Adding per-vertex colours to a transient AutoCAD shell using .NET

In the last post, we introduced some code to generate transient graphics using WorldGeometry.Shell(). In this post we’ll make one simple addition: we’ll add per-vertex colours, to see the effect on the generated box.

We’re not going to perform complex calculations to determine the appropriate colours for each vertex: we’ll just use the index of the vertex itself, in much the same way as we did for the faces. As faces and vertices in no way match, index-wise, we should see some interesting effects.

Here’s the modified C# code. There is only one addition to the previous code: a call to VertexData.SetTrueColors() at the end of the constructor for the TransientBox class.

using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.EditorInput;
using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.Geometry;
using Autodesk.AutoCAD.GraphicsInterface;
using Autodesk.AutoCAD.Colors;
using System.Collections.Generic;
 
namespace TransientSelection
{
  public class TransientBox : Transient
  {
    // Internal state
 
    private TextStyle _style;
    Point3dCollection _verts;
    IntegerCollection _faces;
    EdgeData _edgeData;
    FaceData _faceData;
    VertexData _vertData;
 
    public TransientBox(double side)
    {
      // Create the style for our text
 
      _style = new TextStyle();
      _style.Font =
        new FontDescriptor("Calibri", false, true, 0, 0);
      _style.TextSize = 10;
 
      // Add our vertices manually (8 of them for a box)
 
      _verts = new Point3dCollection();
 
      _verts.Add(Point3d.Origin);                // 0
      _verts.Add(new Point3d(side, 0, 0));       // 1
      _verts.Add(new Point3d(side, side, 0));    // 2
      _verts.Add(new Point3d(0, side, 0));       // 3
 
      _verts.Add(new Point3d(0, 0, side));       // 4
      _verts.Add(new Point3d(side, 0, side));    // 5
      _verts.Add(new Point3d(side, side, side)); // 6
      _verts.Add(new Point3d(0, side, side));    // 7
 
      // Our faces are defined in sets of 3 vertices
      // (listed below two per line, each making a square face)
 
      int[] polys =
      {
        0, 1, 2, 2, 3, 0, // Bottom
        0, 4, 5, 5, 1, 0, // Front
        1, 5, 6, 6, 2, 1, // Right
        2, 6, 7, 7, 3, 2, // Back
        0, 3, 7, 7, 4, 0, // Left
        4, 7, 6, 6, 5, 4  // Top
      };
      const int polySize = 3;
 
      // Create our faces from the polys array
 
      _faces = new IntegerCollection();
      for (int p = 0; p < (polys.Length / polySize); p++)
      {
        _faces.Add(polySize);
        for (int v = 0; v < polySize; v++)
        {
          _faces.Add(polys[p * polySize + v]);
        }
      }
 
      // Create our edge data
 
      _edgeData = new EdgeData();
 
      // Each face's edges should have the same colour as the face
 
      _edgeData.SetColors(
        new short[]
        {
          1, 1, 1, 2, 2, 2, 3, 3, 3,
          4, 4, 4, 5, 5, 5, 6, 6, 6,
          7, 7, 7, 8, 8, 8, 9, 9, 9,
          10, 10, 10, 11, 11, 11, 12, 12, 12
        }
      );
 
      // Create our face data
 
      _faceData = new FaceData();
 
      // The face colours match their edges
 
      _faceData.SetColors(
        new short[]
        {
          1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12
        }
      );
 
      // Create our vertex data
 
      _vertData = new VertexData();
      _vertData.OrientationFlag = OrientationType.Clockwise;
 
      _vertData.SetTrueColors(
        new EntityColor[]
        {
          new EntityColor(ColorMethod.ByAci, 1),
          new EntityColor(ColorMethod.ByAci, 2),
          new EntityColor(ColorMethod.ByAci, 3),
          new EntityColor(ColorMethod.ByAci, 4),
          new EntityColor(ColorMethod.ByAci, 5),
          new EntityColor(ColorMethod.ByAci, 6),
          new EntityColor(ColorMethod.ByAci, 7),
          new EntityColor(ColorMethod.ByAci, 8)
        }
      );
    }
 
    protected override int SubSetAttributes(DrawableTraits traits)
    {
      return (int)DrawableAttributes.None;
    }
 
    protected override void SubViewportDraw(ViewportDraw vd)
    {
      // Draw our screen-fixed text
 
      DrawText(vd.Geometry, "ViewportDraw");
    }
 
    protected override bool SubWorldDraw(WorldDraw wd)
    {
      // Draw our box
 
      wd.Geometry.Shell(
        _verts, _faces, _edgeData, _faceData, _vertData, false
      );
 
      // Draw our screen-fixed text
 
      DrawText(wd.Geometry, "WorldDraw");
      return true;
    }
 
    private void DrawText(Geometry g, string text)
    {
      // We make use of another interface to push our transforms
 
      if (g != null)
      {
        // Push our transforms onto the stack
 
        g.PushOrientationTransform(OrientationBehavior.Screen);
 
        g.PushPositionTransform(
          PositionBehavior.Screen,
          new Point2d(30, 30)
        );
 
        // Draw our screen-fixed text
 
        g.Text(
          new Point3d(0, 0, 0),  // Position
          new Vector3d(0, 0, 1), // Normal
          new Vector3d(1, 0, 0), // Direction
          text,                  // Text
          true,                  // Rawness
          _style                 // TextStyle
        );
 
        // Remember to pop our transforms off the stack
 
        g.PopModelTransform();
        g.PopModelTransform();
      }
    }
 
    protected override void OnDeviceInput(DeviceInputEventArgs e)
    {
      base.OnDeviceInput(e);
    }
 
    protected override void OnPointInput(PointInputEventArgs e)
    {
      base.OnPointInput(e);
    }
  }
 
  public class Commands
  {
    TransientBox _tb = null;
 
    [CommandMethod("TB")]
    public void TransientBox()
    {
      _tb = new TransientBox(10);
 
      // Tell AutoCAD to call into this transient's extended
      // protocol when appropriate
 
      Transient.CapturedDrawable = _tb;
 
      // Go ahead and draw the transient
 
      TransientManager.CurrentTransientManager.AddTransient(
        _tb, TransientDrawingMode.Main,
        128, new IntegerCollection()
      );
    }
 
    [CommandMethod("TBR")]
    public void RemoveTransientBox()
    {
      // Erase the transient graphics and dispose of the transient
 
      if (_tb != null)
      {
        TransientManager.CurrentTransientManager.EraseTransient(
          _tb,
          new IntegerCollection()
        );
        _tb.Dispose();
        _tb = null;
      }
    }
  }
}