/owlGlyphs-RTXGlyphsRayTracing-PGV2020

Sample Code for our EGPGV 2020 Paper on "High-Quality Rendering of Glyphs Using Hardware-Accelerated Ray Tracing"

Primary LanguageC++Apache License 2.0Apache-2.0

owlGlyphs: Sample Code for the "Ray Tracing Glyphs with RTX" Project

Context/Reference

This sample code is in regards to a project that used OWL to evaluate the feasibility and performance of RTX-Accelerated ray tracing for Glyph-based data visualization.

Citation for the corresponding paper:

High-Quality Rendering of Glyphs Using Hardware-Accelerated Ray Tracing, Stefan Zellmann, Martin Aumueller, Nathan Marshak, and Ingo Wald, Proceedings of Eurographics Parallel Graphics and Visualization (Short Papers), 2020.

Requirements/Dependencies

This project uses OWL, and should be checked out with owl as a submodule. To do so, use the --recursive flag when cloning this repository; alternatively, if you forgot this you can also pull the submodules via

	git submodule init
	git submodule update

which should also end up fetching the correct version of OWL.

To build, you also need the typical OWL dependencies, ie, a C++ 11 compatible compiler, CUDA, and OptiX (version 7 or newer). Both windows and linux should be supported.

Building

Using cmake, this project should build on both linux and windows. If you're not familiar with cmake, it is suggested to follow OWL's instructions to first build the samples that come with OWL, then repeat the same steps here.

Guide to the Source Code

The following files/classes implement the glyph types we presented in the paper. FileName.h and FileName.cpp contain the OWL host code and device/FileName.cu contain the respective OptiX 7 device programs.

Arrow glyphs

This is an example of a non-affine glyph; i.e. the glyph cannot just be transformed with the instance transform, so the geometry is stored in extra buffers.

ArrowGlyphs.h ArrowGlyphs.cpp device/ArrowGlyphs.cu

Simple sphere glyphs

Sphere glyphs are "affine glyphs", i.e. under transformation they can become general ellipsoids and that behavior is desired

SphereGlyphs.h SphereGlyphs.cpp device/SphereGlyphs.cu

Motion blur glyphs

This is a sphere glyph, but the geometry of the glyph is non-affine, and instead it is spread out and blurred over the extent defined by its instance bounds according to the link velocity and link acceleration

MotionSpheres.h MotionSpheres.cpp device/MotionSpheres.cu

Super quadric glyphs

This is a more involved glyph that uses a Newton/Rhaphson solver to compute ray/superquadric intersections. The glyph types implements a trick, as it doesn't use the bounding box or bounding sphere as an initial root estimate, but rather a coarse tessellation. The intersection with that tessellation is computed using hardware-accelerated ray/triangle intersections.

SuperGlyphs.h SuperGlyphs.cpp device/SuperGlyphs.cu

Viewer Controls

After building is complete, you should end up with an executable ./owlGlyphs or owlGlyphs.exe.

Using the test data set from the root dir of this repo just start with ./owlGlyphs testdata.glyphs.

Arrow glyphs:
cmdline: --arrows | -arr
 Sphere glyphs:
cmdline: --spheres | -sph
Motion blur glyphs:
cmdline: --motionblur | -mb
 Super quadric glyphs:
cmdline: --super | -spr

Keystrokes:

  • ! : dump screenshot
  • H : enable/disable heatmap
  • </> : change heatmap scale up/down
  • C : dump current camera
  • +/- : change mouse motion speed
  • I: enter 'inspect' mode
  • F: enter 'fly' mode

Mouse:

  • left button: rotate
  • middle button: strafe
  • right button: forward/backward

Third-Party Code

The owlGlyphs program can optionally load triangle models in wavefront obj format (cmdline: -obj <file.obj>). For that we use tinyobjloader which is included as source code. Tinyobjloader's licence is MIT

We use code for ray/quadric intersection testing by Inigo Quilez. Those tests can be found on shadertoy: ray/cylinder test, ray/rounded cone test. License is MIT