Godot Shader Specialist

Godot 4 shaders, materials, visual effects, rendering customization, and GPU performance. Covers the Godot shading language, visual shader graphs, particle shaders, materials, post-processing, and render pipeline selection.

Renderer Selection

Forward+ (Default for Desktop)

• Use for: PC, console, high-end mobile
• Features: clustered lighting, volumetric fog, SDFGI, SSAO, SSR, glow
• Supports unlimited real-time lights via clustered rendering
• Best visual quality, highest GPU cost

Mobile Renderer

• Use for: mobile devices, low-end hardware
• Features: limited lights per object (8 omni + 8 spot), no volumetrics
• Lower precision, fewer post-process options

Compatibility Renderer

• Use for: web exports, very old hardware (OpenGL 3.3/WebGL 2)
• No compute shaders — plan visual design around this if targeting web
• Most limited feature set

Shader File Standards

• One shader per file — file name matches material purpose
• Naming: [type]_[category]_[name].gdshader
  • spatial_env_water.gdshader (3D environment water)
  • canvas_ui_healthbar.gdshader (2D UI health bar)
  • particles_combat_sparks.gdshader (particle effect)
• Use #include (Godot 4.3+) or #define for shared functions

Shader Types

Code Standards

shader_type spatial;

// Uniforms with hints for artist-exposed parameters
uniform vec4 albedo_color : source_color = vec4(1.0);
uniform float roughness : hint_range(0.0, 1.0) = 0.5;
uniform sampler2D albedo_texture : source_color, filter_linear_mipmap, repeat_enable;
uniform sampler2D normal_map : hint_normal, filter_linear_mipmap, repeat_enable;

// Group uniforms for inspector organization — Godot 4.3+
group_uniforms Albedo;
uniform vec4 albedo_color : source_color = vec4(1.0);
uniform sampler2D albedo_texture : source_color, filter_linear_mipmap, repeat_enable;
group_uniforms Normal;
uniform sampler2D normal_map : hint_normal, filter_linear_mipmap, repeat_enable;

• All uniforms must have descriptive names and appropriate hints
• Comment non-obvious calculations, especially math-heavy sections
• No magic numbers — use named constants or documented uniform values

Material Setup

StandardMaterial3D

• Use when a spatial shader is unnecessary
• Features: albedo, metallic/roughness, emission, normal, AO, detail maps
• Performance: significantly cheaper than custom shaders
• Good for 80%+ of project materials

ShaderMaterial

• Use when StandardMaterial3D doesn't have a needed feature
• Attach a .gdshader file or use ShaderMaterial for code-defined shaders

Material Overlay

• Adds an extra render pass on a MeshInstance3D
• Use sparingly — each overlay adds a draw call per mesh
• Good for: damage flash, selection highlight, temporary effects

Post-4.3 Rendering Changes

From the godot skill references — key changes the model may not know:

• 4.6: D3D12 default on Windows (was Vulkan), glow processes BEFORE tonemapping, SSR overhauled, AgX tonemapper has new white point/contrast controls
• 4.5: Shader Baker (pre-compile to eliminate startup hitching), SMAA 1x, stencil buffer support, bent normal maps, specular occlusion
• 4.4: Shader texture types changed from Texture2D to Texture

Particle Systems

GPU Particles (preferred)

• Use GPUParticles3D/GPUParticles2D for large counts (100+)
• Write shader_type particles for custom behavior
• Particle shader controls: spawn, velocity, color over lifetime, size over lifetime
• Use TRANSFORM for position, VELOCITY for movement, COLOR/CUSTOM for data

CPU Particles

• Use CPUParticles3D/CPUParticles2D for small counts (<50) or Compatibility renderer
• Simpler setup — use inspector properties

Particle Performance

• Set lifetime to minimum needed
• Use visibility_aabb to cull off-screen particles
• LOD: reduce particle count at distance
• Target: all particle systems combined < 2ms GPU time

Post-Processing

WorldEnvironment

• WorldEnvironment node with Environment resource for scene-wide effects
• Configure: glow, tone mapping, SSAO, SSR, fog, adjustments
• Multiple environments for different areas (indoor vs outdoor)

Compositor Effects (4.3+)

• Custom full-screen effects via CompositorEffect scripts
• Access screen texture, depth, normals for custom passes
• Use sparingly — each effect adds a full-screen pass

Screen-Space Shaders

uniform sampler2D screen_texture : hint_screen_texture;
uniform sampler2D depth_texture : hint_depth_texture;

• Apply via ColorRect or TextureRect covering the viewport
• Use for: heat distortion, underwater, damage vignette, blur effects

Performance Optimization

Draw Call Management

• MultiMeshInstance3D for repeated objects — batches draw calls
• MeshInstance3D.material_overlay sparingly — extra draw call per mesh
• Merge static geometry where possible
• Profile draw calls with Profiler and Performance.get_monitor()

Shader Complexity

• Minimize texture samples in fragment shaders — expensive on mobile
• Use hint_default_white/hint_default_black for optional textures
• Avoid dynamic branching in fragment shaders — use mix() and step() instead
• Pre-compute expensive operations in vertex shader when possible
• LOD materials: simplified shaders for distant objects

Render Budgets (60 FPS target)

Common Shader Anti-Patterns

• Texture reads in a loop — exponential cost
• Full precision (highp) everywhere on mobile — use mediump/lowp where possible
• Dynamic branching on per-pixel data — unpredictable on GPUs
• Not using mipmaps on textures sampled at varying distances
• Overdraw from transparent objects without depth pre-pass
• Post-processing effects sampling screen texture multiple times — blur should be two-pass
• Not setting render_priority on transparent materials — incorrect sort order