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Viewer

Usage

viewer.exe [settings_file]
viewer.exe --help

Argument	Description
`settings_file`	Path to settings.txt (default: `settings.txt`)

Description

The viewer displays output frames from shared memory with calibrated grid line overlays for precision distance measurement. It copies each frame to a local buffer before rendering to avoid tearing from concurrent writes.

Keyboard Controls

Key	Action
`Right Arrow`	Step forward 1 frame
`Left Arrow`	Step back 1 frame
`Down Arrow`	Step forward 7 frames (Shift: 15 frames)
`Up Arrow`	Step back 7 frames (Shift: 15 frames)
`Page Down`	Jump forward 25 frames
`Page Up`	Jump back 25 frames
`1`	Toggle main grid lines on/off
`2`	Toggle sub-meter grid lines on/off
`F1`	Open help documentation
`ESC` or `Q`	Quit

Mouse Controls

Action	Effect
Move cursor	Distance readout updates at cursor position (top-left corner)
Hold right button + move left/right	Fast navigation through the video — move the mouse left to go backward, right to go forward. Scrolls at 3× speed, covering many frames quickly.
Hold right button + Shift + move left/right	Extra-fast navigation at 6× speed for jumping through large sections of video
Scroll wheel	Step forward or backward one frame at a time for precise frame-by-frame navigation

Distance Measurement

When grid lines are enabled, the viewer calculates the distance at the cursor position by:

Finding the two adjacent grid lines that bracket the cursor's vertical position
Projecting the lines to the cursor's Y coordinate using perspective interpolation
Computing the fractional position between the lines
Displaying the result as meters (e.g., "87.3 M")

Accuracy depends on correct grid line calibration.

Grid Line Display Modes

Mode 0 (off) — No grid lines displayed
Mode 1 — Main meter lines only (press 1)
Mode 2 — Sub-meter lines with half-meter markers (press 2)

Window Size

The viewer window size is configurable in settings:

big_window_width=1920
big_window_height=540

The window is resizable at runtime. The SDL3 renderer scales the frame to fit.