This was done to clean up the license and to ensure that any commercial fork of the engine has to obey the far stricter requirements concerning source distribution. The old license was compatible with GPLv2 whereas combining GPLv2 and LGPLv3 force a license upgrade to GPLv3. The license of code that originates from ZDoomGL has not been changed.
That's again one less write access to the buffer. The uniform method was chosen because this way a buffer update can be completely avoided, and setting a single uniform is a lot cheaper and simpler to handle.
Unfortunately the math behind the old clip planes is utterly impenetrable and so poorly documented that I have no idea how to set that up, so it is deactivated for now. It wasn't working anyway.
- fixed: The shader code for handling special fixed colormaps did not use the color vertex attribute which was most evident with the 'shadow' render style on the spectre.
Due to the way the engine works it needs to render a lot of small primitives with frequent state changes.
But due to the performance of buffer uploads it is impossible to upload each primitive's vertices to a buffer separately because buffer uploads nearly always stall the GPU.
On the other hand, in order to reduce the amount of buffer uploads all the necessary state changes would have to be saved in an array until they can finally be used. This method also imposed an unacceptable overhead.
Fortunately, uploading uniform arrays is very fast and doesn't cause GPU stalls, so now the engine puts the vertex data per primitive into a uniform array and uses a static vertex buffer to index the array in the vertex shader.
This method offers the same performance as immediate mode but only uses core profile features.
