//----------------------------------------------------------------//
USRect MOAIScissorRect::GetScissorRect ( const USMatrix4x4& worldToWndMtx ) const {
USVec3D vtx3D [ 4 ];
vtx3D [ 0 ].mX = this->mRect.mXMin;
vtx3D [ 0 ].mY = this->mRect.mYMin;
vtx3D [ 0 ].mZ = 0.0f;
vtx3D [ 1 ].mX = this->mRect.mXMin;
vtx3D [ 1 ].mY = this->mRect.mYMax;
vtx3D [ 1 ].mZ = 0.0f;
vtx3D [ 2 ].mX = this->mRect.mXMax;
vtx3D [ 2 ].mY = this->mRect.mYMax;
vtx3D [ 2 ].mZ = 0.0f;
vtx3D [ 3 ].mX = this->mRect.mXMax;
vtx3D [ 3 ].mY = this->mRect.mYMin;
vtx3D [ 3 ].mZ = 0.0f;
USMatrix4x4 mtx;
mtx.Init ( this->GetLocalToWorldMtx ());
mtx.Append ( worldToWndMtx );
mtx.Project ( vtx3D [ 0 ]);
mtx.Project ( vtx3D [ 1 ]);
mtx.Project ( vtx3D [ 2 ]);
mtx.Project ( vtx3D [ 3 ]);
USRect scissorRect;
scissorRect.Init ( vtx3D [ 0 ]);
scissorRect.Grow ( vtx3D [ 1 ]);
scissorRect.Grow ( vtx3D [ 2 ]);
scissorRect.Grow ( vtx3D [ 3 ]);
if ( this->mScissorRect ) {
USRect parentRect = this->mScissorRect->GetScissorRect ( worldToWndMtx );
parentRect.Clip ( scissorRect );
}
return scissorRect;
}
//----------------------------------------------------------------//
void USFrustum::Init ( const USMatrix4x4& mtx ) {
// set up the homogenous coordinates of the canonical view volume
USVec3D nlt ( -1.0f, 1.0f, -1.0f );
USVec3D nrt ( 1.0f, 1.0f, -1.0f );
USVec3D nrb ( 1.0f, -1.0f, -1.0f );
USVec3D nlb ( -1.0f, -1.0f, -1.0f );
USVec3D flt ( -1.0f, 1.0f, 1.0f );
USVec3D frt ( 1.0f, 1.0f, 1.0f );
USVec3D frb ( 1.0f, -1.0f, 1.0f );
USVec3D flb ( -1.0f, -1.0f, 1.0f );
// compute the corners of the frustum
mtx.Project ( nlt );
mtx.Project ( nrt );
mtx.Project ( nrb );
mtx.Project ( nlb );
mtx.Project ( flt );
mtx.Project ( frt );
mtx.Project ( frb );
mtx.Project ( flb );
this->mPoints [ NEAR_LT_POINT ].Init ( nlt.mX, nlt.mY, nlt.mZ );
this->mPoints [ NEAR_RT_POINT ].Init ( nrt.mX, nrt.mY, nrt.mZ );
this->mPoints [ NEAR_RB_POINT ].Init ( nrb.mX, nrb.mY, nrb.mZ );
this->mPoints [ NEAR_LB_POINT ].Init ( nlb.mX, nlb.mY, nlb.mZ );
this->mPoints [ FAR_LT_POINT ].Init ( flt.mX, flt.mY, flt.mZ );
this->mPoints [ FAR_RT_POINT ].Init ( frt.mX, frt.mY, frt.mZ );
this->mPoints [ FAR_RB_POINT ].Init ( frb.mX, frb.mY, frb.mZ );
this->mPoints [ FAR_LB_POINT ].Init ( flb.mX, flb.mY, flb.mZ );
// Compute the frustum's axis-aligned bounding box
this->mAABB.Init ( nlt );
this->mAABB.Grow ( nrt );
this->mAABB.Grow ( nrb );
this->mAABB.Grow ( nlb );
this->mAABB.Grow ( flt );
this->mAABB.Grow ( frt );
this->mAABB.Grow ( frb );
this->mAABB.Grow ( flb );
// intialize the planes
this->mPlanes [ LEFT_PLANE ].Init ( nlt, flt, flb );
this->mPlanes [ RIGHT_PLANE ].Init ( nrb, frb, frt );
this->mPlanes [ TOP_PLANE ].Init ( nrt, frt, flt );
this->mPlanes [ BOTTOM_PLANE ].Init ( nlb, flb, frb );
this->mPlanes [ NEAR_PLANE ].Init ( nrt, nlt, nlb );
this->mPlanes [ FAR_PLANE ].Init ( flt, frt, frb );
USVec3D center;
mtx.GetTranslation ( center );
for ( u32 i = 0; i < TOTAL_PLANES; ++i ) {
if ( USDist::VecToPlane ( center, this->mPlanes [ i ]) > 0.0f ) {
this->mPlanes [ i ].Flip ();
}
}
double frustArea = _frustArea ( *this );
double boxArea = this->mAABB.Area ();
this->mUsePlanes = (( float )( frustArea / boxArea )) < MIN_FILL_RATIO;
}
