game-perf-patterns

Game Performance Patterns

MultiMeshInstance3D for Batch Rendering

# Render thousands of identical objects with a single draw call
class_name FoliageRenderer extends Node3D
@export var mesh: Mesh
@export var count: int = 1000
@export var spread_radius: float = 50.0

@onready var multimesh_instance: MultiMeshInstance3D = $MultiMeshInstance3D

func _ready() -> void:
    var multimesh := MultiMesh.new()
    multimesh.mesh = mesh
    multimesh.transform_format = MultiMesh.TRANSFORM_3D
    multimesh.instance_count = count

    for i in count:
        var angle := randf() * TAU
        var radius := randf() * spread_radius
        var pos := Vector3(cos(angle) * radius, 0.0, sin(angle) * radius)
        # Raycast to ground for terrain alignment
        pos.y = _get_ground_height(pos)
        var random_rotation := Basis.from_euler(Vector3(0, randf() * TAU, 0))
        var random_scale := randf_range(0.8, 1.2)
        multimesh.set_instance_transform(i, Transform3D(
            random_rotation.scaled(Vector3.ONE * random_scale),
            pos
        ))

    multimesh_instance.multimesh = multimesh

func _get_ground_height(pos: Vector3) -> float:
    var space := get_world_3d().direct_space_state
    var query := PhysicsRayQueryParameters3D.create(
        pos + Vector3.UP * 100.0,
        pos + Vector3.DOWN * 10.0,
        0b0001  # ground layer
    )
    var result := space.intersect_ray(query)
    return result.position.y if result else 0.0

Custom Performance Monitor

# Add game-specific metrics to Godot's built-in profiler
class_name GameMetrics extends Node
var _enemy_count: int = 0
var _projectile_count: int = 0
var _active_particles: int = 0

func _ready() -> void:
    # Register custom monitors (visible in Godot Profiler > Monitors)
    Performance.add_custom_monitor(
        "game/active_enemies",
        func(): return _enemy_count
    )
    Performance.add_custom_monitor(
        "game/active_projectiles",
        func(): return _projectile_count
    )
    Performance.add_custom_monitor(
        "game/draw_calls",
        func(): return Performance.get_monitor(Performance.RENDER_TOTAL_DRAW_CALLS_IN_FRAME)
    )
    Performance.add_custom_monitor(
        "game/physics_contacts",
        func(): return Performance.get_monitor(Performance.PHYSICS_3D_COLLISION_PAIRS)
    )

func update_counts(enemies: int, projectiles: int) -> void:
    _enemy_count = enemies
    _projectile_count = projectiles