shader-programming skill | PlugMCP

shader-programming

gamedev-skills8.2kstars

Game DevelopmentDeveloper Tools

1---2name: shader-programming3description: >4---56# skills/disciplines/shader-programming/SKILL.md

SKILL.mdAgent skill

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Status: Listed

SKILL.md

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1npx skills add gamedev-skills/awesome-gamedev-agent-skills --skill shader-programming -a cursor -y

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1npx skills add gamedev-skills/awesome-gamedev-agent-skills --skill shader-programming -a codex -y

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1Install this skill: https://github.com/gamedev-skills/awesome-gamedev-agent-skills/tree/HEAD/skills/disciplines/shader-programming

Download skill skills/disciplines/shader-programming/SKILL.md on GitHub

skills/disciplines/shader-programming/SKILL.mdMarkdown · UTF-8

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File: skills/disciplines/shader-programming/SKILL.md
Publisher: gamedev-skills
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SKILL.md

name: shader-programming
description: Write game shaders from cross-engine fundamentals — the vertex→fragment pipeline, coordinate spaces, UV math, and common 2D/3D effects (tint, UV scroll, dissolve, outline, fresnel rim, vignette) in GLSL with HLSL equivalents. Use when the user mentions shaders, fragment/pixel shader, vertex shader, UV, GLSL, HLSL, or effects like dissolve, outline, or rim light.

Shader programming (cross-engine)

Shaders are small programs that run per vertex and per pixel on the GPU. The concepts — the pipeline, coordinate spaces, UVs, and how common effects are built — port across engines; only the language dialect and built-in variable names change. This skill teaches those portable fundamentals in GLSL with HLSL equivalents; use godot-shaders (or Unity/Unreal material docs) for the exact engine syntax and built-ins.

When to use

Use to understand or write vertex/fragment shaders and to reason about UVs, coordinate spaces, and the GPU pipeline.
Use to build common effects: tint/recolor, scrolling textures, dissolve, outlines, fresnel/rim light, vignette, color grading.
Use to translate a shader concept between GLSL and HLSL, or between engines.

When not to use: for an engine's exact shader language and built-ins, use godot-shaders (Godot shading language) or the engine's material docs. For full particle VFX systems, see unreal-niagara. For post-process stacks, defer to the engine's renderer settings.

Core workflow

Know which stage you're in. The vertex shader transforms each vertex into clip space and passes data (UVs, normals) onward; the fragment/pixel shader runs per rasterized pixel and outputs a color. Most game effects live in the fragment stage.
Track coordinate spaces. Positions move model → world → view → clip space; normals belong in world or view space. Mixing spaces is the most common bug.
Drive effects with UVs and time. UVs are 0..1 texture coordinates; offset, scale, or distort them, and animate with a time uniform.
Work per pixel, branch-light. Prefer mix, step, smoothstep, and clamp over if where possible; GPUs run pixels in lockstep, so a branch whose condition differs between neighbouring pixels runs both sides. A branch on a uniform (same for the whole draw) is cheap.
Pass data via uniforms (constant per draw) and varyings (interpolated vertex→fragment). Keep texture samples few; they dominate cost.
For GLSL, run with the matching stage suffix; for WGSL, run . Check Godot files by opening the project in Godot, which has no standalone validator for them.

glslangValidator path/to/shader.frag

naga path/to/shader.wgsl

.gdshader

// Per-pixel: read the texture at this UV, multiply by a color (tint), keep alpha.
uniform sampler2D tex;
uniform vec4 tint;          // e.g. (1,0,0,1) reddens; multiply is non-destructive
in vec2 uv;                 // interpolated 0..1 texture coordinate (a "varying")
out vec4 frag;
void main() {
    vec4 c = texture(tex, uv);   // HLSL: tex.Sample(samp, uv)
    frag = c * tint;             // component-wise multiply tints without clipping
}

// Add time * speed to the UV to scroll. fract() wraps it into 0..1 so it tiles.
uniform sampler2D tex;
uniform float time;          // seconds, supplied by the engine
uniform vec2 scroll_speed;   // UV units per second, e.g. (0.1, 0.0)
in vec2 uv;
out vec4 frag;
void main() {
    vec2 scrolled = fract(uv + scroll_speed * time);  // HLSL: frac(...)
    frag = texture(tex, scrolled);
}
// Drive with a real time uniform, not a per-frame accumulator, so speed is stable.

// Hide pixels where noise < threshold; tint a thin band at the boundary.
uniform sampler2D tex;
uniform sampler2D noise_tex;     // grayscale noise, 0..1
uniform float amount;            // 0 = fully visible, 1 = fully dissolved
uniform float edge = 0.05;       // width of the glowing edge band
uniform vec4 edge_color;
in vec2 uv;
out vec4 frag;
void main() {
    vec4 c = texture(tex, uv);
    float n = texture(noise_tex, uv).r;
    float cut = amount * (1.0 + edge) - edge;  // edge band starts below 0 -> none at amount 0
    if (n <= cut) discard;                     // cut away dissolved pixels (all of them at 1)
    float e = smoothstep(cut, cut + edge, n);  // 0 at the edge -> 1 inside; keep edge > 0
    frag = mix(edge_color, c, e);              // HLSL: lerp(edge_color, c, e)
}
// WRONG: thresholding at `amount` directly — at amount 0 every pixel with
// n < edge is still tinted, so the "fully visible" sprite shows glowing specks.

// Rim = 1 where the surface is edge-on to the camera (silhouette glow).
in vec3 world_normal;        // world space, interpolated from the vertex stage
in vec3 view_dir;            // surface -> camera, world space
uniform float power = 3.0;
uniform vec3 rim_color;
out vec4 frag;
void main() {
    // Interpolation does not preserve unit length, even with normalized vertex outputs.
    vec3 normal = normalize(world_normal);
    vec3 view = normalize(view_dir);
    float f = pow(1.0 - clamp(dot(normal, view), 0.0, 1.0), power);
    frag = vec4(rim_color * f, 1.0);   // add to lighting; f peaks at the silhouette
}
// Correctness: normal and view_dir MUST be in the same space and normalized.

shader-programming

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SKILL.md

Shader programming (cross-engine)

When to use

Core workflow

Patterns

1. Fragment basics: sample, tint, and combine

2. Scrolling UVs (animated texture) — frame-rate independent

3. Dissolve (threshold a noise map, glow the edge)

4. Fresnel rim light (3D) — brighten glancing angles

Pitfalls

References

Related skills