Week 5: UE Physics

Physics in Animation

• Explored how physics adds realism to animations, especially in scenes where objects are falling or impacted.
• Learned that applying physics makes objects react naturally to forces, adding immersion.

Exploring Unreal Engine Modes

• We usually work in Selection Mode, but this week we explored additional modes:
  • Landscape Mode
  • Foliage Mode
  • Fracture Mode – our main focus, used to apply fractures and destruction effects to meshes.

Modeling and Fracturing Meshes

1. Started with Modeling Mode to create and place basic meshes in the scene.
2. Switched to Fracture Mode to break down meshes in various ways:
   • Uniform Fracture – breaks down a mesh evenly.
   • Cluster Fracture – creates smaller, clustered fragments, ideal for explosive effects.
   • Radial Fracture – creates a point-of-impact effect, like a gunshot.
   • Plane Fracture – simulates slicing, like a sword cutting through.
   • Custom Fracture – allows for user-defined break patterns.

Fracturing a Cube Step-by-Step

1. Selected a cube mesh to fracture.
2. Generated a fracture asset:
   • Went to Generate > Save in a folder > Generate Fracture.
3. Enabled physics for realistic impact:
4. In Details Panel, enabled Simulate Physics to respond to gravity and collisions.
5. Applied Uniform Fracture mode:

1. Adjusted the fracture levels to control the number of broken parts.
2. Observed how one cube fractured into 20 separate pieces.

Advanced Fracture and Impact Control

• Further fractured pre-existing fractured parts to create additional detail.
• Adjusted impact strength:
  • Lowered the Damage Threshold in the Details Panel to increase impact sensitivity.
  • Turned off bone colours by unchecking Show Bone Colours in the Details Panel.

Nanite for Performance Optimisation

• Switched to Nanite for performance when using heavy physics scenes:
  • In Chaos Physics settings, located the collection, enabled Nanite in the Content Browser, making physics processing more CPU-efficient.

Adding Material Properties to Enhance Physics

• Applied bounce and material properties to objects:
  • In Details Panel > Collision > Physical Material Override, adjusted friction, density, and strength.

Scene Recording Setup

• Enabled Engine Settings to access built-in blueprints:
  • Activated by ticking Show Engine Content in Content Browser Settings.
  • Located Anchor and FS Master Field in the content browser, then copied them to a custom physics folder.
• Set up the scene for recording:
  • Dragged Anchor and Master Field into the scene.
  • Added an Initialization Field and created a Chaos Solver to simulate physics interactions.
  • Added objects to the Chaos Cache Manager for precise recording.

Using the Sequencer to Capture Scenes

1. Added objects to the Sequencer and set keyframes for start and end points.
2. Worked with Constraint Actors to apply physics constraints:
   • Added two cubes to test the constraint as an anchor point.
   • Observed how one fractured cube reacted to constraints, swinging around the anchor point.

Alternative Recording with Take Recorder

• Enabled Take Recorder in Plugins and added actors for recording:
  • Started simulation with Alt + S to capture real-time physics effects.
  • Viewed recorded sequences in the Content Browser after recording.

Creating a Bouncing Ball

1. Created a sphere and enabled Simulate Physics in Details Panel.
2. Applied a custom physical material for bounce:
   • Created a blueprint class called BP_Ball and added a static mesh.
   • Created a physical material with customised friction and density settings.
3. Applied the physical material to the sphere to achieve the desired bounce.

This week’s exploration provided a solid understanding of fractures, physics settings, and recording techniques in Unreal Engine. These tools allow us to bring more realism and dynamic effects to our animations.