知识大全 java3D中平行光投影的实现

Posted 2022-07-19 知

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　　理论根据:假设一个光的方向是( ) 投影到XZ平面

　　一个是直线方程一个是平面方程求交而且平面方程还比较特殊经过原点法向量是简化后就简单了假定v是直线的方向

　　x vertex x y vertex y z vertex z = = 直线方程 v x v y v z

　　平面方程 y =

　　带入就得到了x = vertex x + v x / v y * ( vertex y)z = vertex z + v x / v z * ( vertex z)

　　源程序:import java applet Applet;import java awt BorderLayout;import java awt GraphicsConfiguration;import java awt Label;import sun j d utils applet MainFrame;import sun j d utils universe *;import sun j d utils geometry *;import dia j d *;import javax vecmath *;public class SimpleShadow extends Applet //三角平面类 public class TriPlane extends Shape D TriPlane(Point f A Point f B Point f C) this setGeometry(this createGeometry (A B C)); this setAppearance(this createAppearance()); //建立三角平面 Geometry createGeometry (Point f A Point f B Point f C) TriangleArray plane=new TriangleArray( GeometryArray COORDINATES|GeometryArray NORMALS); //设置平面个顶点的坐标 plane setCoordinate( A); plane setCoordinate( B); plane setCoordinate( C); //计算平面法向量 Vector f a=new Vector f(A x B x A y B y A z B z); Vector f b=new Vector f(C x B x C y B y C z B z); Vector f n=new Vector f(); n cross(b a); //法向量单位化 n normalize(); //设置平面个顶点的法向量 plane setNormal( n); plane setNormal( n); plane setNormal( n); return plane; //创建Material不为空的外观 Appearance createAppearance() Appearance appear=new Appearance(); Material material=new Material(); appear setMaterial(material); return appear; //四边平面类 public class QuadPlane extends Shape D QuadPlane(Point f A Point f B Point f C Point f D) this setGeometry(this createGeometry (A B C D)); this setAppearance(this createAppearance()); //创建四边性平面 Geometry createGeometry (Point f A Point f B Point f C Point f D) QuadArray plane=new QuadArray( GeometryArray COORDINATES|GeometryArray NORMALS); //设置平面个顶点的坐标 plane setCoordinate( A); plane setCoordinate( B); plane setCoordinate( C); plane setCoordinate( D); //计算平面法向量 Vector f a=new Vector f(A x B x A y B y A z B z); Vector f b=new Vector f(C x B x C y B y C z B z); Vector f n=new Vector f(); n cross(b a); //法向量单位化 n normalize(); //设置平面个顶点的法向量 plane setNormal( n); plane setNormal( n); plane setNormal( n); plane setNormal( n); return plane;

　　//创建Material不为空的外观 Appearance createAppearance() Appearance appear=new Appearance(); Material material=new Material(); appear setMaterial(material); return appear; //阴影类 public class Shadow D extends Shape D Shadow D(GeometryArray geom Vector f direction Color f col float height) int vCount=geom getVertexCount(); TriangleArray poly=new TriangleArray(vCount GeometryArray COORDINATES|GeometryArray COLOR_ ); int v; Point f vertex=new Point f(); Point f shadow=new Point f(); for(v= ;v<vCount;v++) //计算可见面顶点在投影面上的投影坐标 geom getCoordinate(v vertex); System out println(vertex y height); shadow set(vertex x (vertex y height) height+ f vertex z (vertex y height)); poly setCoordinate(v shadow); poly setColor(v col);

　　 this setGeometry(poly); public SimpleShadow() this setLayout(new BorderLayout()); //GraphicsConfiguration config =SimpleUniverse getPreferredConfiguration(); Canvas D c=new Canvas D(null); this add( Center c); //创建分支节点 BranchGroup scene=new BranchGroup(); //创建三角形可见平面 Shape D plane=new TriPlane(new Point f( f f f) new Point f( f f f) new Point f( f f f)); //添加到根分支节点 scene addChild(plane); //创建四边形投影平面 Shape D floor=new QuadPlane(new Point f( f f f) new Point f( f f f) new Point f( f f f) new Point f( f f f)); //添加到根分支节点 scene addChild(floor); //添加到环境光 AmbientLight lightA=new AmbientLight(); lightA setInfluencingBounds(new BoundingSphere()); scene addChild(lightA); //添加平行光 DirectionalLight lightD =new DirectionalLight(); lightD setInfluencingBounds(new BoundingSphere()); Vector f direction=new Vector f( f f f); //方向矢量单位化 direction normalize(); lightD setDirection(direction); scene addChild(lightD ); //创建阴影物体 Shape D shadow=new Shadow D((GeometryArray)plane getGeometry() direction new Color f( f f f) f); scene addChild(shadow); SimpleUniverse u=new SimpleUniverse(c); u getViewingPlatform() setNominalViewingTransform(); u addBranchGraph(scene); public static void main(String argv[]) new MainFrame(new SimpleShadow() );

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