Function customShader

Create a filter from user-provided GLSL.

The source is inserted as the body of main(). You have access to:

• u_texture (sampler2D) — the input image
• v_texCoord (vec2) — current texture coordinate
• u_resolution (vec2) — image dimensions in pixels
• u_texelSize (vec2) — 1.0 / u_resolution
• any uniforms you declare via the uniforms parameter

Write your result to gl_FragColor.

Example: customShader({ source: vec4 color = texture2D(u_texture, v_texCoord); gl_FragColor = vec4(color.r, 0.0, 0.0, color.a); , uniforms: {}, })