Cleanup: CacheFile, use double precision for time

Both the Alembic and USD libraries use double precision floating
point numbers internally to store time. However the Alembic I/O
code defaulted to floats even though Blender's Scene FPS, which is
generally used for look ups, is stored using a double type. Such
downcasts could lead to imprecise lookups, and would cause
compilation warnings (at least on MSVC).

This modifies the Alembic exporter and importer to make use of
doubles for the current scene time, and only downcasting to float
at the very last steps (e.g. for vertex interpolation). For the
importer, doubles are also used for computing interpolation weights,
as it is based on a time offset.

Although the USD code already used doubles internally, floats were used
at the C API level. Those were replaced as well.

Differential Revision: https://developer.blender.org/D13855

1 files changed, 2 insertions, 2 deletions

diff --git a/source/blender/io/usd/intern/usd_capi_import.cc b/source/blender/io/usd/intern/usd_capi_import.cc
index e5083700d7d..58cd7d5014e 100644
--- a/source/blender/io/usd/intern/usd_capi_import.cc
+++ b/source/blender/io/usd/intern/usd_capi_import.cc
@@ -423,7 +423,7 @@ static USDPrimReader *get_usd_reader(CacheReader *reader, Object * /* ob */, con
 struct Mesh *USD_read_mesh(struct CacheReader *reader,
                            struct Object *ob,
                            struct Mesh *existing_mesh,
-                           const float time,
+                           const double time,
                            const char **err_str,
                            const int read_flag)
 {
@@ -437,7 +437,7 @@ struct Mesh *USD_read_mesh(struct CacheReader *reader,
 }
 
 bool USD_mesh_topology_changed(
-    CacheReader *reader, Object *ob, Mesh *existing_mesh, const float time, const char **err_str)
+    CacheReader *reader, Object *ob, Mesh *existing_mesh, const double time, const char **err_str)
 {
   USDGeomReader *usd_reader = dynamic_cast<USDGeomReader *>(get_usd_reader(reader, ob, err_str));