SWGhost Saga

Stage 4 makes the ghost come alive. Two SWSinusoid instances drive a gentle horizontal drift and a subtle vertical hover — no new classes needed, just a few lines added to draw().

How It Works

The sketch tracks a base position (ghostBaseX, ghostBaseY) separate from the instantaneous animated position. Each frame, when the ghost is not being dragged:

const etime = millis() / 1000;  // elapsed seconds
ghost.setPosition(
    ghostBaseX + hSin.getValue(etime),
    ghostBaseY + vSin.getValue(etime)
);

Because setPosition() calls _build() internally, every child — body, toes, and eyes — follows automatically.

Sinusoid Parameters

• Horizontal drift (hSin) — amplitude 0.20 user units, period 5 seconds, phase offset 1.5 s so it starts mid-cycle.
• Vertical hover (vSin) — amplitude 0.30 user units, period 3 seconds, phase 0.
• The two periods are intentionally incommensurable (5 and 3 share no common factor below their LCM of 15) so the combined path never exactly repeats within a typical viewing window.

Drag + Animation Coexistence

The ghost remains fully draggable while animating. When the mouse is released, the base position is resynced:

ghostBaseX = ghost.headCenter.x - hSin.getValue(etime);
ghostBaseY = ghost.headCenter.y - vSin.getValue(etime);

This removes the current sinusoid offset from the drop position so the ghost floats smoothly from wherever it lands instead of snapping back.

Controls

• Drag ghost body → move the ghost; animation resumes seamlessly on release.
• Drag a pupil → reposition that pupil independently.
• SPACE → toggle animation on / off.
• Click outside → toggle the grid.

What Changed in the Sketch

Compared to Stage 3 (single-ghost variant), the sketch gains:

• hSin and vSin — two SWSinusoid instances constructed in setup()
• ghostBaseX / ghostBaseY — base position variables
• Three lines in draw() to apply the animation when not dragging
• Base resync in mouseReleased()
• SPACE toggle in keyPressed()

The Road Ahead

Stage 5 will refine the SWGhost API and produce a class reference page. A future lookAt(targetX, targetY) method will aim both pupils at a point simultaneously.