Parallel rendering support

Notes for !3026

VTKH: Render --> Plot ?

• Data members:
• vtkm::rendering::CanvasRayTracer Canvas
• vtkm::rendering::Camera
• Width, Height, Bounds
• FG and BG colors
• Image name
• Other Methods
• Set World/Scene Annotations
• Set Shading
• SetComments

Scene

• Data Members:
• list vtkh::Renderer*
• vector vtkh::Render

Renderer (e.g., RayTracer, VolumeRenderer, etc)

• Data Members:
• Input, Output
• Compositor
• Mapper
• vector vtkh::Render Renders

Code:

• vtkm::rendering::Camera camera;
• vtkh::Render = vtkh::MakeRender(w,h, bounds, camera, imageName);
• vtkh::RayTracer tracer;
• • tracer.SetInput()
• • tracer.SetField()
• vtkh::Scene scene;
• • scene.AddRender(render);
• • scene.AddRenderer(&tracer);
• • scene.Render();

vtkm::rendering::Actor

• DataMembers:
• • Cells, coords, field, colortable

vtkm::rendering::Scene

• vector Actors;

vtkm::rendering::View3D

• vtkm::rendering::Scene
• vtkm::rendering::Camera
• vtkm::rendering::Mapper *
• vtkm::rendering::Canvas *
• vtkm::rendering::WorldAnnotator *
• vtkm::rendering::TextAnnotation

Code:

• vtkm::rendering::Camera camera;
• vtkm::Actor actor(ds, field, colorTable);
• vtkm::rendering::Scene scene
• • scene.AddActor(actor);
• vtkm::rendering::CanvasRayTracer canvas;
• vtkm::rendering::MapperRayTracer mapper;
• vtkm::rendering::View3D view(scene, mapper, canvas, camera, bg);
• • view.Paint();
• • view.SaveAs("output.png");

Tasks: If Renderer::Mapper can move to Render, then a Render is close to a vtkm::View

Moving Renderer::Mapper to vtkh::Render:

Renderer::DoExecute() -- needs to get the mapper. --DoExecute: pass in Render (View)

VTKM callstack:

• View::Paint()
• • this->GetCanvas().Clear()
• • this->RenderAnnotations()
• • this->GetScene().Render(this->GetMapper(), this->GetCanvas(), this->GetCamera())
• • • Scene::Render(mapper, canvas, camera)
• • • • for (auto actor : this->Actors)
• • • • • actor.Render(mapper, canvas, camera)
• • • • • • mapper.SetCanvas(canvas)
• • • • • • mapper.SetActiveColorTable(this->colortable)
• • • • • • mapper.RenderCells(...)

VTKH callstack:

• Scene::Render()
• • for (render : this->Renders)
• • • render.GetCanvas.Clear()
• • • for (renderer : this->Renderers)
• • • • renderer->SetComposite(...)
• • • • renderer->SetRenders({render})
• • • • renderer->Update() / renderer->DoExecute()
• • • • • for (ds : this->Input->GetPartitions())
• • • • • • for (render : this->Renders)
• • • • • • • this->SetShading(render->GetShading()) ....
• • • • • • • • this->Mapper->SetActiveColorTable(this->ColorTable)
• • • • • • • • camera = render.GetCamera()
• • • • • • • • canvas = render.GetCanvas()
• • • • • • • • this->Mapper->SetCanvas(canvas)
• • • • • • • • this->RenderCells(ds, this->ColorTable, camera, this->Range)
• • • • renderer: this->Composite()

Updates: Most of the functionality of the vtkm::rendering::Actor was inside of vtkh::Renderer. vtkh::Renderer now contains an Actor. All of the access to datasets, field name, colortable is held in the Actor.

Right now the Mapper is in vtkh::Renderer as well. Having it in the Renderer might make sense.

Next steps:

Notes from discussion with @mmathai

1. Render ---> Plot: DONE
2. Actor and Mapper can be together : DONE (removed Mapper from Plot)
3. Actor needs materials
4. Scene: List of Render/Plot, Lights, global stuff (background/env map/skybox)
5. Render/Plot: has a list of Renderers.
6. Renderer: Actor + Mapper. std::vector<std::pair<Actor, Mapper>>

Future:

• custom mappers that can be easily plugged into the system.
• Actor access to more things (e.g., computed normals, etc)
• • be able to set properties in the Actor that can go to the mapper.
• • group the properties. Normal: field, Emmisive: field, .....
• How to pass global information into the mapper (lights, background, etc).
• • Fixed API might be ok: SetLights(), SetSkyBox(), etc.

Post Actor changes:

VTKH: Render --> Plot ?

• Data members:
• vtkm::rendering::CanvasRayTracer Canvas
• vtkm::rendering::Camera
• Width, Height, Bounds
• FG and BG colors
• Image name
• Other Methods
• Set World/Scene Annotations
• Set Shading
• SetComments

Scene

• Data Members:
• list vtkh::Renderer*
• vector vtkh::Render

Renderer (e.g., RayTracer, VolumeRenderer, etc)

• Data Members:
• • Actor
• • Compositor
• • Mapper
• • vector vtkh::Render Renders

Code:

• vtkm::rendering::Camera camera;
• vtkh::Render = vtkh::MakeRender(w,h, bounds, camera, imageName);
• vtkh::RayTracer tracer;
• • tracer.SetInput()
• • tracer.SetField()
• vtkh::Scene scene;
• • scene.AddRender(render);
• • scene.AddRenderer(&tracer);
• • scene.Render();

Scene::Render()

• Cinema batch is on this->Renders
• foreach r : this->Renders
• • foreach R : this->Renderers
• • • R.Update()

Render --> Plot

Scene::Render()

• batch on this->Plots.size()

• assume batchsize is 1.

• for plot in this->Plots :
• • plot.GetCanvas().Clear();
• • numRenderers / opaqueRenderers = this->Renderers.size()
• • //opaque pass
• • for renderer in opaqueRenderers :
• • • if last rendererer: renderer->SetDoComposite(true); else false;
• • • renderer->SetPlots(current_batch)
• • • renderer->Update()
• • • renderer->ClearPlots()
• • if (this->HasVolume)
• • • synch_depths if needed.
• • • renderer->SetDoComposiste(true);
• • • renderer->SetPlots(current_batch)
• • • renderer->Update()
• • if (do_once)
• • • for r : this->Renderers
• • • • Add ranges (r->GetScalarRange)
• • • • Add field names
• • • • Add colortables
• • //render screen annotations.
• • foreach plot : current_batch
• • • plot.RenderWorldAnnotations()
• • • plot.RenderScreenAnnotations()
• • • plot.RenderBackground()
• • • plot.Save()

cinema: image saving is the issue...

Summary of changes.

Current interface:

• vtkm::cont::PartitionedDataSet input = ...
• vtkm::rendering::Camera camera;
• //set camera parameters
• vtkm::rendering::Actor(input, fieldName, colorTable);
• vtkm::rendering::Scene scene;
• vtkm::rendering::CanvasRayTracer canvas(512,512);
• scene.AddActor(actor);
• vtkm::rendering::View3D view(scene, vtkm::rendering::MapperVolume(), canvas, camera, bg);
• view.Paint();

New interface:

• vtkm::cont::PartitionedDataSet input = ...
• vtkm::rendering::Camera camera;
• //set camera parameters
• vtkm::rendering::Actor actor(pds, fieldName, colorTable);
• vtkh::VolumeRenderer tracer;
• tracer.SetInput(actor);
• vtkh::Plot plot = vtkh::MakePlot(512, 512, camera, pds, imgName);
• plot.AddRenderer(&tracer);
• vtkh::Scene scene;
• scene.AddPlot(plot);
• scene.Render();

VTKh classes:

vtkm::rendering::Actor

• Contains vtkm::cont::PartitionedDataSet

vtkm::rendering::vtkh::Scene

• std::vector<vtkm::rendering::vtkh::Plot> Plots;
• void Render();

vtkm::rendering::vtkh::Plot

• Camera
• std::vector<vtkm::rendering::vtkh::Renderer*> Renderers;
• vtkm::rendering::CanvasRayTracer
• Annotations

vtkm::rendering::vtkh::Renderer

• vtkm::rendering::Actor Actor;
• vtkm::rendering::Mapper Mapper
• vtkm::rendering::vtkh::Compositor Compositor

VTKm classes:

vtkm::rendering::Scene

• std::vector<vtkm::rendering::Actor> Actors;

vtkm::rendering::View

• vtkm::rendering::Scene
• vtkm::rendering::Mapper
• vtkm::rendering::Canvas
• vtkm::rendering::WorldAnnotator
• vtkm::rendering::TextAnnotation
• vtkm::rendering::Camera
• void Paint();

Discussion at Hackathon: Intended audience. VTK-m is not going to be a high-end renderer or have all the complexity to replace the renderers in ParaView, VisIt, etc. To do this we need to place bounds on the goals of the rendering system. We envision three different use cases:

• Provide a way to render the results created using VTK-m.
• Tested for research into GPU-accelerated rendering
• Renderer for Ascent who want a dependency-free renderer.

As such this will limit the scope of the rendering system.

Two main tasks: Good class names (API), and better support for multi-pass rendering.

ANARI:

ANARIActor

• CellSet, Coordinates, Field

ANARIMapper

• Actor, colorTable, Name

ANARIScene

• World
• std::vector of {Mapper, ShowFlag}

Camera

• pos, dir, up, etc. Frame
• image size, camera, renderer (options),

Run it: anari_cpp::render(d, frame);

Question: What is the setAndRelease()? Called on a world and given a mapper. World had a named mapper. the 1D array means the world can have a list of mappers with that name.

Volume example

• world = ANARIWorld();
• actor = ANARIActor(dataset, field);
• volMapper = ANARIVolumeMapper(actor);
• world.AddMapper(volMapper);
• camera = ANARICamera(pos, dir, up, etc);
• frame = ANARIFrame(camera, imgSize, world, etc);
• ANARIrender(frame);

Multi-mapper example

• world = ANARIWorld();
• scene = ANARIScene(world);
• scene.AddMapper(ANARIVolumeMapper(actor1));
• scene.AddMapper(ANARISurfaceMapper(actor2));
• camera = ANARICamera(pos, dir, up, etc);
• frame = ANARIFrame(camera, imgSize, world, etc);
• ANARIrender(frame);

Frame:

• Canvas
• Camera
• Renderer (options)
• World
• • Instance/Group
• • • Surface
• • • Volume
• • • Light

• std::vector<Frame> frames
• foreach f in frames
• • f.render()
• • • SM = world.sortmappers (surface, volume, view, etc) also multi-pass.
• • • foreach m in SM
• • • • m.RenderCells (pass in world to get e.g., lights, other fields, etc)
• • • • composite if needed
• • • render annotations (keep this as independent as possible (let Anari do everything else))

mentioned in issue #802