ThinkGeo.com    |     Documentation    |     Premium Support

Position Shapes beside a line

#1

Hello,


I have to create shapes (Point, Lines, Rectangle) and position them beside a line (baseline). 


As parameter I have  the position (distance) on the base line where the elements are in right angle to. Also I know the offset and if the shape has to be positioned left or right side to the base line.


If I use getPointOnALine() I can get the points the shapes would have if they were located on the line. But how can I move those point in a right angle and given distance?



Thanks Thomas



#2

Please, look at the code I am using below. Basically, I think that with the function GetAngleFromTwoVertices you have what you need.




            winformsMap1.MapUnit = GeographyUnit.Meter;
            winformsMap1.CurrentExtent = new RectangleShape(0, 90, 180, 0);

            LineShape lineShape = new LineShape();
            lineShape.Vertices.Add(new Vertex(10, 60));
            lineShape.Vertices.Add(new Vertex(130, 20));

            PointShape pointShape1 = lineShape.GetPointOnALine(StartingPoint.FirstPoint, 30);
            
            double Angle = GetAngleFromTwoVertices(lineShape.Vertices[0], lineShape.Vertices[1]);

            double offsetAngle1 = Angle; 
            double offsetAngle2 = Angle + 180;

            PointShape offsetPointShape1 = (PointShape)pointShape1.CloneDeep();
            PointShape offsetPointShape2 = (PointShape)pointShape1.CloneDeep();

            offsetPointShape1.TranslateByDegree(20, offsetAngle1);
            offsetPointShape2.TranslateByDegree(20, offsetAngle2);

            InMemoryFeatureLayer inMemoryFeatureLayer = new InMemoryFeatureLayer();
            inMemoryFeatureLayer.ZoomLevelSet.ZoomLevel01.DefaultLineStyle = LineStyles.CreateSimpleLineStyle(GeoColor.StandardColors.Red, 3, true);
            inMemoryFeatureLayer.ZoomLevelSet.ZoomLevel01.DefaultPointStyle = PointStyles.CreateSimpleCircleStyle(GeoColor.StandardColors.Green, 10);
            inMemoryFeatureLayer.ZoomLevelSet.ZoomLevel01.ApplyUntilZoomLevel = ApplyUntilZoomLevel.Level20;
            inMemoryFeatureLayer.Open();
            inMemoryFeatureLayer.EditTools.BeginTransaction();
            inMemoryFeatureLayer.EditTools.Add(new Feature(lineShape));
            inMemoryFeatureLayer.EditTools.Add(new Feature(pointShape1));
            inMemoryFeatureLayer.EditTools.Add(new Feature(offsetPointShape1));
            inMemoryFeatureLayer.EditTools.Add(new Feature(offsetPointShape2));
            inMemoryFeatureLayer.EditTools.CommitTransaction();
            inMemoryFeatureLayer.Close();

            LayerOverlay layerOverlay = new LayerOverlay();
            layerOverlay.Layers.Add(inMemoryFeatureLayer);

            winformsMap1.Overlays.Add(layerOverlay);

            winformsMap1.Refresh();


#3

 



 private static double GetAngleFromTwoVertices(Vertex fromVertex, Vertex toVertex)
        {
            double alpha = 0;

            if (fromVertex.X != toVertex.X)
            {
                double tangentAlpha = (fromVertex.Y - toVertex.Y) / (toVertex.X - fromVertex.X);
                alpha = Math.Atan(tangentAlpha) * 180 / Math.PI;
                if (alpha < 0) { alpha += 360; }
            }
            else
            {
                alpha = (fromVertex.Y > toVertex.Y) ? 90 : 270;
            }

            return alpha;
        }


#4

 I let you know that we made a project in the Code Community from your idea of offsetting points at a right angle. You can check it out:


code.thinkgeo.com/projects/show/offsetrightangle