assimp: add various config variables, change default winding order

pandatool/src/assimp/assimpLoader.cxx

@@ -103,9 +103,34 @@ bool AssimpLoader::
 read(const Filename &filename) {
   _filename = filename;
 
-  // I really don't know why we need to flip the winding order, but otherwise
-  // the models I tested with are showing inside out.
-  _scene = _importer.ReadFile(_filename.c_str(), aiProcess_Triangulate | aiProcess_GenUVCoords | aiProcess_FlipWindingOrder);
+  unsigned int flags = aiProcess_Triangulate | aiProcess_GenUVCoords;
+
+  if (assimp_calc_tangent_space) {
+    flags |= aiProcess_CalcTangentSpace;
+  }
+  if (assimp_join_identical_vertices) {
+    flags |= aiProcess_JoinIdenticalVertices;
+  }
+  if (assimp_improve_cache_locality) {
+    flags |= aiProcess_ImproveCacheLocality;
+  }
+  if (assimp_remove_redundant_materials) {
+    flags |= aiProcess_RemoveRedundantMaterials;
+  }
+  if (assimp_fix_infacing_normals) {
+    flags |= aiProcess_FixInfacingNormals;
+  }
+  if (assimp_optimize_meshes) {
+    flags |= aiProcess_OptimizeMeshes;
+  }
+  if (assimp_optimize_graph) {
+    flags |= aiProcess_OptimizeGraph;
+  }
+  if (assimp_flip_winding_order) {
+    flags |= aiProcess_FlipWindingOrder;
+  }
+
+  _scene = _importer.ReadFile(_filename.c_str(), flags);
   if (_scene == nullptr) {
     _error = true;
     return false;

pandatool/src/assimp/config_assimp.cxx

@@ -25,6 +25,50 @@ ConfigureFn(config_assimp) {
   init_libassimp();
 }
 
+ConfigVariableBool assimp_calc_tangent_space
+("assimp-calc-tangent-space", false,
+ PRC_DESC("Calculates tangents and binormals for meshes imported via Assimp."));
+
+ConfigVariableBool assimp_join_identical_vertices
+("assimp-join-identical-vertices", true,
+ PRC_DESC("Merges duplicate vertices.  Set this to false if you want each "
+          "vertex to only be in use on one triangle."));
+
+ConfigVariableBool assimp_improve_cache_locality
+("assimp-improve-cache-locality", true,
+ PRC_DESC("Improves rendering performance of the loaded meshes by reordering "
+          "triangles for better vertex cache locality.  Set this to false if "
+          "you need geometry to be loaded in the exact order that it was "
+          "specified in the file, or to improve load performance."));
+
+ConfigVariableBool assimp_remove_redundant_materials
+("assimp-remove-redundant-materials", true,
+ PRC_DESC("Removes redundant/unreferenced materials from assets."));
+
+ConfigVariableBool assimp_fix_infacing_normals
+("assimp-fix-infacing-normals", false,
+ PRC_DESC("Determines which normal vectors are facing inward and inverts them "
+          "so that they are facing outward."));
+
+ConfigVariableBool assimp_optimize_meshes
+("assimp-optimize-meshes", true,
+ PRC_DESC("Removes the number of draw calls by unifying geometry with the same "
+          "materials.  Especially effective in conjunction with "
+          "assimp-optimize-graph and assimp-remove-redundant-materials."));
+
+ConfigVariableBool assimp_optimize_graph
+("assimp-optimize-graph", false,
+ PRC_DESC("Optimizes the scene geometry by flattening the scene hierarchy.  "
+          "This is very efficient (combined with assimp-optimize-meshes), but "
+          "it may result the hierarchy to become lost, so it is disabled by "
+          "default."));
+
+ConfigVariableBool assimp_flip_winding_order
+("assimp-flip-winding-order", false,
+ PRC_DESC("Set this true to flip the winding order of all models loaded via "
+          "the Assimp loader.  Note that you may need to clear the model-cache "
+          "after changing this."));
+
 /**
  * Initializes the library.  This must be called at least once before any of
  * the functions or classes in this library can be used.  Normally it will be

pandatool/src/assimp/config_assimp.h

@@ -15,12 +15,21 @@
 #define CONFIG_ASSIMP_H
 
 #include "pandatoolbase.h"
-
+#include "configVariableBool.h"
 #include "dconfig.h"
 
 ConfigureDecl(config_assimp, EXPCL_ASSIMP, EXPTP_ASSIMP);
 NotifyCategoryDecl(assimp, EXPCL_ASSIMP, EXPTP_ASSIMP);
 
+extern ConfigVariableBool assimp_calc_tangent_space;
+extern ConfigVariableBool assimp_join_identical_vertices;
+extern ConfigVariableBool assimp_improve_cache_locality;
+extern ConfigVariableBool assimp_remove_redundant_materials;
+extern ConfigVariableBool assimp_fix_infacing_normals;
+extern ConfigVariableBool assimp_optimize_meshes;
+extern ConfigVariableBool assimp_optimize_graph;
+extern ConfigVariableBool assimp_flip_winding_order;
+
 extern EXPCL_ASSIMP void init_libassimp();
 
 #endif