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#include "geoData.h"
#include <fstream>
#include <glm/gtx/intersect.hpp>
#include <maths.h>
GeoData
GeoData::loadFromAsciiGrid(const std::filesystem::path & input)
{
size_t ncols = 0, nrows = 0, xllcorner = 0, yllcorner = 0, cellsize = 0;
std::map<std::string_view, size_t *> properties {
{"ncols", &ncols},
{"nrows", &nrows},
{"xllcorner", &xllcorner},
{"yllcorner", &yllcorner},
{"cellsize", &cellsize},
};
std::ifstream f {input};
while (!properties.empty()) {
std::string property;
f >> property;
f >> *properties.at(property);
properties.erase(property);
}
std::vector<VertexHandle> vertices;
vertices.reserve(ncols * nrows);
GeoData mesh;
mesh.lowerExtent = {xllcorner, yllcorner, std::numeric_limits<float>::max()};
mesh.upperExtent
= {xllcorner + (cellsize * ncols), yllcorner + (cellsize * nrows), std::numeric_limits<float>::min()};
for (size_t row = 0; row < nrows; ++row) {
for (size_t col = 0; col < ncols; ++col) {
float height = 0;
f >> height;
mesh.upperExtent.z = std::max(mesh.upperExtent.z, height);
mesh.lowerExtent.z = std::min(mesh.lowerExtent.z, height);
vertices.push_back(mesh.add_vertex({xllcorner + (col * cellsize), yllcorner + (row * cellsize), height}));
}
}
if (!f.good()) {
throw std::runtime_error("Couldn't read terrain file");
}
for (size_t row = 1; row < nrows; ++row) {
for (size_t col = 1; col < ncols; ++col) {
mesh.add_face({
vertices[ncols * (row - 1) + (col - 1)],
vertices[ncols * (row - 0) + (col - 0)],
vertices[ncols * (row - 0) + (col - 1)],
});
mesh.add_face({
vertices[ncols * (row - 1) + (col - 1)],
vertices[ncols * (row - 1) + (col - 0)],
vertices[ncols * (row - 0) + (col - 0)],
});
}
}
mesh.update_face_normals();
mesh.update_vertex_normals();
return mesh;
};
GeoData
GeoData::createFlat(glm::vec2 lower, glm::vec2 upper, float h)
{
GeoData mesh;
mesh.lowerExtent = lower ^ h;
mesh.upperExtent = upper ^ h;
const auto ll = mesh.add_vertex({lower.x, lower.y, h}), lu = mesh.add_vertex({lower.x, upper.y, h}),
ul = mesh.add_vertex({upper.x, lower.y, h}), uu = mesh.add_vertex({upper.x, upper.y, h});
mesh.add_face(ll, uu, lu);
mesh.add_face(ll, ul, uu);
mesh.update_face_normals();
mesh.update_vertex_normals();
return mesh;
}
OpenMesh::FaceHandle
GeoData::findPoint(glm::vec2 p) const
{
return findPoint(p, *faces_begin());
}
GeoData::PointFace::PointFace(const glm::vec2 p, const GeoData * mesh) : PointFace {p, mesh, *mesh->faces_begin()} { }
GeoData::PointFace::PointFace(const glm::vec2 p, const GeoData * mesh, FaceHandle start) :
PointFace {p, mesh->findPoint(p, start)}
{
}
GeoData::FaceHandle
GeoData::PointFace::face(const GeoData * mesh, FaceHandle start) const
{
if (_face.is_valid()) {
assert(mesh->triangleContainsPoint(point, _face));
return _face;
}
else {
return (_face = mesh->findPoint(point, start));
}
}
GeoData::FaceHandle
GeoData::PointFace::face(const GeoData * mesh) const
{
return face(mesh, *mesh->faces_begin());
}
namespace {
[[nodiscard]] constexpr inline bool
pointLeftOfLine(const glm::vec2 p, const glm::vec2 e1, const glm::vec2 e2)
{
return (e2.x - e1.x) * (p.y - e1.y) > (e2.y - e1.y) * (p.x - e1.x);
}
static_assert(pointLeftOfLine({1, 2}, {1, 1}, {2, 2}));
static_assert(pointLeftOfLine({2, 1}, {2, 2}, {1, 1}));
static_assert(pointLeftOfLine({2, 2}, {1, 2}, {2, 1}));
static_assert(pointLeftOfLine({1, 1}, {2, 1}, {1, 2}));
[[nodiscard]] constexpr inline bool
linesCross(const glm::vec2 a1, const glm::vec2 a2, const glm::vec2 b1, const glm::vec2 b2)
{
return pointLeftOfLine(a2, b1, b2) && pointLeftOfLine(a1, b2, b1) && pointLeftOfLine(b1, a1, a2)
&& pointLeftOfLine(b2, a2, a1);
}
static_assert(linesCross({1, 1}, {2, 2}, {1, 2}, {2, 1}));
}
OpenMesh::FaceHandle
GeoData::findPoint(glm::vec2 p, OpenMesh::FaceHandle f) const
{
while (f.is_valid() && !triangleContainsPoint(p, triangle<2>(f))) {
for (auto next = cfh_iter(f); next.is_valid(); ++next) {
f = opposite_face_handle(*next);
if (f.is_valid()) {
const auto e1 = point(to_vertex_handle(*next));
const auto e2 = point(to_vertex_handle(opposite_halfedge_handle(*next)));
if (pointLeftOfLine(p, e1, e2)) {
break;
}
}
f.reset();
}
}
return f;
}
glm::vec3
GeoData::positionAt(const PointFace & p) const
{
glm::vec3 out {};
const auto t = triangle<3>(p.face(this));
glm::intersectLineTriangle(p.point ^ 0.F, up, t[0], t[1], t[2], out);
return p.point ^ out[0];
}
[[nodiscard]] std::optional<glm::vec3>
GeoData::intersectRay(const Ray & ray) const
{
return intersectRay(ray, findPoint(ray.start));
}
[[nodiscard]] std::optional<glm::vec3>
GeoData::intersectRay(const Ray & ray, FaceHandle face) const
{
std::optional<glm::vec3> out;
walkUntil(PointFace {ray.start, face}, ray.start + (ray.direction * 10000.F), [&out, &ray, this](FaceHandle face) {
glm::vec2 bari {};
float dist {};
const auto t = triangle<3>(face);
if (glm::intersectRayTriangle(ray.start, ray.direction, t[0], t[1], t[2], bari, dist)) {
out = t * bari;
return true;
}
return false;
});
return out;
}
void
GeoData::walk(const PointFace & from, const glm::vec2 to, const std::function<void(FaceHandle)> & op) const
{
walkUntil(from, to, [&op](const auto & fh) {
op(fh);
return false;
});
}
void
GeoData::walkUntil(const PointFace & from, const glm::vec2 to, const std::function<bool(FaceHandle)> & op) const
{
assert(from.face(this).is_valid()); // TODO replace with a boundary search
auto f = from.face(this);
FaceHandle previousFace;
while (f.is_valid() && !op(f)) {
for (auto next = cfh_iter(f); next.is_valid(); ++next) {
f = opposite_face_handle(*next);
if (f.is_valid() && f != previousFace) {
const auto e1 = point(to_vertex_handle(*next));
const auto e2 = point(to_vertex_handle(opposite_halfedge_handle(*next)));
if (linesCross(from.point, to, e1, e2)) {
previousFace = f;
break;
}
}
f.reset();
}
}
}
bool
GeoData::triangleContainsPoint(const glm::vec2 p, const Triangle<2> & t)
{
const auto mul = [](const glm::vec2 a, const glm::vec2 b, const glm::vec2 c) {
return (a.x - b.x) * (c.y - b.y) - (a.y - b.y) * (c.x - b.x);
};
const auto det = mul(t[1], t[0], t[2]);
return det * mul(t[1], t[0], p) >= 0 && det * mul(t[2], t[1], p) >= 0 && det * mul(t[0], t[2], p) >= 0;
}
bool
GeoData::triangleContainsPoint(const glm::vec2 p, FaceHandle face) const
{
return triangleContainsPoint(p, triangle<2>(face));
}
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