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#include "tail.h"
#include "firefly.h"
#include "scene.h"
Tail::Tail(Firefly *_owner)
: owner(_owner)
{
}
#define SET_COLOR(c, a) glColor4f(c[0], c[1], c[2], a)
#define SET_VERTEX(v, dx) glVertex3d(v[0]+dx, v[1], v[2])
#define DO_POINT(t, dx, a)\
SET_COLOR((t).color, a); SET_VERTEX((t).pos, dx)
void Tail::draw()
{
if (links.size() < 2) // need at least 2 links
return;
deque<Link>::iterator it = links.begin();
double glow_width = scene.glow_factor*scene.tail_width;
double stretch_factor = 2*scene.fsize*scene.wind[0];
double dx1, dx2;
dx2 = ((*it).glow ? glow_width : scene.tail_width);
for (; (it+1) != links.end(); it++) {
// half-width of the tail
dx1 = dx2;
dx2 = ((*(it+1)).glow ? glow_width : scene.tail_width);
// have the wind stretch the tail (greater effect on ends)
double age = (*it).age/scene.tail_length;
double stretch = stretch_factor*age*age;
double alpha = 0.9 - age;
if (alpha > scene.tail_opaq)
alpha = scene.tail_opaq;
// two rectangles: outer vertices have alpha=0, inner two have
// alpha based on age. note: alpha goes negative, but opengl
// should clamp it to 0.
if (stretch > 0) { // stretch to the right
glBegin(GL_QUAD_STRIP);
DO_POINT(*it, -dx1, 0);
DO_POINT(*(it+1), -dx2, 0);
DO_POINT(*it, 0, alpha);
DO_POINT(*(it+1), 0, alpha);
DO_POINT(*it, dx1 + stretch, 0);
DO_POINT(*(it+1), dx2 + stretch, 0);
}
else { // stretch to the left
glBegin(GL_QUAD_STRIP);
DO_POINT(*it, -dx1 + stretch, 0);
DO_POINT(*(it+1), -dx2 + stretch, 0);
DO_POINT(*it, 0, alpha);
DO_POINT(*(it+1), 0, alpha);
DO_POINT(*it, dx1, 0);
DO_POINT(*(it+1), dx2, 0);
}
glEnd();
}
}
bool Tail::elapse(double t)
{
// pop off the dead ones.
// note we only have to check the end, since that's where they're gonna
// be dying from. deque is very nice for this, because it has constant
// time insertion/removal from both ends.
while (!links.empty() && links.back().age >= scene.tail_length)
links.pop_back();
deque<Link>::iterator it = links.begin();
for (; it != links.end(); it++) {
(*it).age += t;
double age = (*it).age/scene.tail_length;
(*it).pos += scene.wind*age*age;
}
if (owner == 0) // my owner died! grow no longer
return links.empty(); // if we're empty, tell caller we're dead
links.push_front(Link(owner->pos, owner->color, owner->bait->glow));
return false;
}
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