updated

libs/yocto/yocto_math.h

@@ -1258,6 +1258,67 @@ inline pair<vec3f, vec3f> quad_tangents_fromuv(vec3f p0, vec3f p1, vec3f p2,
 
 }  // namespace yocto
 
+// -----------------------------------------------------------------------------
+// COMPUTATION OF PER_VERTEX PROPERTIES
+// -----------------------------------------------------------------------------
+namespace yocto {
+
+// Compute per-vertex normals/tangents for lines/triangles/quads.
+inline vector<vec3f> lines_tangents(
+    const vector<vec2i>& lines, const vector<vec3f>& positions);
+inline vector<vec3f> triangles_normals(
+    const vector<vec3i>& triangles, const vector<vec3f>& positions);
+inline vector<vec3f> quads_normals(
+    const vector<vec4i>& quads, const vector<vec3f>& positions);
+// Update normals and tangents
+inline void lines_tangents(vector<vec3f>& tangents, const vector<vec2i>& lines,
+    const vector<vec3f>& positions);
+inline void triangles_normals(vector<vec3f>& normals,
+    const vector<vec3i>& triangles, const vector<vec3f>& positions);
+inline void quads_normals(vector<vec3f>& normals, const vector<vec4i>& quads,
+    const vector<vec3f>& positions);
+
+// Compute per-vertex tangent space for triangle meshes.
+// Tangent space is defined by a four component vector.
+// The first three components are the tangent with respect to the u texcoord.
+// The fourth component is the sign of the tangent wrt the v texcoord.
+// Tangent frame is useful in normal mapping.
+inline vector<vec4f> triangle_tangent_spaces(const vector<vec3i>& triangles,
+    const vector<vec3f>& positions, const vector<vec3f>& normals,
+    const vector<vec2f>& texcoords);
+
+}  // namespace yocto
+
+// -----------------------------------------------------------------------------
+// COMPUTATION OF VERTEX PROPERTIES
+// -----------------------------------------------------------------------------
+namespace yocto {
+
+// Flip vertex normals
+inline vector<vec3f> flip_normals(const vector<vec3f>& normals);
+// Flip face orientation
+inline vector<vec3i> flip_triangles(const vector<vec3i>& triangles);
+inline vector<vec4i> flip_quads(const vector<vec4i>& quads);
+// Align vertex positions. Alignment is 0: none, 1: min, 2: max, 3: center.
+inline vector<vec3f> align_vertices(
+    const vector<vec3f>& positions, vec3i alignment);
+
+}  // namespace yocto
+
+// -----------------------------------------------------------------------------
+// SHAPE ELEMENT CONVERSION
+// -----------------------------------------------------------------------------
+namespace yocto {
+
+// Convert quads to triangles
+inline vector<vec3i> quads_to_triangles(const vector<vec4i>& quads);
+// Convert triangles to quads by creating degenerate quads
+inline vector<vec4i> triangles_to_quads(const vector<vec3i>& triangles);
+// Convert beziers to lines using 3 lines for each bezier.
+inline vector<vec4i> bezier_to_lines(vector<vec2i>& lines);
+
+}  // namespace yocto
+
 // -----------------------------------------------------------------------------
 // USER INTERFACE UTILITIES
 // -----------------------------------------------------------------------------
@@ -3013,6 +3074,217 @@ inline pair<vec3f, vec3f> quad_tangents_fromuv(vec3f p0, vec3f p1, vec3f p2,
 
 }  // namespace yocto
 
+// -----------------------------------------------------------------------------
+// IMPLEMENTATION OF COMPUTATION OF PER-VERTEX PROPERTIES
+// -----------------------------------------------------------------------------
+namespace yocto {
+
+// Compute per-vertex tangents for lines.
+inline vector<vec3f> lines_tangents(
+    const vector<vec2i>& lines, const vector<vec3f>& positions) {
+  auto tangents = vector<vec3f>{positions.size()};
+  for (auto& tangent : tangents) tangent = {0, 0, 0};
+  for (auto& l : lines) {
+    auto tangent = line_tangent(positions[l.x], positions[l.y]);
+    auto length  = line_length(positions[l.x], positions[l.y]);
+    tangents[l.x] += tangent * length;
+    tangents[l.y] += tangent * length;
+  }
+  for (auto& tangent : tangents) tangent = normalize(tangent);
+  return tangents;
+}
+
+// Compute per-vertex normals for triangles.
+inline vector<vec3f> triangles_normals(
+    const vector<vec3i>& triangles, const vector<vec3f>& positions) {
+  auto normals = vector<vec3f>{positions.size()};
+  for (auto& normal : normals) normal = {0, 0, 0};
+  for (auto& t : triangles) {
+    auto normal = triangle_normal(
+        positions[t.x], positions[t.y], positions[t.z]);
+    auto area = triangle_area(positions[t.x], positions[t.y], positions[t.z]);
+    normals[t.x] += normal * area;
+    normals[t.y] += normal * area;
+    normals[t.z] += normal * area;
+  }
+  for (auto& normal : normals) normal = normalize(normal);
+  return normals;
+}
+
+// Compute per-vertex normals for quads.
+inline vector<vec3f> quads_normals(
+    const vector<vec4i>& quads, const vector<vec3f>& positions) {
+  auto normals = vector<vec3f>{positions.size()};
+  for (auto& normal : normals) normal = {0, 0, 0};
+  for (auto& q : quads) {
+    auto normal = quad_normal(
+        positions[q.x], positions[q.y], positions[q.z], positions[q.w]);
+    auto area = quad_area(
+        positions[q.x], positions[q.y], positions[q.z], positions[q.w]);
+    normals[q.x] += normal * area;
+    normals[q.y] += normal * area;
+    normals[q.z] += normal * area;
+    if (q.z != q.w) normals[q.w] += normal * area;
+  }
+  for (auto& normal : normals) normal = normalize(normal);
+  return normals;
+}
+
+// Compute per-vertex tangents for lines.
+inline void lines_tangents(vector<vec3f>& tangents, const vector<vec2i>& lines,
+    const vector<vec3f>& positions) {
+  if (tangents.size() != positions.size()) {
+    throw std::out_of_range("array should be the same length");
+  }
+  for (auto& tangent : tangents) tangent = {0, 0, 0};
+  for (auto& l : lines) {
+    auto tangent = line_tangent(positions[l.x], positions[l.y]);
+    auto length  = line_length(positions[l.x], positions[l.y]);
+    tangents[l.x] += tangent * length;
+    tangents[l.y] += tangent * length;
+  }
+  for (auto& tangent : tangents) tangent = normalize(tangent);
+}
+
+// Compute per-vertex normals for triangles.
+inline void triangles_normals(vector<vec3f>& normals,
+    const vector<vec3i>& triangles, const vector<vec3f>& positions) {
+  if (normals.size() != positions.size()) {
+    throw std::out_of_range("array should be the same length");
+  }
+  for (auto& normal : normals) normal = {0, 0, 0};
+  for (auto& t : triangles) {
+    auto normal = triangle_normal(
+        positions[t.x], positions[t.y], positions[t.z]);
+    auto area = triangle_area(positions[t.x], positions[t.y], positions[t.z]);
+    normals[t.x] += normal * area;
+    normals[t.y] += normal * area;
+    normals[t.z] += normal * area;
+  }
+  for (auto& normal : normals) normal = normalize(normal);
+}
+
+// Compute per-vertex normals for quads.
+inline void quads_normals(vector<vec3f>& normals, const vector<vec4i>& quads,
+    const vector<vec3f>& positions) {
+  if (normals.size() != positions.size()) {
+    throw std::out_of_range("array should be the same length");
+  }
+  for (auto& normal : normals) normal = {0, 0, 0};
+  for (auto& q : quads) {
+    auto normal = quad_normal(
+        positions[q.x], positions[q.y], positions[q.z], positions[q.w]);
+    auto area = quad_area(
+        positions[q.x], positions[q.y], positions[q.z], positions[q.w]);
+    normals[q.x] += normal * area;
+    normals[q.y] += normal * area;
+    normals[q.z] += normal * area;
+    if (q.z != q.w) normals[q.w] += normal * area;
+  }
+  for (auto& normal : normals) normal = normalize(normal);
+}
+
+// Compute per-vertex tangent frame for triangle meshes.
+// Tangent space is defined by a four component vector.
+// The first three components are the tangent with respect to the U texcoord.
+// The fourth component is the sign of the tangent wrt the V texcoord.
+// Tangent frame is useful in normal mapping.
+inline vector<vec4f> triangles_tangent_spaces(const vector<vec3i>& triangles,
+    const vector<vec3f>& positions, const vector<vec3f>& normals,
+    const vector<vec2f>& texcoords) {
+  auto tangu = vector<vec3f>(positions.size(), vec3f{0, 0, 0});
+  auto tangv = vector<vec3f>(positions.size(), vec3f{0, 0, 0});
+  for (auto t : triangles) {
+    auto tutv = triangle_tangents_fromuv(positions[t.x], positions[t.y],
+        positions[t.z], texcoords[t.x], texcoords[t.y], texcoords[t.z]);
+    for (auto vid : {t.x, t.y, t.z}) tangu[vid] += normalize(tutv.first);
+    for (auto vid : {t.x, t.y, t.z}) tangv[vid] += normalize(tutv.second);
+  }
+  for (auto& t : tangu) t = normalize(t);
+  for (auto& t : tangv) t = normalize(t);
+
+  auto tangent_spaces = vector<vec4f>(positions.size());
+  for (auto& tangent : tangent_spaces) tangent = vec4f{0, 0, 0, 0};
+  for (auto i = 0; i < positions.size(); i++) {
+    tangu[i] = orthonormalize(tangu[i], normals[i]);
+    auto s   = (dot(cross(normals[i], tangu[i]), tangv[i]) < 0) ? -1.0f : 1.0f;
+    tangent_spaces[i] = {tangu[i].x, tangu[i].y, tangu[i].z, s};
+  }
+  return tangent_spaces;
+}
+
+}  // namespace yocto
+
+// -----------------------------------------------------------------------------
+// COMPUTATION OF PER VERTEX PROPERTIES
+// -----------------------------------------------------------------------------
+namespace yocto {
+
+// Flip vertex normals
+inline vector<vec3f> flip_normals(const vector<vec3f>& normals) {
+  auto flipped = normals;
+  for (auto& n : flipped) n = -n;
+  return flipped;
+}
+// Flip face orientation
+inline vector<vec3i> flip_triangles(const vector<vec3i>& triangles) {
+  auto flipped = triangles;
+  for (auto& t : flipped) swap(t.y, t.z);
+  return flipped;
+}
+inline vector<vec4i> flip_quads(const vector<vec4i>& quads) {
+  auto flipped = quads;
+  for (auto& q : flipped) {
+    if (q.z != q.w) {
+      swap(q.y, q.w);
+    } else {
+      swap(q.y, q.z);
+      q.w = q.z;
+    }
+  }
+  return flipped;
+}
+
+}  // namespace yocto
+
+// -----------------------------------------------------------------------------
+// IMPLEMENTATION OF SHAPE ELEMENT CONVERSION
+// -----------------------------------------------------------------------------
+namespace yocto {
+
+// Convert quads to triangles
+inline vector<vec3i> quads_to_triangles(const vector<vec4i>& quads) {
+  auto triangles = vector<vec3i>{};
+  triangles.reserve(quads.size() * 2);
+  for (auto& q : quads) {
+    triangles.push_back({q.x, q.y, q.w});
+    if (q.z != q.w) triangles.push_back({q.z, q.w, q.y});
+  }
+  return triangles;
+}
+
+// Convert triangles to quads by creating degenerate quads
+inline vector<vec4i> triangles_to_quads(const vector<vec3i>& triangles) {
+  auto quads = vector<vec4i>{};
+  quads.reserve(triangles.size());
+  for (auto& t : triangles) quads.push_back({t.x, t.y, t.z, t.z});
+  return quads;
+}
+
+// Convert beziers to lines using 3 lines for each bezier.
+inline vector<vec2i> bezier_to_lines(const vector<vec4i>& beziers) {
+  auto lines = vector<vec2i>{};
+  lines.reserve(beziers.size() * 3);
+  for (auto b : beziers) {
+    lines.push_back({b.x, b.y});
+    lines.push_back({b.y, b.z});
+    lines.push_back({b.z, b.w});
+  }
+  return lines;
+}
+
+}  // namespace yocto
+
 // -----------------------------------------------------------------------------
 // USER INTERFACE UTILITIES
 // -----------------------------------------------------------------------------