原文轉自:http://www.cnblogs.com/wuhenke/archive/2009/12/14/1624122.html
今天主要是分析學習了Render問題,搞明白了WorldWind中整個Render繪製處理過程。其中關鍵類是:RenderableObject.cs ,RenderobjectList.cs.
WW中所有需要繪製的對象都RenderableObject,WW的各功能的執行顯示都是不斷地調用相應的Render方法。
1.RenderableObject整個繪製對象繼承圖
WW繪製都是通過RenderableObject類,將所有的要繪製對象都看做是RenderableObject,從而統一了整個系統WW的繪製對象的繪製過程。
2.RenderableObjectList也繼承自RenderableObject,先看看它的繼承圖
摘錄內容:
“實際的點線,平面紋理等渲染對象都是從RenderableObject繼承,最終的渲染實現也是在從它繼續下來的類中,RenderableObjectList的成員m_children(protected ArrayList m_children = new ArrayList();)包含WW中所有的渲染對象,繪製過程中按如下的優先級進行:
public enum RenderPriority
{
SurfaceImages = 0,
TerrainMappedImages = 100,
AtmosphericImages = 200,
LinePaths = 300,
Icons = 400,
Placenames = 500,
Custom = 600
}
這裏對WW調試過程中的m_children的成員做個截圖,需要注意的是m_children的成員大部分還是RenderableObjectList對象,向下包含的層次很多,但只有最底層的從RenderableObject繼續的對象纔是渲染的最終實現。”摘自:http://blog.sina.com.cn/s/blog_467b6cd601008mmd.html~type=v5_one&label=rela_nextarticle
RenderableObjectList可以簡單看作RenderableObject對象的集合,但實質上存儲RenderableObject對象集合的僅僅是其中的屬性m_children,它有很多特有的針對m_children管理的方法,如:Add(RenderableObject ro)、Remove(RenderableObject layer)。RenderableObjectList裏通過該Timer.Elapsed 事件實現了自動刷新渲染的功能。這裏還有個知識點,我們可以學習一下,就是Timer.Elapsed
事件使用,請參考MS的http://msdn.microsoft.com/zh-cn/library/system.timers.timer.elapsed(VS.80).aspx。
3.下面讓我們一起看看WW實現渲染繪製的整個代碼調用流程,主要分爲兩部分:一、獲取到所有的要繪製對象集合,二、繪製所有要繪製的對象。分析入口還是從WorldWind.cs的MainAppliaction()方法開始的。
3.1獲取到所有的要繪製對象集合,存放到World.cs中的 RenderableObjects屬性裏
MainAppliaction()中調用OpenStartupWorld()
——》2974行OpenWorld( curWorldFile );調用了private void OpenWorld(string worldXmlFile)方法
——》3049行 worldWindow.CurrentWorld = WorldWind.ConfigurationLoader.Load(worldXmlFile, worldWindow.Cache);調用了CongfigurationLoader.cs的public static World Load(string filename, Cache cache)方法
——》CongfigurationLoader.cs 的110行 newWorld.RenderableObjects = getRenderablesFromLayerDirectory(layerDirectory, newWorld, cache); 看代碼
加載渲染對象代碼
Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/--> public static World Load(string filename, Cache cache)
{
Log.Write(Log.Levels.Debug, "CONF", "Loading " + filename);
// get the World Wind Settings through reflection to avoid changing the signature of Load().
Assembly a = Assembly.GetEntryAssembly();
Type appType = a.GetType("WorldWind.MainApplication");
System.Reflection.FieldInfo finfo = appType.GetField("Settings", BindingFlags.Static | BindingFlags.Public | BindingFlags.GetField);
WorldWindSettings settings = finfo.GetValue(null) as WorldWindSettings;
XmlReaderSettings readerSettings = new XmlReaderSettings();
if (settings.ValidateXML)
{
Log.Write(Log.Levels.Debug, "CONF", "validating " + filename + " against WorldXmlDescriptor.xsd and LayerSet.xsd");
readerSettings.ValidationType = ValidationType.Schema;
/* load the schema to validate against instead of hoping for an inline schema reference */
XmlSchemaSet schemas = new XmlSchemaSet();
schemas.Add(null, settings.ConfigPath + "/WorldXmlDescriptor.xsd");
schemas.Add(null, settings.ConfigPath + "/Earth/LayerSet.xsd");
readerSettings.Schemas = schemas;
readerSettings.ValidationEventHandler += new ValidationEventHandler(XMLValidationCallback);
readerSettings.ValidationFlags |= System.Xml.Schema.XmlSchemaValidationFlags.ReportValidationWarnings;
}
else
{
Log.Write(Log.Levels.Debug, "CONF", "loading " + filename + " without validation");
readerSettings.ValidationType = ValidationType.None;
}
try
{
XmlReader docReader = XmlReader.Create(filename, readerSettings);
XPathDocument docNav = new XPathDocument(docReader);
XPathNavigator nav = docNav.CreateNavigator();
XPathNodeIterator worldIter = nav.Select("/World[@Name]");
if (worldIter.Count > 0)
{
worldIter.MoveNext();
string worldName = worldIter.Current.GetAttribute("Name", "");
double equatorialRadius = ParseDouble(worldIter.Current.GetAttribute("EquatorialRadius", ""));
string layerDirectory = worldIter.Current.GetAttribute("LayerDirectory", "");
if (layerDirectory.IndexOf(":") < 0)
{
layerDirectory = Path.Combine(Path.GetDirectoryName(filename), layerDirectory);
}
TerrainAccessor[] terrainAccessor = getTerrainAccessorsFromXPathNodeIterator(worldIter.Current.Select("TerrainAccessor"),
System.IO.Path.Combine(cache.CacheDirectory, worldName));
World newWorld = new World(
worldName,
new Microsoft.DirectX.Vector3(0, 0, 0),
new Microsoft.DirectX.Quaternion(0, 0, 0, 0),
equatorialRadius,
cache.CacheDirectory,
(terrainAccessor != null ? terrainAccessor[0] : null)//TODO: Oops, World should be able to handle an array of terrainAccessors
);
//加載所有要渲染繪製的對象
newWorld.RenderableObjects = getRenderablesFromLayerDirectory(layerDirectory, newWorld, cache);
return newWorld;
}
}
catch (XmlSchemaException ex)
{
Log.Write(Log.Levels.Error, "CONF", "Exception caught during XML parsing: " + ex.Message);
Log.Write(Log.Levels.Error, "CONF", "File " + filename + " was not read successfully.");
// TODO: should pop up a message box or something.
return null;
}
return null;
}
——》170 public static RenderableObjectList getRenderableFromLayerFile(string layerFile, World parentWorld, Cache cache, bool enableRefresh)方法,真正加載繪製對象集合的函數。
3.2繪製所有要繪製的對象
WorldWind.cs中MainAppliaction()中
——》675worldWindow.Render();調用了WorldWindow.cs的Render()方法
——》785 m_World.Render(this.drawArgs);調用World.cs的public override void Render(DrawArgs drawArgs)方法
分類分層次地調用渲染代碼
Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/--> 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);
//分類、分層次地調用渲染方法
//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);
}
}
——》分類繪製過程中是調用 485行的private void Render(WorldWind.Renderable.RenderableObject renderable, WorldWind.Renderable.RenderPriority priority, DrawArgs drawArgs)方法。
被各類對象調用的渲染方法
Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/-->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)
{
//關鍵代碼,真正調用DirectX實施渲染繪製的,Render()方法被RenderObject類的子類渲染對象重載,實際上調用的是子類的Render()方法。
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);
}
}
說明:該方法中596行 renderable.Render(drawArgs);實質上是調用各個RenderableObject具體的子類重寫的Render()方法,實現繪製的。
4.以WavingFlagLayer.cs類重寫的588行Render()方法爲例,看看是如何完成繪製的。
WavingFlagLayer類渲染代碼
Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/--> public override void Render(DrawArgs drawArgs)
{
if (!isInitialized)
return;
if (m_polygonFeature == null || !drawArgs.WorldCamera.ViewFrustum.Intersects(m_polygonFeature.BoundingBox))
return;
try
{
double offset = 0;
if (Bar3D != null && Bar3D.IsOn)
{
Bar3D.Render(drawArgs);
offset = Bar3D.RenderedHeight;
}
Cull cull = drawArgs.device.RenderState.CullMode;
drawArgs.device.RenderState.CullMode = Cull.None;
drawArgs.device.RenderState.ZBufferEnable = true;
drawArgs.device.TextureState[0].ColorOperation = TextureOperation.SelectArg1;
drawArgs.device.TextureState[0].ColorArgument1 = TextureArgument.TextureColor;
Vector3 surfacePos = MathEngine.SphericalToCartesian(m_latitude, m_longitude, World.EquatorialRadius);
Vector3 rc = new Vector3(
(float)drawArgs.WorldCamera.ReferenceCenter.X,
(float)drawArgs.WorldCamera.ReferenceCenter.Y,
(float)drawArgs.WorldCamera.ReferenceCenter.Z
);
Vector3 projectedPoint = drawArgs.WorldCamera.Project(surfacePos - rc);
int mouseBuffer = 15;
if (projectedPoint.X > DrawArgs.LastMousePosition.X - mouseBuffer &&
projectedPoint.X < DrawArgs.LastMousePosition.X + mouseBuffer &&
projectedPoint.Y > DrawArgs.LastMousePosition.Y - mouseBuffer &&
projectedPoint.Y < DrawArgs.LastMousePosition.Y + mouseBuffer)
{
if (!m_isMouseInside)
{
m_isMouseInside = true;
if (OnMouseEnterEvent != null)
{
OnMouseEnterEvent(this, null);
}
}
}
else
{
if (m_isMouseInside)
{
m_isMouseInside = false;
if (OnMouseLeaveEvent != null)
{
OnMouseLeaveEvent(this, null);
}
}
}
drawArgs.device.RenderState.CullMode = Cull.None;
if (ShowHighlight)
renderHighlight(drawArgs);
RenderFlag(drawArgs, offset);
drawArgs.device.RenderState.CullMode = cull;
}
catch (Exception ex)
{
Log.Write(ex);
}
}