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.
这是修改后的代码：
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 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：