something in the way

Alchemy is going to shake things up a bit.  As witnessed before from Quake running in flash and now ODE compiled to run in flash using Alchemy (LLVM based). It is an early test but shows what could be possible.

Mihai Pricope has a post with sources on how he got the ODE (Open Dynamics Engine) a great open source physics engine for 3D, running on the AVM2 Flash Player virtual machine.

I’ve took Alchemy for a test and decided to compile ODE (Open Dynamic Engine). Just to add yet another physics engine to the Flash World. It was a hell of a ride but I finally got to produce some bouncing balls :). For a still unknown reason some as 3d libraries have been very slow to render 6 translucent walls and 2 balls. Papervision3D seems to move quite decent.

You can download the ode sources from here. To recompile them do (you need to have the Alchemy environment turned on):

Flash 10 will become mainstream shortly and with that the possibilities of using Alchemy in your projects is becoming a reality for production.  But what specifically can you do with Alchemy, a project that helps to compile C/C++ code into AVM2 capable files?

Alchemy described from Adobe:

With Alchemy, Web application developers can now reuse hundreds of millions of lines of existing open source C and C++ client or server-side code on the Flash Platform.  Alchemy brings the power of high performance C and C++ libraries to Web applications with minimal degradation on AVM2.  The C/C++ code is compiled to ActionScript 3.0 as a SWF or SWC that runs on Adobe Flash Player 10 or Adobe AIR 1.5.

Alchemy is based on the LLVM Low Level Virtual Machine that allows new levels of code translation.  Maybe this can lead to more effective and performing code to run on the iPhone with flash player 10. Or some type of system that allows flash developers to code in AS3 or take projects and get them ready to run on the iPhone much like some of the Java to Cocoa compilation systems and Unity3D using mono to compile down to iPhone capable code.

I'm not really sure where the inspiration came from, but I decided to take a stab at doing Motion Trails with Pv3D.  Instead, I ended up with something more like a tail - but left the class name MotionTrail... Anyways - there isn't a whole lot to say on the technique I used here - but I will give a general overview just to save you looking at code.  See the Demo.

The tail is defined by Number3D objects which "chase" each other, with the head node being pinned to the target you are chasing.  Each Number3D, which I've extended into a Trail3D class (its internal - just look in the MotionTrail.as file) - springs after the node ahead of it.  You can control this "springyness" by adjusting the minEase property of the MotionTrail.  The minEase refers to the ease amount of the very last node on the tail - which increases each node up to the head, which has an ease of 1.  So, the lower you set minEase, the slinkier the tail will end up looking.  You can control how many nodes are in the tail by adjusting the "iterations" parameter of the MotionTail class.  You need at least 2.

The tail is actually a triangle strip, which progressively gets smaller the closer to the end it gets.  This 1) lets you use any material you want, and 2)easily adjust the look and feel of the tail all you want. Feel free to override it to affect the width with speed, distance, or any other cool variables you want.  It looked good just tapering so I left it that way.   The triangle strips vertices are adjusted to their corresponding TrailNode, so they always face the camera.  This keeps the tail visible from any direction.  Again, you could change this if you wanted it to be a more obvious flat tail.  My initial idea was to use the delta properties of the adjacent nodes to determine the nodes up vector (find the cross product between the dx/dy/dz values of the nodes on either side of the current node) - but again - I liked how this looks so I left it.

The demo itself just makes use of some bezier curves to keep things moving smoothly.  You will notice the nodes are flocking - but really it is just setting the control point and end point of each node within a certain range - which changes positions when the first object arrives.  You can press "F" to toggle it so that each node has its own unique path.

Anyways - here is the code,

and another look at the demo

enjoy.