Camera interpolation with pauses.

General Discussion Other

addisandr..

Camera interpolation with pauses.

in General Discussion • Other • 1 year ago

I have a list of objects stored in an ArrayList instance that I which to iterate over and for each object in the list I will have the camera interpolate from the current camera position to a new position relative to the next item in the list. I am currently using Proscene library and its camera infrastructure. If I do what I have described then what happens is the camera will move from object to object without stopping until it reaches the end of the list where it will end with the camera looking at the final object. What I want to do is have it pause for 5-10 seconds at each object before moving on to the next. I have done a lot of tween and keyframe based animation with Sparrow and other iOS based libraries and have a good idea of how to solve this problem but I cannot seem to find a method or methods in Processing to allow me to do this. Here is the code that would solve my problem if I was doing this with Sparrow SDK for iOS. I will explain the code after since I cannot expect everyone to understand Objective-C.

[[self.juggler delayInvocationAtTarget:self byTime:5.0] goToNextObject:[objectList objectAtIndex:i+1]];

The above is a simple nested method in Objective-C. Let me explain each part so you can understand what it does.

[self.juggler delayInvocationAtTarget:self byTime:5.0]

This part of the call does one thing. It takes the juggler which manages timers and animation and tells it that to delay invocation to the target "self" by 5 seconds. This means that in 5 seconds from when this call runs it will call a method from the instance of "self".

The next part of the method describes the method that will be called in 5 seconds.

goToNextObject:[objectList objectAtIndex:i+1]

"goToNextObject: object" is the method in the instance of "self" that will be called. I pass to it as an argument the next object in the list, " [objectList objectAtIndex:i+1]" which is one nasty way of getting the next object if this method call was in a loop.

Essentially what this would do is cause the camera to interpolate to each object in the list, pausing for a given amount of time before moving to the next object in the list.

I'm not familiar with programming with Java, and programming with Processing is the closest thing I have done in that respect. I would really like to avoid having to create the wheel with this if the functionality is already out there. If anyone has done something like this or has any insight to how that would be much help. Thanks in advance.

Andrew

Replies(5)

amnon.owed

Re: Camera interpolation with pauses.

1 year ago

So do you have one keyframe per object or does the camera path from one object to the next contain multiple keyframes? Either way you could use the methods available in the Proscene library to solve your problem (if my memory serves me well). If you have a single keyframe per object, then you could use something like scene.camera().interpolateTo() on the keyFrameInterpolator's frames to move from one keyframe (object) to the next, exactly when and at what speed you want. If you have multiple keyframes between objects, then make each keyframe sequence a seperate camera path and just check if it's playing, if not wait 5 seconds, then use scene.camera().playPath() to play the next path.

addisandr..

Re: Camera interpolation with pauses.

1 year ago

void InterpolateToRoomObject(RoomObject obj)
{
// delete the prev path.
scene.camera().deletePath(1);
// add the current keyframe to the path.
scene.camera().addKeyFrameToPath(1);
// Grab the current position of the camera.
PVector currPos = scene.camera().position();
// Grab the next position of the camera.
PVector nextPos = new PVector(obj.mCenterPoint.x, obj.mCenterPoint.y, obj.mCenterPoint.z);
// test the distance between the currPos and nextPos.
float distance = abs(nextPos.x - currPos.x);
println("distance :"+distance);
// if the distance is 0 then don't make an intermitent point.
if (distance > 0)
{
scene.camera().setPosition(new PVector(currPos.x + distance/2, obj.mCenterPoint.y, 600.0));
scene.camera().lookAt(obj.mCenterPoint);
scene.camera().setArcballReferencePoint(obj.mCenterPoint);
scene.camera().addKeyFrameToPath(1);
}
scene.camera().setPosition(nextPos);
scene.camera().lookAt(obj.mCenterPoint);
scene.camera().setArcballReferencePoint(obj.mCenterPoint);
scene.camera().addKeyFrameToPath(1);
// reset the cameraframe.
scene.camera().setPosition(currPos);
scene.camera().lookAt(scene.camera().sceneCenter());
scene.camera().playPath(1);
}

This is the function I use to move to any given object in the room from the camera's current position. I could use the playPath() method from Proscene but then I would have to make and story all of the paths ahead of time. I don't know if this would be a better idea than using this function with some kind of delayed method calling function or not really. Still looking for more input.

amnon.owed

Re: Camera interpolation with pauses.

1 year ago

Wait a minute. If you already have this whole method ready, then it's just a matter of not calling this method until you actually want to interpolate to the next object. I am assuming in your code you currently check somewhere if the camera is still playing a path and when it's not, you interpolate to the next object by calling this method. As you suggested in both your posts a simple delay would suffice. While there is no built-in delay for calling methods, it's actually quite simple to just write a timer yourself using millis().

Pseudo-code

int timer;
boolean stoppedPlaying;
// when the camera stops playing...
if (!scene.camera.isPlaying()) {
// set the start time
if (!stoppedPlaying) {
stoppedPlaying = true;
timer = millis();
}
// if 5 seconds have passed call the method
if (millis()-timer > 5000) {
stoppedPlaying = false; // reset boolean
InterpolateToRoomObject(nextObject);
// will make the camera start playing
}
}

addisandr..

Re: Camera interpolation with pauses.

1 year ago

Yeah that is exactly what I was looking to do. I attempted to create a list of the kfis but it is far to much out of the way from the platform I have currently built. I think I will just create a timer esk class to do exactly what I want. Thanks for the help and for your time.

addisandr..

Re: Camera interpolation with pauses.

1 year ago

So I have a solution that wraps this all into a convenient method call. This currently can only delay methods that have no arguments. I feel that something like this should be included in Processing core. I would also love to turn this into a processing library for others to use. Can anyone help/point me in the direction so I can do that. Again, here is the code.

/********************************************************************
**
** Author: Andrew Addis
** Date: May 31, 2010
** Class: Timer
** Class Description: A simple Timer class used for delaying invocations.
** Inherits From: Thread
**
**********************************************************************/
import java.lang.reflect.InvocationTargetException;
public class Timer extends Thread {
// Member variables
boolean mRunning; // is the thread running, yes or no.
int mWait; // how many milliseconds should we wait.
String mId; // thread name
int mCount; // counter
int mTime; // the amount of time the thread should last.
boolean mIsDelayedInvocation; // is the timer being used for delayed invocation?
Object mObject; // an object linked to the timer, used to delay invocations.
String mMethodName; // if delaying an invocation, this is the name of the method.
// Constructors
Timer(int w, String s)
{
mWait = w*1000;
mRunning = false;
mId = s;
mCount = 1;
mIsDelayedInvocation = false;
}
Timer(int w, String methodName, Object obj)
{
mWait = w*1000;
mRunning = false;
mId = "delayedInvocationThread";
mCount = 1;
mIsDelayedInvocation = true;
mObject = obj;
mMethodName = methodName;
}
// instance methods.
// overriding "start()"
void start()
{
// set mRunning = true
mRunning = true;
// print messages
println("Starting thread (will execute after " + mWait + " milliseconds.)");
// call super.start()
super.start();
}
// overriding "run()"
void run()
{
// Ok, let's wait for however long we should wait
try
{
sleep((long)(mWait));
}
catch (Exception e)
{
}
//
// DO WORK HERE
//
if (mIsDelayedInvocation)
{
java.lang.reflect.Method method;
try
{
println("checking for method...");
method = mObject.getClass().getMethod(mMethodName);
try
{
method.invoke(mObject);
}
catch (IllegalArgumentException e)
{
println("Illegal Argument Exception");
}
catch (IllegalAccessException e)
{
println("Illegal Access Exception");
}
catch (InvocationTargetException e)
{
println("Invocation target exception");
}
}
catch (SecurityException e)
{
println("Security exception.");
}
catch (NoSuchMethodException e)
{
println("No such method exception.");
}
}
System.out.println(mId + " thread is done!"); // The thread is done when we get to the end of run()
}
void quit()
{
System.out.println("Quitting.");
mRunning = false;
interrupt();
}
int getCount()
{
return mCount;
}
}
// Global method: use to delay a method call.
// ARGS: Object obj: the object the method belongs to. CANNOT BE NIL/NULL.
// String methodName: the name of the method you want to call. MUST HAVE NO ARGUMENTS.
void delayInvocation(Object obj, String methodName)
{
Timer aTimer = new Timer(5, methodName, obj);
aTimer.start();
}

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