drawer readme complete

README.md

@@ -98,23 +98,64 @@ Todo
     - `~Drawer()`
 
 - **Public Function Members**
-    - `void start_drawing(const float x, const float y)`
+    - `void start_drawing(const float x, const float y)`:
+
+      Signal that this object's drawing starts at coordinates (`x`, `y`) (typically the fingerdown location). 
+      The two arguments are both in $[-1, 1]$.
+      Nothing is drawn by this function.
+
     - `bool draw(const float x, const float y, Toolbox& tb, bool drawing)`
+      
+      Draws a stroke from the last position to (`x`, `y`). 
+      The `tb` and `drawing` arguments are passed on to `calculate_points`.
+      
+      First calculates updates the position and calculates the new points, uploads them to the current `GL_ARRAY_BUFFER` and finally draws them via `glDrawArrays`.
+
+      Returns `true` if something was drawn, and `false` else (typically if the new point is equal to the previous point).
+
     - `void redraw(Toolbox&)`
+
+      Issues a drawcall (`glDrawArrays`). 
+      The argument is unused. 
+      Correct usage first calls `draw`, then calls `redraw` without changing the state of `GL_ARRAY_BUFFER` in between (typically, framebuffer and texture bindings are changed in between).
+
     - `void erase(const float x, const float y, Toolbox& tb)`
+      
+      Deprecated, use `draw(x, y, tb, false)` instead.
+      
     - `int num_drawn()`
 
+      Returns the number of calls to `draw` and `erase` performed by this object.
+
 - **Private Function Members**
     - `bool calculate_points_(Toolbox& tb, bool drawing)`
+    
+      Calculates the triangulation of the stroke represented by the internal parameters and stores them in `points_`. 
+      The `drawing` argument switches the stroke width (`true`->`tb.drawing_width`, `false`->`tb.erasing_width`). 
+      Uses `tb.texture_w`.
+
+      Returns `true` if new points were calculated, and `false` else (typically if the internal state represents an equal new and old point).
+      
 
 - **Public Data Members**
+  
+  N/A
 
 - **Private Data Members**
     - `float x0_, y0_, x1_, y1_`
+    
+      Internal representation of old ('0') and new ('1') points.
     - `int num_drawn_`
+
+      Number of calls to `draw` and `erase`.
+
     - `std::vector<float> points_`
 
+      Vertex coordinates that represent the stroke between old and new points, as calculated by `calculate_points_`.
+
 - **Notes**
+
+  N/A
 ### DrawingHandler (`drawing_handler.hpp`, `drawing_handler.cpp`)
 Todo
 ### EfficientBlock (`efficient_block.hpp`, `efficient_block.cpp`)