bool DrawList::Cull(const Body &body, const Point &position, const Point &blur)
{
if(!body.HasSprite() || !body.Zoom())
return true;
Point unit = body.Facing().Unit();
// Cull sprites that are completely off screen, to reduce the number of draw
// calls that we issue (which may be the bottleneck on some systems).
Point size(
.5 * (fabs(unit.X() * body.Height()) + fabs(unit.Y() * body.Width()) + fabs(blur.X())),
.5 * (fabs(unit.X() * body.Width()) + fabs(unit.Y() * body.Height()) + fabs(blur.Y())));
Point topLeft = position - size;
Point bottomRight = position + size;
if(bottomRight.X() < Screen::Left() || bottomRight.Y() < Screen::Top())
return true;
if(topLeft.X() > Screen::Right() || topLeft.Y() > Screen::Bottom())
return true;
return false;
}
DrawList::Item::Item(const Body &body, Point pos, Point blur, float cloak, float clip, int swizzle, int step)
: position{static_cast<float>(pos.X()), static_cast<float>(pos.Y())}, clip(clip), flags(swizzle)
{
Body::Frame frame = body.GetFrame(step);
tex0 = frame.first;
tex1 = frame.second;
flags |= static_cast<uint32_t>(frame.fade * 256.f) << 8;
double width = body.Width();
double height = body.Height();
Point unit = body.Facing().Unit();
Point uw = unit * width;
Point uh = unit * height;
if(clip < 1.)
{
// "clip" is the fraction of its height that we're clipping the sprite
// to. We still want it to start at the same spot, though.
pos -= uh * ((1. - clip) * .5);
position[0] = static_cast<float>(pos.X());
position[1] = static_cast<float>(pos.Y());
uh *= clip;
}
// (0, -1) means a zero-degree rotation (since negative Y is up).
transform[0] = -uw.Y();
transform[1] = uw.X();
transform[2] = -uh.X();
transform[3] = -uh.Y();
// Calculate the blur vector, in texture coordinates.
this->blur[0] = unit.Cross(blur) / (width * 4.);
this->blur[1] = -unit.Dot(blur) / (height * 4.);
if(cloak > 0.)
Cloak(cloak);
}
