Adapt: 3D to 2D

适配：3D转2D

Expert guidance for simplifying 3D games into 2D (or 2.5D).

将3D游戏简化为2D（或2.5D）的专业指南。

NEVER Do

绝对不要做这些

NEVER remove Z-axis without gameplay compensation — Blindly flattening 3D to 2D removes spatial strategy. Add other depth mechanics (layers, jump height variations).
NEVER keep 3D collision shapes — Use simpler 2D shapes (CapsuleShape2D, RectangleShape2D). 3D shapes don't convert automatically.
NEVER use orthographic Camera3D as "2D mode" — Use actual Camera2D for proper 2D rendering pipeline and performance.
NEVER assume automatic performance gain — Poorly optimized 2D (too many draw calls, large sprite sheets) can be slower than optimized 3D.
NEVER forget to adjust gravity — 3D gravity is Vector3(0, -9.8, 0). 2D gravity is float (980 pixels/s²). Scale appropriately.

绝对不要在没有游戏玩法补偿的情况下移除Z轴 — 盲目地将3D扁平化到2D会消除空间策略性。应添加其他深度机制（如分层、跳跃高度变化）。
绝对不要保留3D碰撞形状 — 使用更简单的2D形状（CapsuleShape2D、RectangleShape2D）。3D形状无法自动转换。
绝对不要将正交Camera3D当作「2D模式」使用 — 使用真正的Camera2D以获得正确的2D渲染管线和性能表现。
绝对不要想当然地认为性能会自动提升 — 优化不佳的2D游戏（比如过多绘制调用、过大精灵图集）可能比优化后的3D游戏运行更慢。
绝对不要忘记调整重力参数 — 3D重力是Vector3(0, -9.8, 0)，2D重力是浮点数（980像素/秒²），需进行相应缩放。

Available Scripts

可用脚本

MANDATORY: Read the appropriate script before implementing the corresponding pattern.

强制要求：在实现对应模式前，请先阅读相应脚本。

ortho_simulation.gd

Simulates 3D Z-axis height in 2D top-down games. Handles vertical velocity, gravity, sprite offset, and shadow scaling.

在2D俯视角游戏中模拟3D Z轴高度。处理垂直速度、重力、精灵偏移和阴影缩放。

projection_utils.gd

Projects 3D world positions to 2D screen space for nameplates, healthbars, and targeting. Handles behind-camera detection and distance-based scaling.

将3D世界坐标投影到2D屏幕空间，用于名称牌、血条和目标锁定。处理相机后方检测和基于距离的缩放。

Why Go from 3D to 2D?

为什么要从3D转2D？

Reason	Benefit
Mobile performance	5-10x faster on low-end devices
Simpler art pipeline	Sprites easier to create than 3D models
Faster iteration	2D level design is quicker
Accessibility	Lower hardware requirements
Clarity	Reduce visual clutter for puzzle/strategy games

原因	优势
移动平台性能	在低端设备上运行速度提升5-10倍
更简单的美术工作流	制作精灵图比3D模型更容易
更快的迭代速度	2D关卡设计耗时更短
更低的硬件门槛	降低设备配置要求
更清晰的视觉表现	减少解谜/策略游戏中的视觉杂乱

Dimension Reduction Strategies

降维策略

Strategy 1: True 2D (Remove Z-axis)

策略1：纯2D（移除Z轴）

gdscript

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gdscript

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Top-down or side-view

Example: 3D isometric → 2D top-down

Before (3D):

var velocity := Vector3(input.x, 0, input.y) * speed

After (2D):

var velocity := Vector2(input.x, input.y) * speed

Use case: Top-down shooters, RTS, turn-based strategy

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Strategy 2: 2.5D (Fake depth with layers)

策略2：2.5D（用分层模拟深度）

gdscript

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gdscript

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Keep visual depth perception without Z-axis gameplay

Use ParallaxBackground for depth layers

Scene structure:

ParallaxBackground

├─ ParallaxLayer (far mountains, scroll slow)

├─ ParallaxLayer (mid buildings, scroll medium)

└─ ParallaxLayer (near trees, scroll fast)

player.gd

extends CharacterBody2D

func _ready() -> void: var parallax := get_node("../ParallaxBackground") parallax.scroll_base_scale = Vector2(0.5, 0.5) # Parallax strength

undefined

extends CharacterBody2D

func _ready() -> void: var parallax := get_node("../ParallaxBackground") parallax.scroll_base_scale = Vector2(0.5, 0.5) # Parallax strength

undefined

Strategy 3: Fixed Perspective (Isometric Stay)

策略3：固定视角（保持等距视角）

gdscript

undefined

gdscript

undefined

Keep isometric/dimetric view but use 2D physics

Use rotated sprites to simulate 3D angles

const ISO_ANGLE := deg_to_rad(-30) # Isometric tilt

func world_to_iso(pos: Vector2) -> Vector2: return Vector2( pos.x - pos.y, (pos.x + pos.y) * 0.5 )

func iso_to_world(iso_pos: Vector2) -> Vector2: return Vector2( (iso_pos.x + iso_pos.y * 2) * 0.5, (iso_pos.y * 2 - iso_pos.x) * 0.5 )

---

const ISO_ANGLE := deg_to_rad(-30) # Isometric tilt

func world_to_iso(pos: Vector2) -> Vector2: return Vector2( pos.x - pos.y, (pos.x + pos.y) * 0.5 )

func iso_to_world(iso_pos: Vector2) -> Vector2: return Vector2( (iso_pos.x + iso_pos.y * 2) * 0.5, (iso_pos.y * 2 - iso_pos.x) * 0.5 )

---

Node Conversion

节点转换

Physics Bodies

物理刚体

gdscript

undefined

gdscript

undefined

CharacterBody3D → CharacterBody2D

extends CharacterBody3D # Before

const SPEED = 5.0 const JUMP_VELOCITY = 4.5 const GRAVITY = 9.8

func _physics_process(delta: float) -> void: velocity.y -= GRAVITY * delta var input := Input.get_vector("left", "right", "forward", "back") velocity.x = input.x * SPEED velocity.z = input.y * SPEED move_and_slide()

extends CharacterBody3D # Before

const SPEED = 5.0 const JUMP_VELOCITY = 4.5 const GRAVITY = 9.8

func _physics_process(delta: float) -> void: velocity.y -= GRAVITY * delta var input := Input.get_vector("left", "right", "forward", "back") velocity.x = input.x * SPEED velocity.z = input.y * SPEED move_and_slide()

⬇️ Convert to:

extends CharacterBody2D # After

const SPEED = 300.0 const JUMP_VELOCITY = -400.0 const GRAVITY = 980.0 # Pixels per second squared

func _physics_process(delta: float) -> void: velocity.y += GRAVITY * delta var input := Input.get_vector("left", "right", "up", "down") velocity.x = input.x * SPEED # Note: No Z-axis. For platformer, use input.y for jump move_and_slide()

undefined

extends CharacterBody2D # After

const SPEED = 300.0 const JUMP_VELOCITY = -400.0 const GRAVITY = 980.0 # Pixels per second squared

func _physics_process(delta: float) -> void: velocity.y += GRAVITY * delta var input := Input.get_vector("left", "right", "up", "down") velocity.x = input.x * SPEED # Note: No Z-axis. For platformer, use input.y for jump move_and_slide()

undefined

Camera Conversion

相机转换

gdscript

undefined

gdscript

undefined

Camera3D → Camera2D

Before: Third-person 3D camera

extends SpringArm3D

@onready var camera: Camera3D = $Camera3D

func _process(delta: float) -> void: spring_length = 10.0 rotate_y(Input.get_axis("cam_left", "cam_right") * delta)

extends SpringArm3D

@onready var camera: Camera3D = $Camera3D

func _process(delta: float) -> void: spring_length = 10.0 rotate_y(Input.get_axis("cam_left", "cam_right") * delta)

⬇️ Convert to:

extends Camera2D # After

@onready var player: CharacterBody2D = $"../Player"

func _process(delta: float) -> void: global_position = player.global_position zoom = Vector2(2.0, 2.0) # Adjust to taste

---

extends Camera2D # After

@onready var player: CharacterBody2D = $"../Player"

func _process(delta: float) -> void: global_position = player.global_position zoom = Vector2(2.0, 2.0) # Adjust to taste

---

Art Pipeline: 3D Models → Sprites

美术工作流：3D模型 → 精灵图

Option 1: Render Sprites from 3D (Automation)

选项1：从3D渲染精灵图（自动化）

gdscript

undefined

gdscript

undefined

Use Godot to render 3D model from fixed angles

sprite_renderer.gd (tool script)

@tool extends Node3D

@export var model_path: String = "res://models/character.glb" @export var output_dir: String = "res://sprites/" @export var angles: int = 8 # 8-directional sprites @export var render: bool = false: set(value): if value: render_sprites()

func render_sprites() -> void: var model := load(model_path).instantiate() add_child(model)

var camera := Camera3D.new()
camera.position = Vector3(0, 2, 5)
camera.look_at(Vector3.ZERO)
add_child(camera)

var viewport := SubViewport.new()
viewport.size = Vector2i(256, 256)
viewport.transparent_bg = true
viewport.add_child(camera)
add_child(viewport)

for i in range(angles):
    model.rotation.y = (TAU / angles) * i
    
    await RenderingServer.frame_post_draw
    var img := viewport.get_texture().get_image()
    img.save_png("%s/sprite_%d.png" % [output_dir, i])

model.queue_free()
camera.queue_free()
viewport.queue_free()

undefined

@tool extends Node3D

@export var model_path: String = "res://models/character.glb" @export var output_dir: String = "res://sprites/" @export var angles: int = 8 # 8-directional sprites @export var render: bool = false: set(value): if value: render_sprites()

func render_sprites() -> void: var model := load(model_path).instantiate() add_child(model)

var camera := Camera3D.new()
camera.position = Vector3(0, 2, 5)
camera.look_at(Vector3.ZERO)
add_child(camera)

var viewport := SubViewport.new()
viewport.size = Vector2i(256, 256)
viewport.transparent_bg = true
viewport.add_child(camera)
add_child(viewport)

for i in range(angles):
    model.rotation.y = (TAU / angles) * i
    
    await RenderingServer.frame_post_draw
    var img := viewport.get_texture().get_image()
    img.save_png("%s/sprite_%d.png" % [output_dir, i])

model.queue_free()
camera.queue_free()
viewport.queue_free()

undefined

Option 2: Manual Export (Blender)

选项2：手动导出（Blender）

python

undefined

python

undefined

Blender Python script (run in Blender)

import bpy import math

angles = 8 output_dir = "/path/to/sprites/" model = bpy.data.objects["Character"]

for i in range(angles): model.rotation_euler.z = (2 * math.pi / angles) * i bpy.ops.render.render(write_still=True) bpy.data.images['Render Result'].save_render( filepath=f"{output_dir}/sprite_{i}.png" )

undefined

import bpy import math

angles = 8 output_dir = "/path/to/sprites/" model = bpy.data.objects["Character"]

for i in range(angles): model.rotation_euler.z = (2 * math.pi / angles) * i bpy.ops.render.render(write_still=True) bpy.data.images['Render Result'].save_render( filepath=f"{output_dir}/sprite_{i}.png" )

undefined

Option 3: Use Sprite3D as Reference

选项3：使用Sprite3D作为参考

gdscript

undefined

gdscript

undefined

Keep 3D model in editor, export frame-by-frame

---

---

Physics Adjustments

物理系统调整

Gravity Scaling

重力缩放

gdscript

undefined

gdscript

undefined

3D gravity (m/s²): 9.8

2D gravity (pixels/s²): Scale to pixel units

If 1 meter = 100 pixels:

const GRAVITY_2D = 9.8 * 100 # = 980 pixels/s²

Adjust jump velocity proportionally:

3D jump: 4.5 m/s

2D jump: -450 pixels/s

undefined

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Collision Simplification

碰撞简化

gdscript

undefined

gdscript

undefined

3D: CapsuleShape3D (16 segments, expensive)

var shape_3d := CapsuleShape3D.new() shape_3d.radius = 0.5 shape_3d.height = 2.0

2D: CapsuleShape2D (much simpler)

var shape_2d := CapsuleShape2D.new() shape_2d.radius = 16 # pixels shape_2d.height = 64

---

var shape_2d := CapsuleShape2D.new() shape_2d.radius = 16 # pixels shape_2d.height = 64

---

Control Simplification

控制简化

3D Free Movement → 2D Restricted

3D自由移动 → 2D受限移动

gdscript

undefined

gdscript

undefined

3D: Full 3D movement with camera-relative controls

var input_3d := Input.get_vector("left", "right", "forward", "back") var camera_basis := camera.global_transform.basis var direction := (camera_basis * Vector3(input_3d.x, 0, input_3d.y)).normalized()

2D: Simple 4-direction (or 8-direction with diagonals)

var input_2d := Input.get_vector("left", "right", "up", "down") velocity = input_2d.normalized() * SPEED

---

var input_2d := Input.get_vector("left", "right", "up", "down") velocity = input_2d.normalized() * SPEED

---

Performance Gains

性能提升

Expected Improvements

预期改进

Metric	3D	2D	Improvement
Draw calls	100	20	5x
GPU load	High	Low	10x
Battery life (mobile)	1 hour	5 hours	5x
RAM usage	500MB	100MB	5x

指标	3D	2D	提升幅度
绘制调用	100	20	5倍
GPU负载	高	低	10倍
移动设备续航	1小时	5小时	5倍
RAM占用	500MB	100MB	5倍

Optimization Techniques

优化技巧

gdscript

undefined

gdscript

undefined

1. Use TileMapLayer instead of individual Sprite2D nodes

var tilemap := TileMapLayer.new() tilemap.tile_set = load("res://tileset.tres")

2. Batch sprite rendering

Use single large sprite sheet instead of individual textures

3. Reduce particle count

var godot-particles := GPUParticles2D.new() godot-particles.amount = 50 # Down from 200 in 3D

---

var godot-particles := GPUParticles2D.new() godot-particles.amount = 50 # Down from 200 in 3D

---

UI Adaptation

UI适配

gdscript

undefined

gdscript

undefined

Most 3D games already use 2D UI (CanvasLayer)

No changes needed!

Just verify UI scaling for new aspect ratios

get_viewport().size_changed.connect(_on_viewport_resized)

func _on_viewport_resized() -> void: var viewport_size := get_viewport().get_visible_rect().size # Adjust UI anchors/margins

---

get_viewport().size_changed.connect(_on_viewport_resized)

func _on_viewport_resized() -> void: var viewport_size := get_viewport().get_visible_rect().size # Adjust UI anchors/margins

---

Edge Cases

边缘情况

Depth Sorting

深度排序

gdscript

undefined

gdscript

undefined

Problem: Overlapping sprites need sorting

Solution: Use Y-sort or z_index

extends Sprite2D

func _ready() -> void: y_sort_enabled = true # Auto-sort by Y position # Or set z_index manually: z_index = int(global_position.y)

undefined

extends Sprite2D

func _ready() -> void: y_sort_enabled = true # Auto-sort by Y position # Or set z_index manually: z_index = int(global_position.y)

undefined

Lost Spatial Audio

丢失的空间音频

gdscript

undefined

gdscript

undefined

3D spatial audio (AudioStreamPlayer3D) → 2D panning (AudioStreamPlayer2D)

var audio_2d := AudioStreamPlayer2D.new() audio_2d.stream = load("res://sounds/footstep.ogg") audio_2d.max_distance = 1000.0 # 2D range audio_2d.attenuation = 2.0 add_child(audio_2d)

---

var audio_2d := AudioStreamPlayer2D.new() audio_2d.stream = load("res://sounds/footstep.ogg") audio_2d.max_distance = 1000.0 # 2D range audio_2d.attenuation = 2.0 add_child(audio_2d)

---

Decision Tree: When to Simplify to 2D

决策树：何时简化为2D

Factor	Keep 3D	Go 2D
Target platform	Desktop, console	Mobile, web
Art style	Realistic, immersive	Stylized, retro
Gameplay	Requires 3D space	Works in 2D plane
Performance	Have GPU budget	Need 60 FPS on low-end
Team skills	3D artists	2D artists or pixel art

因素	保留3D	转2D
目标平台	桌面、主机	移动、网页
美术风格	写实、沉浸式	风格化、复古
游戏玩法	需要3D空间	可在2D平面实现
性能需求	有足够GPU预算	需要在低端设备上跑60帧
团队技能	有3D美术	有2D美术或像素画能力

Reference

参考

Master Skill: godot-master

核心技能：godot-master

godot-adapt-3d-to-2d

Original

Translation

Adapt: 3D to 2D

适配：3D转2D

NEVER Do

绝对不要做这些

Available Scripts

可用脚本

ortho_simulation.gd

ortho_simulation.gd

projection_utils.gd

projection_utils.gd

Why Go from 3D to 2D?

为什么要从3D转2D？

Dimension Reduction Strategies

降维策略

Strategy 1: True 2D (Remove Z-axis)

策略1：纯2D（移除Z轴）

Top-down or side-view

Top-down or side-view

Example: 3D isometric → 2D top-down

Example: 3D isometric → 2D top-down

Before (3D):

Before (3D):

After (2D):

After (2D):

Use case: Top-down shooters, RTS, turn-based strategy

Use case: Top-down shooters, RTS, turn-based strategy

Strategy 2: 2.5D (Fake depth with layers)

策略2：2.5D（用分层模拟深度）

Keep visual depth perception without Z-axis gameplay

Keep visual depth perception without Z-axis gameplay

Use ParallaxBackground for depth layers

Use ParallaxBackground for depth layers

Scene structure:

Scene structure:

ParallaxBackground

ParallaxBackground

├─ ParallaxLayer (far mountains, scroll slow)

├─ ParallaxLayer (far mountains, scroll slow)

├─ ParallaxLayer (mid buildings, scroll medium)

├─ ParallaxLayer (mid buildings, scroll medium)

└─ ParallaxLayer (near trees, scroll fast)

└─ ParallaxLayer (near trees, scroll fast)

player.gd

player.gd

Strategy 3: Fixed Perspective (Isometric Stay)

策略3：固定视角（保持等距视角）

Keep isometric/dimetric view but use 2D physics

Keep isometric/dimetric view but use 2D physics

Use rotated sprites to simulate 3D angles

Use rotated sprites to simulate 3D angles

Node Conversion

节点转换

Physics Bodies

物理刚体

CharacterBody3D → CharacterBody2D

CharacterBody3D → CharacterBody2D

⬇️ Convert to:

⬇️ Convert to:

Camera Conversion

相机转换

Camera3D → Camera2D

Camera3D → Camera2D

Before: Third-person 3D camera

Before: Third-person 3D camera

⬇️ Convert to:

⬇️ Convert to:

Art Pipeline: 3D Models → Sprites

美术工作流：3D模型 → 精灵图

Option 1: Render Sprites from 3D (Automation)

选项1：从3D渲染精灵图（自动化）

Use Godot to render 3D model from fixed angles

Use Godot to render 3D model from fixed angles

sprite_renderer.gd (tool script)

sprite_renderer.gd (tool script)

Option 2: Manual Export (Blender)

选项2：手动导出（Blender）

Blender Python script (run in Blender)