From 1dabb59a6592a653fb7930e1d13e26c68b8b7b34 Mon Sep 17 00:00:00 2001
From: Grant Horner <h.grant.horner@gmail.com>
Date: Tue, 21 Apr 2026 16:24:56 -0400
Subject: [PATCH] render cursor on y axis

---
 edit.jai | 81 ++++++++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 64 insertions(+), 17 deletions(-)

diff --git a/edit.jai b/edit.jai
index c8d4af8..e71b32e 100644
--- a/edit.jai
+++ b/edit.jai
@@ -12,6 +12,11 @@ window_height := 600;
 
 first_line := 0;
 
+cursor_x := 0;
+cursor_y := 0;
+
+White :: Vector4.{1, 1, 1, 1};
+
 main :: () {
     args := get_command_line_arguments();
     assert(args.count == 2, "The file name must be passed as a CLI argument");
@@ -38,20 +43,7 @@ main :: () {
 
         Input.update_window_events();
 
-        for Input.get_window_resizes() {
-            Simp.update_window(it.window);
-            if it.window == window {
-                should_reinit := (it.width != window_width) || (it.height != window_height);
-
-                window_width  = it.width;
-                window_height = it.height;
-
-                if should_reinit {
-                    my_init_fonts();
-                }
-            }
-        }
-
+        handle_window_resizes(window);
 
         for event : Input.events_this_frame {
             if event.type == .QUIT {
@@ -62,6 +54,11 @@ main :: () {
             if event.type == .KEYBOARD && event.key_pressed {
                 if event.key_code == {
                     case .ESCAPE; should_quit = true;
+
+                    case .ARROW_UP;    #through;
+                    case .ARROW_DOWN;  #through;
+                    case .ARROW_LEFT;  #through;
+                    case .ARROW_RIGHT; handle_arrow(event.key_code);
                 }
             }
         }
@@ -82,14 +79,64 @@ main :: () {
 render_edit_buffer :: () {
     num_lines_in_screen := window_height / line_height - 1;
     viewable_lines := array_view(lines, first_line, num_lines_in_screen);
-    Simp.set_shader_for_text();
-    color :: Vector4.{1, 1, 1, 1};
     for line_buffer: viewable_lines {
+        Simp.set_shader_for_text();
 
         line := builder_to_line(*line_buffer);
 
         Simp.prepare_text(my_font, line);
-        Simp.draw_prepared_text(my_font, 5, window_height - (it_index + 1) * line_height, color);
+        top_of_line := window_height - (it_index + 1) * line_height;
+        Simp.draw_prepared_text(my_font, 5, top_of_line, White);
+
+        if it_index == cursor_y {
+            Simp.set_shader_for_color();
+            Simp.immediate_quad(
+                5., cast(float) top_of_line + line_height,
+                6., cast(float) top_of_line,
+                White);
+        }
+    }
+}
+
+handle_window_resizes :: (window: Window_Type) {
+    for Input.get_window_resizes() {
+        Simp.update_window(it.window);
+        if it.window == window {
+            should_reinit := (it.width != window_width) || (it.height != window_height);
+
+            window_width  = it.width;
+            window_height = it.height;
+
+            if should_reinit {
+                my_init_fonts();
+            }
+        }
+    }
+}
+
+handle_arrow :: (key_code: Input.Key_Code) {
+    num_lines_in_screen := window_height / line_height - 1;
+    viewable_lines := array_view(lines, first_line, num_lines_in_screen);
+
+    max_chars := 30;
+
+    if key_code == {
+        case .ARROW_UP;    
+            cursor_y = ifx cursor_y == 0
+            then 0
+            else cursor_y - 1;
+        case .ARROW_DOWN;
+            cursor_y = ifx cursor_y == viewable_lines.count 
+            then viewable_lines.count
+            else cursor_y + 1;
+        case .ARROW_LEFT;  
+            cursor_x = ifx cursor_x == 0
+            then 0
+            else cursor_x - 1;
+        case .ARROW_RIGHT;
+            cursor_y = ifx cursor_x == max_chars
+            then max_chars
+            else cursor_x + 1;
     }
 }