Forest Pack Effects

Report: Forest Pack Effects – Advanced Scattering Control

Part 6: Writing Your First Custom Effect (Simplified)

If you are intimidated by code, don't be. Forest Pack uses a simple syntax. Let’s build a Color Variation Effect.

Goal: Make trees greener near water, browner away from water.

Setup:

Load a Distance map (where white is the river, black is far away).
Create a new Effect.

The Code:

-- Get the distance value (0 to 255 from the map)
Value = getMapValue(ft_DistanceMap, self.position.x, self.position.y)
-- Remap the value to a tint strength (0 = dry, 1 = wet)
Tint = Value / 255
-- Apply the tint to the material (Simplified)
self.tintColor = lerp([0.5, 0.3, 0.1], [0.1, 0.6, 0.2], Tint)

Result: Trees near the water are lush green; trees on the hilltops are dry brown. Done.

2.3 The Proximity Effect (Forest Ecology)

This is the "Goldilocks" effect. In dense forests, trees closest to each other compete for light.

The Effect: Calculate the distance to the nearest neighbor. If distance is less than 2 meters, scale the tree by 50% (spindly, starved tree). If distance is greater than 5 meters, scale by 120% (mighty oak).
The Visual Result: Natural glades and clustering. Your forest has "breathing room" that looks organic, not mechanical.

1. The Micro-Climate Effect (Ambient Occlusion)

A single tree has simple shadows. A forest pack has cascading occlusion. By enabling "Global Lighting" and "Thin Shadows" within Forest Pack’s effects rollout, you create a natural gradient of light. forest pack effects

How it looks: The center of the forest is dark green/teal (due to bounced light), while the edges are warm yellow/green. This depth cue tricks the brain into perceiving volume.

1. Overview

Forest Pack Pro is a scattering tool for 3ds Max used to create vast forests, crowds, or detailed environments. Forest Pack Effects is a built-in feature set that allows users to control scattered objects (trees, rocks, people, cars) using mathematical expressions, maps, or custom scripts—going far beyond simple random distribution.

Effects provide dynamic, non-destructive control over position, scale, rotation, color, and visibility of every scattered item based on user-defined rules.