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BLI: improve reverse uv sample in edge cases 

Allow for a small epsilon to improve handling of uvs that are on edges.
Generally, when using reverse uv sampling, we expect that the sampling
is supposed to succeed.
This commit is contained in:
Jacques Lucke 2022-07-06 15:20:25 +02:00
parent 9d0777e514
commit 6636edbb00
1 changed files with 27 additions and 2 deletions
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29
source/blender/geometry/intern/reverse_uv_sampler.cc
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@ -45,6 +45,11 @@ ReverseUVSampler::Result ReverseUVSampler::sample(const float2 &query_uv) const
{
const int2 cell_key = uv_to_cell_key(query_uv, resolution_);
const Span<int> looptri_indices = looptris_by_cell_.lookup(cell_key);
float best_dist = FLT_MAX;
float3 best_bary_weights;
const MLoopTri *best_looptri;
for (const int looptri_index : looptri_indices) {
const MLoopTri &looptri = looptris_[looptri_index];
const float2 &uv_0 = uv_map_[looptri.tri[0]];
@ -54,11 +59,31 @@ ReverseUVSampler::Result ReverseUVSampler::sample(const float2 &query_uv) const
if (!barycentric_coords_v2(uv_0, uv_1, uv_2, query_uv, bary_weights)) {
continue;
}
if (IN_RANGE_INCL(bary_weights.x, 0.0f, 1.0f) && IN_RANGE_INCL(bary_weights.y, 0.0f, 1.0f) &&
IN_RANGE_INCL(bary_weights.z, 0.0f, 1.0f)) {
/* If #query_uv is in the triangle, the distance is <= 0. Otherwise, the larger the distance,
* the further away the uv is from the triangle. */
const float x_dist = std::max(-bary_weights.x, bary_weights.x - 1.0f);
const float y_dist = std::max(-bary_weights.y, bary_weights.y - 1.0f);
const float z_dist = std::max(-bary_weights.z, bary_weights.z - 1.0f);
const float dist = MAX3(x_dist, y_dist, z_dist);
if (dist <= 0.0f) {
/* Return early if the uv coordinate is in the triangle. */
return Result{ResultType::Ok, &looptri, bary_weights};
}
if (dist < best_dist) {
best_dist = dist;
best_bary_weights = bary_weights;
best_looptri = &looptri;
}
}
/* Allow for a small epsilon in case the uv is on th edge. */
if (best_dist < 0.00001f) {
return Result{ResultType::Ok, best_looptri, math::clamp(best_bary_weights, 0.0f, 1.0f)};
}
return Result{};
}