#include <OPC_HybridModel.h>
Public Member Functions | |
| inline_ const udword * | GetIndices () const |
| inline_ const LeafTriangles * | GetLeafTriangles () const |
| HybridModel () | |
| override (BaseModel) bool Build(const OPCODECREATE &create) | |
| override (BaseModel) udword GetUsedBytes() const | |
| override (BaseModel) bool Refit() | |
| virtual | ~HybridModel () |
 Public Member Functions inherited from BaseModel | |
| BaseModel () | |
| virtual bool | Build (const OPCODECREATE &create)=0 |
| inline_ const MeshInterface * | GetMeshInterface () const |
| inline_ udword | GetModelCode () const |
| inline_ udword | GetNbNodes () const |
| inline_ const AABBTree * | GetSourceTree () const |
| inline_ const AABBOptimizedTree * | GetTree () const |
| inline_ AABBOptimizedTree * | GetTree () |
| virtual udword | GetUsedBytes () const =0 |
| inline_ BOOL | HasLeafNodes () const |
| inline_ BOOL | HasSingleNode () const |
| inline_ BOOL | IsQuantized () const |
| virtual bool | Refit () |
| inline_ void | SetMeshInterface (const MeshInterface *imesh) |
| virtual | ~BaseModel () |
Private Member Functions | |
| void | Release () |
Private Attributes | |
| udword * | mIndices |
| Array of primitive indices. More... | |
| udword | mNbLeaves |
| Number of leaf nodes in the model. More... | |
| udword | mNbPrimitives |
| Number of primitives in the model. More... | |
| LeafTriangles * | mTriangles |
| Array of mNbLeaves leaf descriptors. More... | |
Additional Inherited Members | |
| Protected Member Functions inherited from BaseModel | |
| bool | CreateTree (bool no_leaf, bool quantized) |
| void | ReleaseBase () |
| Protected Attributes inherited from BaseModel | |
| const MeshInterface * | mIMesh |
| User-defined mesh interface. More... | |
| udword | mModelCode |
| Model code = combination of ModelFlag(s) More... | |
| AABBTree * | mSource |
| Original source tree. More... | |
| AABBOptimizedTree * | mTree |
| Optimized tree owned by the model. More... | |
Detailed Description
An hybrid collision model.
The problem :
Opcode really shines for mesh-mesh collision, especially when meshes are deeply overlapping (it typically outperforms RAPID in those cases).
Unfortunately this is not the typical scenario in games.
For close-proximity cases, especially for volume-mesh queries, it's relatively easy to run faster than Opcode, that suffers from a relatively high setup time.
In particular, Opcode's "vanilla" trees in those cases -can- run faster. They can also use -less- memory than the optimized ones, when you let the system stop at ~10 triangles / leaf for example (i.e. when you don't use "complete" trees). However, those trees tend to fragment memory quite a lot, increasing cache misses : since they're not "complete", we can't predict the final number of nodes and we have to allocate nodes on-the-fly. For the same reasons we can't use Opcode's "optimized" trees here, since they rely on a known layout to perform the "optimization".
Hybrid trees :
Hybrid trees try to combine best of both worlds :
- they use a maximum limit of 16 triangles/leaf. "16" is used so that we'll be able to save the number of triangles using 4 bits only.
- they're still "complete" trees thanks to a two-passes building phase. First we create a "vanilla" AABB-tree with Opcode, limited to 16 triangles/leaf. Then we create a second vanilla tree, this time using the leaves of the first one. The trick is : this second tree is now "complete"... so we can further transform it into an Opcode's optimized tree.
- then we run the collision queries on that standard Opcode tree. The only difference is that leaf nodes contain indices to leaf nodes of another tree. Also, we have to skip all primitive tests in Opcode optimized trees, since our leaves don't contain triangles anymore.
- finally, for each collided leaf, we simply loop through 16 triangles max, and collide them with the bounding volume used in the query (we only support volume-vs-mesh queries here, not mesh-vs-mesh)
All of that is wrapped in this "hybrid model" that contains the minimal data required for this to work. It's a mix between old "vanilla" trees, and old "optimized" trees.
Extra advantages:
- If we use them for dynamic models, we're left with a very small number of leaf nodes to refit. It might be a bit faster since we have less nodes to write back.
- In rigid body simulation, using temporal coherence and sleeping objects greatly reduce the actual influence of one tree over another (i.e. the speed difference is often invisible). So memory is really the key element to consider, and in this regard hybrid trees are just better.
Information to take home:
- they use less ram
- they're not slower (they're faster or slower depending on cases, overall there's no significant difference as long as objects don't interpenetrate too much - in which case Opcode's optimized trees are still notably faster)
- Version
- 1.3
- Date
- May, 18, 2003
Definition at line 46 of file OPC_HybridModel.h.
Constructor & Destructor Documentation
| HybridModel::HybridModel | ( | ) |
|
virtual |
Member Function Documentation
|
inline |
| HybridModel::override | ( | BaseModel | ) | const |
Builds a collision model.
- Parameters
-
create [in] model creation structure
- Returns
- true if success
| HybridModel::override | ( | BaseModel | ) | const |
Gets the number of bytes used by the tree.
- Returns
- amount of bytes used
| HybridModel::override | ( | BaseModel | ) |
Refits the collision model. This can be used to handle dynamic meshes. Usage is:
- modify your mesh vertices (keep the topology constant!)
- refit the tree (call this method)
- Returns
- true if success
|
private |
Member Data Documentation
|
private |
Array of primitive indices.
Definition at line 100 of file OPC_HybridModel.h.
|
private |
Number of leaf nodes in the model.
Definition at line 97 of file OPC_HybridModel.h.
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private |
Number of primitives in the model.
Definition at line 99 of file OPC_HybridModel.h.
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private |
Array of mNbLeaves leaf descriptors.
Definition at line 98 of file OPC_HybridModel.h.
The documentation for this class was generated from the following file: