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Merged
sebsjames merged 4 commits into from
Jan 22, 2026
Merged

Triangle crossing optimization and EyeVisual fix #114

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dc34f94
A small optimization for use when repeatedly calling find_triangle_cr…
sebsjames Jan 22, 2026
467f179
Adds a check
sebsjames Jan 22, 2026
e25d2d5
Fixes a logic error to do with showing cones
sebsjames Jan 22, 2026
5eb0e55
More cone-showing logic fixing, plus avoid recomputing inter-ommatidi…
sebsjames Jan 22, 2026
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48 changes: 41 additions & 7 deletions mplot/NavMesh.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -159,7 +159,7 @@ namespace mplot
}

// Compute the triangle normal for the ordered triplet of triangle vertices, tverts
sm::vec<float, 3> triangle_normal (const sm::vec<sm::vec<float>, 3>& tverts)
sm::vec<float, 3> triangle_normal (const sm::vec<sm::vec<float>, 3>& tverts) const
{
sm::vec<float> n = (tverts[1] - tverts[0]).cross (tverts[2] - tverts[0]);
n.renormalize();
Expand Down Expand Up @@ -317,10 +317,14 @@ namespace mplot
* model. The length of vdir is used to avoid finding the intersection at the 'back' of the
* model.
*
* \param ti_ml The most likely triangle, if you know what it probably is, to reduce the
* search time.
*
* \return a tuple containing crossing location, triangle identity (three indices) and triangle normal vector
*/
std::tuple<sm::vec<float>, std::array<uint32_t, 4>, sm::vec<float>>
find_triangle_crossing (const sm::vec<float>& coord_mf, const sm::vec<float>& vdir) const
find_triangle_crossing (const sm::vec<float>& coord_mf, const sm::vec<float>& vdir,
const std::array<uint32_t, 4> ti_ml = {std::numeric_limits<uint32_t>::max()}) const
{
constexpr auto umax = std::numeric_limits<uint32_t>::max();
constexpr auto fmax = std::numeric_limits<float>::max();
Expand All @@ -333,6 +337,30 @@ namespace mplot

auto isect_d = std::numeric_limits<float>::max(); // distance to intersect

const auto vdsos = vdir.sos();

// Have we been passed a 'most likely triangle' to test first? If so, test it.
if (ti_ml[0] != std::numeric_limits<uint32_t>::max()) {
sm::vec<float> v0 = this->vertex[ti_ml[0]];
sm::vec<float> v1 = this->vertex[ti_ml[1]];
sm::vec<float> v2 = this->vertex[ti_ml[2]];
auto [isect, p] = sm::geometry::ray_tri_intersection<float, float, true, false> (v0, v1, v2, vstart, vdir);
if (isect) {
float d = (p - vstart).sos();
if (d < vdsos) {
sm::vec<sm::vec<float>, 3> tverts = { v0, v1, v2 };
isect_p = p;
isect_ti = ti_ml;
isect_tn = this->triangle_normal (tverts); // compute tn
isect_d = d;
}
}
}
if (isect_d != std::numeric_limits<float>::max()) {
// we found it already!
return { isect_p, isect_ti, isect_tn };
}

for (auto tri : this->triangles) {
auto [ti, tn, tnc, tnd] = tri;
auto [isect, p] = sm::geometry::ray_tri_intersection<float, float, true, false> (this->vertex[ti[0]], this->vertex[ti[1]], this->vertex[ti[2]], vstart, vdir);
Expand All @@ -341,7 +369,7 @@ namespace mplot
// closest one that isn't.
if (isect) {
float d = (p - vstart).sos();
if (d < isect_d && d < vdir.sos()) {
if (d < isect_d && d < vdsos) {
isect_p = p;
isect_ti = ti;
isect_tn = tn;
Expand All @@ -350,8 +378,9 @@ namespace mplot
}
}

if (isect_p[0] == fmax) {
// Found no triangle intersection; check vertices, in case vdir points perfectly at a vertex
if (isect_p[0] == fmax && this->vertex.size() < 10000) {
// Found no triangle intersection; check vertices, in case vdir points perfectly at a vertex.
// This can be computationally expensive, hence the hacky check, above.
for (uint32_t ti = 0; ti < this->vertex.size(); ++ti) {
sm::vec<float> vertex_n = this->find_vertex_normal (ti); // also loops
vertex_n.renormalize();
Expand Down Expand Up @@ -805,17 +834,22 @@ namespace mplot
* large, flat, one-sided landscape, we want to make vdir long. search_dist_mult is applied
* to vdir.
*
* \param ti_ml The most likely triangle, if you know what it probably is, to reduce the
* search time.
*
* \return tuple containing: the hit point in scene coordinates; the triangle normal of the
* triangle we hit; and the indices of the triangle we hit.
*/
std::tuple<sm::vec<float>, sm::vec<float>, std::array<uint32_t, 4>>
find_triangle_hit (const sm::mat44<float>& model_to_scene,
const sm::vec<float>& camloc_mf, const sm::vec<float>& vdir)
const sm::vec<float>& camloc_mf, const sm::vec<float>& vdir,
const std::array<uint32_t, 4> ti_ml = {std::numeric_limits<uint32_t>::max()})
{
this->ti0 = {};
this->tn0 = {};
sm::vec<float> hit = {};
std::tie (hit, this->ti0, this->tn0) = this->find_triangle_crossing (camloc_mf, vdir);
// Want to pass 'best tri' to this
std::tie (hit, this->ti0, this->tn0) = this->find_triangle_crossing (camloc_mf, vdir, ti_ml);

if (this->ti0[0] == std::numeric_limits<uint32_t>::max()) { std::cout << __func__ << ": No hit\n"; }

Expand Down
52 changes: 39 additions & 13 deletions mplot/compoundray/EyeVisual.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -107,7 +107,7 @@ namespace mplot::compoundray
if (show_3d) {
// Replace colours for the 3D part of the model
int num_vertices = disc_vertices;
if (this->show_cones == true) {
if (this->show_cones == true && this->cones_will_show) {
num_vertices = cone_vertices + disc_vertices;
} // else num_vertices = disc_vertices;

Expand Down Expand Up @@ -280,19 +280,21 @@ namespace mplot::compoundray
float ray_radius = ommrng.span().max() / 500.0f;

// Find mean minimum ommatidial distance
sm::vvec<float> dist_to_other (n_omm, 0.0f);
sm::vvec<float> min_dist_to_other (n_omm, 0.0f);
for (size_t i = 0u; i < n_omm; ++i) {
for (size_t j = 0u; j < n_omm; ++j) {
if (i == j) {
dist_to_other[j] = 10000.0f;
} else {
dist_to_other[j] = ((*ommatidia)[i].relativePosition - (*ommatidia)[j].relativePosition).length();
if (this->min_dist_to_other.empty()) {
sm::vvec<float> dist_to_other (n_omm, 0.0f);
min_dist_to_other.resize (n_omm, 0.0f);
for (size_t i = 0u; i < n_omm; ++i) {
for (size_t j = 0u; j < n_omm; ++j) {
if (i == j) {
dist_to_other[j] = 10000.0f;
} else {
dist_to_other[j] = ((*ommatidia)[i].relativePosition - (*ommatidia)[j].relativePosition).length();
}
}
min_dist_to_other[i] = dist_to_other.min();
}
min_dist_to_other[i] = dist_to_other.min();
}
std::cerr << "Mean ommatidial distance: " << min_dist_to_other.mean() << std::endl;
std::cerr << "Mean ommatidial distance: " << this->min_dist_to_other.mean() << std::endl;

// First find out if all focal points are 0
this->focal_point_sum = 0.0f;
Expand All @@ -301,6 +303,7 @@ namespace mplot::compoundray
}

if (show_3d && this->focal_point_sum > 0.0f) {
std::cout << "Stanza 1\n";
// We have focal points, so draw with the relativePosition representing the centre
// of the ommatidial lens - the base of a cone - which then extends back to the cone
// tip, which can be thought of as the location of the ommatidial 'sensor'
Expand All @@ -316,22 +319,32 @@ namespace mplot::compoundray
sm::vec<float, 3> ommatidial_detector_point = pos - dir * focal_point;
// work out a radius from acceptance angle and focal_point
// The discs are based on the inter-ommatidial distances in space, which have to have been computed
float dw = min_dist_to_other[i];
float dw = this->min_dist_to_other[i];
this->computeTube (pos, pos + (0.05f * dw * dir), colour, colour, dw * 0.5f, tube_faces);

// This visualizes the optical cones
if (this->show_cones == true && this->show_fov == false) {
float optical_radius = focal_point * std::tan (angle / 2.0f);
// Colour comes from ommData. ringoffset is 1.0f
this->computeCone (pos, ommatidial_detector_point, 0.0f, colour, optical_radius, tube_faces);
this->cones_will_show = true;

} else if (this->show_fov == true) {
// do a cone of angle 'acceptanceAngle' using user-supplied cone_length, starting FROM the disc to show field of view of the eye
sm::vec<float, 3> ommatidial_cone_pos = pos + dir * this->cone_length;
float radius = this->cone_length * std::tan (angle / 2.0f);
this->computeCone (ommatidial_cone_pos, pos, 0.0f, colour, radius, tube_faces);
}
}

if ((this->show_cones == true || this->show_fov == true) && n_omm > 0) {
this->cones_will_show = true;
} else {
this->cones_will_show = false;
}

} else if (show_3d && this->focal_point_sum <= 0.0f) {
std::cout << "Stanza 2\n";
// All our focal_points are 0. Don't have focal point offset to help define our
// cones, only acceptance angle. Use manually specified tube_length (or computed
// radius) to figure out the size of a cone, whose tip is the location of the
Expand All @@ -344,7 +357,7 @@ namespace mplot::compoundray
sm::vec<float, 3> dir = (*ommatidia)[i].relativeDirection;
dir.renormalize();

float dw = min_dist_to_other[i];
float dw = this->min_dist_to_other[i];
this->computeTube (pos, pos + (0.05f * dw * dir), colour, colour, dw * 0.5f, tube_faces);
// We don't have a focal length to show cones, but we can still show the acceptance angle
if (this->show_fov == true) {
Expand All @@ -354,6 +367,15 @@ namespace mplot::compoundray
this->computeCone (ommatidial_cone_pos, pos, 0.0f, colour, radius, tube_faces);
}
}

if (this->show_fov == true && n_omm > 0) {
this->cones_will_show = true;
} else {
this->cones_will_show = false;
}

} else {
this->cones_will_show = false;
}

// 2D projections
Expand Down Expand Up @@ -525,10 +547,14 @@ namespace mplot::compoundray
// If true, show 'field of view' cones. Overrides show_cones. Control size of cones with
// this->cone_length
bool show_fov = false;
// either show_cones or show_fov are enabled and cones have been drawn
bool cones_will_show = false;
// The colours detected by each ommatidium
std::vector<std::array<float, 3>>* ommData = nullptr;
// The position and orientation of each ommatidium
std::vector<mplot::compoundray::Ommatidium>* ommatidia = nullptr;
// Distances to the nearest ommatidia, for choosing disc size. Computed once only
sm::vvec<float> min_dist_to_other = {};
// An optional head mesh
const mplot::meshgroup* head_mesh = nullptr;
// If sum is 0, then we have a special case for rendering the eye as we have no focal point
Expand Down