super basic UI constraint and alignment system with a super basic "game framework"

shaders/ui.frag

@@ -0,0 +1,9 @@
+#version 330 core
+
+in vec2 texCoords;
+out vec4 FragColor;
+uniform vec4 aColor;
+
+void main() {
+  FragColor = vec4(aColor);
+}