shader_uniform(3)

💅 shader_uniform(3) — Arcan Lua API ✨

🌸 NAME 🌸

shader_uniform — Set values for a uniform values in a specific shader. 🫶

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🎀 SYNOPSIS 🎀

nil
shader_uniform( shid, symlbl, typestr, vals )

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✨ DESCRIPTION ✨

Okay bestie, so a shader can have a number of uniform variables declared, right? The specific values of such a uniform can be set through this function. 💖

• shid is a reference to a shader allocated through build_shader.
• symlbl is the identifier of the uniform.
• typestr is a string that specifies the actual type of the uniform.

Accepted patterns for typestr include:

• "b" — bool
• "i" — int
• "f" — float
• "ff" — vec2
• "fff" — vec3
• "ffff" — vec4
• f*16 — mat4

It is also possible for one shaderid to maintain different sets of uniform values. Each group is tied to the life-cycle of the program and is allocated with shader_ugroup. The id that is returned can then be used in image_shader to specify which subgroup that is to be used. 👑

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💀 NOTES 💀

1. There is a deprecated version of this function around that has a PERSIST or NOPERSIST value placed after typestr. This is now ignored and forced to PERSIST (keep local copies of uniforms that can survive video layer resets). This has the side-effect that the argument validation is less aggressive and may permit a mismatch of up to one argument. ⚠️

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🧚 EXAMPLE 🧚

       function shader_uniform0()
             local shid = build_shader(nil, [[ uniform float vec3 col;
             void shader_uniform0(){
                   gl_FragColor = vec4(col, 1.0);
             }]], "csh");
             a = fill_surface(128, 128, 0, 0, 0);
             show_image(a);
             image_shader(a, shid);
             shader_uniform(shid, "col", "fff", PERSIST, 0.0, 1.0, 0.0);
       end

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💜 SEE ALSO 💜

• shader_ugroup(3)
• image_shader(3)
• build_shader(3)

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xoxo, vidsys 💖 October 2026 — shader_uniform(3) out, periodt 🎀