Zero Gravity 6-DOF

Overview

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Zero Gravity 6-DOF is a technical demo focusing on complex physics interactions and 6-Degrees-of-Freedom movement.

Architecture

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The system is structured around a Finite State Machine (FSM) pattern, which cleanly separates movement logic into distinct, manageable states. This approach prevents “spaghetti code” and ensures that physics interactions are handled in a modular, predictable way.

Hybrid Physics Model

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The movement system aims to provide players with a “floaty” sensation while enabling precise climbing across a variety of surfaces.

• Zero-G State: Utilizes a non-kinematic Rigidbody. Movement is force-based, preserving momentum and inertia. Dynamic drag is applied to simulate microgravity and control drifting.
• Climbing State: Switches the Rigidbody to isKinematic = true. Movement is handled via direct translation, projecting input vectors onto the surface plane. This eliminates jitter caused by physics collisions on complex meshes.

Zero-G Camera Behavior

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The camera features a subtle but noticeable drag effect that enhances the low-gravity feel. This drag is also visible when the player rolls on their Y rotation, creating an immersive weightless experience.

Technical Deep Dive

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Advanced Surface Detection

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To enable climbing on any surface and at any angle, as well as seamless transitions between objects, a multilayer detection system is used.

• In climbing mode, the player fires multiple raycasts in the direction of input. These raycasts detect edges and trigger transitions to new surface faces.
• To support high-speed jumps between climbing objects, a conditional spherecast projects the player’s velocity forward. If the player is moving too fast for raycasts to detect a surface, the spherecast “pre-detects” upcoming collisions, enabling smooth landings and transitions.

Climbing on Simple Surfaces

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Basic climbing movement on a 3D rectangle demonstrates the core mechanics:

Curved Surface Navigation

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Navigating curved surfaces required a dedicated curvature detection system.

• While climbing, a ring of raycasts is fired around the contact point to calculate the average surface normal.
• The controller samples the surface ahead of the player’s movement, pre-rotating the character to match upcoming curvature. This results in smooth, natural movement over low-poly spheres and complex geometry.

Climbing on a Torus

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Complex curved geometry like a torus showcases the adaptive surface detection:

Climbing on a Sphere

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Smooth navigation across a spherical surface:

Climbing Inside a Pipe

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Demonstrating correct concave angle detection and seamless transitions inside a pipe:

Camera System

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• In Zero-G, the camera controls the body’s rotation (yaw/pitch).
• In Climbing mode, the camera is decoupled, allowing the player to look around freely while the body remains aligned to the wall.
• The system dynamically adjusts the field of view based on speed and state to enhance the sensation of movement.

Grabbing & Pulling Mechanics

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• An extendable hand system, built with raycasts and LineRenderer, allows the player to grab specific surfaces.
• When the hand latches onto a surface, a velocity vector is applied toward the anchor point, creating a satisfying, weighty pull.
• If the player pulls themselves into a wall, the system detects the collision and automatically transitions to the Climbing state.

Basic Grabbing State

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The extendable hand mechanic and pull system in action:

Grabbing While Climbing

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The grabbing mechanic integrates seamlessly with climbing mode:

Grabbing in Zero-G Mode

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Using the grab mechanic while floating in zero gravity:

Grabbing + Jumping Interactions

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The grabbing/pull mechanic combined with jumping creates fun force-based interactions:

Jumping Across Objects

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Jumping movement across multiple climbing objects demonstrates the seamless state transitions:

Tools & Workflow

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A ScriptableObject with over 50 parameters (drag, acceleration, camera smoothing, roll speed, etc.) enables rapid tuning of player movement during development.

Debug Visualization

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Custom gizmos were developed to visualize the system’s internal logic:

Debug Gizmos on Simple Surface

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Visualization on a 3D rectangle:

Debug Gizmos on Low-Poly Sphere

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Visualization showing surface normal smoothing on a low-poly sphere: