Particle trace report

In order to debug particle systems, HH-Fx designer provides a few tools. One of these tools is the trace report. It allows you, at any time, to inspect individual particle's properties, using mouse-picking in the realtime viewport. It can be a powerful aid when used in conjunction with the particle history, allowing you to trace and inspect previous frames, in case you spotted a glitch and want to make sure where it came from.

(you can also see the trace report video tutorial)

Overview

To use the tool, you just need to pause the effect, and left-click on the particle you wish to inspect, in the realtime viewport. The values of all its fields will appear in the "TraceReport" panel, located on the top-left corner of the default layout, along with the "Node Properties" and "Environment" panels:

You cannot currently edit these values directly, It might be implemented in a future release of the editor.

Multi-Pick

The picked particle will have red outlines rendered (matching its billboard's triangles). However, unless the particle system is very sparse, there most likely won't be a single particle picked. All particles hit by the picking ray will be highlighted with light white outlines.

You can cycle through all traced particles by repeatingly left-clicking on the same spot. If you move the mouse between two clicks, a whole new trace will be cast, and cycling will start over.

The ray used for picking is also rendered as a bright red line, due to projection on the screen plane, it appears as a single dot, but you can visualize it better by moving the camera around:

Trace filtering

Picking is affected by layer visibility. That can be useful if you wish to isolate a specific layer out of a big mess.

In the example below (the Blast.hfx, coming in the default FX sample package), we trace the 11 different layers (8 main layers + 3 sub-layers that are trail spawners in the 'Debris_Smoking' layer).

The result is pretty horrifying, and it can be tedious to isolate a specific particle:

If we hide the layers we're not interested in, we can pick only the smoke trails layers, and the result is much easier to work with: