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Merge pull request #68732 from AThousandShips/bit_map_polygon_fix

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Fix polygon generation in BitMap
This commit is contained in:
Rémi Verschelde 2022-11-17 14:44:30 +01:00
commit d33e584607
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GPG Key ID: C3336907360768E1
3 changed files with 156 additions and 41 deletions
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164
scene/resources/bit_map.cpp
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@ -169,7 +169,15 @@ Dictionary BitMap::_get_data() const {
return d;
}
Vector<Vector2> BitMap::_march_square(const Rect2i &p_rect, const Point2i &p_start) const {
struct CrossStackEntry {
Point2i cross;
Vector<int> ranges;
_FORCE_INLINE_ bool operator==(const CrossStackEntry &p_other) const { return cross == p_other.cross; }
_FORCE_INLINE_ bool operator!=(const CrossStackEntry &p_other) const { return cross != p_other.cross; }
};
Vector<Vector<Vector2>> BitMap::_march_square(const Rect2i &p_rect, const Point2i &p_start) const {
int stepx = 0;
int stepy = 0;
int prevx = 0;
@ -179,9 +187,20 @@ Vector<Vector2> BitMap::_march_square(const Rect2i &p_rect, const Point2i &p_sta
int curx = startx;
int cury = starty;
unsigned int count = 0;
HashSet<Point2i> case9s;
HashSet<Point2i> case6s;
Vector<Vector2> _points;
Vector<CrossStackEntry> cross_stack;
int cross_stack_size = 0;
// Add starting point to stack as the default entry.
cross_stack.push_back({ Point2i(-1, -1), Vector<int>({ 0 }) });
cross_stack_size++;
Vector<Point2i> _points;
Vector<Vector<Vector2>> ret;
// Add starting entry at start of return.
ret.resize(1);
do {
int sv = 0;
{ // Square value
@ -202,7 +221,7 @@ Vector<Vector2> BitMap::_march_square(const Rect2i &p_rect, const Point2i &p_sta
sv += (p_rect.has_point(bl) && get_bitv(bl)) ? 4 : 0;
Point2i br = Point2i(curx, cury);
sv += (p_rect.has_point(br) && get_bitv(br)) ? 8 : 0;
ERR_FAIL_COND_V(sv == 0 || sv == 15, Vector<Vector2>());
ERR_FAIL_COND_V(sv == 0 || sv == 15, Vector<Vector<Vector2>>());
}
switch (sv) {
@ -266,70 +285,139 @@ Vector<Vector2> BitMap::_march_square(const Rect2i &p_rect, const Point2i &p_sta
stepy = 0;
break;
case 9:
/*
/* Going DOWN if coming from the LEFT, otherwise go UP.
9
+---+---+
| 1 | |
+---+---+
| | 8 |
+---+---+
this should normally go UP, but if we already been here, we go down
*/
if (case9s.has(Point2i(curx, cury))) {
//found, so we go down, and delete from case9s;
if (prevx == 1) {
stepx = 0;
stepy = 1;
case9s.erase(Point2i(curx, cury));
} else {
//not found, we go up, and add to case9s;
stepx = 0;
stepy = -1;
case9s.insert(Point2i(curx, cury));
}
break;
case 6:
/*
/* Going RIGHT if coming from BELOW, otherwise go LEFT.
6
+---+---+
| | 2 |
+---+---+
| 4 | |
+---+---+
this normally go RIGHT, but if it's coming from RIGHT, it should go LEFT
*/
if (case6s.has(Point2i(curx, cury))) {
//found, so we go left, and delete from case6s;
stepx = -1;
stepy = 0;
case6s.erase(Point2i(curx, cury));
} else {
//not found, we go right, and add to case6s;
if (prevy == -1) {
stepx = 1;
stepy = 0;
case6s.insert(Point2i(curx, cury));
} else {
stepx = -1;
stepy = 0;
}
break;
default:
ERR_PRINT("this shouldn't happen.");
}
// Handle crossing points.
if (sv == 6 || sv == 9) {
const int new_index = _points.size() - 1;
// Add previous point to last stack entry.
cross_stack.write[cross_stack_size - 1].ranges.push_back(new_index);
// Create temporary entry to maybe insert, for searching.
const CrossStackEntry new_entry = { _points[new_index], Vector<int>({ new_index }) };
// Attempt to find matching entry.
const int found = cross_stack.rfind(new_entry, cross_stack_size - 1);
if (found != -1) {
Vector<Vector2> tmp;
// Iterate over entries between end of stack and found, adding ranges to result.
for (int i = found; i < cross_stack_size; i++) {
const Vector<int> &ranges = cross_stack[i].ranges;
for (int j = 0; j < ranges.size() / 2; j++) {
int first = ranges[2 * j];
const int last = ranges[2 * j + 1];
int new_pos = tmp.size();
tmp.resize(tmp.size() + (last - first));
Vector2 *tmp_ptrw = tmp.ptrw();
for (; first < last; first++, new_pos++) {
tmp_ptrw[new_pos].x = (float)(_points[first].x - p_rect.position.x);
tmp_ptrw[new_pos].y = (float)(_points[first].y - p_rect.position.y);
}
}
}
ret.push_back(tmp);
// Shrink stack.
cross_stack_size = found;
// Add previous point to last stack entry.
cross_stack.write[cross_stack_size - 1].ranges.push_back(new_index);
} else {
cross_stack.resize(MAX(cross_stack_size + 1, cross_stack.size()));
cross_stack.set(cross_stack_size, new_entry);
cross_stack_size++;
}
}
// Small optimization:
// If the previous direction is same as the current direction,
// then we should modify the last vector to current.
curx += stepx;
cury += stepy;
if (stepx == prevx && stepy == prevy) {
_points.write[_points.size() - 1].x = (float)(curx - p_rect.position.x);
_points.write[_points.size() - 1].y = (float)(cury + p_rect.position.y);
_points.write[_points.size() - 1].x = curx;
_points.write[_points.size() - 1].y = cury;
} else {
_points.push_back(Vector2((float)(curx - p_rect.position.x), (float)(cury + p_rect.position.y)));
_points.push_back(Point2i(curx, cury));
}
count++;
prevx = stepx;
prevy = stepy;
ERR_FAIL_COND_V((int)count > width * height, _points);
ERR_FAIL_COND_V((int)count > width * height, Vector<Vector<Vector2>>());
} while (curx != startx || cury != starty);
return _points;
// Add last position to last stack entry.
cross_stack.write[cross_stack_size - 1].ranges.push_back(_points.size());
for (int i = 0; i < cross_stack_size; i++) {
const Vector<int> &ranges = cross_stack[i].ranges;
for (int j = 0; j < ranges.size() / 2; j++) {
int first = ranges[2 * j];
const int last = ranges[2 * j + 1];
int new_pos = ret[0].size();
ret.write[0].resize(ret[0].size() + (last - first));
Vector2 *tmp_ptrw = ret.write[0].ptrw();
for (; first < last; first++, new_pos++) {
tmp_ptrw[new_pos].x = (float)(_points[first].x - p_rect.position.x);
tmp_ptrw[new_pos].y = (float)(_points[first].y - p_rect.position.y);
}
}
}
return ret;
}
static float perpendicular_distance(const Vector2 &i, const Vector2 &start, const Vector2 &end) {
@ -442,7 +530,7 @@ static void fill_bits(const BitMap *p_src, Ref<BitMap> &p_map, const Point2i &p_
for (int j = next_j; j <= pos.y + 1; j++) {
if (popped) {
// The next loop over j must start normally.
next_j = pos.y;
next_j = pos.y - 1;
popped = false;
// Skip because an iteration was already executed with current counter values.
continue;
@ -486,13 +574,10 @@ static void fill_bits(const BitMap *p_src, Ref<BitMap> &p_map, const Point2i &p_
}
}
} while (reenter || popped);
print_verbose("BitMap: Max stack size: " + itos(stack.size()));
}
Vector<Vector<Vector2>> BitMap::clip_opaque_to_polygons(const Rect2i &p_rect, float p_epsilon) const {
Rect2i r = Rect2i(0, 0, width, height).intersection(p_rect);
print_verbose("BitMap: Rect: " + r);
Point2i from;
Ref<BitMap> fill;
@ -505,17 +590,16 @@ Vector<Vector<Vector2>> BitMap::clip_opaque_to_polygons(const Rect2i &p_rect, fl
if (!fill->get_bit(j, i) && get_bit(j, i)) {
fill_bits(this, fill, Point2i(j, i), r);
Vector<Vector2> polygon = _march_square(r, Point2i(j, i));
print_verbose("BitMap: Pre reduce: " + itos(polygon.size()));
polygon = reduce(polygon, r, p_epsilon);
print_verbose("BitMap: Post reduce: " + itos(polygon.size()));
for (Vector<Vector2> polygon : _march_square(r, Point2i(j, i))) {
polygon = reduce(polygon, r, p_epsilon);
if (polygon.size() < 3) {
print_verbose("Invalid polygon, skipped");
continue;
if (polygon.size() < 3) {
print_verbose("Invalid polygon, skipped");
continue;
}
polygons.push_back(polygon);
}
polygons.push_back(polygon);
}
}
}

2
scene/resources/bit_map.h
View File

@ -46,7 +46,7 @@ class BitMap : public Resource {
int width = 0;
int height = 0;
Vector<Vector2> _march_square(const Rect2i &p_rect, const Point2i &p_start) const;
Vector<Vector<Vector2>> _march_square(const Rect2i &p_rect, const Point2i &p_start) const;
TypedArray<PackedVector2Array> _opaque_to_polygons_bind(const Rect2i &p_rect, float p_epsilon) const;

31
tests/scene/test_bit_map.h
View File

@ -434,6 +434,37 @@ TEST_CASE("[BitMap] Clip to polygon") {
polygons = bit_map.clip_opaque_to_polygons(Rect2i(0, 0, 128, 128));
CHECK_MESSAGE(polygons.size() == 1, "We should have exactly 1 polygon");
CHECK_MESSAGE(polygons[0].size() == 6, "The polygon should have exactly 6 points");
reset_bit_map(bit_map);
bit_map.set_bit_rect(Rect2i(0, 0, 64, 64), true);
bit_map.set_bit_rect(Rect2i(64, 64, 64, 64), true);
bit_map.set_bit_rect(Rect2i(192, 128, 64, 64), true);
bit_map.set_bit_rect(Rect2i(128, 192, 64, 64), true);
polygons = bit_map.clip_opaque_to_polygons(Rect2i(0, 0, 256, 256));
CHECK_MESSAGE(polygons.size() == 4, "We should have exactly 4 polygons");
CHECK_MESSAGE(polygons[0].size() == 4, "The polygon should have exactly 4 points");
CHECK_MESSAGE(polygons[1].size() == 4, "The polygon should have exactly 4 points");
CHECK_MESSAGE(polygons[2].size() == 4, "The polygon should have exactly 4 points");
CHECK_MESSAGE(polygons[3].size() == 4, "The polygon should have exactly 4 points");
reset_bit_map(bit_map);
bit_map.set_bit(0, 0, true);
bit_map.set_bit(2, 0, true);
bit_map.set_bit_rect(Rect2i(1, 1, 1, 2), true);
polygons = bit_map.clip_opaque_to_polygons(Rect2i(0, 0, 3, 3));
CHECK_MESSAGE(polygons.size() == 3, "We should have exactly 3 polygons");
CHECK_MESSAGE(polygons[0].size() == 4, "The polygon should have exactly 4 points");
CHECK_MESSAGE(polygons[1].size() == 4, "The polygon should have exactly 4 points");
CHECK_MESSAGE(polygons[2].size() == 4, "The polygon should have exactly 4 points");
reset_bit_map(bit_map);
bit_map.set_bit_rect(Rect2i(0, 0, 2, 1), true);
bit_map.set_bit_rect(Rect2i(0, 2, 3, 1), true);
bit_map.set_bit(0, 1, true);
bit_map.set_bit(2, 1, true);
polygons = bit_map.clip_opaque_to_polygons(Rect2i(0, 0, 4, 4));
CHECK_MESSAGE(polygons.size() == 1, "We should have exactly 1 polygon");
CHECK_MESSAGE(polygons[0].size() == 6, "The polygon should have exactly 6 points");
}
} // namespace TestBitmap