/*
 * MIT License
 *
 * Copyright (c) 2026 Mark Allyn
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

/*
 * 02_text_description_frag.glsl
 * Author: Mark Allyn
 * Component: 02_text_description
 *
 * Fragment shader for FreeType glyph rendering.
 * Glyphs are uploaded as GL_RED single-channel textures; the red channel
 * drives the alpha so the background shows through unfilled pixels.
 */

#version 430 core

in vec2 tex_coords;
out vec4 frag_color;

uniform sampler2D text_sampler; // bound to texture unit 0
uniform vec3      text_color;   // RGB, 0.0–1.0

void main() {
    float alpha  = texture(text_sampler, tex_coords).r;
    frag_color   = vec4(text_color, alpha);
}