adjust imperative shell to use xyz coordinates for position, instead of simply xy; need to ensure the functional core code outputs a vector in this format too

fcore/text-builder.sml

@@ -40,12 +40,10 @@ struct
 
       val textAcc = Vector.concat textAcc
       val bgAcc = Vector.concat bgAcc
-
-      val textMsg = REDRAW_TEXT textAcc
-      val cursorMsg = REDRAW_CURSOR cursorAcc
-      val bgMsg = REDRAW_BG bgAcc
+      val vec = Vector.concat [textAcc, bgAcc, cursorAcc]
+      val drawMsg = DRAW_TEXT vec
     in
-      DRAW bgMsg :: DRAW textMsg :: DRAW cursorMsg :: msgs
+      DRAW drawMsg :: msgs
     end
 
   (* builds text from a string with char-wrap.

message-types/draw-msg.sml

@@ -1,8 +1,2 @@
 structure DrawMsg =
-struct
-  datatype t =
-    REDRAW_TEXT of Real32.real vector
-  | REDRAW_CURSOR of Real32.real vector
-  | REDRAW_BG of Real32.real vector
-  | YANK of string
-end
+struct datatype t = DRAW_TEXT of Real32.real vector | YANK of string end

shell/gl-draw.sml

@@ -1,7 +1,8 @@
 structure GlDraw =
 struct
   open CML
-  open DrawMsg K
+  open DrawMsg
+
   (* The name doesn't make it clear, but this structure
    * couples GLFW and OpenGL.
    * I'm not sure if I will use native windowing systems
@@ -76,7 +77,7 @@ struct
         shellState
 
       val _ = Gles3.bufferData (vec, Vector.length vec, Gles3.STATIC_DRAW)
-      val newTextDrawLength = Vector.length vec div 5
+      val newTextDrawLength = Vector.length vec div 6
     in
       { textVertexBuffer = textVertexBuffer
       , textProgram = textProgram
@@ -90,7 +91,7 @@ struct
       val {textVertexBuffer, textDrawLength, textProgram, window = _} =
         drawObject
     in
-      Gles3.drawArrays (Gles3.TRIANGLES, 0, drawLength)
+      Gles3.drawArrays (Gles3.TRIANGLES, 0, textDrawLength)
     end
 
   fun yank (shellState: t, str) =
@@ -109,7 +110,7 @@ struct
         shellState
     in
       case msg of
-        DRAW vec => uploadText (shellState, textVec)
+        DRAW_TEXT textVec => uploadText (shellState, textVec)
       | YANK str => yank (shellState, str)
     end
 

shell/gl-shaders.sml

@@ -1,6 +1,6 @@
 structure GlShaders =
 struct
-  val xyrgbVertexShaderString =
+  val xyzRgbVertexShaderString =
     "#version 300 es\n\
     \layout (location = 0) in vec3 apos;\n\
     \layout (location = 1) in vec3 col;\n\