AI Metrics

The majority of this information is for the Half-Life 2 ai.

Introduction

The NPCs in Half-Life 2 have a variety of constraints influencing how they behave and interact. This includes everything from cover search distance to jump height, and as a level designer this information can be quite handy when constructing an encounter. All the distances listed are in Hammer editor units.

Default Metrics

These are the default metrics for the NPCs; information such as jump height can change between different classes.

Jumping

This information applies to jump hint nodes as well.

• Max Jump Drop = 192
• Max Jump Up = 80
• Max Jump Distance = 250

Cover and Line-Of-Sight Acquisition

• Crouching eye height (used to test low cover) = 40
• Standing eye height = 64
• Max cover search distance from NPC = 784
• Max Line-Of-Sight search distance from target = 1024

Weapon Metrics

This is the information the NPCs use when handling weapons. Minimum and maximum ranges are the distances that the NPC will actually fire the weapon, this can be modified by the long range spawn flag, and sometimes change depending on the running behavior. The accuracy cones for different NPCs are listed here as well,

AR2

• Minimum range = 65
• Maximum range = 2048
• NPC damage = 3
• Alt fire decay distance = 2000
• NPC alt fire damage to player = 20
• Accuracy:
  • combine soldier = 5 degrees (9 degrees in Half-Life 2)
  • citizen = 5 degrees

Pistol

• Minimum range = 24
• Maximum range = 1500
• NPC damage = 3
• Accuracy:
  • Metrocop = 12.5 degrees
  • citizen = 5 degrees

RPG

• Minimum range = 480
• Maximum range = 6000