// speed up calculations
float invZ1, invZ2; // 1/z values for endpoints
float k, b; // coefficients of equation: 1/z=k*x+b
Span * next;' //nextspan
Span * prev; // previous span;
Polygon3D * facet; // facet it belongs to
float f (float x, float invZ ) const {
return k * x + b - invZ;
}
// clip the span at the begining void clipAtXI (float newX1 )
{
invZ1 = k * newX1 + b; x1 = newX1;
}
// clip the span at the end void clipAtX2 (float newX2 ) {
invZ2 = k * newX2 + b; x2 = newX2;
}
// precompute k and b coefficients void precompute ()
{
if ( x1 != x2 ) {
k = (invZ2-invZ1)/(x2-x1); b = invZ1 - k * x1;Компьютерная графика. Полигональные модели
}
else
{
k = 0; b = invZ1;
}
}
// whether the span is empty int isEmpty ()
{
return x1 > x2;
}
// insert current span before s void insertBefore ( Span * s ) { *
prev = s -> prev;
s -> prev -> next = this; s -> prev = this;
next = s;
}
// insert current span after s void insertAfter ( Span * s )
{
if ( s -> next != NULL ) s -> next -> prev = this;
prev = s;
next = s -> next;
s -> next = this;
}
// remove current span from list void remove ()
{
prev -> next = next; if ( next != NULL ) next -> prev = prev;
}
};
class SpanPool {
public:
Span * pool; // pool of Span strctures
int poolSize; // # of structures allocated Span * firstAvailable; //pointer to 1st struct after
// all allocated
Span * astAvailable; // last item in the pool Span * free; // pointer to free structs list
// (below firstAvailable)
SpanPool (int maxSize ) {
pool = new Span [poolSize = maxSize];
firstAvailable = pool;10. Удаление невидимых линий и поверхносте
lastAvailable = pool + poolSize - 1; free - NULL;
}
-SpanPool () {
delete [] pool;
>
void freeAII () // free all spans {
firstAvailable = pool; free = NULL;
}
Span * allocSpan ( Span * s = NULL ) // allocate free span { // when no free spans
if (free == NULL )
if (firstAvailable <= lastAvailable )