---
id: jame581/GodotPrompter/shader-basics
version: "8f2d284e"
license: MIT
install: manual
updated: 2026-07-27
---

# shader-basics — This skill equips you with essential shader techniques for Godot game development, covering both 2D and 3D rendering pipelines. You'll explore shader syntax, material properties, and practical effects that bring visual polish to your projects. Perfect for developers ready to move beyond built-in materials into custom visual solutions.

Publisher: jame581 · Stars: 487 · Updated: 2026-07-27

Install (manual): `git clone https://github.com/jame581/GodotPrompter`

## SKILL.md

# Shaders in Godot 4.3+

All examples target Godot 4.3+ with no deprecated APIs.

> **Related skills:** **animation-system** for shader-driven effects like hit flash, **godot-optimization** for shader performance considerations, **camera-system** for post-processing camera effects, **2d-essentials** for 2D lighting, pixel-art shaders, and CanvasTexture normal maps, **3d-essentials** for spatial shaders and environment materials, **particles-vfx** for custom particle shaders, **tween-animation** for animating shader parameters at runtime.

---

## 1. Core Concepts

### Shader Types

| Shader Type | Applied To | Use For |
|------------------|--------------------------|--------------------------------------------------|
| `canvas_item` | 2D nodes (Sprite2D, Control, etc.) | 2D effects — outlines, dissolve, color swap |
| `spatial` | 3D meshes (MeshInstance3D) | 3D materials — water, terrain, toon shading |
| `particles` | GPUParticles2D/3D | Custom particle behavior |
| `sky` | WorldEnvironment | Procedural sky rendering |
| `fog` | FogVolume | Volumetric fog effects |

### Shader vs ShaderMaterial

```
Shader (.gdshader)        → The code (GLSL-like language)
ShaderMaterial            → Instance of a shader with specific uniform values
CanvasItemMaterial / StandardMaterial3D → Built-in materials (no code needed)
```

Multiple nodes can share the same Shader but have different ShaderMaterial instances with different uniform values (e.g., same dissolve shader but different dissolve progress per enemy).

### Creating a Shader

1. Select a node (e.g., Sprite2D)
2. In Inspector → Material → New ShaderMaterial
3. On the ShaderMaterial → Shader → New Shader
4. Edit the `.gdshader` file in the built-in editor

Or create a `.gdshader` file directly in the FileSystem dock.

---

## 2. Godot Shader Language Basics

Godot uses a GLSL ES 3.0-like language with Godot-specific additions.

### Minimal Canvas Item Shader

```glsl
shader_type canvas_item;

void fragment() {
    // COLOR is the output pixel color
    // TEXTURE is the sprite's texture
    // UV is the texture coordinate (0,0 top-left to 1,1 bottom-right)
    vec4 tex = texture(TEXTURE, UV);
    COLOR = tex;
}
```

### Minimal Spatial Shader

```glsl
shader_type spatial;

void fragment() {
    // ALBEDO is the base color (vec3)
    ALBEDO = vec3(0.8, 0.2, 0.2);
}
```

### Built-in Variables (canvas_item)

| Variable | Type | Description |
|------------|--------|---------------------------------------|
| `UV` | `vec2` | Texture coordinates |
| `COLOR` | `vec4` | Output color (set this in `fragment()`) |
| `TEXTURE` | `sampler2D` | The node's texture |
| `VERTEX` | `vec2` | Vertex position (in `vertex()`) |
| `TIME` | `float`| Elapsed time in seconds |
| `SCREEN_UV`| `vec2` | Screen-space UV (for screen effects) |

> `SCREEN_TEXTURE` was removed in Godot 4.0. To read the screen, declare a uniform: `uniform sampler2D screen_texture : hint_screen_texture, filter_linear_mipmap;`

### Built-in Variables (spatial)

| Variable | Type | Description |
|-------------|--------|---------------------------------------|
| `ALBEDO` | `vec3` | Base surface color |
| `METALLIC` | `float`| Metallic value (0.0–1.0) |
| `ROUGHNESS` | `float`| Roughness value (0.0–1.0) |
| `NORMAL` | `vec3` | Surface normal (for normal mapping) |
| `EMISSION` | `vec3` | Emissive color |
| `ALPHA` | `float`| Transparency (enable in render mode) |
| `VERTEX` | `vec3` | Vertex position (in `vertex()`) |

### Uniforms (Shader Parameters)

Uniforms expose shader values to the Inspector and code.

```glsl
shader_type canvas_item;

uniform float speed : hint_range(0.0, 10.0, 0.1) = 1.0;
uniform vec4 tint_color : source_color = vec4(1.0, 1.0, 1.0, 1.0);
uniform sampler2D noise_texture : filter_linear_mipmap;

void fragment() {
    vec4 tex = texture(TEXTURE, UV);
    COLOR = tex * tint_color;
}
```

### Common Uniform Hints

| Hint | Type | Description |
|-----------------------------|--------------|-------------------------------------|
| `hint_range(min, max, step)` | `float/int` | Slider in Inspector |
| `source_color` | `vec4` | Color picker in Inspector |
| `filter_linear_mipmap` | `sampler2D` | Texture filtering mode |
| `repeat_enable` | `sampler2D` | Allow texture tiling |
| `hint_normal` | `sampler2D` | Treat as normal map |

### Setting Uniforms from Code

#### GDScript

```gdscript
var mat: ShaderMaterial = $Sprite2D.material
mat.set_shader_parameter("speed", 2.0)
mat.set_shader_parameter("tint_color", Color.RED)
```

#### C#

```csharp
var mat = GetNode<Sprite2D>("Sprite2D").Material as ShaderMaterial;
mat.SetShaderParameter("speed", 2.0f);
mat.SetShaderParameter("tint_color", Colors.Red);
```

---

## 3. Common 2D Shader Recipes

The canvas_item recipes most projects need: **dissolve** (noise + edge glow), **outline** (sample neighbors, expand alpha), **flash-white** (uniform-driven hit effect), **color swap** (palette shift), **scrolling UV** (water/lava/clouds), **wave distortion**.

> See [references/2d-shader-recipes.md](references/2d-shader-recipes.md) for complete shader code for all six recipes.

---

## 4. Common 3D Shader Recipes

Spatial-shader recipes: **toon/cel shading** (banded NdotL), **rim lighting / Fresnel** (1 - NdotV), **simple water surface** (UV scroll + normal-map blend + Fresnel).

> See [references/3d-shader-recipes.md](references/3d-shader-recipes.md) for the full shader source for each recipe.

---

## 5. Visual Shaders

Visual shaders provide a node-based graph editor — no code required.

### When to Use Visual Shaders

| Use Visual Shaders When | Use Code Shaders When |
|--------------------------------|------------------------------------|
| Prototyping effects quickly | Complex math or branching logic |
| Artists need to tweak values | Need precise control over every line |
| Learning shader concepts | Performance-critical shaders |
| Simple effects (color adjust, UV scroll) | Loops or advanced techniques |

### Creating a Visual Shader

1. Select node → Inspector → Material → New ShaderMaterial
2. Shader → New VisualShader
3. Click the shader to open the Visual Shader editor
4. Add nodes from the palette, connect pins
5. Output nodes (Output, FragmentOutput) are pre-placed

### Key Visual Shader Nodes

| Node | Purpose |
|---------------------|--------------------------------------|
| `Texture2D` | Sample a texture |
| `ColorConstant` | Solid color value |
| `VectorOp` | Math operations on vectors |
| `ScalarOp` | Math operations on floats |
| `Mix` | Lerp between two values |
| `Step` / `SmoothStep` | Threshold / smooth threshold |
| `Time` | Current time (for animation) |
| `UV` | Texture coordinates |
| `Input` (custom) | Expose a uniform to Inspector |

> Visual shaders compile to the same GPU code as written shaders. There is no performance difference.

> **Godot 4.7+:** Two new spatial `Input` nodes — `in_shadow_pass` (vertex/fragment; maps to the `IN_SHADOW_PASS` built-in, `true` when the shader is being rendered in a shadow mapping pass — render objects differently in shadow maps than in the regular pass) and `specular_amount` (`light()`; maps to `SPECULAR_AMOUNT` — `2.0` × `light_specular` for OmniLight3D/SpotLight3D, `1.0` for DirectionalLight3D).

> ⚠️ **Changed in Godot 4.7:** The `LinearToSRGB` visual shader node no longer clamps its output to `[0.0, 1.0]` when using the Forward+ or Mobile renderer — HDR values above `1.0` now pass through. Graphs that relied on the implicit clamp produce different output; add an explicit `Clamp` node to restore the old behavior. See the [4.7 migration guide](https://docs.godotengine.org/en/latest/tutorials/migrating/upgrading_to_godot_4.7.html).

---

## 6. Post-Processing Effects

The standard pattern: full-rect `ColorRect` with a canvas_item shader on top of the gameplay canvas. For 3D, use a `WorldEnvironment` Adjustment, Glow, or custom shader. For chained effects, render the world to a `SubViewport` then sample its texture in a final shader pass.

> See [references/post-processing.md](references/post-processing.md) for the ColorRect overlay pattern, vignette + CRT/scanline shader source, the SubViewport pipeline, and WorldEnvironment 3D post-processing notes.

---

## 7. Compositor Effects (Godot 4.3+)

`CompositorEffect` runs custom render passes within Godot's render pipeline (post-tonemap or pre-tonemap). Use when ColorRect overlays aren't enough — multi-pass effects, depth-aware effects, custom AO/SSR variants. Heavier setup than a screen-space shader; reach for it only when needed.

> See [references/compositor-effects.md](references/compositor-effects.md) for setup, a custom CompositorEffect GDScript example, and built-in Compositor use cases.

---

## 8. Render Modes

Render modes go on the first line after `shader_type` and control how the shader interacts with the rendering pipeline.

### Canvas Item Render Modes

```glsl
shader_type canvas_item;
render_mode unshaded;           // Ignore all lighting
render_mode light_only;         // Only visible where lit
render_mode blend_add;          // Additive blending (glow, fire)
render_mode blend_mix;          // Standard alpha blending (default)
render_mode blend_premul_alpha; // Pre-multiplied alpha
```

### Spatial Render Modes

```glsl
shader_type spatial;
render_mode unshaded;              // No lighting calculations
render_mode cull_disabled;         // Render both sides of faces
render_mode depth_draw_always;     // Always write to depth buffer
render_mode specular_toon;         // Toon specular model
render_mode diffuse_toon;          // Toon diffuse model
render_mode blend_add;             // Additive blending
```

---

## 9. Stencil Buffer Effects (Godot 4.5+)

Godot 4.5 exposes stencil write/read in spatial and canvas_item shaders via `stencil_write_mode`, `stencil_read_mode`, `stencil_value`, etc. across all rendering backends. Enables portals, X-ray vision, outline masks, and holes-in-geometry effects that previously required compositor-level work.

> See [references/stencil-buffer.md](references/stencil-buffer.md) for render-mode reference and the X-ray vision portal worked example.

---

## 10. SMAA Antialiasing (Godot 4.5+)

Sub-pixel Morphological Antialiasing (SMAA 1x) is a built-in post-processing AA mode added in Godot 4.5. It produces sharper, more temporally stable results than FXAA and is less costly than MSAA for deferred-heavy scenes.

### Enabling SMAA

1. Open **Project Settings**
2. Navigate to **Rendering → Anti Aliasing → Quality**
3. Set **Screen Space AA** to **SMAA**

SMAA can be combined with MSAA (for geometry edge aliasing) or used standalone. It does not require any shader code changes.

| AA Mode | Sharpness | GPU cost | Ghosting |
|---------|-----------|----------|----------|
| Disabled | N/A | None | None |
| FXAA | Low (blurry) | Very low | Low |
| **SMAA** | High | Low | Very low |
| TAA | Medium (slight blur) | Medium | Possible |
| MSAA 4x | High | High | None |

> **When to use SMAA:** Prefer SMAA over FXAA for most desktop projects — it delivers noticeably sharper text and thin edges with a similar performance profile. Combine SMAA + MSAA 2x for best quality at moderate cost.

This is an editor/export setting only — no runtime API is needed.

---

## 11. Shader Baker — Export-time Pre-compilation (Godot 4.5+)

The Shader Baker pre-compiles all project shaders for the target platform at export time, eliminating the stutter players experience the first time a new material renders in-game — especially severe on macOS/Apple Silicon (Metal) and Windows (D3D12), where shader translation is expensive. Enable it per export preset for release builds; leave it off for development builds to keep exports fast. It operates at the Godot export pipeline level — see the **export-pipeline** skill for export preset configuration.

> See [references/shader-baker.md](references/shader-baker.md) for enabling steps and the with/without comparison.

---

## 12. Common Pitfalls

| Symptom | Cause | Fix |
|-------------------------------------|----------------------------------------------------|------------------------------------------------------------------|
| Shader has no visible effect | Material not assigned or shader not saved | Check node's Material property in Inspector |
| Transparent parts render as black | Alpha not handled in shader | Set `COLOR.a = tex.a;` and use appropriate blend mode |
| Uniform doesn't appear in Inspector | Typo in uniform name or wrong type | Re-save the shader; check for compilation errors |
| Texture appears stretched/tiled | Missing `repeat_enable` or wrong UV scale | Add `repeat_enable` hint to sampler2D uniform |
| Shader works in editor but not in game | Screen texture uniform needs backbuffer | Use `hint_screen_texture` on a `sampler2D` uniform (Godot 4.x) |
| Performance drops with many shaders | Each unique shader = draw call break | Share ShaderMaterial instances; use uniforms for variation |
| Screen-space UV is wrong | `SCREEN_UV` not available in some contexts | Ensure the node is rendered in the correct viewport |
| Visual shader node missing | Node was renamed or removed in newer Godot version | Check Godot docs for the current node name |

> ⚠️ **Changed in Godot 4.7:** `textureQueryLod()` is available only in the fragment shader, and Godot 4.7 enforces this with a compile error — shaders calling it from `vertex()` stop compiling after upgrading. Move the call into `fragment()`. See [GH-118962](https://github.com/godotengine/godot/pull/118962).

---

## 13. Implementation Checklist

- [ ] Shader type matches the node type (`canvas_item` for 2D, `spatial` for 3D)
- [ ] Uniforms use appropriate hints (`hint_range`, `source_color`, `filter_linear_mipmap`)
- [ ] Shared visual effects use the same Shader resource with separate ShaderMaterial instances
- [ ] Post-processing shaders are on a CanvasLayer (2D) or WorldEnvironment (3D), not on game objects
- [ ] `TEXTURE` is sampled in canvas_item shaders (otherwise sprite content is lost)
- [ ] Alpha-transparent shaders set `COLOR.a` correctly and use `blend_mix` render mode
- [ ] Animated shader parameters (dissolve, flash) are driven by Tweens or AnimationPlayer, not `_process`
- [ ] Screen-reading shaders use `hint_screen_texture` on a `sampler2D` uniform (Godot 4.x approach)
- [ ] Complex shaders are profiled with the Godot profiler to check GPU frame time
- [ ] Stencil effects use two-pass materials (write pass first, read pass second) with correct render priority (Godot 4.5+)
- [ ] SMAA is preferred over FXAA for desktop builds (sharper edges, similar cost) — set in Project Settings → Rendering → Anti Aliasing (Godot 4.5+)
- [ ] Shader Baker is enabled in all release export presets to eliminate first-use compilation stutters (Godot 4.5+)


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