Får jag lov att presentera min nyfödda dotter:

http://www.aac.acuavida.com/gallery/AAC_2009/grandes_acuarios/Massimo+Faberi/

Ok, I need a source code formatter for my blog. Wanted to share this, because I have a feeling the first thing most Java 3D programmers want to do when using the PickTool is visualize the pick-shapes.

This code will transform each type of PickShape to a corresponding 3D-object and draw it in the scene with transparancy to see if the picker is picking in the correct direction and correct size etc.

Hold your breath. Here is the code:


public class PickUtils {

public static final void drawPicker(final BranchGroup scene, final PickShape pickShape) {
scene.addChild(getPickShapeAsGroup(pickShape));
}

public static final BranchGroup getPickShapeAsGroup(final PickShape pickShape) {
final double rayLength = 1000;
final BranchGroup group = new BranchGroup();
final Appearance appearance = new Appearance();

final Color3f yellow = new Color3f(1.0f, 1.0f, 0.0f);
final ColoringAttributes ca = new ColoringAttributes(yellow, ColoringAttributes.SHADE_GOURAUD);
appearance.setColoringAttributes(ca);

final TransparencyAttributes transparency = new TransparencyAttributes();
transparency.setTransparencyMode(TransparencyAttributes.BLENDED);
transparency.setTransparency(0.6f);
appearance.setTransparencyAttributes(transparency);

if (pickShape instanceof PickBounds) {
// Note that you need to use flag PickInfo.NODE and mode PickInfo.PICK_BOUNDS to use this..
final PickBounds pickBounds = (PickBounds) pickShape;

final BoundingSphere boundingSphere = (BoundingSphere) pickBounds.get();

final Point3d pointCoordinates = new Point3d();
boundingSphere.getCenter(pointCoordinates);
final double radius = boundingSphere.getRadius();

Sphere sphere = new Sphere((float) radius, appearance);

TransformGroup directionRotation = new TransformGroup();
Transform3D t3d = new Transform3D();
t3d.setTranslation(new Vector3d(pointCoordinates));
directionRotation.setTransform(t3d);

directionRotation.addChild(sphere);

group.addChild(directionRotation);
} else if (pickShape instanceof PickRay) {
final PickRay pickRay = (PickRay) pickShape;

final Point3d origin = new Point3d();
final Vector3d direction = new Vector3d();
pickRay.get(origin, direction);

direction.scale(rayLength);
final Point3d firstEndPoint = new Point3d(direction.getX(), direction.getY(), direction.getZ());
direction.negate();
final Point3d secondEndPoint = new Point3d(direction.getX(), direction.getY(), direction.getZ());

final Point3d[] lineEndPoints = new Point3d[2];
lineEndPoints[0] = firstEndPoint;
lineEndPoints[1] = secondEndPoint;
final LineArray lineArray = new LineArray(2, LineArray.COORDINATES);
lineArray.setCoordinates(0, lineEndPoints);
final Shape3D plShape = new Shape3D(lineArray, appearance);
plShape.setName("Pick ray");

group.addChild(plShape);
} else if (pickShape instanceof PickSegment) {
final PickSegment pickSegment = (PickSegment) pickShape;

final Point3d origin = new Point3d();
final Point3d end = new Point3d();
pickSegment.get(origin, end);

final Point3d[] lineEndPoints = new Point3d[2];
lineEndPoints[0] = origin;
lineEndPoints[1] = end;
final LineArray lineArray = new LineArray(2, LineArray.COORDINATES);
lineArray.setCoordinates(0, lineEndPoints);
final Shape3D plShape = new Shape3D(lineArray, appearance);
plShape.setName("Pick segment");

group.addChild(plShape);
} else if (pickShape instanceof PickCylinderRay) {
final PickCylinderRay pickCylinderRay = (PickCylinderRay) pickShape;

final float radius = (float) pickCylinderRay.getRadius();
final Point3d origin = new Point3d();
pickCylinderRay.getOrigin(origin);
final Vector3d direction = new Vector3d();
pickCylinderRay.getDirection(direction);

Cylinder cylinder = new Cylinder(radius, (float) rayLength, appearance);

TransformGroup directionRotation = new TransformGroup();
Transform3D t3d = new Transform3D();
t3d.setRotation(new Quat4d(direction.getX(), direction.getY(), direction.getZ(), 1));
directionRotation.setTransform(t3d);

directionRotation.addChild(cylinder);

group.addChild(directionRotation);
} else if (pickShape instanceof PickCylinderSegment) {
final PickCylinderSegment pickCylinderSegment = (PickCylinderSegment) pickShape;

final float radius = (float) pickCylinderSegment.getRadius();
final Point3d origin = new Point3d();
pickCylinderSegment.getOrigin(origin);
final Vector3d direction = new Vector3d();
pickCylinderSegment.getDirection(direction);
final Point3d end = new Point3d();
pickCylinderSegment.getEnd(end);
double cylLength = origin.distance(end);

Cylinder cylinder = new Cylinder(radius, (float) cylLength, appearance);

TransformGroup directionRotation = new TransformGroup();
Transform3D t3d = new Transform3D();
t3d.setRotation(new Quat4d(direction.getX(), direction.getY(), direction.getZ(), 1));
directionRotation.setTransform(t3d);

directionRotation.addChild(cylinder);

group.addChild(directionRotation);
} else if (pickShape instanceof PickConeRay) {
final PickConeRay pickConeRay = (PickConeRay) pickShape;
final float coneLength = 10;

final double spreadAngle = pickConeRay.getSpreadAngle();
final Point3d origin = new Point3d();
pickConeRay.getOrigin(origin);
final Vector3d direction = new Vector3d();
pickConeRay.getDirection(direction);
final float radius = coneLength * (float) Math.tan(spreadAngle);
final Cone cone = new Cone(radius, coneLength, appearance);

final TransformGroup directionRotation = new TransformGroup();
final Transform3D t3d = new Transform3D();
t3d.setRotation(new Quat4d(direction.getX(), direction.getY(), direction.getZ(), 1));
directionRotation.setTransform(t3d);

directionRotation.addChild(cone);
group.addChild(directionRotation);
} else if (pickShape instanceof PickConeSegment) {
final PickConeSegment pickConeSegment = (PickConeSegment) pickShape;

final double spreadAngle = pickConeSegment.getSpreadAngle();
final Point3d origin = new Point3d();
pickConeSegment.getOrigin(origin);
final Point3d end = new Point3d();
pickConeSegment.getEnd(end);
final Vector3d direction = new Vector3d();
pickConeSegment.getDirection(direction);
final float coneLength = (float) origin.distance(end);
final float radius = coneLength * (float) Math.tan(spreadAngle);

final Cone cone = new Cone(radius, coneLength, appearance);

final TransformGroup directionRotation = new TransformGroup();
final Transform3D t3d = new Transform3D();
t3d.setRotation(new Quat4d(direction.getX(), direction.getY(), direction.getZ(), 1));
directionRotation.setTransform(t3d);

directionRotation.addChild(cone);
group.addChild(directionRotation);
}

return group;
}
}

It took me awhile to figure out how to use the new Java3D pickfast API with setShapeRay. It was straightforward when I had figured out the need for setting the mode and flag of PickTool. But until I had figured that out the shapeRay was not working at all. Here is some example code:

// Test intersection from y=1.5 with a small vector pointing downwards the y-axis
final Point3d startPoint = new Point3d(0f, 1.5f, 0f);
final Vector3d direction = new Vector3d(0, -0.05, 0);
final PickTool myPicker = new PickTool(scene);
myPicker.setMode(PickInfo.PICK_GEOMETRY);
myPicker.setFlags(PickInfo.CLOSEST_INTERSECTION_POINT);
myPicker.setShapeRay(startPoint, direction);
final PickInfo closest = myPicker.pickClosest();

System.out.println("getClosestDistance: " + closest.getClosestDistance());
System.out.println("getClosestIntersectionPoint: " + closest.getClosestIntersectionPoint());

Inladdning av godtycklig 3D-modell - Check.
Hårdvaruaccelererad realtidsvisualisering av 3D-modellen - Check.
Ett styck fejkstråle skjuten genom hela modellen - Check.

Bara det svåra kvar med andra ord. Jag har dock ett äss i skjortärmen. Jag har fixat en mentor som gjort en egen spektralbaserad metropolis-renderare och han har redan gett mig lite feedback på vilken typ av renderare jag förmodligen är intresserad av. Turligt nog kommer det handla om photon mapping som konceptuellt är relativt "enkelt", eventuellt en hybridiserad form av Metropolis Light Transport och Photon Mapping som kallas "Metropolis Photon Sampling":
http://pages.cs.wisc.edu/~yu-chi/research/mps/MetropolisPhotonSampling.html

Det häftiga med den metoden är att man kan ge den tips om var i scenen den ska lägga mest krut (skjuta mest fotoner). Det passar väldigt bra in i vårt fall med en glaslåda med vatten i eftersom vi vet exakt varifrån ljuset alltid skjuts och kan därför ge tydliga och enkla tips till renderingsmotorn vilka ytor som är mest intressanta.

Igårnatt låg jag och funderade om det inte kommer vara väldigt enkelt att räkna alla fotoner som tar sig ut ur "glaslådan", dvs för en viss reflektor på en viss höjd direkt kunna se hur mycket ljus som går till spillo aka reflektoreffektivitet..