feat: Terrain conforming particles

[stephanmeesters]

Merge by rebase

• Relates to Radiation & Toxin Fields Render Incorrectly on Uneven Terrain #1913
• Relates to bugfix: Contamination fields render incorrectly on uneven terrain GeneralsGamePatch2#177

This adds a new render method for particles by allowing them to be terrain conforming. This feature can be enabled for a particle system by using the new INI option IsGroundConforming. The feature as a whole can be enabled/disabled by using the new define ENABLE_TERRAIN_CONFORMING_PARTICLES. It has been integrated with Mauller/Ronin's particle batching.

Design decisions -- todo

Testing

This can be tested by building Patch2 with a modification to particle systems see the data PR.

Alternatively, you can cherry-pick this commit:

git cherry-pick 22dcc0eed

Or use this test build which force-enables the terrain conforming particles.

Performance impact

The test build was used to test a moderately heavy scene (3 nuke cannons + 3 nukes shooting at a hill in Alpine Assault) using a Macbook Pro 2013 base spec aka Potato, which showed a 5.5% average FPS loss.

Test results

Graphics Settings	Resolution	Mode	FPS
Lowest	800x600	Batching	56
Lowest	800x600	No Batching	55
Lowest	800x600	Conforming disabled	57
Very High	800x600	Batching	50
Very High	800x600	No Batching	49
Very High	800x600	Conforming	53
Low	1920x1080	Batching	24
Low	1920x1080	No Batching	24
Low	1920x1080	Conforming	24
Very High	1920x1080	Batching	20
Very High	1920x1080	No Batching	18
Very High	1920x1080	Conforming	22
Very High	3072x1920	Batching	8
Very High	3072x1920	No Batching	8
Very High	3072x1920	Conforming	9

Image gallery

More

Todo

• Rebase after perf(particlesys): Batch same type particles to reduce cost of particle rendering by 15 to 30% #3155
• Add pull ID to commits
• Clean up commits after review
• Replicate in Generals