[WorldWind学习]6.World类

public class World : RenderableObject

World对象是WW中最重要的对象，他包含了一个渲染对象的集合，同时他自身也是一个渲染对象。

重载的Render方法：

 public override void Render(DrawArgs drawArgs)
        {
            try
            {

                if (m_WorldSurfaceRenderer != null && World.Settings.UseWorldSurfaceRenderer)
                {
                    m_WorldSurfaceRenderer.RenderSurfaceImages(drawArgs);
                }

                //  Old method -- problems with RenderPriority sorting
                //    RenderableObjects.Render(drawArgs);

                RenderStars(drawArgs, RenderableObjects);

                if (drawArgs.CurrentWorld.IsEarth && World.Settings.EnableAtmosphericScattering)
                {
                    float aspectRatio = (float)drawArgs.WorldCamera.Viewport.Width / drawArgs.WorldCamera.Viewport.Height;
                    float zNear = (float)drawArgs.WorldCamera.Altitude * 0.1f;
                    double distToCenterOfPlanet = (drawArgs.WorldCamera.Altitude + equatorialRadius);
                    double tangentalDistance = Math.Sqrt(distToCenterOfPlanet * distToCenterOfPlanet - equatorialRadius * equatorialRadius);
                    double amosphereThickness = Math.Sqrt(m_outerSphere.m_radius * m_outerSphere.m_radius + equatorialRadius * equatorialRadius);
                    Matrix proj = drawArgs.device.Transform.Projection;
                    drawArgs.device.Transform.Projection = Matrix.PerspectiveFovRH((float)drawArgs.WorldCamera.Fov.Radians, aspectRatio, zNear, (float)(tangentalDistance + amosphereThickness));
                    drawArgs.device.RenderState.ZBufferEnable = false;
                    drawArgs.device.RenderState.CullMode = Cull.CounterClockwise;
                    m_outerSphere.Render(drawArgs);
                    drawArgs.device.RenderState.CullMode = Cull.Clockwise;
                    drawArgs.device.RenderState.ZBufferEnable = true;

                    drawArgs.device.Transform.Projection = proj;
                }

                if (World.Settings.EnableSunShading)
                    RenderSun(drawArgs);

                //render SurfaceImages
                Render(RenderableObjects, WorldWind.Renderable.RenderPriority.TerrainMappedImages, drawArgs);

                if (m_projectedVectorRenderer != null)
                    m_projectedVectorRenderer.Render(drawArgs);

                //render AtmosphericImages
                Render(RenderableObjects, WorldWind.Renderable.RenderPriority.AtmosphericImages, drawArgs);

                //render LinePaths
                Render(RenderableObjects, WorldWind.Renderable.RenderPriority.LinePaths, drawArgs);

                //render Placenames
                Render(RenderableObjects, WorldWind.Renderable.RenderPriority.Placenames, drawArgs);

                //render Icons
                Render(RenderableObjects, WorldWind.Renderable.RenderPriority.Icons, drawArgs);

                //render Custom
                Render(RenderableObjects, WorldWind.Renderable.RenderPriority.Custom, drawArgs);

                if (Settings.showPlanetAxis)
                    this.DrawAxis(drawArgs);
            }
            catch (Exception ex)
            {
                Log.Write(ex);
            }
        }

其中多次调用的Render私有方法：

private void Render(WorldWind.Renderable.RenderableObject renderable, WorldWind.Renderable.RenderPriority priority, DrawArgs drawArgs)
        {
            if (!renderable.IsOn || (renderable.Name != null && renderable.Name.Equals("Starfield")))
                return;

            try
            {
                if (priority == WorldWind.Renderable.RenderPriority.Icons && renderable is Icons)
                {
                    renderable.Render(drawArgs);
                }
                else if (renderable is WorldWind.Renderable.RenderableObjectList)
                {
                    WorldWind.Renderable.RenderableObjectList rol = (WorldWind.Renderable.RenderableObjectList)renderable;
                    for (int i = 0; i < rol.ChildObjects.Count; i++)
                    {
                        Render((WorldWind.Renderable.RenderableObject)rol.ChildObjects[i], priority, drawArgs);
                    }
                }
                // hack at the moment
                else if (priority == WorldWind.Renderable.RenderPriority.TerrainMappedImages)
                {
                    if (renderable.RenderPriority == WorldWind.Renderable.RenderPriority.SurfaceImages || renderable.RenderPriority == WorldWind.Renderable.RenderPriority.TerrainMappedImages)
                    {
                        renderable.Render(drawArgs);
                    }
                }
                else if (renderable.RenderPriority == priority)
                {
                    renderable.Render(drawArgs);
                }
            }
            catch (Exception ex)
            {
                Log.Write(ex);
            }
        }

重载的Update方法：

  public override void Update(DrawArgs drawArgs)
        {
            if (!this.isInitialized)
            {
                this.Initialize(drawArgs);
            }

            if (this.RenderableObjects != null)
            {
                this.RenderableObjects.Update(drawArgs);
            }
            if (this.m_WorldSurfaceRenderer != null)
            {
                this.m_WorldSurfaceRenderer.Update(drawArgs);
            }

            if (this.m_projectedVectorRenderer != null)
            {
                this.m_projectedVectorRenderer.Update(drawArgs);
            }

            if (this.TerrainAccessor != null)
            {
                if (drawArgs.WorldCamera.Altitude < 300000)
                {
                    if (System.DateTime.Now - this.lastElevationUpdate > TimeSpan.FromMilliseconds(500))
                    {
                        drawArgs.WorldCamera.TerrainElevation = (short)this.TerrainAccessor.GetElevationAt(drawArgs.WorldCamera.Latitude.Degrees, drawArgs.WorldCamera.Longitude.Degrees, 100.0 / drawArgs.WorldCamera.ViewRange.Degrees);
                        this.lastElevationUpdate = System.DateTime.Now;
                    }
                }
                else
                    drawArgs.WorldCamera.TerrainElevation = 0;
            }
            else
            {
                drawArgs.WorldCamera.TerrainElevation = 0;
            }

            if (World.Settings.EnableAtmosphericScattering && m_outerSphere != null)
                m_outerSphere.Update(drawArgs);
        }

重载的PerformSelectionAction方法：

public override bool PerformSelectionAction(DrawArgs drawArgs)
        {
            return this._renderableObjects.PerformSelectionAction(drawArgs);
        }