[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]

[pygame] Formal definitions for the BLEND operations



Hi,

I am trying to write unit tests for the blit blend operations and am running into problems. There are no formal definitions as to what exactly a BLEND_ADD, BLEND_SUB and BLEND_MULT do. Sure they are add, subtract and multiply. But what happens with overflow and underflow. Do they truncate or just return maximum or minimum values. I will not look as the source for the answers because then I would just write the tests to pass rather than making tests that reflect the original intent of the operations.

Lenard

--
Lenard Lindstrom
<len-l@xxxxxxxxx>