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Camera Path

A camera path is a keyframed fly-through defined entirely within this sample. It can be authored in the UI, is copy/paste friendly, and can be provided on the command line just like the camera string. Its main purpose is deterministic benchmarking: with fixed-step playback the camera visits the exact same positions every run, independent of frame rate or GPU speed.

UI (Misc Settings → Camera Paths):

  • File: Save / Load write and read all paths to a text file stored next to the model file, named after it (<model>.camerapaths.txt, shown under the buttons). This file is auto-loaded whenever that scene is loaded.
  • Path: New / Delete add or remove a path, Copy / Paste exchange the selected path with the clipboard as a string; the dropdown below selects the active path (the index used by --runcamerapath).
  • Key: New captures the current camera as a keyframe (inserted after the selected one); Update / Delete edit the selection. The list below shows the keyframes — selecting one previews it.
  • Smooth uses Catmull-Rom interpolation (otherwise piecewise linear), Loop and Duration (s) affect real-time playback. When Loop is on and the first and last keyframes coincide, the smoothing wraps around the join for a seamless loop.
  • Play / Stop / Restart and the t slider drive a real-time preview.
  • Run fixed plays the path across Fixed frames frames, exactly as --runcamerapath does.

Command line / benchmarking:

Paths are defined with one or more --addcamerapath options; the index equals the order in which they were added (the first is 0). --loadcamerapaths "file.txt" instead replaces the whole set with the paths from a text file (see the format below). Paths given on the command line are global and take precedence: when any are present the per-scene <scene>.camerapaths.txt file is not auto-loaded. --runcamerapath <index> <framecount> then spreads the selected path across exactly <framecount> rendered frames (frame f maps to path position f / (framecount-1)), so it is fully deterministic.

Note: the per-scene file is loaded only after its scene finishes loading (which is asynchronous), so a command-line --runcamerapath at startup cannot reference it yet. For benchmarking either provide the path on the command line with --addcamerapath / --loadcamerapaths, or place --runcamerapath inside the sequences of a --sequencefile (which run after the scene is resident).

For benchmarking, put --runcamerapath in each sequence and match --sequenceframes to the frame count. For example a sequence script (--sequencefile bench.txt):

SEQUENCE "flythrough raytrace"
--renderer 1
--runcamerapath 0 256

SEQUENCE "flythrough raster"
--renderer 0
--runcamerapath 0 256

with the path stored in a file flythrough.camerapaths.txt:

smooth 1 loop 0 dur 10 ;
  {0, 2, 5}, {0, 0, 0}, {0, 1, 0}, {60} ;
  {5, 2, 0}, {0, 0, 0}, {0, 1, 0}, {60} ;
  {0, 2, -5}, {0, 0, 0}, {0, 1, 0}, {60}

run with:

vk_lod_clusters --sequenceframes 256 --loadcamerapaths flythrough.camerapaths.txt --sequencefile bench.txt

String format (also valid inside .cfg files as a single-line, quoted value): an optional header of smooth <0/1> loop <0/1> dur <seconds>, followed by ;-separated keyframes each written as {eye}, {center}, {up}, {fov} (the per-keyframe fov is optional). The Copy button produces this canonical form. In the paths file a path may span any number of lines and is parsed until the next path begins (each path starts with the smooth header keyword); anything from a # to the end of a line is a comment.