Update node struct to know about noodle connected to it

include/nodes.h

@@ -9,6 +9,7 @@
 #define OP_INPUT_COUNT 2
 #define EMPTY_NODE 0
 #define NODE_START 1
+#define CONNECTION_START 1
 
 typedef i32 (*node_func)(i32 a, i32 b);
 typedef enum node_type node_type;
@@ -31,6 +32,7 @@ union node_data {
 struct noodle {
   line ln;
   u64 connected_node;
+  u64 connection_idx;
 };
 
 struct node {
@@ -39,7 +41,9 @@ struct node {
   node_type type;
   node_data data;
   u64 inputs;
+  u64 connected;
   noodle *noodles;
+  noodle **connected_noodles;
 };
 
 #endif // !NODES_H

src/compositor.c

@@ -183,6 +183,15 @@ internal void add_node(compositor *comp, node_type type, node_data data,
     return;
   }
 
+  u64 connected_alloc_size = MAX_NODES * sizeof(noodle *);
+  noodle **connected_noodles =
+      mem_arena_alloc(comp->arena, connected_alloc_size);
+  noodle **connected_back_noodles =
+      mem_arena_alloc(comp->arena, connected_alloc_size);
+  if (!connected_noodles || !connected_back_noodles) {
+    return;
+  }
+
   rect rec = (rect){
       .topleft.x = x,
       .topleft.y = y,
@@ -198,10 +207,13 @@ internal void add_node(compositor *comp, node_type type, node_data data,
       .type = type,
       .data.path = data.path,
       .inputs = inputs,
+      .connected = 0,
       .noodles = noodles,
+      .connected_noodles = connected_noodles,
   };
 
   comp->back_nodes[idx].noodles = back_noodles;
+  comp->back_nodes[idx].connected_noodles = connected_back_noodles;
 }
 
 internal void update_node_graph(compositor *comp, const window *wnd) {
@@ -210,13 +222,17 @@ internal void update_node_graph(compositor *comp, const window *wnd) {
     const node *back_node = &(comp->back_nodes[i]);
 
     node_elem->rec = back_node->rec;
+    node_elem->connected = back_node->connected;
 
     for (u64 j = 0; j < node_elem->inputs; ++j) {
       noodle *ndl = &(node_elem->noodles[j]);
       const noodle *back_ndl = &(back_node->noodles[j]);
 
-      ndl->connected_node = back_ndl->connected_node;
+      *ndl = *back_ndl;
-      ndl->ln = back_ndl->ln;
+    }
+
+    for (u64 j = CONNECTION_START; j <= back_node->connected; ++j) {
+      node_elem->connected_noodles[j] = back_node->connected_noodles[j];
     }
   }
 }
@@ -251,6 +267,7 @@ internal void draw_node_graph(compositor *comp, const window *wnd) {
         break;
       case NOODLE_ACTION_RELEASED: {
         bool connected = false;
+        bool disconnect = false;
 
         for (u64 k = NODE_START; k <= comp->count; ++k) {
           if (k == i) {
@@ -258,19 +275,53 @@ internal void draw_node_graph(compositor *comp, const window *wnd) {
           }
 
           const node *nd = &(comp->nodes[k]);
+          node *back_node = &(comp->back_nodes[k]);
 
           if (aabb(nd->rec, comp->ctx.mouse_x, comp->ctx.mouse_y)) {
             point p0 = {nd->rec.topleft.x + nd->rec.w / 2,
                         nd->rec.topleft.y + nd->rec.h / 2};
 
             back_ndl->ln.p0 = p0;
-            back_ndl->connected_node = k;
 
             connected = true;
+            disconnect = back_ndl->connected_node != EMPTY_NODE &&
+                         back_ndl->connected_node != k;
+
+            if (back_ndl->connected_node != k) {
+              back_ndl->connected_node = k;
+              u64 idx = ++(back_node->connected);
+              back_ndl->connection_idx = idx;
+              back_node->connected_noodles[idx] = back_ndl;
+            }
+
             break;
+          } else {
+            if (back_ndl->connected_node != EMPTY_NODE) {
+              disconnect = true;
+            }
           }
         }
 
+        if (disconnect) {
+          u64 conntection_idx = back_ndl->connection_idx;
+          u64 node_idx = back_ndl->connected_node;
+
+          node *connected_node = &(comp->back_nodes[node_idx]);
+
+          if (conntection_idx == connected_node->connected) {
+            connected_node->connected_noodles[conntection_idx] = NULL;
+          } else {
+            connected_node->connected_noodles[conntection_idx] =
+                connected_node->connected_noodles[connected_node->connected];
+            connected_node->connected_noodles[connected_node->connected] = NULL;
+
+            connected_node->connected_noodles[conntection_idx]->connection_idx =
+                conntection_idx;
+          }
+
+          connected_node->connected -= 1;
+        }
+
         if (!connected) {
           back_ndl->ln.p0 = ndl->ln.p1;
           back_ndl->connected_node = EMPTY_NODE;
@@ -310,23 +361,11 @@ internal void draw_node_graph(compositor *comp, const window *wnd) {
         back_ndl->ln.p1.y += comp->ctx.rel_y;
       }
 
-      for (u64 j = NODE_START; j <= comp->count; ++j) {
+      for (u64 j = CONNECTION_START; j <= back_node->connected; ++j) {
-        if (j == i) {
+        noodle *ndl = back_node->connected_noodles[j];
-          continue;
-        }
 
-        node *nd = &(comp->back_nodes[j]);
+        ndl->ln.p0.x += comp->ctx.rel_x;
-        if (nd->inputs == 0) {
+        ndl->ln.p0.y += comp->ctx.rel_y;
-          continue;
-        }
-
-        for (u64 k = 0; k < nd->inputs; ++k) {
-          noodle *ndl = &(nd->noodles[k]);
-          if (ndl->connected_node == i) {
-            ndl->ln.p0.x += comp->ctx.rel_x;
-            ndl->ln.p0.y += comp->ctx.rel_y;
-          }
-        }
       }
     }
   }