DrawViewportMeshes could not trigger correctly

Grasshopper
,
#1

Hi Everyone, I written an component named TextDot to create textdot object in grasshopper. recently.
And there have an problem about the component . the problem is that. when i create an textdot object using the component and it could not invoke the DrawViewportMeshes and could not see the preview content in rhino viewport. but when I drag another TextDot Component into grasshopper canvas , something strange has happen, the component that could not draw preview content before become can draw preview content .

the TextDot source code is attach at below

TextDot.cs (3.6 KB)

DrawPreviewMeshes%20Problem
DrawPreviewMeshes Problem.gif1884×1047 810 KB

#2

You are not overriding the clipping box, which Grasshopper preview needs to make sure your previews are fully within the z-buffer.

Does it work if your dot is ‘inside’ some pre-existing geometry in Rhino?

#3

Hi @DavidRutten, It Works When I override Clippingbox properties. Thanks

And could you show me some more detail about the clippingbox and how the clippingobx affect the Grasshopper preview?

#4 
using System;
using System.Drawing;
using System.Collections.Generic;

using Rhino.Geometry;
using Grasshopper.Kernel;

namespace CSCECDEC.Okavango.Dimension
{
  public class TextDotObj : GH_Component
  {
    public TextDotObj() : base("TextDot", "TextDot", "Display a collection of text dots", "Display", "Custom") { }

    protected override void RegisterInputParams(GH_Component.GH_InputParamManager pManager)
    {
      pManager.AddPointParameter("Point", "P", "Dot location", GH_ParamAccess.item, Point3d.Origin);
      pManager.AddTextParameter("Text", "T", "Dot text", GH_ParamAccess.item);
      pManager.AddColourParameter("Colour", "C", "Dot colour", GH_ParamAccess.item, Color.Crimson);
    }
    protected override void RegisterOutputParams(GH_Component.GH_OutputParamManager pManager)
    {
      pManager.AddGenericParameter("TextDot", "D", "Text dot", GH_ParamAccess.item);
    }

    public override Guid ComponentGuid
    {
      get { return new Guid("24a24263-416b-48c6-a199-680d50e3ffaa"); }
    }

    protected override void BeforeSolveInstance()
    {
      _dots.Clear();
      _fill.Clear();
      _edge.Clear();
    }
    protected override void AfterSolveInstance()
    {
      _box = BoundingBox.Empty;
      foreach (var dot in _dots)
        _box.Union(dot.Point);
    }

    protected override void SolveInstance(IGH_DataAccess access)
    {
      var point = Point3d.Unset;
      var text = string.Empty;
      var colour = Color.Transparent;

      if (!access.GetData(0, ref point)) return;
      if (!access.GetData(1, ref text)) return;
      if (!access.GetData(2, ref colour)) return;

      if (!point.IsValid) return;
      if (string.IsNullOrEmpty(text)) return;
      if (colour.A == 0) return;

      var dot = new TextDot(text, point);
      _dots.Add(dot);
      _fill.Add(colour);
      _edge.Add(colour.GetBrightness() < 0.3 ? Color.White : Color.Black);

      access.SetData(0, dot);
    }

    public override void BakeGeometry(Rhino.RhinoDoc doc, List<Guid> obj_ids)
    {
      for (int i = 0; i < _dots.Count; i++)
      {
        var attributes = doc.CreateDefaultAttributes();
        attributes.ColorSource = Rhino.DocObjects.ObjectColorSource.ColorFromObject;
        attributes.ObjectColor = _fill[i];
        obj_ids.Add(doc.Objects.AddTextDot(_dots[i], attributes));
      }
    }

    public override BoundingBox ClippingBox
    {
      get { return _box; }
    }
    public override void DrawViewportWires(IGH_PreviewArgs args)
    {
      // I prefer drawing in wires as dots are usually not transparent.
      // Wires are drawn first so any transparent meshes in front of the dots won't obscure them.

      if (_dots.Count == 0)
        return;

      if (Attributes.Selected)
      {
        var fill = args.WireColour_Selected;
        var edge = fill.GetBrightness() < 0.3 ? Color.White : Color.Black;
        for (int i = 0; i < _dots.Count; i++)
          args.Display.DrawDot(_dots[i], fill, edge, edge);
      }
      else
      {
        for (int i = 0; i < _dots.Count; i++)
          args.Display.DrawDot(_dots[i], _fill[i], _edge[i], _edge[i]);
      }
    }

    private readonly List<TextDot> _dots = new List<TextDot>();
    private readonly List<Color> _fill = new List<Color>();
    private readonly List<Color> _edge = new List<Color>();
    private /*....*/ BoundingBox _box;
  }
}
#5

Thanks ，@David It is Very nice of You, Thanks Again