Support drawing a node with connection that can be modified by user

src/compositor.c

@@ -148,8 +148,8 @@ i32 run_main_loop(void) {
     }
 
     for (u64 i = 0; i < comp.count; ++i) {
-      comp.nodes[i].rec = ui_node(main_window, &(comp.ctx), comp.nodes[i].rec,
-                                  comp.nodes[i].colours);
+      comp.nodes[i].node = ui_node(main_window, &(comp.ctx), comp.nodes[i].node,
+                                   comp.nodes[i].colours);
     }
 
     for (u64 i = 0; i < MAX_WINDOWS; ++i) {
@@ -175,12 +175,16 @@ void add_node(compositor *comp, node_type type, node_data data, i32 x, i32 y,
   }
 
   comp->nodes[(comp->count)++] = (node){
-      .rec =
-          (rect){
-              .topleft.x = x,
-              .topleft.y = y,
-              .w = NODE_WIDTH,
-              .h = NODE_HEIGHT,
+      .node =
+          (ui_node_elem){
+              .rec =
+                  (rect){
+                      .topleft.x = x,
+                      .topleft.y = y,
+                      .w = NODE_WIDTH,
+                      .h = NODE_HEIGHT,
+                  },
+              .noodle = (line){0},
           },
       .colours = colours,
       .type = type,

src/ui.c

@@ -10,6 +10,8 @@
 #define NOODLE_HALF_WIDTH 2
 #define DEFAULT_NOODLE_LENGTH 60
 
+line ui_noodle(const window *wnd, ui_ctx *ctx, line ln,
+               ui_elem_colours colours);
 INTERNAL bool aabb(rect rec, i32 x, i32 y);
 INTERNAL line line_from_origin(point origin, f64 angle, i32 line_length);
 
@@ -93,36 +95,52 @@ bool ui_button(const window *wnd, ui_ctx *ctx, rect rec,
   return false;
 }
 
-rect ui_node(const window *wnd, ui_ctx *ctx, rect rec,
-             ui_elem_colours colours) {
+ui_node_elem ui_node(const window *wnd, ui_ctx *ctx, ui_node_elem node,
+                     ui_elem_colours colours) {
   if (ctx->count + 1 >= MAX_UI_ELEMENTS) {
-    return (rect){0};
+    return (ui_node_elem){0};
   }
 
   u64 id = (ctx->count)++;
 
-  fill_rect(wnd, rec, colours.fill);
-  draw_rect(wnd, rec, colours.border);
+  line ln;
+  if (node.noodle.p0.x == node.noodle.p1.x &&
+      node.noodle.p0.y == node.noodle.p1.y) {
+    ln = line_from_origin((point){node.rec.topleft.x + node.rec.w / 2,
+                                  node.rec.topleft.y + node.rec.h / 2},
+                          90.0, DEFAULT_NOODLE_LENGTH);
+  } else {
+    ln = node.noodle;
+  }
+
+  node.noodle = ui_noodle(wnd, ctx, ln, colours);
+
+  fill_rect(wnd, node.rec, colours.fill);
+  draw_rect(wnd, node.rec, colours.border);
 
   if (wnd != ctx->wnd || (ctx->active >= 0 && ctx->active != id)) {
-    return rec;
+    return node;
   }
 
   if (ctx->mouse_up) {
     ctx->hovered = ctx->active = -1;
     ctx->rel_x = ctx->rel_y = 0;
-    return rec;
+    return node;
   }
 
   if (ctx->hovered == id && ctx->active == id) {
-    rec.topleft.x += ctx->rel_x;
-    rec.topleft.y += ctx->rel_y;
+    node.rec.topleft.x += ctx->rel_x;
+    node.rec.topleft.y += ctx->rel_y;
+    node.noodle.p0.x += ctx->rel_x;
+    node.noodle.p0.y += ctx->rel_y;
+    node.noodle.p1.x += ctx->rel_x;
+    node.noodle.p1.y += ctx->rel_y;
 
-    return rec;
+    return node;
   }
 
-  if (!aabb(rec, ctx->mouse_x, ctx->mouse_y)) {
-    return rec;
+  if (!aabb(node.rec, ctx->mouse_x, ctx->mouse_y)) {
+    return node;
   }
 
   ctx->hovered = id;
@@ -131,7 +149,7 @@ rect ui_node(const window *wnd, ui_ctx *ctx, rect rec,
     ctx->active = id;
   }
 
-  return rec;
+  return node;
 }
 
 line ui_noodle(const window *wnd, ui_ctx *ctx, line ln,