OptiX Demand Loading Library Change Log

June 30, 2025 ยท View on GitHub

v0.9.4

  • Renamed DemandLoader::unloadResource() to invalidatePage()

v0.9.3

  • The DemandLoader interface now provides a setPageTableEntry method, which is helpful for asynchronous resource request handling. In such an approach ResourceCallback can enqueue a request and return false, indicating that the request has not yet been satisfied. Later, when the request has been processed, setPageTableEntry can called to update the page table. Note that it's not necessary to call this method when requests are processed synchronously: if the ResourceCallback returns true, the page table is automatically updated.

Version 0.9

  • The DemandLoader API has changed to simplify the handling of multiple GPUs and the management of the corresponding CUDA contexts.

    • Previously a single DemandLoader instance managed multipe GPUs, and several methods took a deviceIndex parameter specifying which GPU should be operated on.
    • Now the client application should create a CUDA context and call createDemandLoader() for each GPU.
    • When calling DemandLoader methods, the client application must ensure that the current CUDA context matches the context that was active when that DemandLoader was created.

  • The demand texturing library now supports cascading texture sizes. This feature can be turned on by setting the useCascadingTextureSizes field in the demand loading Options struct. When enabled, cascading texture sizes instantiates hardware sparse textures at a small initial size, and then expands them as needed to fill tile requests. Creating sparse textures in this way has the benefits that:

    • It increases the virtual texture that can be defined in the demand texturing system, from 4 TB to over 100 TB in some scenes.
    • It reduces startup time for scenes with many textures since small sparse textures take less time to instantiate than large ones.

  • The error message was improved when loading a texture sampler fails during request processing.

  • A Tile structure was introduced to clearly distinguish tile coordinates vs. pixel coordinates.

  • A MipMapImageSource adapter was added that adapts a single level image source into a mipmapped image source, using point sampling to generate smaller mip levels.

  • A TiledImageSource adapter was added that adapts a non-tiled image source into a tiled image source by fetching mip levels into a memory buffer and serving tiles from there.

  • The MockOptix google mock class was expanded to cover the entire OptiX API.

  • PNG and JPEG image source tests were enabled when OpenImageIO is available.

  • The Demand Geometry library received some bug fixes related to updating internal data structures.

  • The Demand Material library was extracted from the Demand Geometry Viewer sample.

Version 0.8

The demand loading library was factored into two layers:

  • A layer that deals only in requested page ids
  • A layer that maps requested page ids to textures and resources

This change should not affect clients of the existing demand loading library. Applications that wish to employ their own mapping of requested pages to resources can use the lower layer.

A simple demand load geometry library was added. Instead of loading geometry directly into the scene, the application adds proxies associated with a bounding box. After launch, the demand geometry library reports back which proxies were intersected and the application can use this to load the corresponding geometry. See the DemandGeometry README for details on the API.

The demand loading library now depends on the otk-memory repository, which is a sibling submodule in the optix-toolkit repository.

The ImageSource library now provides an OIIOReader class that wraps OpenImageIO. This allows a wide range of image files to be read, including TIFF, JPEG, and PNG.

  • For best performance, EXR files should be read via CoreEXRReader, not OIIOReader.
  • Use ImageSource::createImageSource to create an appropriate ImageSource based on a filename extension.
  • The OIIOReader class is built only when OpenImageIO is found during CMake configuration.
    • The vcpkg package system is a convenient way to install OpenImageIO and its prerequisites.