Shader Basics

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 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

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

shader_type spatial;

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

Built-in Variables (canvas_item)

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)

Uniforms (Shader Parameters)

Uniforms expose shader values to the Inspector and code.

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

Setting Uniforms from Code

GDScript

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

C#

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 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 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

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

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.

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 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 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

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

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 for render-mode reference and the X-ray vision portal worked example.