why are shaders on geometry slow?

everytime someone goes on the shaders forum with a question about shaders on blocks, every says that shaders on blocks are slow, personally i have never tested this because i dont really make much use of blocks, so i bring the question to you, why are they so slow?

i think because of how the bsp-tree works. it requires too many state changes because polygons with the same material can't be grouped into bigger batches for rendering them at once.

I think this is a good explanation of ventilator. But then how do engines solve this problem like the ones from id software, or the JupiterX Engine (F.E.A.R.) or the one from the game "Chronicles of Riddick" or even the Lawmaker Engine? They all support CSG objects for big indoor worlds with shaders on level geometry.

But I really hope that the new render kernel will have a similar solution to support modern gpu's.

It has nothing to do with a "BSP-Tree", but otherwise Ventilators explanation goes into the right direction.

A6 renders level blocks not as a whole mesh but as a stream of single polygons. This has no big disadvantage with normal surfaces, but becomes slow when using effects or shaders because the effect is then initialized for every single polygon.

For this reason the new kernel we're currently working on does not render polygon streams anymore, but meshes.

Hi JCL. So are you saying once the new rendering kernel is finished, wed blocks (BSP) will perform well with shaders applied to them? If this is the case, it may change my workflow a bit.

Then the blocks will be as fast as entitys, so you can use what you want. And it will be possible to convert entitys to blocks for having shadows etc.

So shaders will run with the same speed at both.

... yes that would be a designers dream: static soft shadows on top of geometry with shaders applied. When we also have a good working real-time shadow then there is everything you need to create top edge visuals.