Why can't blender internal use GPU cores ?

Greetings,
No solar flare damage I hope. Can a kind soul give me a summary on why the blender internal render engine can’t use GPU cores? Blender internal gets the job done for every feature in Blender, however on slow hardware large scenes or animations can be slow to render. I am grateful for Blender and Cycles BUT I have a hole in my understanding of how this works and it drives me nuts. :confused:
Thank you for your time,
Tom

To put it simply, in order to use GPUs the renderer must be designed with some special constraints and considerations in mind. Blender Internal wasn’t designed that way since it was written a long time before GPU rendering was even a possibility. Making BI use the GPU isn’t a viable project at this point, the methods used by BI are not a good match for GPU rendering.

If you are rendering large scenes, don’t use approximate AO as that scales badly with scene complexity.

I am grateful for Blender and Cycles BUT I have a hole in my understanding of how this works and it drives me nuts. :confused:
Few parts of blender internal could be moved to the GPU without basically redesigning the whole thing, and the speed gained from that isn’t necessarily worth the effort. But more importantly: There are no developers available to work on BI. There’s basically one guy that used to work on it, and now he’s doing Cycles.

Yeah, BI was not designed with these things in mind so it’s practically the same as starting a new renderer from scratch (or perhaps worse). During the Durian project (Sintel) there was a special “render25” branch where experimental features like micropolygons and GI were added to blender internal. That proved to be more of a headache than it was worth, so a decision was made to start fresh with Cycles.

Another thing to take into account is that GPU rendering isn’t a magic bullet that will speed everything up. GPUs are mainly good for parallel tasks like raytracing. As fast as they are, they are not as versatile as a CPU is.

Thank you all for the explanations and history. Makes sense. And thanks for the AO tip.
Cheers.

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