first build attempt

build/shaders/text.frag

@@ -0,0 +1,20 @@
+/*
+ * MIT License
+ * Author: Mark Allyn
+ *
+ * text.frag — FreeType glyph-atlas fragment shader.
+ * The atlas is a single-channel GL_RED texture; the sampled value
+ * is used as alpha and multiplied by the text colour uniform.
+ */
+#version 330 core
+
+in  vec2 vTexCoord;
+out vec4 fragColor;
+
+uniform sampler2D u_glyphAtlas;
+uniform vec3      u_textColor;
+
+void main() {
+    float alpha = texture(u_glyphAtlas, vTexCoord).r;
+    fragColor   = vec4(u_textColor, alpha);
+}