first build attempt

shaders/text.vert

@@ -0,0 +1,27 @@
+/*
+ * MIT License
+ * Author: Mark Allyn
+ *
+ * text.vert — vertex shader for FreeType glyph-atlas text rendering.
+ * Each glyph is a textured quad. Vertices are in window pixels
+ * (top-left origin); the shader converts to NDC and passes the
+ * glyph atlas UV coordinates to the fragment shader.
+ */
+#version 330 core
+
+layout(location = 0) in vec4 aVertex;  // xy = screen pos (px), zw = atlas UV
+
+out vec2 vTexCoord;
+
+uniform vec2 u_viewportSize;   // (WINDOW_WIDTH, WINDOW_HEIGHT)
+
+void main() {
+    vec2 pos = aVertex.xy;
+    vTexCoord = aVertex.zw;
+
+    vec2 ndc = vec2(
+         pos.x / u_viewportSize.x * 2.0 - 1.0,
+        -pos.y / u_viewportSize.y * 2.0 + 1.0
+    );
+    gl_Position = vec4(ndc, 0.0, 1.0);
+}