Re: [JAVA3D] TexCoords for non regular shapes

[Yazel, David J.]

We recently implemented creating roads along a spline path.

Here is an excerp which should be of help.  The texture coordinates are
calculated in this piece
of the code:

   /**
    * Create the path over the terrain map, along the path nodes specified
    * in the constructor.
    */

   public GeometryArray getGeometry(HeightMapInterface map, Brush brush) {

      GeneralPath gp = getGeneralPath(points);
      float[] sPoints =  getSpecificPath(gp,density);

      // create a triangle strip, which should have

      TriangleStripArray geom;

      int vertexCounts[] = new int[1];
      vertexCounts[0] = sPoints.length;

      if (brush.dtexEnable) {
         int texMapping[] = {0,1};
         geom = new
TriangleStripArray(sPoints.length,GeometryArray.COORDINATES |
            GeometryArray.COLOR_4 |
            GeometryArray.TEXTURE_COORDINATE_2 |
GeometryArray.NORMALS,2,texMapping,vertexCounts);
      } else {
         geom = new TriangleStripArray(sPoints.length,
GeometryArray.COORDINATES |
            GeometryArray.COLOR_4 |
            GeometryArray.TEXTURE_COORDINATE_2 |
GeometryArray.NORMALS,vertexCounts);
      }

      Point3d curPoint = new Point3d();
      Point3d nextPoint = new Point3d();
      Vector3d vec = new Vector3d();
      Point3f p1 = new Point3f();
      Point3f p2 = new Point3f();
      Vector3f straightUp = new Vector3f(0,1,0);
      int vertex = 0;
      TexCoord2f tex = new TexCoord2f();
      float length = 0;
//      Color4f white = new Color4f(1f,1f,1f,1f);
      Color4f white = new Color4f(130f/255f,78f/255f,10f/255f,1f);
//      Color4f white = new Color4f(169f/255f,139f/255f,87f/255f,1f);
      Color4f invisible = new Color4f(white.x,white.y,white.z,0f);
      Random r = new Random(183483);

      // some transforms we are going to use

      Transform3D rot = new Transform3D();

      // step through all the vertices and write them out.  For each point
in the sPoints
      // we will create 2 points in the geometry

      for (int i=0;i<sPoints.length/2-1;i++) {

         // create the points then calculate the vector from the current
         // point to the next point

         curPoint.x = sPoints[i*2];
         curPoint.z = sPoints[i*2+1];

         nextPoint.x = sPoints[(i+1)*2];
         nextPoint.z = sPoints[(i+1)*2+1];

         float l = (float)(curPoint.distance(nextPoint));

         // build a vector from the current point to the next
         // point of length equal to 1/2 the path width

         vec.set(curPoint);
         vec.sub(nextPoint);
         vec.normalize();
         vec.scale(width/2);

         // rotate the vector right 90 degrees

         rot.rotY(90*(3.14/180));
         rot.transform(vec);
         p2.set(vec);
         p2.x += curPoint.x;
         p2.z += curPoint.z;

         // now reverse it to get the other point

         rot.rotY(-180*(3.14/180));
         rot.transform(vec);
         p1.set(vec);
         p1.x += curPoint.x;
         p1.z += curPoint.z;

         // now we have 2 points straddling the path we need to determine
their
         // height

         p1.y = map.getY(p1.x,p1.z)+0.3f;
         p2.y = map.getY(p2.x,p2.z)+0.3f;

         // determine if this is alpha blended

         Color4f color = white;
         if (brush.hasAlpha) {
            if ((i==0) || (i>=sPoints.length/2-2))
               color = invisible;
         }

//         System.out.println("p1:"+p1+",  p2:"+p2);

         geom.setCoordinate(vertex,p1);
         geom.setNormal(vertex,straightUp);
         geom.setColor(vertex,color);
         tex.x = 0;
         tex.y = (length/width)/8;
         geom.setTextureCoordinate(0,vertex,tex);
         vertex++;

         geom.setCoordinate(vertex,p2);
         geom.setNormal(vertex,straightUp);
         geom.setColor(vertex,color);
         tex.x = 1;
         geom.setTextureCoordinate(0,vertex,tex);
         vertex++;

         length += l;
      }

      return geom;
   }

-----Original Message-----
From: Alvaro Zabala [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, June 06, 2001 12:32 PM
To: [EMAIL PROTECTED]
Subject: [JAVA3D] TexCoords for non regular shapes


I want to apply a texture on a road which I have made with a
triangleStripArray.

The road's shape is very non regular, so compute his TexCoords maybe too
much difficult.

I'm using a TexCoordGenerator, but I don't like the result.

How can I apply a texture over a very non regular shape??

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