Basics of washable 'gunk'

asset_dev/props/icosahedron.blend.import

@@ -0,0 +1,50 @@
+[remap]
+
+importer="scene"
+importer_version=1
+type="PackedScene"
+uid="uid://bg5qmh1jufujy"
+valid=false
+
+[deps]
+
+source_file="res://asset_dev/props/icosahedron.blend"
+
+[params]
+
+nodes/root_type=""
+nodes/root_name=""
+nodes/apply_root_scale=true
+nodes/root_scale=1.0
+nodes/import_as_skeleton_bones=false
+meshes/ensure_tangents=true
+meshes/generate_lods=true
+meshes/create_shadow_meshes=true
+meshes/light_baking=1
+meshes/lightmap_texel_size=0.2
+meshes/force_disable_compression=false
+skins/use_named_skins=true
+animation/import=true
+animation/fps=30
+animation/trimming=false
+animation/remove_immutable_tracks=true
+animation/import_rest_as_RESET=false
+import_script/path=""
+_subresources={}
+blender/nodes/visible=0
+blender/nodes/active_collection_only=false
+blender/nodes/punctual_lights=true
+blender/nodes/cameras=true
+blender/nodes/custom_properties=true
+blender/nodes/modifiers=1
+blender/meshes/colors=false
+blender/meshes/uvs=true
+blender/meshes/normals=true
+blender/meshes/tangents=true
+blender/meshes/skins=2
+blender/meshes/export_bones_deforming_mesh_only=false
+blender/materials/unpack_enabled=true
+blender/materials/export_materials=1
+blender/animation/limit_playback=true
+blender/animation/always_sample=true
+blender/animation/group_tracks=true

asset_dev/props/monkey.blend.import

@@ -0,0 +1,50 @@
+[remap]
+
+importer="scene"
+importer_version=1
+type="PackedScene"
+uid="uid://c43vybloao3v5"
+valid=false
+
+[deps]
+
+source_file="res://asset_dev/props/monkey.blend"
+
+[params]
+
+nodes/root_type=""
+nodes/root_name=""
+nodes/apply_root_scale=true
+nodes/root_scale=1.0
+nodes/import_as_skeleton_bones=false
+meshes/ensure_tangents=true
+meshes/generate_lods=true
+meshes/create_shadow_meshes=true
+meshes/light_baking=1
+meshes/lightmap_texel_size=0.2
+meshes/force_disable_compression=false
+skins/use_named_skins=true
+animation/import=true
+animation/fps=30
+animation/trimming=false
+animation/remove_immutable_tracks=true
+animation/import_rest_as_RESET=false
+import_script/path=""
+_subresources={}
+blender/nodes/visible=0
+blender/nodes/active_collection_only=false
+blender/nodes/punctual_lights=true
+blender/nodes/cameras=true
+blender/nodes/custom_properties=true
+blender/nodes/modifiers=1
+blender/meshes/colors=false
+blender/meshes/uvs=true
+blender/meshes/normals=true
+blender/meshes/tangents=true
+blender/meshes/skins=2
+blender/meshes/export_bones_deforming_mesh_only=false
+blender/materials/unpack_enabled=true
+blender/materials/export_materials=1
+blender/animation/limit_playback=true
+blender/animation/always_sample=true
+blender/animation/group_tracks=true

assets/props/icosahedron/icosahedron.mtl

@@ -0,0 +1,2 @@
+# Blender 4.3.2 MTL File: 'icosahedron.blend'
+# www.blender.org

assets/props/icosahedron/icosahedron.obj

@@ -0,0 +1,79 @@
+# Blender 4.3.2
+# www.blender.org
+mtllib icosahedron.mtl
+o Icosphere
+v 0.000000 -1.000000 0.000000
+v 0.723600 -0.447215 0.525720
+v -0.276385 -0.447215 0.850640
+v -0.894425 -0.447215 0.000000
+v -0.276385 -0.447215 -0.850640
+v 0.723600 -0.447215 -0.525720
+v 0.276385 0.447215 0.850640
+v -0.723600 0.447215 0.525720
+v -0.723600 0.447215 -0.525720
+v 0.276385 0.447215 -0.850640
+v 0.894425 0.447215 0.000000
+v 0.000000 1.000000 0.000000
+vn 0.1876 -0.7947 0.5774
+vn 0.6071 -0.7947 -0.0000
+vn -0.4911 -0.7947 0.3568
+vn -0.4911 -0.7947 -0.3568
+vn 0.1876 -0.7947 -0.5774
+vn 0.9822 -0.1876 -0.0000
+vn 0.3035 -0.1876 0.9342
+vn -0.7946 -0.1876 0.5774
+vn -0.7946 -0.1876 -0.5774
+vn 0.3035 -0.1876 -0.9342
+vn 0.7946 0.1876 0.5774
+vn -0.3035 0.1876 0.9342
+vn -0.9822 0.1876 -0.0000
+vn -0.3035 0.1876 -0.9342
+vn 0.7946 0.1876 -0.5774
+vn 0.4911 0.7947 0.3568
+vn -0.1876 0.7947 0.5774
+vn -0.6071 0.7947 -0.0000
+vn -0.1876 0.7947 -0.5774
+vn 0.4911 0.7947 -0.3568
+vt 0.181819 0.000000
+vt 0.272728 0.157461
+vt 0.090910 0.157461
+vt 0.363637 0.000000
+vt 0.454546 0.157461
+vt 0.909091 0.000000
+vt 1.000000 0.157461
+vt 0.818182 0.157461
+vt 0.727273 0.000000
+vt 0.636364 0.157461
+vt 0.545455 0.000000
+vt 0.363637 0.314921
+vt 0.181819 0.314921
+vt 0.909091 0.314921
+vt 0.727273 0.314921
+vt 0.545455 0.314921
+vt 0.000000 0.314921
+vt 0.272728 0.472382
+vt 0.090910 0.472382
+vt 0.818182 0.472382
+vt 0.636364 0.472382
+vt 0.454546 0.472382
+s 0
+f 1/1/1 2/2/1 3/3/1
+f 2/2/2 1/4/2 6/5/2
+f 1/6/3 3/7/3 4/8/3
+f 1/9/4 4/8/4 5/10/4
+f 1/11/5 5/10/5 6/5/5
+f 2/2/6 6/5/6 11/12/6
+f 3/3/7 2/2/7 7/13/7
+f 4/8/8 3/7/8 8/14/8
+f 5/10/9 4/8/9 9/15/9
+f 6/5/10 5/10/10 10/16/10
+f 2/2/11 11/12/11 7/13/11
+f 3/3/12 7/13/12 8/17/12
+f 4/8/13 8/14/13 9/15/13
+f 5/10/14 9/15/14 10/16/14
+f 6/5/15 10/16/15 11/12/15
+f 7/13/16 11/12/16 12/18/16
+f 8/17/17 7/13/17 12/19/17
+f 9/15/18 8/14/18 12/20/18
+f 10/16/19 9/15/19 12/21/19
+f 11/12/20 10/16/20 12/22/20

assets/props/icosahedron/icosahedron.obj.import

@@ -0,0 +1,22 @@
+[remap]
+
+importer="wavefront_obj"
+importer_version=1
+type="Mesh"
+uid="uid://lvats6ptrcxt"
+path="res://.godot/imported/icosahedron.obj-8f3e6519933309a73eb5326f98a3de95.mesh"
+
+[deps]
+
+files=["res://.godot/imported/icosahedron.obj-8f3e6519933309a73eb5326f98a3de95.mesh"]
+
+source_file="res://assets/props/icosahedron/icosahedron.obj"
+dest_files=["res://.godot/imported/icosahedron.obj-8f3e6519933309a73eb5326f98a3de95.mesh", "res://.godot/imported/icosahedron.obj-8f3e6519933309a73eb5326f98a3de95.mesh"]
+
+[params]
+
+generate_tangents=true
+scale_mesh=Vector3(1, 1, 1)
+offset_mesh=Vector3(0, 0, 0)
+optimize_mesh=true
+force_disable_mesh_compression=false

assets/props/monkey/monkey.mtl

@@ -0,0 +1,2 @@
+# Blender 4.3.2 MTL File: 'monkey.blend'
+# www.blender.org

assets/props/monkey/monkey.obj.import

@@ -0,0 +1,22 @@
+[remap]
+
+importer="wavefront_obj"
+importer_version=1
+type="Mesh"
+uid="uid://e6syamfwiitk"
+path="res://.godot/imported/monkey.obj-ee24e6fed272edb0c774a26f0a399a12.mesh"
+
+[deps]
+
+files=["res://.godot/imported/monkey.obj-ee24e6fed272edb0c774a26f0a399a12.mesh"]
+
+source_file="res://assets/props/monkey/monkey.obj"
+dest_files=["res://.godot/imported/monkey.obj-ee24e6fed272edb0c774a26f0a399a12.mesh", "res://.godot/imported/monkey.obj-ee24e6fed272edb0c774a26f0a399a12.mesh"]
+
+[params]
+
+generate_tangents=true
+scale_mesh=Vector3(1, 1, 1)
+offset_mesh=Vector3(0, 0, 0)
+optimize_mesh=true
+force_disable_mesh_compression=false

levels/sandbox/debug_draw.gd

@@ -0,0 +1,28 @@
+class_name DebugDraw extends Control
+
+const COLOR := Color.ORANGE
+const WIDTH := 4
+
+var lines: Array = []
+
+
+func _process(_delta: float) -> void:
+	if visible:
+		queue_redraw()
+	else:
+		lines = []
+
+
+func draw_vector(vec: Vector3, origin: Vector3) -> void:
+	var camera := get_viewport().get_camera_3d()
+	var start := camera.unproject_position(origin)
+	var end := camera.unproject_position(origin + vec)
+
+	lines.push_back([start, end])
+
+
+func _draw() -> void:
+	while lines:
+		var line: Array[Vector2] = []
+		line.assign(lines.pop_back() as Array)
+		draw_line(line[0], line[1], COLOR, WIDTH)

levels/sandbox/debug_gunk_mat.tres

@@ -0,0 +1,34 @@
+[gd_resource type="StandardMaterial3D" load_steps=8 format=3 uid="uid://byyjoruj8mwe0"]
+
+[ext_resource type="Shader" path="res://src/shaders/gunk.gdshader" id="1_dot5s"]
+
+[sub_resource type="PlaceholderTexture2D" id="PlaceholderTexture2D_pinpy"]
+size = Vector2(256, 256)
+
+[sub_resource type="FastNoiseLite" id="FastNoiseLite_f8h21"]
+
+[sub_resource type="NoiseTexture2D" id="NoiseTexture2D_dj5ow"]
+seamless = true
+noise = SubResource("FastNoiseLite_f8h21")
+
+[sub_resource type="FastNoiseLite" id="FastNoiseLite_1ennl"]
+
+[sub_resource type="NoiseTexture2D" id="NoiseTexture2D_kkru7"]
+seamless = true
+as_normal_map = true
+noise = SubResource("FastNoiseLite_1ennl")
+
+[sub_resource type="ShaderMaterial" id="ShaderMaterial_0jkcp"]
+render_priority = 0
+shader = ExtResource("1_dot5s")
+shader_parameter/color_1 = Color(0, 0.03, 0.1, 1)
+shader_parameter/color_2 = Color(0, 0.1, 0.3, 1)
+shader_parameter/roughness = 0.15
+shader_parameter/specular_contribution = 0.2
+shader_parameter/gunk_mask = SubResource("PlaceholderTexture2D_pinpy")
+shader_parameter/gunk_noise = SubResource("NoiseTexture2D_dj5ow")
+shader_parameter/gunk_normal_map = SubResource("NoiseTexture2D_kkru7")
+
+[resource]
+next_pass = SubResource("ShaderMaterial_0jkcp")
+albedo_color = Color(1, 0.403922, 1, 1)

src/player/player.gd

@@ -2,11 +2,13 @@ class_name Player extends CharacterBody3D
 
 const RUN_SPEED := 80.0
 const SPRINT_SPEED := 160.0
-const AIR_SPEED := 30.0
+const AIR_SPEED := 10.0
 const JUMP_FORCE := 4.5
 const GROUND_FRICTION := 0.3
 const AIR_FRICTION := 0.03
 
+const SPRAY_RADIUS := 15
+
 var gravity: Vector3 = (
 	ProjectSettings.get_setting("physics/3d/default_gravity")
 	* ProjectSettings.get_setting("physics/3d/default_gravity_vector")
@@ -14,6 +16,8 @@ var gravity: Vector3 = (
 
 @onready var camera_pivot: Node3D = %CameraPivot
 
+@onready var spray_effect: MeshInstance3D = %SprayEffect
+
 
 func get_speed() -> float:
 	if is_on_floor():
@@ -29,7 +33,23 @@ func get_friction() -> float:
 	return AIR_FRICTION
 
 
+func fire_spray() -> void:
+	for raycast: RayCast3D in get_tree().get_nodes_in_group("SprayCast"):
+		if raycast.is_colliding():
+			var collider := raycast.get_collider()
+			if collider is GunkBody:
+				(collider as GunkBody).paint_mask(
+					raycast.get_collision_point(), raycast.get_collision_normal(), SPRAY_RADIUS
+				)
+
+
 func _physics_process(delta: float) -> void:
+	if Input.is_action_pressed("fire"):
+		fire_spray()
+		spray_effect.visible = true
+	else:
+		spray_effect.visible = false
+
 	# Gravity
 	if not is_on_floor():
 		velocity += gravity * delta

src/player/player.tscn

@@ -1,8 +1,24 @@
-[gd_scene load_steps=4 format=3 uid="uid://bwe2jdmvinhqd"]
+[gd_scene load_steps=8 format=3 uid="uid://bwe2jdmvinhqd"]
 
 [ext_resource type="Script" path="res://src/player/player.gd" id="1_npueo"]
 [ext_resource type="Script" path="res://src/player/camera_controller.gd" id="2_veeqv"]
 
+[sub_resource type="BoxMesh" id="BoxMesh_ua7a2"]
+size = Vector3(0.05, 0.05, 0.3)
+
+[sub_resource type="StandardMaterial3D" id="StandardMaterial3D_ng43h"]
+transparency = 1
+shading_mode = 0
+vertex_color_use_as_albedo = true
+albedo_color = Color(0, 1, 0.301961, 0.254902)
+
+[sub_resource type="PrismMesh" id="PrismMesh_ow0jh"]
+material = SubResource("StandardMaterial3D_ng43h")
+size = Vector3(1, 2, 0.1)
+
+[sub_resource type="QuadMesh" id="QuadMesh_cn0yq"]
+size = Vector2(1, 0.05)
+
 [sub_resource type="CapsuleShape3D" id="CapsuleShape3D_s7f0r"]
 
 [node name="Player" type="CharacterBody3D"]
@@ -14,8 +30,44 @@ unique_name_in_owner = true
 transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0.5, 0)
 script = ExtResource("2_veeqv")
 
+[node name="SprayNozzle" type="MeshInstance3D" parent="CameraPivot"]
+transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 0.15, -0.1, -0.1)
+mesh = SubResource("BoxMesh_ua7a2")
+
+[node name="SprayMuzzle" type="Marker3D" parent="CameraPivot/SprayNozzle"]
+transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, -0.15)
+
+[node name="RayCast3D" type="RayCast3D" parent="CameraPivot/SprayNozzle/SprayMuzzle" groups=["SprayCast"]]
+enabled = false
+target_position = Vector3(-0.4, 0.1, -2)
+
+[node name="RayCast3D2" type="RayCast3D" parent="CameraPivot/SprayNozzle/SprayMuzzle" groups=["SprayCast"]]
+target_position = Vector3(-0.2, 0.1, -2)
+
+[node name="RayCast3D3" type="RayCast3D" parent="CameraPivot/SprayNozzle/SprayMuzzle" groups=["SprayCast"]]
+target_position = Vector3(0, 0.1, -2)
+
+[node name="RayCast3D4" type="RayCast3D" parent="CameraPivot/SprayNozzle/SprayMuzzle" groups=["SprayCast"]]
+target_position = Vector3(0.2, 0.1, -2)
+
+[node name="RayCast3D5" type="RayCast3D" parent="CameraPivot/SprayNozzle/SprayMuzzle" groups=["SprayCast"]]
+enabled = false
+target_position = Vector3(0.4, 0.1, -2)
+
+[node name="SprayEffect" type="MeshInstance3D" parent="CameraPivot/SprayNozzle/SprayMuzzle"]
+unique_name_in_owner = true
+transform = Transform3D(1, 0, 0, 0, -0.0697565, -0.997564, 0, 0.997564, -0.0697565, 0, 0.0436133, -1)
+visible = false
+mesh = SubResource("PrismMesh_ow0jh")
+skeleton = NodePath("../../..")
+
 [node name="Camera3D" type="Camera3D" parent="CameraPivot"]
 current = true
 
+[node name="SprayZone" type="MeshInstance3D" parent="CameraPivot"]
+transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 0.166592, 0, -2.25)
+visible = false
+mesh = SubResource("QuadMesh_cn0yq")
+
 [node name="CollisionShape3D" type="CollisionShape3D" parent="."]
 shape = SubResource("CapsuleShape3D_s7f0r")

src/shaders/gunk.gdshader

@@ -0,0 +1,30 @@
+shader_type spatial;
+render_mode cull_back;
+
+uniform vec4 color_1: source_color = vec4(0.0, 0.03, 0.1, 1.0);
+uniform vec4 color_2: source_color = vec4(0.0, 0.1, 0.3, 1.0);
+uniform float roughness: hint_range(0.0, 1.0) = 0.15;
+uniform float specular_contribution = 0.2;
+
+uniform sampler2D gunk_mask;
+
+uniform highp sampler2D gunk_noise;
+uniform highp sampler2D gunk_normal_map;
+
+
+void fragment() {
+	float mask = texture(gunk_mask, UV).r;
+	if(mask < 0.1) {
+		float value = texture(gunk_noise, UV).r;
+		vec4 color = mix(color_1, color_2, value);
+		float roughness_mix = value * roughness;
+
+		ALBEDO = color.rgb;
+		ROUGHNESS = roughness_mix;
+		SPECULAR = 0.5 * inversesqrt(specular_contribution);
+		NORMAL_MAP = texture(gunk_normal_map, UV).xyz;
+		ALPHA = 1.0;
+	} else {
+		ALPHA = 0.0;
+	}
+}

src/world/gunk_body.gd

@@ -0,0 +1,96 @@
+class_name GunkBody extends StaticBody3D
+## StaticBody3D with an associated "gunkable" mesh.
+
+const MASK_DIM := 512
+const FACE_EPSILON := 0.4
+const MASK_COLOR := Color.RED
+
+@export var mask_image: Image
+
+var meshtool := MeshDataTool.new()
+
+@onready var mesh_instance: MeshInstance3D = $MeshInstance3D
+@onready var mesh: ArrayMesh = mesh_instance.mesh
+@onready var gunk_mat: ShaderMaterial = mesh_instance.get_surface_override_material(0).next_pass
+
+@onready var debug_draw: DebugDraw = %DebugDraw
+
+
+func _ready() -> void:
+	if not mask_image:
+		mask_image = Image.create_empty(MASK_DIM, MASK_DIM, false, Image.FORMAT_L8)
+		_update_gunk_material()
+
+	meshtool.create_from_surface(mesh, 0)
+
+
+## Must be called internally whenever `mask_image` is updated
+func _update_gunk_material() -> void:
+	gunk_mat.set_shader_parameter("gunk_mask", ImageTexture.create_from_image(mask_image))
+
+
+## Transform cartesian coordinates to barycentric wrt the given triangle
+func _barycentric(p: Vector3, a: Vector3, b: Vector3, c: Vector3) -> Vector3:
+	var v0 := b - a
+	var v1 := c - a
+	var v2 := p - a
+	var d00 := v0.dot(v0)
+	var d01 := v0.dot(v1)
+	var d11 := v1.dot(v1)
+	var d20 := v2.dot(v0)
+	var d21 := v2.dot(v1)
+	var denom := d00 * d11 - d01 * d01
+	var v := (d11 * d20 - d01 * d21) / denom
+	var w := (d00 * d21 - d01 * d20) / denom
+	var u := 1.0 - v - w
+	return Vector3(u, v, w)
+
+
+func _is_in_triangle(point: Vector3, v1: Vector3, v2: Vector3, v3: Vector3) -> bool:
+	var bc := _barycentric(point, v1, v2, v3)
+	return (bc.x > 0 and bc.x < 1) and (bc.y > 0 and bc.y < 1) and (bc.z > 0 and bc.z < 1)
+
+
+func _get_face(point: Vector3, normal: Vector3) -> int:
+	for i in range(meshtool.get_face_count()):
+		if meshtool.get_face_normal(i).distance_squared_to(normal) > FACE_EPSILON:
+			continue
+		# Normals match, so check if the point is on this face
+		var v1 := meshtool.get_vertex(meshtool.get_face_vertex(i, 0))
+		var v2 := meshtool.get_vertex(meshtool.get_face_vertex(i, 1))
+		var v3 := meshtool.get_vertex(meshtool.get_face_vertex(i, 2))
+		if _is_in_triangle(point, v1, v2, v3):
+			return i
+	return -1
+
+
+func _get_uv(point: Vector3, normal: Vector3) -> Vector2:
+	var face := _get_face(point, normal)
+	if face < 0:
+		return Vector2.INF
+	var fv0 := meshtool.get_face_vertex(face, 0)
+	var fv1 := meshtool.get_face_vertex(face, 1)
+	var fv2 := meshtool.get_face_vertex(face, 2)
+	var v1 := meshtool.get_vertex(fv0)
+	var v2 := meshtool.get_vertex(fv1)
+	var v3 := meshtool.get_vertex(fv2)
+	var bc := _barycentric(point, v1, v2, v3)  # TODO memoize
+	var uv1 := meshtool.get_vertex_uv(fv0)
+	var uv2 := meshtool.get_vertex_uv(fv1)
+	var uv3 := meshtool.get_vertex_uv(fv2)
+	return (uv1 * bc.x) + (uv2 * bc.y) + (uv3 * bc.z)
+
+
+## Paint a rectangle on the mask at a given point & normal on the mesh.
+func paint_mask(point: Vector3, normal: Vector3, radius: int) -> void:
+	# debug_draw.draw_vector(normal, point)
+	var local_point := point * global_transform
+	var local_normal := normal * global_basis
+	var uv := _get_uv(local_point, local_normal)
+	if uv == Vector2.INF:
+		return
+	var px_center: Vector2i = Vector2i(uv * Vector2(mask_image.get_size()))
+	var rect := Rect2i(px_center.x - radius, px_center.y - radius, 2 * radius, 2 * radius)
+	mask_image.fill_rect(rect, MASK_COLOR)
+	# TODO: can we call this once after all painting in a single frame is finished?
+	_update_gunk_material()