pDirectionalForce Node

pDirectionalForce adds a constant force vector to every particle on every frame. Unlike pPointForce (attraction toward a point) or pVortex (rotation around a center), this force is uniform everywhere in the scene.

It is the force used for gravity (Direction -90° on Y, adjusted Strength), wind (horizontal Direction), or any global acceleration phenomenon.

• Effects Library: Tools > Particles > pDirectionalForce
• Quick add: right-click in the Node Editor → Add Tool > Particles > pDirectionalForce

• Particle Input (orange) - output of a particle node.
• Region Input (green/magenta) - optional. Limits the force to an area (bitmap or 3D mesh). Without a Region, the force applies everywhere in the field.

Standard gravity:
pEmitter → pDirectionalForce (Strength 0.01, Direction -90° Y) → pRender
(particles accelerate downward)

Strong horizontal wind:
pEmitter → pDirectionalForce (Strength 0.02, Direction 0° X) → pRender
(particles pushed sideways)

Wind zone inside a tunnel:
pEmitter → pDirectionalForce ← Shape 3D (cube as a tunnel)
        → pRender
(wind only inside the cube, particles outside are not affected)

Reverse gravity + turbulence (fire):
pEmitter → pDirectionalForce (Strength 0.01, Direction +90° Y rising)
        → pTurbulence
        → pRender

Strength

Amplitude of the force. Positive = in the chosen direction, negative = the opposite direction. 0.01 = weak (dust), 0.05+ = strong gravity/wind.

X / Y Direction

Angle of the force in the horizontal/vertical plane. Default -90° Y = downward (classic gravity).

Z Direction

Depth component. 0 = force in the XY plane. +/- to add depth (e.g. wind pushing toward the camera).

Randomize

Randomizer seed for subtle variations (when enabled in some options).

Conditions (Sets)

The force only applies to certain sets. Useful when you have "snow" particles (gravity) and "smoke" particles (no gravity) in the same comp.

• Standard gravity (rain, snow, falling) - Strength 0.005-0.02, Direction -90° Y. Essential for any falling particle.
• Horizontal wind - Direction 0° X, Strength set by the wind intensity you want. Often combined with gravity.
• Reverse gravity (fire, smoke rise) - Direction +90° Y = particles rise. Simulates heat making the air rise.
• Sudden gust - Strength animated (0 → peak → 0) over 20 frames = a gust of wind that suddenly pushes.
• Water current - a downward diagonal Direction + moderate Strength = a simulated river carrying particles away.
• Directional explosion - a brief high Strength + a Direction opposite the center = particles thrown far in the direction you want.
• Localized wind zone (tunnel) - Region Shape 3D Cube = wind only in a precise area; particles that enter are pushed, those outside are not.

• Realistic Strength: 0.005-0.02 for gravity. Beyond that, particles accelerate too fast and look unrealistic.
• Always combine with pFriction - real gravity is countered by the air (friction). Without pFriction, particles accelerate forever.
• Direction -90° Y by default = a classic fall. For sideways wind, switch to 0° X or 180° X (right or left).
• Animate Strength for intermittence - wind blowing in gusts, gravity disappearing in zero-g, etc.
• Several stacked pDirectionalForce nodes - gravity (negative Y) + wind (positive X) = particles that fall while being pushed.
• Sets for selectivity - snow on Set 1 with gravity, smoke on Set 2 without gravity (but with reverse heat gravity) - two pDirectionalForce nodes with different Conditions.
• For non-uniform forces (attraction toward a point, vortex), use pPointForce or pVortex - pDirectionalForce is uniform everywhere.