shader

osl/shader allows writing fragment and vertex shaders in OSL syntax or standard GLSL, compiling them into valid GLSL code, and rendering procedural graphics directly to images or raylib windows.

import "std:shader"
import "std:img"

string plasma = "def mainImage(fragCoord) (
    vec2 uv = fragCoord / iResolution.xy
    number t = iTime * 1.5
    number v = sin(uv.x * 10.0 + t) + sin(uv.y * 10.0 + t)
    vec3 col = 0.5 + 0.5 * cos(v + vec3(0.0, 2.0, 4.0))
    return vec4(col, 1.0)
)"

// Render directly to an image without opening a window
auto image = shader.renderImage(plasma, 400, 300, {time: 1.0})
img.savePNG(image, "plasma.png")

Functions

shader.toGLSL(code, [type])

Transpiles OSL-style shader syntax into complete, valid GLSL shader source code. Accepts "frag" (default) or "vert".

OSL syntax features supported:

• Block delimiters ( ... ) mapped to { ... }

• Functions: def mainImage(fragCoord) ( ... ) and def name(args) returnType ( ... )

• Type keywords: number mapped to float, vec2, vec3, vec4, mat2, mat3, mat4

• Automatic semicolon insertion for line endings

• Standard uniform injection (iResolution, iTime, iTimeDelta, iFrame, iMouse, iDate, iChannel0..3, texture0, colDiffuse)

• Automatic main() entrypoint generation

shader.renderImage(code, width, height, [uniforms])

Evaluates the shader across a width by height pixel grid and returns an *img.Image object. uniforms is an optional object supporting time (iTime) and mouse coordinates.

shader.vertexDefault()

Returns the standard Raylib-compatible 2D vertex shader source code.

shader.plasma()

Returns a built-in OSL-style plasma fragment shader source string.

shader.gradient()

Returns a built-in cosine gradient fragment shader source string.

shader.eval(expr, [context])

Evaluates a mathematical shader expression with the provided uniform context.