Add option to mjspec for creating a texture directly from a buffer.

PiperOrigin-RevId: 662186527
Change-Id: I469c876681d52964ac971c0bb2ec3517224d3a3d

src/user/user_api.cc

@@ -14,8 +14,10 @@
 
 #include "user/user_api.h"
 
+#include <algorithm>
 #include <cstddef>
 #include <functional>
+#include <iterator>
 #include <map>
 #include <new>
 #include <string>
@@ -877,6 +879,16 @@ mjsMaterial* mjs_asMaterial(mjsElement* element) {
 
 
 
+// copy buffer to destination buffer
+void mjs_setBuffer(mjBuffer* dest, const void* array, int size) {
+  const std::byte* buffer = static_cast<const std::byte*>(array);
+  dest->clear();
+  dest->reserve(size);
+  std::copy_n(buffer, size, std::back_inserter(*dest));
+}
+
+
+
 // set string
 void mjs_setString(mjString* dest, const char* text) {
   std::string* str = static_cast<std::string*>(dest);