revert change which broke default structure getter, fix slice plane volume mesh logic

Author: nmwsharp

src/polyscope.cpp

@@ -1060,8 +1060,6 @@ bool registerStructure(Structure* s, bool replaceIfPresent) {
 
 Structure* getStructure(std::string type, std::string name) {
 
-  if (type == "" || name == "") return nullptr;
-
   // If there are no structures of that type it is an automatic fail
   if (state::structures.find(type) == state::structures.end()) {
     exception("No structures of type " + type + " registered");
@@ -1097,7 +1095,7 @@ bool hasStructure(std::string type, std::string name) {
   // Special automatic case, return any
   if (name == "") {
     if (sMap.size() != 1) {
-      exception("Cannot use automatic structure get with empty name unless there is exactly one structure of that type "
+      exception("Cannot use automatic has-structure test with empty name unless there is exactly one structure of that type "
                 "registered");
     }
     return true;

src/slice_plane.cpp

@@ -125,12 +125,12 @@ void SlicePlane::setSliceGeomUniforms(render::ShaderProgram& p) {
 
 
 void SlicePlane::setVolumeMeshToInspect(std::string meshname) {
-  VolumeMesh* oldMeshToInspect = polyscope::getVolumeMesh(inspectedMeshName);
+  VolumeMesh* oldMeshToInspect = inspectedMeshName == "" ? nullptr : polyscope::getVolumeMesh(inspectedMeshName);
   if (oldMeshToInspect != nullptr) {
     oldMeshToInspect->removeSlicePlaneListener(this);
   }
   inspectedMeshName = meshname;
-  VolumeMesh* meshToInspect = polyscope::getVolumeMesh(inspectedMeshName);
+  VolumeMesh* meshToInspect = inspectedMeshName == "" ? nullptr : polyscope::getVolumeMesh(inspectedMeshName);
   if (meshToInspect == nullptr) {
     inspectedMeshName = "";
     shouldInspectMesh = false;
@@ -153,7 +153,7 @@ void SlicePlane::ensureVolumeInspectValid() {
   // This method exists to save us in any cases where we might be inspecting a volume mesh when that mesh is deleted. We
   // can't just call setVolumeMeshToInspect(""), because that tries to look up the volume mesh.
 
-  if (!hasVolumeMesh(inspectedMeshName)) {
+  if (inspectedMeshName == "" || !hasVolumeMesh(inspectedMeshName)) {
     inspectedMeshName = "";
     shouldInspectMesh = false;
     volumeInspectProgram = nullptr;
@@ -210,7 +210,7 @@ void SlicePlane::drawGeometry() {
   ensureVolumeInspectValid();
 
   if (shouldInspectMesh) {
-    VolumeMesh* vMesh = polyscope::getVolumeMesh(inspectedMeshName);
+    VolumeMesh* vMesh = inspectedMeshName == "" ? nullptr : polyscope::getVolumeMesh(inspectedMeshName);
 
     // guard against situations where the volume mesh we are slicing has been deleted
     if (vMesh == nullptr) {

test/src/volume_mesh_test.cpp

@@ -235,6 +235,10 @@ TEST_F(PolyscopeTest, VolumeMeshCellVector) {
 }
 
 TEST_F(PolyscopeTest, VolumeMeshInspect) {
+
+  // in another test below we repeat the same logic, but with a second mesh present
+  // to ensure the volume mesh lookup logic in the slice plane works right
+
   std::vector<glm::vec3> verts;
   std::vector<std::array<int, 8>> cells;
   std::tie(verts, cells) = getVolumeMeshData();
@@ -256,7 +260,45 @@ TEST_F(PolyscopeTest, VolumeMeshInspect) {
   q1Cat->setEnabled(true);
   polyscope::show(3);
 
-  polyscope::removeAllStructures();
+  // clear it out
+  p->setVolumeMeshToInspect("vol");
+  polyscope::show(3);
 
+  polyscope::removeAllStructures();
   polyscope::removeLastSceneSlicePlane();
 }
+
+TEST_F(PolyscopeTest, VolumeMeshInspectWithExtra) {
+
+  // same as above, but with an additional mesh present
+  // to ensure the volume mesh lookup logic in the slice plane works right
+
+  std::vector<glm::vec3> verts;
+  std::vector<std::array<int, 8>> cells;
+  std::tie(verts, cells) = getVolumeMeshData();
+  polyscope::VolumeMesh* psVol = polyscope::registerVolumeMesh("vol", verts, cells);
+  polyscope::VolumeMesh* psVolExtra = polyscope::registerVolumeMesh("vol extra", verts, cells);
+
+  // plain old inspecting
+  polyscope::SlicePlane* p = polyscope::addSceneSlicePlane();
+  p->setVolumeMeshToInspect("vol");
+  polyscope::show(3);
+
+  // with a scalar quantity
+  std::vector<float> vals(verts.size(), 0.44);
+  auto q1 = psVol->addVertexScalarQuantity("vals", vals);
+  q1->setEnabled(true);
+  polyscope::show(3);
+
+  // with a categorical quantity
+  auto q1Cat = psVol->addVertexScalarQuantity("vals", vals, polyscope::DataType::CATEGORICAL);
+  q1Cat->setEnabled(true);
+  polyscope::show(3);
+
+  // clear it out
+  p->setVolumeMeshToInspect("vol");
+  polyscope::show(3);
+
+  polyscope::removeAllStructures();
+  polyscope::removeLastSceneSlicePlane();
+}