Uniforms

Uniforms are how a shader reads values that change per frame or per setup: time, resolution, mouse state, input channels, and your own custom parameters. Shader Studio declares the built-ins for you and can inject custom ones from a script pass.

Built-in uniforms

These are always available — no declaration needed. Types differ slightly between GLSL and Slang:

Uniform	GLSL	Slang	Meaning
iResolution	vec3	float3	Canvas size in xy, aspect ratio in z
iTime	float	float	Elapsed time in seconds
iTimeDelta	float	float	Time since the previous frame
iFrameRate	float	float	Current frames per second
iMouse	vec4	float4	Mouse position in xy, click position in zw
iFrame	int	int	Frame counter starting at zero
iDate	vec4	float4	Year, month, day, seconds since midnight
iChannelTime	float[1024]	—	Playback time per input channel
iChannelResolution	vec3[1024]	—	Resolution per input channel
iSampleRate	float	float	Audio sample rate in hertz
iCameraPos	vec3	float3	Camera position in world space
iCameraDir	vec3	float3	Normalised camera look direction
iChannel0–iChannel3	sampler2D (or cube/3D)	—	Input channel textures in configured slot order
iCh0–iCh3	channel metadata struct	—	Input channel with sampler, size, playback time, and loaded state
inputs.<name>	—	ShaderStudioChannel2D / …Cube / …3D	Input channel object: sampling, size, playback time, loaded state, native texture and sampler
iDispatch	—	int	Compute only: zero-based dispatch index
iWorldPosition	vec3	float3	Fragment only: world-space position of the fragment; zero for fullscreen geometry
iNormal	vec3	float3	Fragment only: world-space interpolated normal; zero for fullscreen geometry
iCameraPosition	vec3	float3	Fragment only: world-space camera position for mesh fragments; zero for fullscreen geometry

iWorldPosition, iNormal, and iCameraPosition carry values only when the pass renders 3D geometry — see Vertex Shaders.

Slang has no iChannelN, iChN, iChannelTime, or iChannelResolution symbols. Channels are members of inputs, named by the exact configuration key — iChannel0 becomes inputs.iChannel0, a channel named noise becomes inputs.noise — and per-channel metadata comes from that object (inputs.noise.size, .time, .loaded). See Channels for configuring input slots.

Custom uniforms

Add a Script pass in the config panel to compute custom uniform values each frame from TypeScript or JavaScript:

// shader.uniforms.ts
export function uniforms(ctx: { time: number }) {
  return {
    uSpeed: 1.5,
    uOffset: [0.1, 0.2],
  };
}

Types are inferred from the return value on the first call. Supported types: float, vec2, vec3, vec4, bool — in Slang they arrive as float, float2, float3, float4, and bool. The values are injected as uniforms automatically — use uSpeed and uOffset in your shader with no declaration. See The Script Pass for exporting, polling, and Node.js APIs.

Next

Time And Playback Controls — scrub, loop, and drive iTime