/* =============================================================================
* setEdge
*
* Note: Makes pairPtr sorted; i.e., coordinate_compare(first, second) < 0
* =============================================================================
*/
static void
setEdge (element_t* elementPtr, long i)
{
long numCoordinate = elementPtr->numCoordinate;
coordinate_t* coordinates = elementPtr->coordinates;
coordinate_t* firstPtr = &coordinates[i];
coordinate_t* secondPtr = &coordinates[(i + 1) % numCoordinate];
edge_t* edgePtr = &elementPtr->edges[i];
long cmp = coordinate_compare(firstPtr, secondPtr);
assert(cmp != 0);
if (cmp < 0) {
edgePtr->firstPtr = (void*)firstPtr;
edgePtr->secondPtr = (void*)secondPtr;
} else {
edgePtr->firstPtr = (void*)secondPtr;
edgePtr->secondPtr = (void*)firstPtr;
}
coordinate_t* midpointPtr = &elementPtr->midpoints[i];
midpointPtr->x = (firstPtr->x + secondPtr->x) / 2.0;
midpointPtr->y = (firstPtr->y + secondPtr->y) / 2.0;
elementPtr->radii[i] = coordinate_distance(firstPtr, midpointPtr);
}
static void
calculateCircumCircle (element_t* elementPtr)
{
long numCoordinate = elementPtr->numCoordinate;
coordinate_t* coordinates = elementPtr->coordinates;
coordinate_t* circumCenterPtr = &elementPtr->circumCenter;
((void) (0));
if (numCoordinate == 2) {
circumCenterPtr->x = (coordinates[0].x + coordinates[1].x) / 2.0;
circumCenterPtr->y = (coordinates[0].y + coordinates[1].y) / 2.0;
}
else {
double ax = coordinates[0].x;
double ay = coordinates[0].y;
double bx = coordinates[1].x;
double by = coordinates[1].y;
double cx = coordinates[2].x;
double cy = coordinates[2].y;
double bxDelta = bx - ax;
double byDelta = by - ay;
double cxDelta = cx - ax;
double cyDelta = cy - ay;
double bDistance2 = (bxDelta * bxDelta) + (byDelta * byDelta);
double cDistance2 = (cxDelta * cxDelta) + (cyDelta * cyDelta);
double xNumerator = (byDelta * cDistance2) - (cyDelta * bDistance2);
double yNumerator = (bxDelta * cDistance2) - (cxDelta * bDistance2);
double denominator = 2 * ((bxDelta * cyDelta) - (cxDelta * byDelta));
double rx = ax - (xNumerator / denominator);
double ry = ay + (yNumerator / denominator);
circumCenterPtr->x = rx;
circumCenterPtr->y = ry;
}
elementPtr->circumRadius = coordinate_distance(circumCenterPtr,
&coordinates[0]);
}
/* =============================================================================
* element_isInCircumCircle
* =============================================================================
*/
bool
element_isInCircumCircle (element_t* elementPtr, coordinate_t* coordinatePtr)
{
double distance = coordinate_distance(coordinatePtr,
&elementPtr->circumCenter);
return ((distance <= elementPtr->circumRadius) ? true : false);
}
