它是光明节,我正在尝试动画陀螺(dreidel)：
我可以让它在自己的轴上旋转.这是我的代码：
import static javafx.scene.paint.Color.*; import javafx.animation.KeyFrame; import javafx.animation.KeyValue; import javafx.animation.Timeline; import javafx.application.Application; import javafx.beans.property.DoubleProperty; import javafx.beans.property.SimpleDoubleProperty; import javafx.geometry.Point3D; import javafx.scene.Camera; import javafx.scene.Group; import javafx.scene.PerspectiveCamera; import javafx.scene.Scene; import javafx.scene.SceneAntialiasing; import javafx.scene.paint.PhongMaterial; import javafx.scene.shape.Box; import javafx.scene.shape.Cylinder; import javafx.scene.shape.Sphere; import javafx.scene.transform.Rotate; import javafx.scene.transform.Translate; import javafx.stage.Stage; import javafx.util.Duration; public class DreidelAnim extends Application { private double bodyBase = 30; private double bodyHeight = bodyBase * 3 / 2; private double baseRadius = bodyBase / 2; @Override public void start(Stage stage) throws Exception { DoubleProperty spinAngle = new SimpleDoubleProperty(); Rotate spin = new Rotate(0,Rotate.Z_AXIS); spin.angleProperty().bind(spinAngle); Timeline spinAnim = new Timeline(new KeyFrame(Duration.seconds(2),new KeyValue(spinAngle,360))); spinAnim.setCycleCount(Timeline.INDEFINITE); spinAnim.play(); Group dreidel = createDreidel(); Translate zTrans = new Translate(0,-(bodyHeight/2 + baseRadius)); dreidel.getTransforms().addAll(spin,zTrans); Scene scene = new Scene(dreidel,200,true,SceneAntialiasing.BALANCED); scene.setFill(SKYBLUE); scene.setCamera(createCamera()); stage.setScene(scene); stage.show(); } private Group createDreidel() { double handleHeight = bodyBase * 3/4; Cylinder handle = new Cylinder(bodyBase / 6,handleHeight); handle.setTranslateZ(-(bodyHeight + handleHeight) / 2); handle.setRotationAxis(Rotate.X_AXIS); handle.setRotate(90); handle.setMaterial(new PhongMaterial(RED)); Box body = new Box(bodyBase,bodyBase,bodyHeight); body.setMaterial(new PhongMaterial(BLUE)); Sphere base = new Sphere(baseRadius); base.setTranslateZ(bodyHeight / 2); base.setMaterial(new PhongMaterial(GREEN)); return new Group(handle,body,base); } private Camera createCamera() { PerspectiveCamera camera = new PerspectiveCamera(true); camera.setFarClip(1000); int xy = 150; Translate trans = new Translate(-xy,xy,-120); Rotate rotXY = new Rotate(70,new Point3D(1,1,0)); Rotate rotZ = new Rotate(45,new Point3D(0,1)); camera.getTransforms().addAll(trans,rotXY,rotZ); return camera; } public static void main(String[] args) { launch(); } }
我创建了一个简单的模型,围绕其轴旋转,并将其翻译为其尖端(0,0).结果如下：
如何才能实现与顶部图片类似的旋转轴旋转？
解决方法
物体旋转的轴的旋转称为
Precession.旋转顶部运动需要2次旋转：
>物体围绕其内轴旋转(与红色手柄平行).
>围绕静态轴旋转其中一个内部轴(在本例中为z).
从表面上看,你需要2个动画实例.但是,两个旋转实际上是相同的.两者的轴心点是(0,0)(在zTrans之后)并且它们都在z轴周围,只有一个以一定角度倾斜.
import static javafx.scene.paint.Color.*; import javafx.animation.KeyFrame; import javafx.animation.KeyValue; import javafx.animation.Timeline; import javafx.application.Application; import javafx.beans.property.DoubleProperty; import javafx.beans.property.SimpleDoubleProperty; import javafx.geometry.Point3D; import javafx.scene.Camera; import javafx.scene.Group; import javafx.scene.PerspectiveCamera; import javafx.scene.Scene; import javafx.scene.SceneAntialiasing; import javafx.scene.paint.PhongMaterial; import javafx.scene.shape.Box; import javafx.scene.shape.Cylinder; import javafx.scene.shape.Sphere; import javafx.scene.transform.Rotate; import javafx.scene.transform.Translate; import javafx.stage.Stage; import javafx.util.Duration; public class FinalDreidelSpin extends Application { private double bodyBase = 30; private double bodyHeight = bodyBase * 3 / 2; private double baseRadius = bodyBase / 2; @Override public void start(Stage stage) throws Exception { double tiltAngle = 40; DoubleProperty spinAngle = new SimpleDoubleProperty(); Rotate spin = new Rotate(0,Rotate.Z_AXIS); Rotate tilt = new Rotate(tiltAngle,Rotate.X_AXIS); spin.angleProperty().bind(spinAngle); Timeline spinAnim = new Timeline(); spinAnim.getKeyFrames().add(new KeyFrame(Duration.seconds(2),tilt,spin,zTrans); Scene scene = new Scene(new Group(dreidel,createAxes()),-100); Rotate rotXY = new Rotate(70,rotZ); return camera; } private Group createAxes() { int axisWidth = 1; int axisLength = 400; Cylinder xAxis = new Cylinder(axisWidth,axisLength); xAxis.setMaterial(new PhongMaterial(CYAN)); Cylinder yAxis = new Cylinder(axisWidth,axisLength); yAxis.setRotationAxis(Rotate.Z_AXIS); yAxis.setRotate(90); yAxis.setMaterial(new PhongMaterial(MAGENTA)); Cylinder zAxis = new Cylinder(axisWidth,axisLength); zAxis.setRotationAxis(Rotate.X_AXIS); zAxis.setRotate(90); zAxis.setMaterial(new PhongMaterial(YELLOW)); return new Group(xAxis,yAxis,zAxis); } public static void main(String[] args) { launch(); } }
我添加了轴表示以方便查看.请注意,getTransforms()列表不要求其对象是唯一的(与getChildren()不同),这允许我们重用相同的动画.如下所述,动画的顺序也很重要.
倾斜是围绕x或y轴的简单旋转.
如果我们倾斜然后旋转,getTransforms().addAll(tilt,zTrans),我们将得到内部旋转(上面列出的1),只是倾斜：
如果我们旋转然后倾斜,getTransforms().addAll(spin,我们就会得到进动(上面列出的2)：
在完整代码中组合2将得到所需的结果：
