Updated README

README.md

@@ -1,2 +1,31 @@
-# RDIC
+# RDIC - Retained Data, Immediate Code
+
+Serious GUI programming has long been dominated by retained mode APIs, where a tree of GUI objects that hold function pointers for callbacks is built and a central "do the GUI thing" procedure is called, which takes care of handling all the GUI functionality and calls the callbacks as necessary.
+
+A competitor to retained mode GUIs is the immediate mode GUI paradigm, which prioritizes locality of GUI element definition and its behavior.
+The specification of GUI elements is done by calling procedures that instantiate them every frame that they should appear on the screen.
+For instance, a button is achieved by calling some procedure, e.g. `gui_button`, which would return true if the button was clicked on and false otherwise.
+
+There are tradeoffs in choosing one or the other. Retained mode required you to use inversion of control, which to some is a violation of good programming principles.
+Immediate mode is in many regards simpler, but has the downside that it forgoes exposing a data structure to the user at all, and has to use clever techniques to identify the same GUI elements across frames.
+
+The RDIC approach combines retained and immediate techniques.
+In retained mode it is normal to use handles into a behind-the-scenes data structure, which is used to make state changes requests in order to manipulate the GUI.
+RDIC introduces the use of references into an exposed, retained data structure, where you re-use your references across frames, in an immediate style API.
+When passing the same, stable reference to e.g. a button call every frame, it is determined that this is in fact the same button across consecutive frames.
+
+RDIC example:
+```C
+static RDIC_Reference my_button = {0};
+if(button(&my_button, "Button Label")) {
+    printf("Printed if button is clicked.\n");
+}
+```
+
+The stable data structure in RDIC can be leveraged for features such as accessibility.
+One example of how this data structure is used in the example GUI in this repository is conditional redrawing. It stores a "dirty" flag with each node, which is used to skip over non-"dirty" nodes when generating draw commands. This is very useful for the implementation, which draws using only the CPU.
+
+
+
+