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shader_ugroup(3) Arcan Lua API shader_ugroup(3) NAME shader_ugroup - Allocate a uniform group inside a shader SYNOPSIS out_shid or nil shader_ugroup( shid ) DESCRIPTION All shaders have a default group of shaders that the shader_uniform func- tion applies to. In many cases, however, one might want to have multiple objects that uses the same shader but with a slightly different set of uni- forms. shader_ugroup can be used to create a derivative shader that uses most of the same underlying resources but switches to a different set of uniforms when activated. The returned shader is valid for all shader re- lated calls but has its lifecycle to the shader it was derived from. Any forced uniform at the time of group creation will be copied from the group associated with the specified shid. There's a finite amount of uniform group slots available to each shader, and if the provided shid is invalid or there are not enough free group slots left in the shader, the out_shid will be nil. NOTES 1 Though it is bad form to ever rely in the specific value of a shid, shaders that are derived typically have a value > 65535. EXAMPLE function shader_ugroup0() local frag = [[ uniform float r; uniform float g; uniform float b; void shader_ugroup0(){ gl_FragColor = vec4(r, g, b, 1.0); } ]]; local shid = build_shader(nil, frag, "csh"); a = fill_surface(64, 64, 0, 0, 0); b = fill_surface(64, 64, 0, 0, 0); show_image({a, b}); move_image(b, 64, 0); image_shader(a, shid); shader_uniform(shid, "r", "f", 1.0); shader_uniform(shid, "b", "f", 0.0); -- r and b values will be inherited, g is undefined local shid2 = shader_ugroup(shid); image_shader(b, shid2); -- g is now defined in shid1, undefined in shid2 shader_uniform(shid, "g", "f", 1.0); shader_uniform(shid2, "g", "f", 0.0); end SEE ALSO: build_shader(3) delete_shader(3) vidsys August 2026 shader_ugroup(3)
NAME | SYNOPSIS | DESCRIPTION | NOTES | EXAMPLE | SEE ALSO:
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