NAME

shader_uniform - Set values for a uniform values in a specific shader.

SYNOPSIS

nil
shader_uniform( shid, symlbl, typestr, vals )

DESCRIPTION

A shader can have a number of uniform variables declared. 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 and 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.

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.

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

SEE ALSO:

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