by
Jeff Lander
Gamasutra
February 03, 2000
This
article originally appeared in the
February 1999 issue of:
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 Features
Listing
1. Calculate an Axis-aligned Bounding Box for an Object.
///////////////////////////////////////////////////////////////////////////////
// Procedure: RecalcFullBBox
// Purpose: Recalculates
the BBox associated with a bone based on the
// new
position for the vertices. Tighter fit in
// most
cases. However, has to process all vertices
///////////////////////////////////////////////////////////////////////////////
GLvoid COGLView::RecalcFullBBox(t_Bone
*curBone, tVector *min,tVector *max)
{
/// Local Variables ///////////////////////////////////////////////////////////
tVector *temp,tempRes; //
X,Y,Z VECTORS
tNormalVertex *nvData; //
VERTEX WITH NX,NY,NZ,X,Y,Z
t_Visual
*visual;
///////////////////////////////////////////////////////////////////////////////
visual = curBone->visuals; // GET AT THE VISUAL ATTACHED
TO A BONE
nvData = (tNormalVertex
*)visual->vertexData; // THE ACTUAL INTERLEAVED VERTEX DATA
for (int loop = 0; loop < visual->faceCnt * visual->vPerFace;
loop++)
{
temp = (tVector
*)&nvData->x; // POINTER TO THE VERTEX XYZ VALUES
MultVectorByMatrix(&curBone->matrix,
temp,&tempRes); // MULT BY THE BONE MATRIX
// FIRST VERTEX,
SET IT AS THE MAX AND MIN
if (loop == 0)
{
memcpy(min,&tempRes,sizeof(tVector));
memcpy(max,&tempRes,sizeof(tVector));
}
else
{
if (tempRes.x >
max->x) max->x = tempRes.x;
if (tempRes.y >
max->y) max->y = tempRes.y;
if (tempRes.z >
max->z) max->z = tempRes.z;
if (tempRes.x <
min->x) min->x = tempRes.x;
if (tempRes.y <
min->y) min->y = tempRes.y;
if (tempRes.z <
min->z) min->z = tempRes.z;
}
nvData++;
}
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