alexmeckes Godot Shader Skill
You are an expert at writing Godot 4.x shaders (.gdshader files) for 2D effects, 3D materials, and post-processing.
Shader Types
shader_type canvas_item; // 2D sprites, UI, CanvasItem nodes
shader_type spatial; // 3D materials
shader_type particles; // GPU particle systems
shader_type sky; // Sky/environment
shader_type fog; // Volumetric fog
Basic Shader Structure
shader_type canvas_item;
// Render modes (optional)
render_mode unshaded, blend_mix;
// Uniforms (exposed to inspector)
uniform vec4 tint_color : source_color = vec4(1.0);
uniform float intensity : hint_range(0.0, 1.0) = 0.5;
uniform sampler2D noise_texture : hint_default_white;
// Varyings (pass data vertex -> fragment)
varying vec2 world_position;
void vertex() {
// Modify vertex position
world_position = (MODEL_MATRIX * vec4(VERTEX, 0.0, 1.0)).xy;
}
void fragment() {
// Output color
vec4 tex_color = texture(TEXTURE, UV);
COLOR = tex_color * tint_color;
}
Uniform Hints
// Color picker in inspector
uniform vec4 color : source_color = vec4(1.0);
// Slider with range
uniform float value : hint_range(0.0, 1.0, 0.01) = 0.5;
// Texture hints
uniform sampler2D albedo_tex : source_color, filter_linear_mipmap;
uniform sampler2D normal_tex : hint_normal;
uniform sampler2D noise_tex : hint_default_white;
uniform sampler2D mask_tex : hint_default_black;
// Instance uniforms (per-instance values)
instance uniform vec4 instance_color : source_color = vec4(1.0);
Built-in Variables
Canvas Item (2D)
// Vertex shader
VERTEX // vec2 - vertex position
UV // vec2 - texture coordinates
COLOR // vec4 - vertex color
POINT_SIZE // float - point size
// Fragment shader
UV // vec2 - interpolated UVs
SCREEN_UV // vec2 - screen space UVs
FRAGCOORD // vec4 - fragment coordinates
COLOR // vec4 - output color
NORMAL // vec3 - normal for 2D lighting
TEXTURE // sampler2D - sprite texture
TEXTURE_PIXEL_SIZE // vec2 - texel size
// Both
TIME // float - shader time
PI // float - 3.14159...
TAU // float - 6.28318...
Spatial (3D)
// Vertex shader
VERTEX // vec3 - vertex position (local)
NORMAL // vec3 - vertex normal
UV // vec2 - primary UVs
UV2 // vec2 - secondary UVs
COLOR // vec4 - vertex color
POSITION // vec4 - clip space position (output)
// Fragment shader
ALBEDO // vec3 - base color (output)
ALPHA // float - transparency (output)
METALLIC // float - metalness (output)
ROUGHNESS // float - roughness (output)
EMISSION // vec3 - emissive color (output)
NORMAL_MAP // vec3 - normal map (output)
NORMAL_MAP_DEPTH // float - normal map strength
AO // float - ambient occlusion (output)
RIM // float - rim lighting (output)
RIM_TINT // float - rim tint amount
Common 2D Shader Patterns
Flash/Hit Effect
shader_type canvas_item;
uniform vec4 flash_color : source_color = vec4(1.0, 1.0, 1.0, 1.0);
uniform float flash_amount : hint_range(0.0, 1.0) = 0.0;
void fragment() {
vec4 tex_color = texture(TEXTURE, UV);
COLOR = mix(tex_color, flash_color, flash_amount);
COLOR.a = tex_color.a;
}
Outline
shader_type canvas_item;
uniform vec4 outline_color : source_color = vec4(0.0, 0.0, 0.0, 1.0);
uniform float outline_width : hint_range(0.0, 10.0) = 1.0;
void fragment() {
vec2 size = TEXTURE_PIXEL_SIZE * outline_width;
float outline = texture(TEXTURE, UV + vec2(-size.x, 0)).a;
outline += texture(TEXTURE, UV + vec2(size.x, 0)).a;
outline += texture(TEXTURE, UV + vec2(0, -size.y)).a;
outline += texture(TEXTURE, UV + vec2(0, size.y)).a;
outline = min(outline, 1.0);
vec4 tex_color = texture(TEXTURE, UV);
COLOR = mix(outline_color * outline, tex_color, tex_color.a);
}
Dissolve Effect
shader_type canvas_item;
uniform sampler2D dissolve_texture : hint_default_white;
uniform float dissolve_amount : hint_range(0.0, 1.0) = 0.0;
uniform float edge_width : hint_range(0.0, 0.2) = 0.05;
uniform vec4 edge_color : source_color = vec4(1.0, 0.5, 0.0, 1.0);
void fragment() {
vec4 tex_color = texture(TEXTURE, UV);
float noise = texture(dissolve_texture, UV).r;
float edge = smoothstep(dissolve_amount, dissolve_amount + edge_width, noise);
float alpha = step(dissolve_amount, noise);
COLOR = mix(edge_color, tex_color, edge);
COLOR.a = tex_color.a * alpha;
}
Pixelate
shader_type canvas_item;
uniform float pixel_size : hint_range(1.0, 100.0) = 4.0;
void fragment() {
vec2 grid_uv = round(UV * pixel_size) / pixel_size;
COLOR = texture(TEXTURE, grid_uv);
}
Wave/Distortion
shader_type canvas_item;
uniform float wave_amplitude : hint_range(0.0, 0.1) = 0.02;
uniform float wave_frequency : hint_range(0.0, 50.0) = 10.0;
uniform float wave_speed : hint_range(0.0, 10.0) = 2.0;
void fragment() {
vec2 uv = UV;
uv.x += sin(uv.y * wave_frequency + TIME * wave_speed) * wave_amplitude;
COLOR = texture(TEXTURE, uv);
}
Gradient Map
shader_type canvas_item;
uniform sampler2D gradient : hint_default_white;
void fragment() {
vec4 tex_color = texture(TEXTURE, UV);
float luminance = dot(tex_color.rgb, vec3(0.299, 0.587, 0.114));
vec3 mapped = texture(gradient, vec2(luminance, 0.0)).rgb;
COLOR = vec4(mapped, tex_color.a);
}
Screen-Space Chromatic Aberration
shader_type canvas_item;
uniform float offset : hint_range(0.0, 0.01) = 0.005;
void fragment() {
vec2 dir = UV - vec2(0.5);
float r = texture(TEXTURE, UV + dir * offset).r;
float g = texture(TEXTURE, UV).g;
float b = texture(TEXTURE, UV - dir * offset).b;
float a = texture(TEXTURE, UV).a;
COLOR = vec4(r, g, b, a);
}
Common 3D Shader Patterns
Basic PBR Override
shader_type spatial;
uniform vec4 albedo_color : source_color = vec4(1.0);
uniform sampler2D albedo_texture : source_color, hint_default_white;
uniform float metallic : hint_range(0.0, 1.0) = 0.0;
uniform float roughness : hint_range(0.0, 1.0) = 0.5;
void fragment() {
vec4 tex = texture(albedo_texture, UV);
ALBEDO = tex.rgb * albedo_color.rgb;
METALLIC = metallic;
ROUGHNESS = roughness;
ALPHA = tex.a * albedo_color.a;
}
Fresnel/Rim Lighting
shader_type spatial;
uniform vec4 rim_color : source_color = vec4(1.0);
uniform float rim_power : hint_range(0.0, 10.0) = 3.0;
void fragment() {
float fresnel = pow(1.0 - dot(NORMAL, VIEW), rim_power);
EMISSION = rim_color.rgb * fresnel * rim_color.a;
}
Triplanar Mapping
shader_type spatial;
uniform sampler2D texture_albedo : source_color;
uniform float blend_sharpness : hint_range(1.0, 10.0) = 3.0;
varying vec3 world_position;
varying vec3 world_normal;
void vertex() {
world_position = (MODEL_MATRIX * vec4(VERTEX, 1.0)).xyz;
world_normal = (MODEL_MATRIX * vec4(NORMAL, 0.0)).xyz;
}
void fragment() {
vec3 blending = pow(abs(world_normal), vec3(blend_sharpness));
blending /= blending.x + blending.y + blending.z;
vec3 x_proj = texture(texture_albedo, world_position.yz).rgb;
vec3 y_proj = texture(texture_albedo, world_position.xz).rgb;
vec3 z_proj = texture(texture_albedo, world_position.xy).rgb;
ALBEDO = x_proj * blending.x + y_proj * blending.y + z_proj * blending.z;
}
Hologram Effect
shader_type spatial;
render_mode cull_disabled, depth_draw_opaque;
uniform vec4 hologram_color : source_color = vec4(0.0, 1.0, 1.0, 1.0);
uniform float scan_speed : hint_range(0.0, 10.0) = 2.0;
uniform float scan_line_count : hint_range(10.0, 200.0) = 50.0;
uniform float flicker_speed : hint_range(0.0, 20.0) = 5.0;
void fragment() {
float scan = sin((UV.y + TIME * scan_speed) * scan_line_count) * 0.5 + 0.5;
float flicker = sin(TIME * flicker_speed) * 0.1 + 0.9;
float fresnel = pow(1.0 - dot(NORMAL, VIEW), 2.0);
ALBEDO = hologram_color.rgb;
EMISSION = hologram_color.rgb * (scan * 0.5 + 0.5) * flicker;
ALPHA = (fresnel + 0.3) * scan * flicker * hologram_color.a;
}
Post-Processing (Screen Shaders)
Apply to ColorRect covering viewport:
Vignette
shader_type canvas_item;
uniform float vignette_intensity : hint_range(0.0, 1.0) = 0.4;
uniform float vignette_opacity : hint_range(0.0, 1.0) = 0.5;
void fragment() {
vec4 color = texture(TEXTURE, UV);
float vignette = UV.x * UV.y * (1.0 - UV.x) * (1.0 - UV.y);
vignette = clamp(pow(16.0 * vignette, vignette_intensity), 0.0, 1.0);
color.rgb = mix(color.rgb, color.rgb * vignette, vignette_opacity);
COLOR = color;
}
CRT Effect
shader_type canvas_item;
uniform float scanline_count : hint_range(0.0, 1000.0) = 400.0;
uniform float scanline_intensity : hint_range(0.0, 1.0) = 0.1;
uniform float curvature : hint_range(0.0, 0.1) = 0.02;
void fragment() {
// Barrel distortion
vec2 uv = UV - 0.5;
float dist = dot(uv, uv);
uv *= 1.0 + dist * curvature;
uv += 0.5;
vec4 color = texture(TEXTURE, uv);
// Scanlines
float scanline = sin(uv.y * scanline_count * PI) * 0.5 + 0.5;
color.rgb -= scanline_intensity * scanline;
// Edge fade
if (uv.x < 0.0 || uv.x > 1.0 || uv.y < 0.0 || uv.y > 1.0) {
color = vec4(0.0);
}
COLOR = color;
}
Particle Shaders
shader_type particles;
uniform float spread : hint_range(0.0, 180.0) = 45.0;
uniform float initial_speed : hint_range(0.0, 100.0) = 10.0;
void start() {
float angle = radians(spread) * (RANDOM.x - 0.5);
vec3 direction = vec3(sin(angle), cos(angle), 0.0);
VELOCITY = direction * initial_speed;
}
void process() {
// Apply gravity
VELOCITY.y -= 9.8 * DELTA;
// Fade out
COLOR.a = 1.0 - LIFETIME;
// Scale down
TRANSFORM[0].x = 1.0 - LIFETIME * 0.5;
TRANSFORM[1].y = 1.0 - LIFETIME * 0.5;
}
Tips for AI Shader Generation
- Start simple - Begin with basic structure, add complexity iteratively
- Use hints -
hint_range,source_colormake shaders usable - Comment uniforms - Explain what each parameter does
- Provide defaults - Always set sensible default values
- Consider performance - Avoid expensive operations in fragment shader when possible
- Test edge cases - UV boundaries, alpha handling, blend modes
- Match shader type to use case - canvas_item for 2D, spatial for 3D
- Use built-ins - TIME, UV, TEXTURE are optimized