Java tutorial
/* * Copyright 1996-2008 Sun Microsystems, Inc. All Rights Reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Sun designates this * particular file as subject to the "Classpath" exception as provided * by Sun in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, * CA 95054 USA or visit www.sun.com if you need additional information or * have any questions. * */ package javax.media.j3d; import java.util.Enumeration; import javax.vecmath.AxisAngle4d; import javax.vecmath.Point3d; import javax.vecmath.Point3f; import javax.vecmath.Vector3d; import javax.vecmath.Vector3f; /** * The Billboard behavior node operates on the TransformGroup node * to cause the local +z axis of the TransformGroup to point at * the viewer's eye position. This is done regardless of the transforms * above the specified TransformGroup node in the scene graph. * * <p> * If the alignment mode is ROTATE_ABOUT_AXIS, the rotation will be * around the specified axis. If the alignment mode is * ROTATE_ABOUT_POINT, the rotation will be about the specified * point, with an additional rotation to align the +y axis of the * TransformGroup with the +y axis in the View. * * <p> * Note that in a multiple View system, the alignment is done to * the primary View only. * * <p> * Billboard nodes are ideal for drawing screen aligned-text or * for drawing roughly-symmetrical objects. A typical use might * consist of a quadrilateral that contains a texture of a tree. * * @see OrientedShape3D */ public class Billboard extends Behavior { /** * Specifies that rotation should be about the specified axis. */ public static final int ROTATE_ABOUT_AXIS = 0; /** * Specifies that rotation should be about the specified point and * that the children's Y-axis should match the view object's Y-axis. */ public static final int ROTATE_ABOUT_POINT = 1; // Wakeup condition for Billboard node WakeupOnElapsedFrames wakeupFrame = new WakeupOnElapsedFrames(0, true); // Specifies the billboard's mode of operation. One of ROTATE_AXIAL, // ROTATE_POINT_VIEW, or ROTATE_POINT_WORLD. int mode = ROTATE_ABOUT_AXIS; // Axis about which to rotate. Vector3f axis = new Vector3f(0.0f, 1.0f, 0.0f); Point3f rotationPoint = new Point3f(0.0f, 0.0f, 1.0f); private Vector3d nAxis = new Vector3d(0.0, 1.0, 0.0); // normalized axis // TransformGroup to operate on. TransformGroup tg = null; // reused temporaries private Point3d viewPosition = new Point3d(); private Point3d yUpPoint = new Point3d(); private Vector3d eyeVec = new Vector3d(); private Vector3d yUp = new Vector3d(); private Vector3d zAxis = new Vector3d(); private Vector3d yAxis = new Vector3d(); private Vector3d vector = new Vector3d(); private AxisAngle4d aa = new AxisAngle4d(); static final double EPSILON = 1.0e-6; /** * Constructs a Billboard node with default parameters. * The default values are as follows: * <ul> * alignment mode : ROTATE_ABOUT_AXIS<br> * alignment axis : Y-axis (0,1,0)<br> * rotation point : (0,0,1)<br> * target transform group: null<br> *</ul> */ public Billboard() { nAxis.x = 0.0; nAxis.y = 1.0; nAxis.z = 0.0; } /** * Constructs a Billboard node with default parameters that operates * on the specified TransformGroup node. * The default alignment mode is ROTATE_ABOUT_AXIS rotation with the axis * pointing along the Y axis. * @param tg the TransformGroup node that this Billboard * node operates upon */ public Billboard(TransformGroup tg) { this.tg = tg; nAxis.x = 0.0; nAxis.y = 1.0; nAxis.z = 0.0; } /** * Constructs a Billboard node with the specified axis and mode * that operates on the specified TransformGroup node. * The specified axis must not be parallel to the <i>Z</i> * axis--(0,0,<i>z</i>) for any value of <i>z</i>. It is not * possible for the +<i>Z</i> axis to point at the viewer's eye * position by rotating about itself. The target transform will * be set to the identity if the axis is (0,0,<i>z</i>). * * @param tg the TransformGroup node that this Billboard * node operates upon * @param mode alignment mode, one of ROTATE_ABOUT_AXIS or * ROTATE_ABOUT_POINT * @param axis the ray about which the billboard rotates */ public Billboard(TransformGroup tg, int mode, Vector3f axis) { this.tg = tg; this.mode = mode; this.axis.set(axis); double invMag; invMag = 1.0 / Math.sqrt(axis.x * axis.x + axis.y * axis.y + axis.z * axis.z); nAxis.x = (double) axis.x * invMag; nAxis.y = (double) axis.y * invMag; nAxis.z = (double) axis.z * invMag; } /** * Constructs a Billboard node with the specified rotation point and mode * that operates on the specified TransformGroup node. * @param tg the TransformGroup node that this Billboard * node operates upon * @param mode alignment mode, one of ROTATE_ABOUT_AXIS or * ROTATE_ABOUT_POINT * @param point the position about which the billboard rotates */ public Billboard(TransformGroup tg, int mode, Point3f point) { this.tg = tg; this.mode = mode; this.rotationPoint.set(point); } /** * Sets the alignment mode. * @param mode one of: ROTATE_ABOUT_AXIS or ROTATE_ABOUT_POINT */ public void setAlignmentMode(int mode) { this.mode = mode; } /** * Gets the alignment mode. * @return one of: ROTATE_ABOUT_AXIS or ROTATE_ABOUT_POINT */ public int getAlignmentMode() { return this.mode; } /** * Sets the alignment axis. * The specified axis must not be parallel to the <i>Z</i> * axis--(0,0,<i>z</i>) for any value of <i>z</i>. It is not * possible for the +<i>Z</i> axis to point at the viewer's eye * position by rotating about itself. The target transform will * be set to the identity if the axis is (0,0,<i>z</i>). * * @param axis the ray about which the billboard rotates */ public void setAlignmentAxis(Vector3f axis) { this.axis.set(axis); double invMag; invMag = 1.0 / Math.sqrt(axis.x * axis.x + axis.y * axis.y + axis.z * axis.z); nAxis.x = (double) axis.x * invMag; nAxis.y = (double) axis.y * invMag; nAxis.z = (double) axis.z * invMag; } /** * Sets the alignment axis. * The specified axis must not be parallel to the <i>Z</i> * axis--(0,0,<i>z</i>) for any value of <i>z</i>. It is not * possible for the +<i>Z</i> axis to point at the viewer's eye * position by rotating about itself. The target transform will * be set to the identity if the axis is (0,0,<i>z</i>). * * @param x the x component of the ray about which the billboard rotates * @param y the y component of the ray about which the billboard rotates * @param z the z component of the ray about which the billboard rotates */ public void setAlignmentAxis(float x, float y, float z) { this.axis.set(x, y, z); this.axis.set(axis); double invMag; invMag = 1.0 / Math.sqrt(axis.x * axis.x + axis.y * axis.y + axis.z * axis.z); nAxis.x = (double) axis.x * invMag; nAxis.y = (double) axis.y * invMag; nAxis.z = (double) axis.z * invMag; } /** * Gets the alignment axis and sets the parameter to this value. * @param axis the vector that will contain the ray about which * the billboard rotates */ public void getAlignmentAxis(Vector3f axis) { axis.set(this.axis); } /** * Sets the rotation point. * @param point the point about which the billboard rotates */ public void setRotationPoint(Point3f point) { this.rotationPoint.set(point); } /** * Sets the rotation point. * @param x the x component of the point about which the billboard rotates * @param y the y component of the point about which the billboard rotates * @param z the z component of the point about which the billboard rotates */ public void setRotationPoint(float x, float y, float z) { this.rotationPoint.set(x, y, z); } /** * Gets the rotation point and sets the parameter to this value. * @param point the position the Billboard rotates about */ public void getRotationPoint(Point3f point) { point.set(this.rotationPoint); } /** * Sets the tranformGroup for this Billboard object. * @param tg the transformGroup node which replaces the current * transformGroup node for this Billboard */ public void setTarget(TransformGroup tg) { this.tg = tg; } /** * Returns a copy of the transformGroup associated with this Billboard. * @return the TranformGroup for this Billboard */ public TransformGroup getTarget() { return (tg); } /** * Initialize method that sets up initial wakeup criteria. */ @Override public void initialize() { // Insert wakeup condition into queue wakeupOn(wakeupFrame); } /** * Process stimulus method that computes appropriate transform. * @param criteria an enumeration of the criteria that caused the * stimulus */ @Override public void processStimulus(Enumeration criteria) { double angle = 0.0; double sign; if (tg == null) { wakeupOn(wakeupFrame); return; } // get viewplatforms's location in virutal world View v = this.getView(); if (v == null) { wakeupOn(wakeupFrame); return; } Canvas3D canvas = v.getCanvas3D(0); boolean status; Transform3D xform = new Transform3D(); Transform3D bbXform = new Transform3D(); Transform3D prevTransform = new Transform3D(); ((TransformGroupRetained) tg.retained).getTransform(prevTransform); if (mode == ROTATE_ABOUT_AXIS) { // rotate about axis canvas.getCenterEyeInImagePlate(viewPosition); canvas.getImagePlateToVworld(xform); // xform is imagePlateToLocal xform.transform(viewPosition); // get billboard's transform // since we are using getTransform() to get the transform // of the transformGroup, we need to use getLocalToVworld() // to get the localToVworld which includes the static transform ((NodeRetained) tg.retained).getLocalToVworld(xform); xform.invert(); // xform is now vWorldToLocal // transform the eye position into the billboard's coordinate system xform.transform(viewPosition); // eyeVec is a vector from the local origin to the eye pt in local eyeVec.set(viewPosition); eyeVec.normalize(); // project the eye into the rotation plane status = projectToPlane(eyeVec, nAxis); // If the first project was successful .. if (status) { // project the z axis into the rotation plane zAxis.x = 0.0; zAxis.y = 0.0; zAxis.z = 1.0; status = projectToPlane(zAxis, nAxis); } ((TransformGroupRetained) tg.retained).getTransform(xform); if (status) { // compute the sign of the angle by checking if the cross product // of the two vectors is in the same direction as the normal axis vector.cross(eyeVec, zAxis); if (vector.dot(nAxis) > 0.0) { sign = 1.0; } else { sign = -1.0; } // compute the angle between the projected eye vector and the // projected z double dot = eyeVec.dot(zAxis); if (dot > 1.0f) { dot = 1.0f; } else if (dot < -1.0f) { dot = -1.0f; } angle = sign * Math.acos(dot); // use -angle because xform is to *undo* rotation by angle aa.x = nAxis.x; aa.y = nAxis.y; aa.z = nAxis.z; aa.angle = -angle; bbXform.set(aa); if (!prevTransform.epsilonEquals(bbXform, EPSILON)) { // Optimization for Billboard since it use passive // behavior // set the transform on the Billboard TG tg.setTransform(bbXform); } } else { bbXform.setIdentity(); if (!prevTransform.epsilonEquals(bbXform, EPSILON)) { tg.setTransform(bbXform); } } } else { // rotate about point // Need to rotate Z axis to point to eye, and Y axis to be // parallel to view platform Y axis, rotating around rotation pt Transform3D zRotate = new Transform3D(); // get the eye point canvas.getCenterEyeInImagePlate(viewPosition); // derive the yUp point yUpPoint.set(viewPosition); yUpPoint.y += 0.01; // one cm in Physical space // transform the points to the Billboard's space canvas.getImagePlateToVworld(xform); // xform is ImagePlateToVworld xform.transform(viewPosition); xform.transform(yUpPoint); // get billboard's transform // since we are using getTransform() to get the transform // of the transformGroup, we need to use getLocalToVworld() // to get the localToVworld which includes the static transform ((NodeRetained) tg.retained).getLocalToVworld(xform); xform.invert(); // xform is vWorldToLocal // transfom points to local coord sys xform.transform(viewPosition); xform.transform(yUpPoint); // Make a vector from viewPostion to 0,0,0 in the BB coord sys eyeVec.set(viewPosition); eyeVec.normalize(); // create a yUp vector yUp.set(yUpPoint); yUp.sub(viewPosition); yUp.normalize(); // find the plane to rotate z zAxis.x = 0.0; zAxis.y = 0.0; zAxis.z = 1.0; // rotation axis is cross product of eyeVec and zAxis vector.cross(eyeVec, zAxis); // vector is cross product // if cross product is non-zero, vector is rotation axis and // rotation angle is acos(eyeVec.dot(zAxis))); double length = vector.length(); if (length > 0.0001) { double dot = eyeVec.dot(zAxis); if (dot > 1.0f) { dot = 1.0f; } else if (dot < -1.0f) { dot = -1.0f; } angle = Math.acos(dot); aa.x = vector.x; aa.y = vector.y; aa.z = vector.z; aa.angle = -angle; zRotate.set(aa); } else { // no rotation needed, set to identity (scale = 1.0) zRotate.set(1.0); } // Transform the yAxis by zRotate yAxis.x = 0.0; yAxis.y = 1.0; yAxis.z = 0.0; zRotate.transform(yAxis); // project the yAxis onto the plane perp to the eyeVec status = projectToPlane(yAxis, eyeVec); if (status) { // project the yUp onto the plane perp to the eyeVec status = projectToPlane(yUp, eyeVec); } ((TransformGroupRetained) tg.retained).getTransform(xform); if (status) { // rotation angle is acos(yUp.dot(yAxis)); double dot = yUp.dot(yAxis); // Fix numerical error, otherwise acos return NULL if (dot > 1.0f) { dot = 1.0f; } else if (dot < -1.0f) { dot = -1.0f; } angle = Math.acos(dot); // check the sign by looking a the cross product vs the eyeVec vector.cross(yUp, yAxis); // vector is cross product if (eyeVec.dot(vector) < 0) { angle *= -1; } aa.x = eyeVec.x; aa.y = eyeVec.y; aa.z = eyeVec.z; aa.angle = -angle; xform.set(aa); // xform is now yRotate // rotate around the rotation point vector.x = rotationPoint.x; vector.y = rotationPoint.y; vector.z = rotationPoint.z; // vector to translate to RP bbXform.set(vector); // translate to RP bbXform.mul(xform); // yRotate bbXform.mul(zRotate); // zRotate vector.scale(-1.0); // vector to translate back xform.set(vector); // xform to translate back bbXform.mul(xform); // translate back if (!prevTransform.epsilonEquals(bbXform, EPSILON)) { // set the transform on the Billboard TG tg.setTransform(bbXform); } } else { bbXform.setIdentity(); if (!prevTransform.epsilonEquals(bbXform, EPSILON)) { tg.setTransform(bbXform); } } } // Insert wakeup condition into queue wakeupOn(wakeupFrame); } private boolean projectToPlane(Vector3d projVec, Vector3d planeVec) { double dis = planeVec.dot(projVec); projVec.x = projVec.x - planeVec.x * dis; projVec.y = projVec.y - planeVec.y * dis; projVec.z = projVec.z - planeVec.z * dis; double length = projVec.length(); if (length < EPSILON) { return false; } projVec.scale(1 / length); return true; } /** * Creates a new instance of the node. This routine is called * by <code>cloneTree</code> to duplicate the current node. * @param forceDuplicate when set to <code>true</code>, causes the * <code>duplicateOnCloneTree</code> flag to be ignored. When * <code>false</code>, the value of each node's * <code>duplicateOnCloneTree</code> variable determines whether * NodeComponent data is duplicated or copied. * * @see Node#cloneTree * @see Node#cloneNode * @see Node#duplicateNode * @see NodeComponent#setDuplicateOnCloneTree */ @Override public Node cloneNode(boolean forceDuplicate) { Billboard b = new Billboard(); b.duplicateNode(this, forceDuplicate); return b; } /** * Copies all Billboard information from * <code>originalNode</code> into * the current node. This method is called from the * <code>cloneNode</code> method which is, in turn, called by the * <code>cloneTree</code> method.<P> * * @param originalNode the original node to duplicate. * @param forceDuplicate when set to <code>true</code>, causes the * <code>duplicateOnCloneTree</code> flag to be ignored. When * <code>false</code>, the value of each node's * <code>duplicateOnCloneTree</code> variable determines whether * NodeComponent data is duplicated or copied. * * @exception RestrictedAccessException if this object is part of a live * or compiled scenegraph. * * @see Node#duplicateNode * @see Node#cloneTree * @see NodeComponent#setDuplicateOnCloneTree */ @Override void duplicateAttributes(Node originalNode, boolean forceDuplicate) { super.duplicateAttributes(originalNode, forceDuplicate); Billboard bb = (Billboard) originalNode; setAlignmentMode(bb.getAlignmentMode()); Vector3f v = new Vector3f(); bb.getAlignmentAxis(v); setAlignmentAxis(v); Point3f p = new Point3f(); bb.getRotationPoint(p); setRotationPoint(p); // this will be updated by updateNodeReferences() later setTarget(bb.getTarget()); } /** * Callback used to allow a node to check if any scene graph objects * referenced * by that node have been duplicated via a call to <code>cloneTree</code>. * This method is called by <code>cloneTree</code> after all nodes in * the sub-graph have been duplicated. The cloned Leaf node's method * will be called and the Leaf node can then look up any object references * by using the <code>getNewObjectReference</code> method found in the * <code>NodeReferenceTable</code> object. If a match is found, a * reference to the corresponding object in the newly cloned sub-graph * is returned. If no corresponding reference is found, either a * DanglingReferenceException is thrown or a reference to the original * object is returned depending on the value of the * <code>allowDanglingReferences</code> parameter passed in the * <code>cloneTree</code> call. * <p> * NOTE: Applications should <i>not</i> call this method directly. * It should only be called by the cloneTree method. * * @param referenceTable a NodeReferenceTableObject that contains the * <code>getNewObjectReference</code> method needed to search for * new object instances. * @see NodeReferenceTable * @see Node#cloneTree * @see DanglingReferenceException */ @Override public void updateNodeReferences(NodeReferenceTable referenceTable) { super.updateNodeReferences(referenceTable); // check for new TransformGroup TransformGroup g = getTarget(); if (g != null) { setTarget((TransformGroup) referenceTable.getNewObjectReference(g)); } } }