本文整理汇总了C++中Lines::at方法的典型用法代码示例。如果您正苦于以下问题：C++ Lines::at方法的具体用法？C++ Lines::at怎么用？C++ Lines::at使用的例子？那么, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类Lines的用法示例。
在下文中一共展示了Lines::at方法的1个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的C++代码示例。
示例1: unscale
// caller is responsible for supplying NO lines with zero length
void
_3DScene::_extrusionentity_to_verts_do(const Lines &lines, const std::vector<double> &widths,
const std::vector<double> &heights, bool closed, double top_z, const Point ©,
GLVertexArray* qverts, GLVertexArray* tverts)
{
/* It looks like it's faster without reserving capacity...
// each segment has 4 quads, thus 16 vertices; + 2 caps
qverts->reserve_more(3 * 4 * (4 * lines.size() + 2));
// two triangles for each corner
tverts->reserve_more(3 * 3 * 2 * (lines.size() + 1));
*/
Line prev_line;
Pointf prev_b1, prev_b2;
Vectorf3 prev_xy_left_normal, prev_xy_right_normal;
// loop once more in case of closed loops
bool first_done = false;
for (size_t i = 0; i <= lines.size(); ++i) {
if (i == lines.size()) i = 0;
const Line &line = lines.at(i);
if (i == 0 && first_done && !closed) break;
double len = line.length();
double unscaled_len = unscale(len);
double bottom_z = top_z - heights.at(i);
double middle_z = (top_z + bottom_z) / 2;
double dist = widths.at(i)/2; // scaled
Vectorf v = Vectorf::new_unscale(line.vector());
v.scale(1/unscaled_len);
Pointf a = Pointf::new_unscale(line.a);
Pointf b = Pointf::new_unscale(line.b);
Pointf a1 = a;
Pointf a2 = a;
a1.translate(+dist*v.y, -dist*v.x);
a2.translate(-dist*v.y, +dist*v.x);
Pointf b1 = b;
Pointf b2 = b;
b1.translate(+dist*v.y, -dist*v.x);
b2.translate(-dist*v.y, +dist*v.x);
// calculate new XY normals
Vector n = line.normal();
Vectorf3 xy_right_normal = Vectorf3::new_unscale(n.x, n.y, 0);
xy_right_normal.scale(1/unscaled_len);
Vectorf3 xy_left_normal = xy_right_normal;
xy_left_normal.scale(-1);
if (first_done) {
// if we're making a ccw turn, draw the triangles on the right side, otherwise draw them on the left side
double ccw = line.b.ccw(prev_line);
if (ccw > EPSILON) {
// top-right vertex triangle between previous line and this one
{
// use the normal going to the right calculated for the previous line
tverts->push_norm(prev_xy_right_normal);
tverts->push_vert(prev_b1.x, prev_b1.y, middle_z);
// use the normal going to the right calculated for this line
tverts->push_norm(xy_right_normal);
tverts->push_vert(a1.x, a1.y, middle_z);
// normal going upwards
tverts->push_norm(0,0,1);
tverts->push_vert(a.x, a.y, top_z);
}
// bottom-right vertex triangle between previous line and this one
{
// use the normal going to the right calculated for the previous line
tverts->push_norm(prev_xy_right_normal);
tverts->push_vert(prev_b1.x, prev_b1.y, middle_z);
// normal going downwards
tverts->push_norm(0,0,-1);
tverts->push_vert(a.x, a.y, bottom_z);
// use the normal going to the right calculated for this line
tverts->push_norm(xy_right_normal);
tverts->push_vert(a1.x, a1.y, middle_z);
}
} else if (ccw < -EPSILON) {
// top-left vertex triangle between previous line and this one
{
// use the normal going to the left calculated for the previous line
tverts->push_norm(prev_xy_left_normal);
tverts->push_vert(prev_b2.x, prev_b2.y, middle_z);
// normal going upwards
tverts->push_norm(0,0,1);
tverts->push_vert(a.x, a.y, top_z);
// use the normal going to the right calculated for this line
tverts->push_norm(xy_left_normal);
tverts->push_vert(a2.x, a2.y, middle_z);
//.........这里部分代码省略.........