Detonate rifle grenades on impact with original Half-Life fireball

scripts/grenade.gd

@@ -1,6 +1,8 @@
 extends RigidBody3D
 signal detonated
-const FUSE_SECONDS := 4.0
+# No timed fuse: the rifle grenade detonates on its first physical contact.
+const MAX_LIFETIME := 15.0
+const Explosion = preload("res://scripts/grenade_explosion.gd")
 const BLAST_RADIUS := 5.0
 const MAX_DAMAGE := 160.0
 const Audio = preload("res://scripts/hl_audio.gd")
@@ -8,18 +10,24 @@ const Blood = preload("res://scripts/blood_effects.gd")
 var age := 0.0
 var exploded := false
 var thrower: CharacterBody3D
+var previous_position := Vector3.ZERO
+var impact_position := Vector3.ZERO
 
 func _ready() -> void:
 	name = "Grenade"
 	add_to_group("grenades")
+	previous_position = global_position
 	collision_layer = 16
 	collision_mask = 1 | 4
 	mass = 0.4
 	continuous_cd = true
+	contact_monitor = true
+	max_contacts_reported = 8
+	body_entered.connect(_on_body_entered)
 	linear_damp = 0.15
 	angular_damp = 0.6
 	var physics := PhysicsMaterial.new()
-	physics.bounce = 0.45
+	physics.bounce = 0.0
 	physics.friction = 0.65
 	physics_material_override = physics
 	var collider := CollisionShape3D.new()
@@ -39,9 +47,36 @@ func _ready() -> void:
 
 func _physics_process(delta: float) -> void:
 	age += delta
-	if age >= FUSE_SECONDS and not exploded:
-		exploded = true
-		call_deferred("_explode")
+	# Window panes are Area3D on layer 8, not PhysicsBody3D. A swept ray catches
+	# those too, even if a fast grenade crosses the whole pane in one tick.
+	if not exploded and not previous_position.is_equal_approx(global_position):
+		var query := PhysicsRayQueryParameters3D.create(previous_position, global_position, 8)
+		query.collide_with_areas = true
+		query.collide_with_bodies = false
+		var hit := get_world_3d().direct_space_state.intersect_ray(query)
+		if not hit.is_empty():
+			_request_detonation(hit.position + hit.normal * 0.13)
+	previous_position = global_position
+	# Safety cleanup only: a projectile lost outside the map must not explode in air.
+	if age >= MAX_LIFETIME and not exploded:
+		queue_free()
+
+func _integrate_forces(state: PhysicsDirectBodyState3D) -> void:
+	if not exploded and state.get_contact_count() > 0:
+		# Save the physics position before deferring scene/shape changes. The sphere
+		# centre stays on the free side of the surface, also for damage LOS rays.
+		_request_detonation(state.transform.origin)
+
+func _on_body_entered(body: Node) -> void:
+	if body != thrower:
+		_request_detonation(global_position)
+
+func _request_detonation(point: Vector3) -> void:
+	if exploded:
+		return
+	exploded = true
+	impact_position = point
+	call_deferred("_explode")
 
 func _explode() -> void:
 	freeze = true
@@ -49,7 +84,7 @@ func _explode() -> void:
 	collision_mask = 0
 	hide()
 	var world := get_parent() as Node3D
-	var point := global_position
+	var point := impact_position
 	var targets := get_tree().get_nodes_in_group("live_zombies")
 	if is_instance_valid(thrower) and not thrower.death_started:
 		targets.append(thrower)
@@ -74,20 +109,13 @@ func _explode() -> void:
 	queue_free()
 
 func _effect(world: Node3D, point: Vector3) -> void:
-	var effect := Node3D.new()
-	effect.name = "GrenadeExplosion"
+	var effect := Explosion.new()
 	world.add_child(effect)
 	effect.global_position = point
 	Audio.play(effect, "weapons/explode%d.wav" % randi_range(3, 5), true, -7)
-	var light := OmniLight3D.new()
-	light.light_color = Color(1, 0.45, 0.08)
-	light.light_energy = 8
-	light.omni_range = 10
-	effect.add_child(light)
-	var tween := effect.create_tween()
-	tween.tween_property(light, "light_energy", 0.0, 0.3)
+	# Secondary embers only: the original fireball is now the main visual.
 	var particles := CPUParticles3D.new()
-	particles.amount = 60
+	particles.amount = 18
 	particles.lifetime = 0.85
 	particles.one_shot = true
 	particles.explosiveness = 1
@@ -97,8 +125,8 @@ func _effect(world: Node3D, point: Vector3) -> void:
 	particles.initial_velocity_max = 6
 	particles.gravity = Vector3(0, -3, 0)
 	var mesh := SphereMesh.new()
-	mesh.radius = 0.06
-	mesh.height = 0.12
+	mesh.radius = 0.018
+	mesh.height = 0.036
 	var material := StandardMaterial3D.new()
 	material.albedo_color = Color(1, 0.3, 0.05)
 	material.shading_mode = BaseMaterial3D.SHADING_MODE_UNSHADED
@@ -110,4 +138,3 @@ func _effect(world: Node3D, point: Vector3) -> void:
 	particles.color_ramp = colors
 	effect.add_child(particles)
 	particles.emitting = true
-	world.get_tree().create_timer(4).timeout.connect(effect.queue_free)

scripts/grenade_explosion.gd

@@ -0,0 +1,61 @@
+extends Node3D
+## Original Half-Life fireball, 15 frames at 15 FPS, additive camera-facing quad.
+## A PNG atlas avoids the native GoldSrc importer in Web exports.
+const ATLAS = preload("res://assets/effects/explosion/zerogxplode_atlas.png")
+const FRAME_COUNT := 15
+const FPS := 15.0
+const DURATION := FRAME_COUNT / FPS
+const SIZE := 3.2
+var elapsed := 0.0
+var frame_index := 0
+var fireball: MeshInstance3D
+var material: StandardMaterial3D
+
+func _ready() -> void:
+	name = "GrenadeExplosion"
+	material = StandardMaterial3D.new()
+	material.shading_mode = BaseMaterial3D.SHADING_MODE_UNSHADED
+	material.transparency = BaseMaterial3D.TRANSPARENCY_ALPHA
+	material.blend_mode = BaseMaterial3D.BLEND_MODE_ADD
+	material.billboard_mode = BaseMaterial3D.BILLBOARD_ENABLED
+	material.cull_mode = BaseMaterial3D.CULL_DISABLED
+	material.albedo_texture = ATLAS
+	material.texture_filter = BaseMaterial3D.TEXTURE_FILTER_LINEAR
+	material.texture_repeat = false
+	# Two-pixel black gutters prevent adjacent frames bleeding under filtering.
+	material.uv1_scale = Vector3(64.0 / 340.0, 64.0 / 204.0, 1)
+	fireball = MeshInstance3D.new()
+	fireball.name = "Fireball"
+	fireball.cast_shadow = GeometryInstance3D.SHADOW_CASTING_SETTING_OFF
+	var quad := QuadMesh.new()
+	quad.size = Vector2(SIZE, SIZE)
+	quad.material = material
+	fireball.mesh = quad
+	# Raise the fireball, but leave the damage origin at the physical impact.
+	fireball.position.y = 0.8
+	add_child(fireball)
+	_set_frame(0)
+	var light := OmniLight3D.new()
+	light.name = "Flash"
+	light.light_color = Color(1, 0.45, 0.08)
+	light.light_energy = 8
+	light.omni_range = 10
+	light.shadow_enabled = false
+	add_child(light)
+	create_tween().tween_property(light, "light_energy", 0.0, 0.3)
+	# Keep the node alive for the original explosion sound to finish.
+	get_tree().create_timer(4).timeout.connect(queue_free)
+
+func _process(delta: float) -> void:
+	elapsed += delta
+	if elapsed >= DURATION:
+		fireball.hide()
+		set_process(false)
+		return
+	_set_frame(mini(int(elapsed * FPS), FRAME_COUNT - 1))
+
+func _set_frame(index: int) -> void:
+	frame_index = index
+	material.uv1_offset = Vector3(
+		(float(index % 5) * 68 + 2) / 340.0,
+		(float(index / 5) * 68 + 2) / 204.0, 0)

scripts/grenade_explosion.gd.uid

@@ -0,0 +1 @@
+uid://d030pl0ug1qcs