new code

shaders/02_text_description_frag.glsl

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+/*
+ * 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);
+}