Zylann/godot_voxel
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Fix rare bug with vertex sharing causing long spiky artifacts

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Basically we were checking case code of the ReuseCell to know if we can
re-use a vertex from it, but sometimes the associated cell did not write
a re-usable vertex, and we were not resetting such vertex indices.
So in some cases, we were accessing a very old index.
The case code doesn't need to be remembered, we just reset the first vertex.
No need to check if the ReuseCell was empty, we can read the vertex directly,
as it will be -1 anyways if it isn't re-usable. At least, this fixed the bug
and did not reproduce after testing a lot of noise data sets.
This commit is contained in:
Marc Gilleron 2020-01-01 00:39:47 +00:00
parent ee8a70bc75
commit d4986489cf
2 changed files with 26 additions and 57 deletions
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75
meshers/transvoxel/voxel_mesher_transvoxel.cpp
View File

@ -294,10 +294,9 @@ void VoxelMesherTransvoxel::build_internal(const VoxelBuffer &voxels, unsigned i
case_code |= (sign(cell_samples[6]) << 6);
case_code |= (sign(cell_samples[7]) << 7);
{
ReuseCell &rc = get_reuse_cell(pos);
rc.case_index = case_code;
}
ReuseCell &current_reuse_cell = get_reuse_cell(pos);
// Mark as unusable for now
current_reuse_cell.vertices[0] = -1;
if (case_code == 0 || case_code == 255) {
// If the case_code is 0 or 255, there is no triangulation to do
@ -398,14 +397,8 @@ void VoxelMesherTransvoxel::build_internal(const VoxelBuffer &voxels, unsigned i
if (present) {
Vector3i cache_pos = pos + L::dir_to_prev_vec(reuse_dir);
ReuseCell &prev_cell = get_reuse_cell(cache_pos);
if (prev_cell.case_index == 0 || prev_cell.case_index == 255) {
// TODO I don't think this can happen for non-corner vertices.
cell_vertex_indices[i] = -1;
} else {
// Will reuse a previous vertice
cell_vertex_indices[i] = prev_cell.vertices[reuse_vertex_index];
}
// Will reuse a previous vertice
cell_vertex_indices[i] = prev_cell.vertices[reuse_vertex_index];
}
if (!present || cell_vertex_indices[i] == -1) {
@ -435,8 +428,7 @@ void VoxelMesherTransvoxel::build_internal(const VoxelBuffer &voxels, unsigned i
if (reuse_dir & 8) {
// Store the generated vertex so that other cells can reuse it.
ReuseCell &rc = get_reuse_cell(pos);
rc.vertices[reuse_vertex_index] = cell_vertex_indices[i];
current_reuse_cell.vertices[reuse_vertex_index] = cell_vertex_indices[i];
}
}
@ -458,8 +450,7 @@ void VoxelMesherTransvoxel::build_internal(const VoxelBuffer &voxels, unsigned i
cell_vertex_indices[i] = emit_vertex(primary, normal, border_mask, secondary);
ReuseCell &rc = get_reuse_cell(pos);
rc.vertices[0] = cell_vertex_indices[i];
current_reuse_cell.vertices[0] = cell_vertex_indices[i];
} else {
// The vertex is either on p0 or p1
@ -476,14 +467,7 @@ void VoxelMesherTransvoxel::build_internal(const VoxelBuffer &voxels, unsigned i
if (present) {
Vector3i cache_pos = pos + L::dir_to_prev_vec(reuse_dir);
ReuseCell prev_cell = get_reuse_cell(cache_pos);
// The previous cell might not have any geometry, and we
// might therefore have to create a new vertex anyway.
if (prev_cell.case_index == 0 || prev_cell.case_index == 255) {
cell_vertex_indices[i] = -1;
} else {
cell_vertex_indices[i] = prev_cell.vertices[0];
}
cell_vertex_indices[i] = prev_cell.vertices[0];
}
if (!present || cell_vertex_indices[i] < 0) {
@ -747,6 +731,10 @@ void VoxelMesherTransvoxel::build_transition(const VoxelBuffer &p_voxels, unsign
case_code |= (sign(cell_samples[3]) << 7);
case_code |= (sign(cell_samples[4]) << 8);
ReuseTransitionCell &current_reuse_cell = get_reuse_cell_2d(fx, fy);
// Mark current cell unused for now
current_reuse_cell.vertices[0] = -1;
if (case_code == 0 || case_code == 511) {
// The cell contains no triangles.
continue;
@ -754,8 +742,6 @@ void VoxelMesherTransvoxel::build_transition(const VoxelBuffer &p_voxels, unsign
CRASH_COND(case_code > 511);
get_reuse_cell_2d(fx, fy).case_index = case_code;
const uint8_t cell_class = Transvoxel::get_transition_cell_class(case_code);
CRASH_COND((cell_class & 0x7f) > 55);
@ -813,16 +799,9 @@ void VoxelMesherTransvoxel::build_transition(const VoxelBuffer &p_voxels, unsign
if (present) {
// The previous cell is available. Retrieve the cached cell
// from which to retrieve the reused vertex index from.
const ReuseTransitionCell &prev = get_reuse_cell_2d(fx - (reuse_direction & 1), fy - ((reuse_direction >> 1) & 1));
if (prev.case_index == 0 || prev.case_index == 511) {
// Previous cell does not contain any geometry.
cell_vertex_indices[i] = -1;
} else {
// Reuse the vertex index from the previous cell.
cell_vertex_indices[i] = prev.vertices[vertex_index_to_reuse_or_create];
}
// Reuse the vertex index from the previous cell.
cell_vertex_indices[i] = prev.vertices[vertex_index_to_reuse_or_create];
}
if (!present || cell_vertex_indices[i] == -1) {
@ -878,17 +857,9 @@ void VoxelMesherTransvoxel::build_transition(const VoxelBuffer &p_voxels, unsign
if (present) {
// The previous cell is available. Retrieve the cached cell
// from which to retrieve the reused vertex index from.
const ReuseTransitionCell &prev = get_reuse_cell_2d(fx - (reuse_direction & 1), fy - ((reuse_direction >> 1) & 1));
if (prev.case_index == 0 || prev.case_index == 511) {
// Previous cell had no geometry
cell_vertex_indices[i] = -1;
} else {
// Reuse the vertex index from the previous cell.
cell_vertex_indices[i] = prev.vertices[vertex_index_to_reuse_or_create];
}
// Reuse the vertex index from the previous cell.
cell_vertex_indices[i] = prev.vertices[vertex_index_to_reuse_or_create];
}
if (!present || cell_vertex_indices[i] == -1) {
@ -942,15 +913,21 @@ void VoxelMesherTransvoxel::reset_reuse_cells(Vector3i block_size) {
_block_size = block_size;
unsigned int deck_area = block_size.x * block_size.y;
for (int i = 0; i < _cache.size(); ++i) {
_cache[i].clear();
_cache[i].resize(deck_area);
std::vector<ReuseCell> &deck = _cache[i];
deck.resize(deck_area);
for (int j = 0; j < deck.size(); ++j) {
deck[j].vertices.fill(-1);
}
}
}
void VoxelMesherTransvoxel::reset_reuse_cells_2d(Vector3i block_size) {
for (int i = 0; i < _cache_2d.size(); ++i) {
_cache_2d[i].clear();
_cache_2d[i].resize(block_size.x);
std::vector<ReuseTransitionCell> &row = _cache_2d[i];
row.resize(block_size.x);
for (int j = 0; j < row.size(); ++j) {
row[j].vertices.fill(-1);
}
}
}

8
meshers/transvoxel/voxel_mesher_transvoxel.h
View File

@ -25,18 +25,10 @@ protected:
private:
struct ReuseCell {
FixedArray<int, 4> vertices;
int case_index = 0;
ReuseCell() {
vertices.fill(-1);
}
};
struct ReuseTransitionCell {
FixedArray<int, 12> vertices;
int case_index = 0;
ReuseTransitionCell() {
vertices.fill(-1);
}
};
struct TransitionVoxels {