Is there a difference between VISIBLE DISABLED and ALPHA 0?

Ape · December 16, 2024, 11:30am

In my GUI I often use invisible boxes to group nodes. What is the recommended way of doing it? Is there any difference in performance?

Visible = DISABLED
Alpha = 0

britzl · December 16, 2024, 5:17pm

It seems like these two options are treated the same:

github.com

defold/defold/blob/dev/engine/gui/src/gui.cpp#L1369

    
      
          static void CollectNodes(HScene scene, dmArray<InternalClippingNode>& clippers, dmArray<RenderEntry>& render_entries)
          {
              CollectClippers(scene, scene->m_RenderHead, 0, 0, clippers, INVALID_INDEX);
              CollectRenderEntries(scene, scene->m_RenderHead, 0, clippers, render_entries);
          }
          
          
static inline bool IsVisible(InternalNode* n, float opacity)
          {
              bool use_clipping = n->m_ClipperIndex != INVALID_INDEX;
          
          
    return n->m_Node.m_IsVisible && (opacity != 0.0f || use_clipping);
          }
          
          
void RenderScene(HScene scene, const RenderSceneParams& params, void* context)
          {
              Context* c = scene->m_Context;
          
          
    c->m_RenderNodes.SetSize(0);
              c->m_RenderTransforms.SetSize(0);
              c->m_RenderOpacities.SetSize(0);
              c->m_StencilClippingNodes.SetSize(0);

github.com

defold/defold/blob/dev/engine/gui/src/gui.cpp#L1435

    
      
          
          
// Ideally, we'd like to be able to do this in an Update step,
          // but since the gui script is updated _after_ the gui component, we need to accomodate
          // for any late scripting changes
          // Note: We need this update step for bones as well, since they update their transform
          CalculateNodeSize(n);
          CalculateNodeTransformAndAlphaCached(scene, n, CalculateNodeTransformFlags(CALCULATE_NODE_INCLUDE_SIZE | CALCULATE_NODE_RESET_PIVOT), transform, opacity);
          
          
// Ideally, we'd like to have this update step in the Update function (I'm not even sure why it isn't tbh)
          // But for now, let's prune the list here
          if (!IsVisible(n, opacity) || n->m_Node.m_IsBone)
          {
              entry.m_Node = INVALID_HANDLE;
              entry.m_RenderKey = INVALID_RENDER_KEY;
              ++num_pruned;
              continue;
          }
          
          
c->m_RenderTransforms.Push(transform);
          c->m_RenderOpacities.Push(opacity);
          if (n->m_ClipperIndex != INVALID_INDEX) {

AGulev · December 16, 2024, 7:55pm

A node can be enabled but invisible. This is useful if you use the node as a click-zone or as a “folder”—a container for other nodes.
In such cases, you usually don’t want the nodes to be rendered (visible) even if they are enabled (i.e., is_enabled returns true and they can be animated).