void sat_render(Satellite* sat, SDL_Surface* canvas) {
Node* current = sat->parts;
// render every part separately
while(current != NULL) {
SatPart* part = (SatPart*)current->data;
// calculate offset by following tree to root part
int dx = 0;
int dy = 0;
SatPart* child = part;
SatPart* parent = child->parent;
while(parent != NULL) {
// gather connection information
Connector* connChild = child->connection->child;
Connector* connParent = child->connection->parent;
// offset based on connector location
dx += rot_x_pt(&connParent->position, parent->rotation) -
rot_x_pt(&connChild->position, child->rotation);
dy += rot_y_pt(&connParent->position, parent->rotation) -
rot_y_pt(&connChild->position, child->rotation);
// offset based on connector directions
Dir dc = (connChild->direction + child->rotation)%4;
Dir dp = (connParent->direction + parent->rotation)%4;
if(dc == UP && dp == DOWN) {
dy += 1;
} else if(dc == DOWN && dp == UP) {
dy -= 1;
} else if(dc == LEFT && dp == RIGHT) {
dx += 1;
} else if(dc == RIGHT && dp == LEFT) {
dx -= 1;
} else {
printf("error: invalid connection - %d to %d\n", dc, dp);
exit(0);
}
child = parent;
parent = child->parent;
}
// render sprite at offset
sprite_render(canvas, part, sat->x + dx, sat->y + dy, part->rotation);
current = current->next;
}
}
void background_render_handler(actor *a)
{
background_actor *bg = (background_actor *)a;
sprite_render(&(bg->background_sprite));
}