Fix size_t -> int -> size_t round trip in Cycles

There are two things achieved by this change:

- No possible downcast of size_t to int when calculating motion steps.
- Disambiguate call to `min()` which was for some reason considered
  ambiguous on 32bit platforms `min(int, unsigned int)`.
- Do the same for the `max()` call to keep them symmetrical.

On an implementation side the `min()` is defined for a fixed width
integer type to disambiguate uint from size_t on 32bit platforms,
and yet be able to use it for 32bit operands on 64bit platforms without
upcast.

This ended up in a bit bigger change as the conditional compile-in of
functions is easiest if the functions is templated. Making the functions
templated required to remove the other source of ambiguity which is
`algorithm.h` which was pulling min/max from std.

Now it is the `math.h` which is the source of truth for min/max.
It was only one place which was relying on `algorithm.h` for these
functions, hence the choice of `math.h` as the safest and least
intrusive.

Fixes 32bit platforms (such as i386) in Debian package build system.

Differential Revision: https://developer.blender.org/D14062

1 files changed, 2 insertions, 2 deletions

diff --git a/intern/cycles/scene/light.cpp b/intern/cycles/scene/light.cpp
index 83e531f42ef..415c4044aee 100644
--- a/intern/cycles/scene/light.cpp
+++ b/intern/cycles/scene/light.cpp
@@ -606,8 +606,8 @@ void LightManager::device_update_background(Device *device,
       ImageMetaData metadata;
       if (!env->handle.empty()) {
         ImageMetaData metadata = env->handle.metadata();
-        environment_res.x = max(environment_res.x, metadata.width);
-        environment_res.y = max(environment_res.y, metadata.height);
+        environment_res.x = max(environment_res.x, (int)metadata.width);
+        environment_res.y = max(environment_res.y, (int)metadata.height);
       }
     }
     if (node->type == SkyTextureNode::get_node_type()) {