The aim of this repo is to serve as a "tutorial" in how to set
up a full Scene - i.e., OptiX Context, Module, Programs, Pipeline,
Shader Binding Table (SBT), Accel Struct (AS), Build Inputs, Texture
Samplers, etc., in the newly introduced OptiX 7.
To do this, this repo intentionally does not provide one example
that has the final code, but instead is split into 12 smaller
examples, each of which modifies and extends the previous one,
hopefully in a way that it is relatively easy to spot the differences
(i.e., to spot what exactly had to be added to go from "A" to "B").
Note this tutorial does (intentionally) not end in a
overwhelming-wow-factor full-featured renderer - its aim is to only
help you get started with OptiX 7, exactly up to the point where
"Textbook Ray Tracing 101" would usually kick in.
With that - enjoy!
PS: I tried my best to make sure that code is correct, and will work
out of the box in both Linux and Windows. However, I assume it's safe
to expect that some one or other bug has crept in somewhere that I
haven't found yet. If you do find one, please feel free to let me know
via email or bug report, or send a push request, so others will be
spared from finding it again. Any other feedback is welcome, too!
Building the Code
This code was intentionally written with minimal dependencies,
requiring only CMake (as a build system), your favorite
compiler (tested with Visual Studio 2017 and 2019 under Windows, and GCC under
Linux), and the OptiX 7 SDK (including CUDA 10.1 and NVIDIA driver recent
enough to support OptiX).
Dependencies
a compiler
On Windows, tested with Visual Studio 2017 and 2019 community editions
On Linux, tested with Ubuntu 18 and Ubuntu 19 default gcc installs
CUDA 10.1
Download from developer.nvidia.com
on Linux, suggest to put /usr/local/cuda/bin into your PATH
latest NVIDIA developer driver that comes with the SDK
on linux, suggest to set the environment variable OptiX_INSTALL_DIR to wherever you installed the SDK. export OptiX_INSTALL_DIR=<wherever you installed OptiX 7.0 SDK>
on windows, the installer should automatically put it into the right directory
The only external library we use is GLFW for windowing, and
even this one we build on the fly under Windows, so installing
it is required only under Linux.
Detailed steps below:
Building under Linux
Install required packages
on Debian/Ubuntu: sudo apt install libglfw3-dev cmake-curses-gui
git clone https://gitlab.com/ingowald/optix7course.git
cd optix7course
create (and enter) a build directory
mkdir build
cd build
configure with cmake
Ubuntu: cmake ..
CentOS 7: cmake3 ..
and build
make
Building under Windows
Install Required Packages
see above: CUDA 10.1, OptiX 7 SDK, latest driver, and cmake
download or clone the source repository
Open CMake GUI from your start menu
point "source directory" to the downloaded source directory
point "build directory" to /build (agree to create this directory when prompted)
click 'configure', then specify the generator as Visual Studio 2017 or 2019, and the Optional platform as x64. If CUDA, SDK, and compiler are all properly installed this should enable the 'generate' button. If not, make sure all dependencies are properly installed, "clear cache", and re-configure.
click 'generate' (this creates a Visual Studio project and solutions)
click 'open project' (this should open the project in Visual Studio)
Examples Overview
Example 1: Hello World
This is simplest example, that only initializes the OptiX Library,
prints "hello world", and exits. It's pretty much testing only whether
your SDK, driver, and PATH/LD_LIBRARY_PATH are properly set up to
build, link, and run this tutorial.
This is how this should look like in Linux:
And here, in Windows:
Note: if you do not see this output file, you may have a driver that
does not work properly with OptiX 7 or some other cause. Normally the
console window will disappear before you can see the error. To run and
see the console window's messages, use the Visual Studio option "Start
Without Debugging" (or hit Ctrl+F5), which will keep the console window
visible after exit. The other option (or for Linux) is to run the program
in a console window, e.g., run build\Debug\ex01_helloOptix.exe
Example 2: First Pipeline Setup and Raygen Program
This is the first "real" OptiX example, and maybe somewhat
surprisingly, the biggest "step" in all the examples.
The actual raygen program that this example launches is actually
very (!) small, and pretty much trivial; and there are no other programs,
not even geometry, nor a single ray being traced ... but to launch
this simple raygen program we nevertheless have to go through the
entire process of creating Modules, Programs, and, in particular, a
valid "Shader Binding Table" (SBT), before we can launch our little
raygen sample.
On the upside: Once this initial setup is done, everything will get
much simpler in the following examples.
Example 3: Rendering in a GLFW Window
Rendering to files is nice and well, but probably you want to
eventually do some online rendering; so this example moves the
previous raygen example into a 3D viewer window (created and run using
GLFW). For now this viewer just displays the rendered images, with no
user interaction.
Example 4: Creating a first Triangle Mesh and Accel Struct
Though the previous setup steps were important to get right, eventually
you want to use a ray tracer to trace some real rays against some
real geometry.
This example introduces how to create some Triangle Mesh Geometry (in
this example, two simple, hardcoded, cubes), how to build an
Acceleration Structure over this "BuildInput", and how to trace rays
against it. To do this we also need to introduce a simple camera model.
Example 5: First Shader Binding Table (SBT) Data
The earlier examples created an SBT (they had to, else they couldn't
have executed any OptiX launch), but didn't actually put any data into
the SBT. This example introduces how to do that, by putting just some
simple constant per-object color into the mesh's SBT entry, then shading
it based on the surface normal's angle to the view ray.
Example 6: Multiple Triangle Meshes
This example introduces the concept of having multiple different
meshes (each with their own programs and SBT data) into the same accel
structure. Whereas the previous example used two (same color) cubes in
one triangle mesh, this example split this test scene into two
meshes with one cube (and one color) each.
Example 7: First Real Model
This example takes the previous "multiple meshes" code unmodified, but
introduces a simple OBJ file format parser (using Syoyo Fuyita's
tinyobj, and hooks the resulting triangle meshes up to
the previous example's render code.
For this example, you must download the Crytek Sponza model and unzip it to the (non-existent, until you create it) subdirectory optix7course/models.
And la-voila, with exactly the same render code from Sample 6, it
suddenly starts to take shape:
Example 8: Adding Textures via CUDA Texture Objects
This example shows how to create and set up CUDA texture objects on
the host, with the host passing those to the device via the SBT, and how to use
those texture objects on the device. This one will take a bit of time
to load in Debug - it's worth the wait! Or simply build and run in Release.
Example 9: Adding a second ray type: Shadows
This is the last example that focuses on host-side setup, in this
case adding a second ray type (for shadow rays), which also requires
changing the way the SBT is being built.
This sample also shows how to shoot secondary rays (the shadow rays)
in device programs, how to use an any-hit program for the shadow rays,
how to call optixTerminateRay from within an any-hit program, and how
to use the optixTrace call's SBT index/offset values to specify the
ray type.
Example 10: Soft Shadows
Whereas the first 9 examples focused on how to perform all the
required host-side setup for various incremental features, this
example can now start to focus more on the "ray tracing 101" style
additions that focus what rays to trace to add certain rendering
effects.
This simple example intentionally only adds soft shadows from area
lights, but extending this to add reflections, refraction, diffuse
bounces, better material models/BRDFs, etc., should from now on be
straightforward.
Please feel free to play with adding these examples ... and share what
you did!
Example 11: Simple Denoising (LDR, color only)
This example takes the code from the previous example and simply runs
the optix denoiser on the final frame (ie, color) buffer computed by
this optix launch. It does not store any albedo or normal buffers,
not compute HDR intensity, etc.
To fully see the impact of denoising without progressive resampling,
feel free to turn denoising and/or progressive refinemnt on and off
via the 'd' (denoising) and 'a' (accumulate) keys.
Example 11, single sample per pixel, no denoising:
The same, with denoiser turned on:
Example 12: Denoising with HDR and separate Normal Channel
This example improves on the simple denoising by computing
a separate normal buffer (which improves the denoiser quality), and
by doing denoising in HDR, with an added gamma pass after denoising.
As with example 11, to fully see the impact of denoising without
progressive resampling, feel free to turn denoising and/or progressive
refinemnt on and off via the 'd' (denoising) and 'a' (accumulate)
keys.
Example 12, single sample per pixel, no denoising:
The same, with denoiser turned on:
Example 13: It's up to you ...
From here on, there are multiple different avenues of how to add to
this simple viewer, in terms of visual features, performance, kind
and complexity of geometry, etc. In no particular order, and just
to serve as inspiration:
Performance
Multi-GPU
Denoising
Better random numbers, better sampling, importance sampling, ...
...
Shading Effects
More/better light sources (eventually with importance sampling for multiple lights!)
Better camera model, with depth of field
Alpha/Transparency Textures for Cut-outs (Tip: often used in landscape scenes)
Better material model / BRDF
Indirect Illumination / path tracing
...
Geometry-related Capabilities
Instancing, possibly multi-level instancing
Animation
Motion Blur
...
Viewer/app extensions
Camera motion based on user input
More importers (PBRT parser?)
Picking and editing
...
Whichever of these - or other - features you might want to play around with: Let me know how it works out ... and have fun doing it!
