
 OPCODE distribution 1.3 (june 2003)
 -----------------------

    New in Opcode 1.3:
    - fixed the divide by 0 bug that was happening when all centers where located on a coordinate axis (thanks to Jorrit T)
    - linearized "complete" vanilla AABB trees
    - ANSI-compliant "for" loops (for the ones porting it to Linux...)
    - callbacks & pointers moved to mesh interface
    - support for triangle & vertex strides
    - optimized the sphere-triangle overlap code a bit
    - dynamic trees (refit)
    - more builders
    - ValidateSubdivision in builders
    - LSS collider
    - primitive-bv tests can now be skipped in most volume queries
    - temporal coherence now also works for airborne objects
    - temporal coherence completed for boxes / all contacts, LSS, etc
    - ray-collider now uses a callback
    - some common "usages" have been introduced (only picking for now)
    - SPLIT_COMPLETE removed (now implicitely using mLimit = 1)
    - hybrid collision models
    - sweep-and-prune code added, moved from my old Z-Collide lib
    - it now works with meshes made of only 1 triangle (except in mesh-mesh case!)

    Disclaimer:

    - I forced myself to actually *do* the release today no matter what. Else it would never have been done. That's
      why the code may not be very polished. I also removed a *lot* of things (more usages, distance queries, etc...)
      that weren't ready for prime-time (or that were linked to too many of my supporting libs)

    - Some comments may also be obsolete here and there. The old User Manual for Opcode 1.2 may not fit version 1.3
      either, since there's a new "mesh interface" to support strides, etc.

    - Everything in the "Ice" directory has been hacked out of my engine and edited until everything compiled. Don't
      expect anything out there to be cute or something. In particular, some CPP files are not even included when not
      needed, so you can expect some linker errors if you try messing around with them...

    Otherwise, it should be just like previous version, only better. In particular, hybrid models can be very
    memory-friendly (sometimes using like 10 times less ram than the best trees from version 1.2). The possible
    speed hit is often invisible (if it even exists), especially using temporal coherence in "all contacts" mode.
    (Admittedly, this depends on your particular usage pattern / what you do on collided triangles).

    The sweep-and-prune code is similar to the "vanilla" version found in V-Collide (but that one's better IMHO...)
    The simple "radix" version is often just as good, see for yourself.

 OPCODE distribution 1.2 (august 2002)
 -----------------------

    New in Opcode 1.2:
    - new VolumeCollider base class
    - simplified callback setup
    - you can now use callbacks or pointers (setup at compile time)
    - destination array not needed anymore in the RayCollider (faster in-out tests)
    - renamed classes: AABBRayCollider => RayCollider, AABBSphereCollider => SphereCollider
    - the sphere query now only returns a list of faces (extra info discarded). On the other hand it's a lot faster.
    - OBB, AABB and planes queries. Original OBB and AABB queries contributed by Erwin de Vries.
    - cosmetic changes in OPC_BoxBoxOverlap.h contributed by Gottfried Chen
    - some inlining problems fixed
    - faster ray-mesh tests using the separating axis theorem
    - new split value in AABB tree construction (contributed by Igor Kravtchenko). Provides faster queries most of the time.
    - improved temporal coherence for sphere & AABB queries (works in "All contacts" mode)

    Notes:

    - Everything in the "Ice code" directory (in VC++) is basically copy-pasted from my engine, with a lot
      of code removed until there was no link error anymore. Don't expect those files to be cute or anything,
      they've never been meant to be released and they're often updated/modified/messy.
    - Some experimental features have been removed as well. Else I would never have released the 1.2...
    - Not as polished/optimal as I would like it to be, but that's life. I promised myself to release it
      before october 2002 (one YEAR later ?!).... That's the only reason why it's there.
    - Some people reported ColDet was faster. Uh, come on. They were using Opcode in
      "All contacts" mode whereas ColDet was doing "first contact"...

 OPCODE distribution 1.1 (october 2001)
 -----------------------

    New in Opcode 1.1:
    - stabbing queries
    - sphere queries
    - abtract base class for colliders
    - settings validation methods
    - compilation flags now grouped in OPC_Settings.h
    - smaller files, new VC++ virtual dirs (cleaner)

    Notes:

    - "override(baseclass)" is a personal cosmetic thing. It's the same as "virtual", but provides more info.
    - I code in 1600*1200, so some lines may look a bit long..
    - This version is not as polished as the previous one due to lack of time. The stabbing & sphere queries
      can still be optimized: for example by trying other atomic overlap tests. I'm using my first ray-AABB
      code, but the newer one seems better. Tim Schröder's one is good as well. See: www.codercorner.com/RayAABB.cpp
    - The trees can easily be compressed even more, I save this for later (lack of time, lack of time!)
    - I removed various tests before releasing this one:
        - a separation line, a.k.a. "front" in QuickCD, because gains were unclear
        - distance queries in a PQP style, because it was way too slow
        - support for deformable models, too slow as well
    - You can easily use Opcode to do your player-vs-world collision detection, in a Nettle/Telemachos way.
      If someone out there wants to donate some art / level for the cause, I'd be glad to release a demo. (current
      demo uses copyrighted art I'm not allowed to spread)
    - Sorry for the lack of real docs and/or solid examples. I just don't have enough time.

 OPCODE distribution 1.0 (march 2001)
 -----------------------

    - First release

 ===============================================================================

 WHAT ?

    OPCODE means OPtimized COllision DEtection.
    So this is a collision detection package similar to RAPID. Here's a
    quick list of features:

    - C++ interface, developed for Windows systems using VC++ 6.0
    - Works on arbitrary meshes (convex or non-convex), even polygon soups
    - Current implementation uses AABB-trees
    - Introduces Primitive-BV overlap tests during recursive collision queries (whereas
      standard libraries only rely on Primitive-Primitive and BV-BV tests)
    - Introduces no-leaf trees, i.e. collision trees whose leaf nodes have been removed
    - Supports collision queries on quantized trees (decompressed on-the-fly)
    - Supports "first contact" or "all contacts" modes (ā la RAPID)
    - Uses temporal coherence for "first contact" mode (~10 to 20 times faster, useful
      in rigid body simulation during bisection)
    - Memory footprint is 7.2 times smaller than RAPID's one, which is ideal for console
      games with limited ram (actually, if you use the unmodified RAPID code using double
      precision, it's more like 13 times smaller...)
    - And yet it often runs faster than RAPID (according to RDTSC, sometimes more than 5
      times faster when objects are deeply overlapping)
    - Performance is usually close to RAPID's one in close-proximity situations
    - Stabbing, planes & volume queries (sphere, AABB, OBB, LSS)
    - Sweep-and-prune
    - Now works with deformable meshes
    - Hybrid trees


    What it can be used for:
    - standard mesh-mesh collision detection (similar to RAPID, SOLID, QuickCD, PQP, ColDet...)
    - N-body collisions (similar to V-Collide)
    - camera-vs-world collisions (similar to Telemachos/Paul Nettle/Stan Melax articles)
    - shadow feelers to speed up lightmap computations
    - in-out tests to speed up voxelization processes
    - picking
    - rigid body simulation
    - view frustum culling
    - etc

 WHY ?

    - Because RAPID uses too many bytes.
    - Because the idea was nice...

 WHEN ?

    It's been coded in march 2001 following a thread on the GD-Algorithms list.

      GDAlgorithms-list mailing list
      GDAlgorithms-list@lists.sourceforge.net
      http://lists.sourceforge.net/lists/listinfo/gdalgorithms-list

 WHO ?

    Pierre Terdiman
    June, 1, 2003

    p.terdiman@wanadoo.fr
    p.terdiman@codercorner.com
 
    http://www.codercorner.com
    http://www.codercorner.com/Opcode.htm
