gala/data/shaders/monochrome.vert

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/*
* Copyright 2023 elementary, Inc. <https://elementary.io>
* SPDX-License-Identifier: GPL-3.0-or-later
*/
uniform sampler2D tex;
uniform float STRENGTH;
void main() {
vec2 uv = cogl_tex_coord0_in.xy;
vec4 sample = texture2D (tex, uv);
vec3 luminance = vec3 (0.2126, 0.7512, 0.0722);
float gray = luminance.r * sample.r + luminance.g * sample.g + luminance.b * sample.b;
cogl_color_out = vec4 (
sample.r * (1.0 - STRENGTH) + gray * STRENGTH,
sample.g * (1.0 - STRENGTH) + gray * STRENGTH,
sample.b * (1.0 - STRENGTH) + gray * STRENGTH,
sample.a
) ;
}