DisplacementHandler
DisplacementInterface
Availability LightWave 6.0
Component Layout
Header lwdisplce.h
Displacement plug-ins deform objects by moving their points at each time step.
Handler Activation Function
XCALL_( int ) MyDisplacement( long version, GlobalFunc *global,
LWDisplacementHandler *local, void *serverData );
The local argument to a displacement plug-in's activation function is an
LWDisplacementHandler.
typedef struct st_LWDisplacementHandler {
LWInstanceFuncs *inst;
LWItemFuncs *item;
LWRenderFuncs *rend;
void (*evaluate) (LWInstance, LWDisplacementAccess *);
unsigned int (*flags) (LWInstance);
} LWDisplacementHandler;
The first three members of this structure are the standard handler
functions. The context argument to the inst->create function is
the LWItemID of the object associated with this instance.
In addition to the standard functions, a displacement plug-in provides an evaluation
function and a flags function.
- evaluate( instance, access )
- This is where the displacement happens. At each time step, the evaluation function is
called for each vertex in the object. The position of the vertex is examined and modified
through the access structure described below.
f = flags( instance )- Returns bit flags combined using bitwise-or. The flags tell Layout whether the
displacement will be in world coordinates and whether it should occur before or after the
object has been deformed by bones. Only one of these flags should be set.
LWDMF_WORLD
LWDMF_BEFOREBONES
Interface Activation Function
XCALL_( int ) MyInterface( long version, GlobalFunc *global,
LWInterface *local, void *serverData );
This is the standard interface activation for
handlers.
Displacement Access
The LWDisplacementAccess passed to the evaluation function contains two point
positions, the point ID, and a mesh info for the object the
point belongs to.
typedef struct st_LWDisplacementAccess {
LWDVector oPos;
LWDVector source;
LWPntID point;
LWMeshInfo *info;
} LWDisplacementAccess;
- oPos
- The original point location in object coordinates. This is read-only.
source- The location to be transformed in place by the displacement. If the flags function
returned the LWDMF_WORLD bit, the source is in world coordinates and has already
been modified by morphing, bones and object motion. Otherwise the source is in object
coordinates (after morphing, before item motion, and before or after bone effects,
depending on whether the flags function returned LWDMF_BEFOREBONES).
point- The point ID. This can be used to retrieve other information about the point from the
mesh info structure.
info- A mesh info structure for the object.
History
In LightWave 7.0, LWDISPLACEMENT_VERSION was incremented to 5. This reflects
additions to the LWMeshInfo structure, but in all other respects, displacement handlers
were unchanged.
Example
The inertia sample is a displacement handler that
causes points to "lag behind" as the object moves. This plug-in was formerly
known as LazyPoints. |
