Improve performance of Bufferable::update_buffer_data

[libs/gl.git] / source / bufferable.cpp

diff --git a/source/bufferable.cpp b/source/bufferable.cpp
index 4660e9c31b32f787bfc553326078da669063b0a5..12e0aef7d345da45e948820606211926c1de9b49 100644 (file)
--- a/source/bufferable.cpp
+++ b/source/bufferable.cpp
@@ -74,19 +74,22 @@ void Bufferable::update_buffer_offset()
 
 void Bufferable::update_buffer_data() const
 {
-       const Bufferable *first = this;
-       for(; first->prev_in_buffer; first=first->prev_in_buffer) ;
-
-       unsigned total_size = 0;
-       for(const Bufferable *b=first; b; b=b->next_in_buffer)
-               total_size += b->get_data_size();
-
-       if(total_size!=buffer->get_size())
+       if(buffer_offset+get_data_size()>=buffer->get_size())
        {
-               buffer->data(total_size, 0);
-               // Resizing the buffer invalidates its contents.
-               for(const Bufferable *b=first; b; b=b->next_in_buffer)
-                       b->dirty = true;
+               const Bufferable *last = this;
+               for(; last->next_in_buffer; last=last->next_in_buffer) ;
+
+               unsigned total_size = last->buffer_offset+last->get_data_size();
+
+               if(total_size>buffer->get_size())
+               {
+                       buffer->data(total_size, 0);
+                       /* Resizing the buffer invalidates its contents.  Non-dirty data may
+                       be in use, so reupload it. */
+                       for(const Bufferable *b=last; b; b=b->prev_in_buffer)
+                               if(!b->dirty)
+                                       b->upload_data();
+               }
        }
 
        upload_data();