Writing Shaders

Any of these work:

• Import… in the launcher's Post-processing section, or in the in-stream menu (Tab).
• Drag the file onto the window.
• Drop it in the shaders folder yourself and press Reload.

The folder is:

~/Library/Application Support/Uncapped/Uncapped/shaders/

A copy of the built-in grade is written there as color-grade.cvfx.example the first time the app runs. It's the best thing to read first — a real multi-pass effect rather than a toy.

Effects run on the finished video frame, in image space. Colour grading, bloom, sharpening, grain, scanlines, vignettes, chromatic aberration and CRT emulation all work.

Depth-dependent effects can't be ported here at all. SSAO, depth of field and ray-traced GI read a game's depth buffer. Uncapped receives an HDMI stream — flat pixels, with the 3D information gone long before capture. No version of the app can add that back.

//! name: Saturation

uniform float Amount : default=1.0, min=0.0, max=2.0, label="Saturation";

float4 effect(float2 uv) {
    float4 c = sample_input(uv);
    c.rgb = lerp(float3(luminance(c.rgb)), c.rgb, Amount);
    return c;
}

A file with no //! pass: lines is a single pass, and the function must be called effect.

//! name: Colour & Bloom          what the menu shows
//! author: someone
//! description: One line under the checkbox.
//! pass: blurH  scale=0.5        declares a pass

Unknown //! directives are ignored, so a file written for a later version still loads.

uniform <type> <Name> : default=..., min=..., max=..., label="...";

Each one becomes a widget automatically — an effect ships its own UI. Values are saved per effect and survive edits to the file: renaming a uniform resets that one and leaves the rest alone.

Everything else is Metal Shading Language: float2/3/4, saturate, clamp, dot, pow, smoothstep, min, max, swizzles, for, if.

Helper functions can read uniforms and sample textures, just like pass functions:

uniform float Amount : default=0.5, min=0.0, max=1.0;

float falloff(float2 uv) {          // reads Amount directly
    float2 d = uv - 0.5;
    return 1.0 - Amount * dot(d, d) * 2.2;
}

float4 effect(float2 uv) {
    return sample_input(uv) * falloff(uv);
}

Declare them in order. Each may render at reduced scale, and may sample any pass declared before it. The last pass is what the next effect — or the screen — receives.

//! pass: bright     scale=0.5
//! pass: blurH      scale=0.5
//! pass: blurV      scale=0.5
//! pass: composite

float4 bright(float2 uv) { ... }
float4 composite(float2 uv) {
    float3 base  = sample_input(uv).rgb;       // still the original image
    float3 bloom = sample_pass(blurV, uv).rgb; // an earlier pass
    return float4(base + bloom, 1.0);
}

sample_input always means the image that entered this effect, in every pass — which is what lets a composite pass blend the blurred result back over the original. Sampling a later pass returns black rather than garbage.

The effect stays in the menu, greyed out, with the compiler's message attached — the app keeps running and the picture is untouched. The line number is for the generated shader, not your file, so it'll be offset by the boilerplate wrapping your code; the message and the quoted source line still point at the mistake.

Two constraints worth knowing, both consequences of how little this format parses:

• A uniform declaration must be one line, ending in ;.
• Uniform names become variables in your shader, so don't declare a local with the same name.

With frame generation at 2×, the chain runs twice per captured frame — a generated frame is graded too, or it would flicker against the real ones. Budget accordingly: an expensive effect costs double at 2×, triple at 3×.

Host the .cvfx file anywhere that serves it over https — a GitHub repo, a Gist, Drive — then sign in and hit Publish on the library. Give it a name, a line or two on what it does and what it looks best on, and a screenshot, which you upload rather than link. People can like it, and the most-liked sit at the top. You can edit or remove your own entry at any time.