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Commented and integrated new pad wall triangulation

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tamasmeszaros 2019-02-14 11:23:43 +01:00
parent daa8f7ef1b
commit 1e9b64b971
2 changed files with 117 additions and 113 deletions
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3
sandboxes/slabasebed/CMakeLists.txt
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@ -1,3 +1,2 @@
add_executable(slabasebed #EXCLUDE_FROM_ALL
slabasebed.cpp)
add_executable(slabasebed EXCLUDE_FROM_ALL slabasebed.cpp)
target_link_libraries(slabasebed libslic3r ${Boost_LIBRARIES} ${TBB_LIBRARIES} ${Boost_LIBRARIES} ${CMAKE_DL_LIBS})

221
src/libslic3r/SLA/SLABasePool.cpp
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@ -30,109 +30,161 @@ Contour3D convert(const Polygons& triangles, coord_t z, bool dir) {
return {points, indices};
}
// This function will return a triangulation of a sheet connecting an upper
// and a lower plate given as input polygons. It will not triangulate the plates
// themselves only the robe.
/// This function will return a triangulation of a sheet connecting an upper
/// and a lower plate given as input polygons. It will not triangulate the
/// plates themselves only the sheet. The caller has to specify the lower and
/// upper z levels in world coordinates as well as the offset difference
/// between the sheets.
///
/// IMPORTANT: This is not a universal triangulation algorithm. It assumes
/// that the lower and upper polygons are offsetted versions of the same
/// original polygon. In general, it assumes that one of the polygons is
/// completely inside the other. The offset difference is the reference
/// distance from the inner polygon's perimeter to the outer polygon's
/// perimeter. The real distance will be variable as the clipper offset has
/// different strategies (rounding, etc...). This algorithm should have
/// O(2n + 3m) complexity where n is the number of upper vertices and m is the
/// number of lower vertices.
Contour3D walls(const Polygon& lower, const Polygon& upper,
double floor_z_mm, double ceiling_z_mm,
double lower_z_mm, double upper_z_mm,
double offset_difference_mm, ThrowOnCancel thr)
{
Contour3D ret;
if(upper.points.size() < 3 || lower.size() < 3) return ret;
// The concept of the algorithm is relatively simple. It will try to find
// the closest vertices from the upper and the lower polygon and use those
// as starting points. Then it will create the triangles sequentially using
// an edge from the upper polygon and a vertex from the lower or vice versa,
// depending on the resulting triangle's quality.
// The quality is measured by a scalar value. So far it looks like it is
// enough to derive it from the slope of the triangle's two edges connecting
// the upper and the lower part. A reference slope is calculated from the
// height and the offset difference.
// Offset in the index array for the ceiling
const auto offs = long(upper.points.size());
ret.points.reserve(upper.points.size() + lower.points.size());
for(auto& p : upper.points)
ret.points.emplace_back(unscale(p.x(), p.y(), mm(ceiling_z_mm)));
// Shorthand for the vertex arrays
auto& upoints = upper.points, &lpoints = lower.points;
for(auto& p : lower.points)
ret.points.emplace_back(unscale(p.x(), p.y(), mm(floor_z_mm)));
// If the Z levels are flipped, or the offset difference is negative, we
// will interpret that as the triangles normals should be inverted.
bool inverted = upper_z_mm < lower_z_mm || offset_difference_mm < 0;
auto uit = upper.points.begin();
auto lit = lower.points.begin();
// Copy the points into the mesh, convert them from 2D to 3D
ret.points.reserve(upoints.size() + lpoints.size());
for(auto& p : upoints)
ret.points.emplace_back(unscale(p.x(), p.y(), mm(upper_z_mm)));
for(auto& p : lpoints)
ret.points.emplace_back(unscale(p.x(), p.y(), mm(lower_z_mm)));
// We need to find the closest point on outer polygon to the first point on
// the inner polygon. These will be our starting points.
// Create cyclic iterators for the vertices in both polygons.
auto uit = upoints.begin();
auto lit = lpoints.begin();
// We need to find the closest point on lower polygon to the first point on
// the upper polygon. These will be our starting points.
double distmin = std::numeric_limits<double>::max();
for(auto lt = lower.points.begin(); lt != lower.points.end(); ++lt) {
for(auto lt = lpoints.begin(); lt != lpoints.end(); ++lt) {
thr();
Vec2d p = (*lt - *uit).cast<double>();
double d = p.transpose() * p;
if(d < distmin) { lit = lt; distmin = d; }
}
auto unext = std::next(uit);
auto lnext = std::next(lit);
if(lnext == lower.points.end()) lnext = lower.points.begin();
// Iterators to the polygon vertices which are always ahead of uit and lit
// in cyclic mode.
auto unextit = std::next(uit);
auto lnextit = std::next(lit);
if(lnextit == lower.points.end()) lnextit = lower.points.begin();
// Get the integer vertex indices from the iterators.
auto uidx = uit - upper.points.begin();
auto unextidx = unext - upper.points.begin();
auto unextidx = unextit - upper.points.begin();
auto lidx = offs + lit - lower.points.begin();
auto lnextidx = offs + lnext - lower.points.begin();
auto lnextidx = offs + lnextit - lower.points.begin();
// This will be the flip switch to toggle between upper and lower triangle
// creation mode
enum class Proceed {
UPPER, LOWER
UPPER, // A segment from the upper polygon and one vertex from the lower
LOWER // A segment from the lower polygon and one vertex from the upper
} proceed = Proceed::UPPER;
// Flags to help evaluating loop termination.
bool ustarted = false, lstarted = false;
double current_fit = 0;
double prev_fit = 0;
// The variables for the fitness values, one for the actual and one for the
// previous.
double current_fit = 0, prev_fit = 0;
// Simple distance calculation.
auto distfn = [](const Vec3d& p1, const Vec3d& p2) {
auto p = p1 - p2;
return std::sqrt(p.transpose() * p);
auto p = p1 - p2; return std::sqrt(p.transpose() * p);
};
// Calculate the reference fitness value. It will be the sine of the angle
// from the upper to the lower plate according to the triangle noted by the
// Z difference and the offset difference.
const double required_fit = offset_difference_mm /
std::sqrt( std::pow(offset_difference_mm, 2) +
std::pow(ceiling_z_mm - floor_z_mm, 2));
std::pow(upper_z_mm - lower_z_mm, 2));
// Mark the current vertex iterator positions. If the iterators return to
// the same position, the loop can be terminated.
auto uend = uit; auto lend = lit;
do {
thr();
prev_fit = current_fit;
// Get the actual 2D vertices from the upper and lower polygon.
Vec2d ip = unscale(uit->x(), uit->y());
Vec2d inextp = unscale(unext->x(), unext->y());
Vec2d inextp = unscale(unextit->x(), unextit->y());
Vec2d op = unscale(lit->x(), lit->y());
Vec2d onextp = unscale(lnext->x(), lnext->y());
Vec2d onextp = unscale(lnextit->x(), lnextit->y());
switch(proceed) {
switch(proceed) { // proceed depending on the current state
case Proceed::UPPER:
if(!ustarted || uit != uend) {
Vec3d p1(ip.x(), ip.y(), ceiling_z_mm);
Vec3d p2(op.x(), op.y(), floor_z_mm);
Vec3d p3(inextp.x(), inextp.y(), ceiling_z_mm);
if(!ustarted || uit != uend) { // if there are vertices remaining
// Get the 3D vertices in order
Vec3d p1(ip.x(), ip.y(), upper_z_mm);
Vec3d p2(op.x(), op.y(), lower_z_mm);
Vec3d p3(inextp.x(), inextp.y(), upper_z_mm);
// Calculate fitness: the worst of the two connecting edges
double a = required_fit - offset_difference_mm / distfn(p1, p2);
double b = required_fit - offset_difference_mm / distfn(p3, p2);
current_fit = std::max(std::abs(a), std::abs(b));
if(current_fit > prev_fit) {
if(current_fit > prev_fit) { // fit is worse than previously
proceed = Proceed::LOWER;
} else {
} else { // good to go, create the triangle
inverted? ret.indices.emplace_back(unextidx, lidx, uidx) :
ret.indices.emplace_back(uidx, lidx, unextidx) ;
++uit; ++unext;
if(unext == upper.points.end()) unext = upper.points.begin();
if(uit == upper.points.end()) uit = upper.points.begin();
unextidx = unext - upper.points.begin();
uidx = uit - upper.points.begin();
// Increment the iterators, rotate if necessary
++uit; ++unextit;
if(unextit == upoints.end()) unextit = upoints.begin();
if(uit == upoints.end()) uit = upoints.begin();
unextidx = unextit - upoints.begin();
uidx = uit - upoints.begin();
ustarted = true;
ustarted = true; // mark the movement of the iterators
// so that the comparison to uend can be made correctly
}
} else proceed = Proceed::LOWER;
break;
case Proceed::LOWER:
// Mode with lower segment, upper vertex. Same structure:
if(!lstarted || lit != lend) {
Vec3d p1(op.x(), op.y(), floor_z_mm);
Vec3d p2(onextp.x(), onextp.y(), floor_z_mm);
Vec3d p3(ip.x(), ip.y(), ceiling_z_mm);
Vec3d p1(op.x(), op.y(), lower_z_mm);
Vec3d p2(onextp.x(), onextp.y(), lower_z_mm);
Vec3d p3(ip.x(), ip.y(), upper_z_mm);
double a = required_fit - offset_difference_mm / distfn(p3, p1);
double b = required_fit - offset_difference_mm / distfn(p3, p2);
@ -141,77 +193,26 @@ Contour3D walls(const Polygon& lower, const Polygon& upper,
if(current_fit > prev_fit) {
proceed = Proceed::UPPER;
} else {
inverted? ret.indices.emplace_back(uidx, lnextidx, lidx) :
ret.indices.emplace_back(lidx, lnextidx, uidx);
++lit; ++lnext;
if(lnext == lower.points.end()) lnext = lower.points.begin();
if(lit == lower.points.end()) lit = lower.points.begin();
lnextidx = offs + lnext - lower.points.begin();
lidx = offs + lit - lower.points.begin();
++lit; ++lnextit;
if(lnextit == lpoints.end()) lnextit = lpoints.begin();
if(lit == lpoints.end()) lit = lpoints.begin();
lnextidx = offs + lnextit - lpoints.begin();
lidx = offs + lit - lpoints.begin();
lstarted = true;
}
} else proceed = Proceed::UPPER;
break;
} // switch
} // end of switch
} while(!ustarted || !lstarted || uit != uend || lit != lend);
return ret;
// using std::transform; using std::back_inserter;
// ExPolygon poly;
// poly.contour.points = floor_plate.contour.points;
// poly.holes.emplace_back(ceiling.contour);
// auto& h = poly.holes.front();
// std::reverse(h.points.begin(), h.points.end());
// Polygons tri = triangulate(poly);
// Contour3D ret;
// ret.points.reserve(tri.size() * 3);
// double fz = floor_z_mm;
// double cz = ceiling_z_mm;
// auto& rp = ret.points;
// auto& rpi = ret.indices;
// ret.indices.reserve(tri.size() * 3);
// coord_t idx = 0;
// auto hlines = h.lines();
// auto is_upper = [&hlines](const Point& p) {
// return std::any_of(hlines.begin(), hlines.end(),
// [&p](const Line& l) {
// return l.distance_to(p) < mm(1e-6);
// });
// };
// for(const Polygon& pp : tri) {
// thr(); // may throw if cancellation was requested
// for(auto& p : pp.points)
// if(is_upper(p))
// rp.emplace_back(unscale(x(p), y(p), mm(cz)));
// else rp.emplace_back(unscale(x(p), y(p), mm(fz)));
// coord_t a = idx++, b = idx++, c = idx++;
// if(fz > cz) rpi.emplace_back(c, b, a);
// else rpi.emplace_back(a, b, c);
// }
// return ret;
}
Contour3D walls(const ExPolygon& floor_plate, const ExPolygon& ceiling,
double floor_z_mm, double ceiling_z_mm, ThrowOnCancel thr)
{
return walls(floor_plate.contour, ceiling.contour, floor_z_mm, ceiling_z_mm,
0, thr);
}
/// Offsetting with clipper and smoothing the edges into a curvature.
void offset(ExPolygon& sh, coord_t distance) {
using ClipperLib::ClipperOffset;
@ -384,7 +385,8 @@ Contour3D round_edges(const ExPolygon& base_plate,
wh = ceilheight_mm - radius_mm + stepy;
Contour3D pwalls;
pwalls = walls(ob.contour, ob_prev.contour, wh, wh_prev, xx, throw_on_cancel);
double prev_x = xx - (i - 1) * stepx;
pwalls = walls(ob.contour, ob_prev.contour, wh, wh_prev, s*prev_x, throw_on_cancel);
curvedwalls.merge(pwalls);
ob_prev = ob;
@ -407,7 +409,8 @@ Contour3D round_edges(const ExPolygon& base_plate,
wh = ceilheight_mm - radius_mm - stepy;
Contour3D pwalls;
pwalls = walls(ob_prev.contour, ob.contour, wh_prev, wh, xx, throw_on_cancel);
double prev_x = xx - radius_mm + (i - 1)*stepx;
pwalls = walls(ob_prev.contour, ob.contour, wh_prev, wh, s*prev_x, throw_on_cancel);
curvedwalls.merge(pwalls);
ob_prev = ob;
@ -700,7 +703,8 @@ void create_base_pool(const ExPolygons &ground_layer, TriangleMesh& out,
// Now that we have the rounded edge connencting the top plate with
// the outer side walls, we can generate and merge the sidewall geometry
auto pwalls = walls(ob.contour, inner_base.contour, wh, -fullheight, (s_thickness + s_wingdist) * SCALING_FACTOR, thrcl);
auto pwalls = walls(ob.contour, inner_base.contour, wh, -fullheight,
(s_thickness + s_wingdist) * SCALING_FACTOR, thrcl);
pool.merge(pwalls);
if(wingheight > 0) {
@ -708,7 +712,7 @@ void create_base_pool(const ExPolygons &ground_layer, TriangleMesh& out,
auto cavityedges = round_edges(middle_base,
r,
phi - 90, // from tangent lines
0,
0, // z position of the input plane
false,
thrcl,
ob, wh);
@ -716,13 +720,14 @@ void create_base_pool(const ExPolygons &ground_layer, TriangleMesh& out,
// Next is the cavity walls connecting to the top plate's
// artificially created hole.
auto cavitywalls = walls(inner_base.contour, ob.contour, -wingheight, wh, s_safety_dist * SCALING_FACTOR,thrcl);
auto cavitywalls = walls(inner_base.contour, ob.contour, -wingheight,
wh, -s_safety_dist * SCALING_FACTOR, thrcl);
pool.merge(cavitywalls);
}
// Now we need to triangulate the top and bottom plates as well as the
// cavity bottom plate which is the same as the bottom plate but it is
// eleveted by the thickness.
// elevated by the thickness.
Polygons top_triangles, bottom_triangles;
triangulate(top_poly, top_triangles);