/Rendering/WebGPU/ShaderCache';

import { registerOverride } from 'vtk.js/Sources/Rendering/WebGPU/ViewNodeFactory';

const { BufferUsage, PrimitiveTypes } = vtkWebGPUBufferManager;
const { vtkErrorMacro } = macro;

const vtkWebGPUSphereMapperVS = `
//VTK::Renderer::Dec

//VTK::Mapper::Dec

//VTK::Color::Dec

//VTK::IOStructs::Dec

[[stage(vertex)]]
fn main(
//VTK::IOStructs::Input
)
//VTK::IOStructs::Output
{
var output : vertexOutput;

var vertexVC: vec4<f32> = rendererUBO.SCVCMatrix * mapperUBO.BCSCMatrix * vec4<f32>(vertexBC.x, vertexBC.y, vertexBC.z, 1.0);

//VTK::Color::Impl

// compute the projected vertex position
output.centerVC = vertexVC.xyz;
output.radiusVC = length(offsetMC)*0.5;

// make the triangle face the camera
if (rendererUBO.cameraParallel == 0u)
{
var dir: vec3<f32> = normalize(-vertexVC.xyz);
var base2: vec3<f32> = normalize(cross(dir,vec3<f32>(1.0,0.0,0.0)));
var base1: vec3<f32> = cross(base2,dir);
dir = vertexVC.xyz + offsetMC.x*base1 + offsetMC.y*base2;
vertexVC = vec4<f32>(dir, 1.0);
}
else
{
// add in the offset
var tmp2: vec2<f32> = vertexVC.xy + offsetMC;
vertexVC = vec4<f32>(tmp2, vertexVC.zw);
}

output.vertexVC = vertexVC.xyz;

//VTK::Position::Impl

return output;
}
`;

// ----------------------------------------------------------------------------
// vtkWebGPUSphereMapper methods
// ----------------------------------------------------------------------------

function vtkWebGPUSphereMapper(publicAPI, model) {
// Set our className
model.classHierarchy.push('vtkWebGPUSphereMapper');

publicAPI.replaceShaderNormal = (hash, pipeline, vertexInput) => {
const vDesc = pipeline.getShaderDescription('vertex');
vDesc.addOutput('vec3<f32>', 'vertexVC');
vDesc.addOutput('vec3<f32>', 'centerVC');
vDesc.addOutput('f32', 'radiusVC');

const fDesc = pipeline.getShaderDescription('fragment');
fDesc.addBuiltinOutput('f32', '[[builtin(frag_depth)]] fragDepth');
const sphereFrag = `
// compute the eye position and unit direction
var vertexVC: vec4<f32>;
var EyePos: vec3<f32>;
var EyeDir: vec3<f32>;
var invertedDepth: f32 = 1.0;
if (rendererUBO.cameraParallel != 0u) {
EyePos = vec3<f32>(input.vertexVC.x, input.vertexVC.y, input.vertexVC.z + 3.0*input.radiusVC);
EyeDir = vec3<f32>(0.0, 0.0, -1.0);
}
else {
EyeDir = input.vertexVC.xyz;
EyePos = vec3<f32>(0.0,0.0,0.0);
var lengthED: f32 = length(EyeDir);
EyeDir = normalize(EyeDir);
// we adjust the EyePos to be closer if it is too far away
// to prevent floating point precision noise
if (lengthED > input.radiusVC*3.0) {
EyePos = input.vertexVC.xyz - EyeDir*3.0*input.radiusVC;
}
}

// translate to Sphere center
EyePos = EyePos - input.centerVC;
// scale to radius 1.0
EyePos = EyePos * (1.0 / input.radiusVC);
// find the intersection
var b: f32 = 2.0*dot(EyePos,EyeDir);
var c: f32 = dot(EyePos,EyePos) - 1.0;
var d: f32 = b*b - 4.0*c;
var normal: vec3<f32> = vec3<f32>(0.0,0.0,1.0);
if (d < 0.0) { discard; }
else {
var t: f32 = (-b - invertedDepth*sqrt(d))*0.5;

// compute the normal, for unit sphere this is just
// the intersection point
normal = invertedDepth*normalize(EyePos + t*EyeDir);
// compute the intersection point in VC
vertexVC = vec4<f32>(normal * input.radiusVC + input.centerVC, 1.0);
}
// compute the pixel's depth
var pos: vec4<f32> = rendererUBO.VCPCMatrix * vertexVC;
output.fragDepth = pos.z / pos.w;
`;

let code = fDesc.getCode();
code = vtkWebGPUShaderCache.substitute(code, '//VTK::Normal::Impl', [
sphereFrag,
]).result;
fDesc.setCode(code);
};

publicAPI.replaceShaderPosition = (hash, pipeline, vertexInput) => {
const vDesc = pipeline.getShaderDescription('vertex');
vDesc.addBuiltinOutput('vec4<f32>', '[[builtin(position)]] Position');
let code = vDesc.getCode();
code = vtkWebGPUShaderCache.substitute(code, '//VTK::Position::Impl', [
' output.Position = rendererUBO.VCPCMatrix*vertexVC;',
]).result;
vDesc.setCode(code);
};

// compute a unique hash for a pipeline, this needs to be unique enough to
// capture any pipeline code changes (which includes shader changes)
// or vertex input changes/ bind groups/ etc
publicAPI.computePipelineHash = (vertexInput) => {
let pipelineHash = 'spm';
if (vertexInput.hasAttribute(`colorVI`)) {
pipelineHash += `c`;
}
pipelineHash += model.renderEncoder.getPipelineHash();

return pipelineHash;
};

// was originally buildIBOs() but not using IBOs right now
publicAPI.buildPrimitives = () => {
const poly = model.currentInput;

const device = model.WebGPURenderWindow.getDevice();

model.renderable.mapScalars(poly, 1.0);

// handle triangles
const i = PrimitiveTypes.Triangles;

const points = poly.getPoints();
const numPoints = points.getNumberOfPoints();
const pointArray = points.getData();
const primHelper = model.primitives[i];

// default to one instance and computed number of verts
primHelper.setNumberOfInstances(1);
primHelper.setNumberOfVertices(3 * numPoints);

const vertexInput = model.primitives[i].getVertexInput();

let buffRequest = {
hash: points.getMTime(),
source: points,
time: points.getMTime(),
usage: BufferUsage.RawVertex,
format: 'float32x3',
};
if (!device.getBufferManager().hasBuffer(buffRequest)) {
// xyz v1 v2 v3
const tmpVBO = new Float32Array(3 * numPoints * 3);

let pointIdx = 0;
let vboIdx = 0;
for (let id = 0; id < numPoints; ++id) {
pointIdx = id * 3;
tmpVBO[vboIdx++] = pointArray[pointIdx];
tmpVBO[vboIdx++] = pointArray[pointIdx + 1];
tmpVBO[vboIdx++] = pointArray[pointIdx + 2];
tmpVBO[vboIdx++] = pointArray[pointIdx];
tmpVBO[vboIdx++] = pointArray[pointIdx + 1];
tmpVBO[vboIdx++] = pointArray[pointIdx + 2];
tmpVBO[vboIdx++] = pointArray[pointIdx];
tmpVBO[vboIdx++] = pointArray[pointIdx + 1];
tmpVBO[vboIdx++] = pointArray[pointIdx + 2];
}
buffRequest.nativeArray = tmpVBO;
const buff = device.getBufferManager().getBuffer(buffRequest);
vertexInput.addBuffer(buff, ['vertexBC']);
}

// compute offset VBO
const pointData = poly.getPointData();
let scales = null;
if (
model.renderable.getScaleArray() != null &&
pointData.hasArray(model.renderable.getScaleArray())
) {
scales = pointData.getArray(model.renderable.getScaleArray()).getData();
}

const defaultRadius = model.renderable.getRadius();
if (scales || defaultRadius !== model._lastRadius) {
buffRequest = {
hash: scales,
source: scales,
time: scales
? pointData.getArray(model.renderable.getScaleArray()).getMTime()
: 0,
usage: BufferUsage.RawVertex,
format: 'float32x2',
};
if (!device.getBufferManager().hasBuffer(buffRequest)) {
const tmpVBO = new Float32Array(3 * numPoints * 2);

const cos30 = Math.cos(vtkMath.radiansFromDegrees(30.0));
let vboIdx = 0;
for (let id = 0; id < numPoints; ++id) {
let radius = model.renderable.getRadius();
if (scales) {
radius = scales[id];
}
tmpVBO[vboIdx++] = -2.0 * radius * cos30;
tmpVBO[vboIdx++] = -radius;
tmpVBO[vboIdx++] = 2.0 * radius * cos30;
tmpVBO[vboIdx++] = -radius;
tmpVBO[vboIdx++] = 0.0;
tmpVBO[vboIdx++] = 2.0 * radius;
}
buffRequest.nativeArray = tmpVBO;
const buff = device.getBufferManager().getBuffer(buffRequest);
vertexInput.addBuffer(buff, ['offsetMC']);
}
model._lastRadius = defaultRadius;
}

model.renderable.mapScalars(poly, 1.0);

// deal with colors but only if modified
let haveColors = false;
if (model.renderable.getScalarVisibility()) {
const c = model.renderable.getColorMapColors();
if (c) {
buffRequest = {
hash: c,
source: c,
time: c.getMTime(),
usage: BufferUsage.RawVertex,
format: 'unorm8x4',
};
if (!device.getBufferManager().hasBuffer(buffRequest)) {
const colorComponents = c.getNumberOfComponents();
if (colorComponents !== 4) {
vtkErrorMacro('this should be 4');
}
const tmpVBO = new Uint8Array(3 * numPoints * 4);
let vboIdx = 0;
const colorData = c.getData();
for (let id = 0; id < numPoints; ++id) {
const colorIdx = id * colorComponents;
for (let v = 0; v < 3; v++) {
tmpVBO[vboIdx++] = colorData[colorIdx];
tmpVBO[vboIdx++] = colorData[colorIdx + 1];
tmpVBO[vboIdx++] = colorData[colorIdx + 2];
tmpVBO[vboIdx++] = colorData[colorIdx + 3];
}
}
buffRequest.nativeArray = tmpVBO;
const buff = device.getBufferManager().getBuffer(buffRequest);
vertexInput.addBuffer(buff, ['colorVI']);
}
haveColors = true;
}
}
if (!haveColors) {
vertexInput.removeBufferIfPresent('colorVI');
}

primHelper.setPipelineHash(publicAPI.computePipelineHash(vertexInput));
primHelper.setWebGPURenderer(model.WebGPURenderer);
primHelper.setTopology('triangle-list');
primHelper.build(model.renderEncoder, device);
primHelper.registerToDraw();
};
}

// ----------------------------------------------------------------------------
// Object factory
// ----------------------------------------------------------------------------

const DEFAULT_VALUES = {};

// ----------------------------------------------------------------------------

export function extend(publicAPI, model, initialValues = {}) {
Object.assign(model, DEFAULT_VALUES, initialValues);

// Inheritance
vtkWebGPUPolyDataMapper.extend(publicAPI, model, initialValues);

model.primitives[PrimitiveTypes.Triangles].setVertexShaderTemplate(
vtkWebGPUSphereMapperVS
);

// Object methods
vtkWebGPUSphereMapper(publicAPI, model);

const sr = model.primitives[PrimitiveTypes.Triangles].getShaderReplacements();
sr.set('replaceShaderPosition', publicAPI.replaceShaderPosition);
sr.set('replaceShaderNormal', publicAPI.replaceShaderNormal);
}

// ----------------------------------------------------------------------------

export const newInstance = macro.newInstance(extend, 'vtkWebGPUSphereMapper');

// ----------------------------------------------------------------------------

export default { newInstance, extend };

// Register ourself to WebGPU backend if imported
registerOverride('vtkSphereMapper', newInstance);