Tree branches contact - Drag or damage in Battle of Britain?

[X32Wright]

The placement of the 'high resolution' polygons are not determined by where they are 'positioned' in the map but rather how close they are to the 'virtual camera'. Although this cane be done too by the game developer meaning it can program the higher density polygons to be loaded near the bases but in general LOD (level of detail) loading is determined by view and camera distance. So this means if you are looking 'externally or 'from inside the cockpit' this distance to the trees determines HOW and WHEN the high resolution polygons are loaded. The issue is still the same because even with LOD too much detailed trees would still increase the overall polygon load specially with damage modeling on them.

Surely 2D polygon cutout trees as modeled and rendered can be made to orient to the camera hereby making it appear 3D, it is the number of them thats still an issue in a fli-sim. This 'polyface orientation based on camera view' technique is already being used int eh game though in the cloud generation.

FPS games tho cheats, they dont exactly show all the trees or all the polygons since there is a lot of CLIPPING and CULLING (back-face) happening there based on occlusion. This means objects that are obscured even temporarily by the camera are immediately removed or buffered so in these fps games they always look like there is more in the scene than actually is being 'rendered' in real-time. This is harder to do with fli-sim where your view extends 'forever' at at least as far as the camera near and far clipping planes are set to.

[JVM]

If it was possible indeed to use the technique I described higher in the post, technique which involves only a computation based on relative heigth, it would be the cherry on the cake to make one (or two, varying the cut heigth) damaged tree model (= cut normal tree...would you believe that?) for each tree type and

- either to replace entirely every tree impacted in the crash by its closest damaged counter part...
- or to make it simple remove the impacted trees and then no need to make a damaged tree!

Both would be visually quite good...Now what impact would it have on the FPS, compared to a normal crash with associated crater for example?

This being said I hope the craters will be a lot better and more complex than in IL2...whether they are from bomb or crashes...the Il2 ones are ugly and nowhere near realistic, even for a texture! I have never understood why? Immersion killer again...

JVM

[X32Wright]

I dont think you understand the enormity and complexity of tree interaction and the resulting increase in polygon load. Surely there would be programmed to have localized adaptive subdivision when it comes to collision detection based on proximity of a plane to the ground and trees but those would still require enormous resources (CPU,GPU and polygon load). Most GPU today are not made for handling enormous polygon loads but rather are optimized for enormous TEXTURE handling instead as well as shader processing and some geometry calculations. They aren't geared for handling 'interactive' 4 million polygon scenes at all (although they might be able to load that in memory but not interactively) while the CAD workstation cards are (which renders everything accurately and NOT cheat like the game cards which do not render everything), although things are changing.

Computation based on the height will work since they trees and such are placed on 'height field' generated terain as it is already but even with a simple 4 triangle tree that would require more resources and more polygons to pull off IF you want interactivity with the plane instead of a simple collision detection that we have now. I am asuming that the collision detection (plane vs ground or trees collision detection) in the game isnt even collision detection per se but rather based on the coordinates of the plane's axis. IF the computed vector (for the plane) falls beyond the 'ZERO ground axis' the plane is designated as crashed. But this is a guess. Having to apply this to trees is a waste of time. This is why we crash on the large 'invisible trees' (which are 'height displaced geometry' (pancaked) mapped with alpha channels to look like forrests) but pass through the ones that look and feel solid (those with swaying detailed leaves).

As for better craters well, Oleg can always implement bump mapping and procedural displacement (even animated) but didnt chose to do so in Il-2. My guess would be due to the video cards' capability limitations when Il-2 was released.

[JVM]

Originally Posted by X32Wright

I dont think you understand the enormity and complexity of tree interaction and the resulting increase in polygon load. Surely there would be programmed to have localized adaptive subdivision when it comes to collision detection based on proximity of a plane to the ground and trees but those would still require enormous resources (CPU,GPU and polygon load). Most GPU today are not made for handling enormous polygon loads but rather are optimized for enormous TEXTURE handling instead as well as shader processing and some geometry calculations. They aren't geared for handling 'interactive' 4 million polygon scenes at all (although they might be able to load that in memory but not interactively) while the CAD workstation cards are (which renders everything accurately and NOT cheat like the game cards which do not render everything), although things are changing.

Computation based on the height will work since they trees and such are placed on 'height field' generated terain as it is already but even with a simple 4 triangle tree that would require more resources and more polygons to pull off IF you want interactivity with the plane instead of a simple collision detection that we have now. I am asuming that the collision detection (plane vs ground or trees collision detection) in the game isnt even collision detection per se but rather based on the coordinates of the plane's axis. IF the computed vector (for the plane) falls beyond the 'ZERO ground axis' the plane is designated as crashed. But this is a guess. Having to apply this to trees is a waste of time. This is why we crash on the large 'invisible trees' (which are 'height displaced geometry' (pancaked) mapped with alpha channels to look like forrests) but pass through the ones that look and feel solid (those with swaying detailed leaves).

As for better craters well, Oleg can always implement bump mapping and procedural displacement (even animated) but didnt chose to do so in Il-2. My guess would be due to the video cards' capability limitations when Il-2 was released.

I may not have explained myself clearly: in the system I was thinking about, the collision detection is between a segment (representing he tree trunk at the tree geographical position) whose length and altitude is known and the parts of the A/C model used in the collision detection. I agree with you in that no additional part of the tree and notably not the triangles giving it volume (assuming the trees would be real individual 3D objects) would be involved, because there is no need, trees being what they are. For a building it would be more complicated, but there are less of them fortunately!

As for the craters I also agree with you, the graphical processors of the time were not up to the task of depicting them realistically...but why so horrible textures? The Il2 craters do not resemble at all to bomb craters (have you ever seen earth projections going in zigzag like that?) They do no look like craters at all...It is a tad bizarre as there never was any shortage of real crater pictures around...

[X32Wright]

Still, this means at least that the trees will have to be modeled with a TRUNK and then the 4 sided leaves (top area) so that means 4 triangles plus at least another three triangles for the trunk. Considering that it has no 'bounding boxes' for collision detetcion thats still 4x3=12 polygons per tree X thousands. If you make the tree TRUNK as a SINGLE polygon that ORIENTS to the camera this means 5 polygons per tree, thats still alot to render for most graphic cards.


As for the crater effect they just used texture maps mapped to flat polygons for most effect in this game including smoke and clouds, they just either is animated and moved to create an moving effect. The crate effect itself could just be texture serial replacement.

[BENGALtiger]

A more efficient approach:

How about giving the forest area a damage effect like we have in water (and maybe slightly modified variables for a different effect)

Imagine it.

Softly landing on trees will give an effect like getting stuck in the trees, and then slowly going downward (trough trees, breaking them due to weight) until you reach ground (Il2 water already does this). You can maybe bail out of your plane like you can in water.

Smacking into trees at high speed gives you explosion like in water.

Wingtip touching trees will cause that wing to get break off like in water (or edit some properties from what we have now in Il2, to cause damage instead of total break off of the wing or whatever body part that is in contact with trees [virtually Il2 water])

Have sparks and twigs and leaves flying instead of ripples in water, obviously. Hmm I'm trying to imagine the sound from cockpit

It seems like the simplest solution to me. Basically forest areas will be like water, with raised altitude.

What do you guys think?

- Bengal

[X32Wright]

Water is treated like the ground (treated Z and Y axis only even with height field displacement) so I think that depends on the vector computations as well as geometry axis displacement. Since trees cannot be treated like a 'single complete surface' (it has X,Y and Z 'depth' dimensions) since it has dimensions, the problem is much more complex with trees if it is desired to have this interactivity.

Don't get me wrong I want to see this too but I am practical too since I know what would BOG down the resources in the game. I would rather have all tehse extra polygons in the plane for detailed damage modeling rather than being used for trees.

[BG-09]

Originally Posted by BENGALtiger

A more efficient approach:
Softly landing on trees will give an effect like getting stuck in the trees, and then slowly going downward (trough trees, breaking them due to weight) until you reach ground (Il2 water already does this). You can maybe bail out of your plane like you can in water.

Smacking into trees at high speed gives you explosion like in water.

Wingtip touching trees will cause that wing to get break off like in water (or edit some properties from what we have now in Il2, to cause damage instead of total break off of the wing or whatever body part that is in contact with trees [virtually Il2 water])

Have sparks and twigs and leaves flying instead of ripples in water, obviously. Hmm I'm trying to imagine the sound from cockpit

Nice effects You are describing BENGALtiger. I belive that the forests and trees are the most neglected objects in to the current simulator. But with new CPU, and Olegs determination to rule the world of aircraft simulation in to the next 20 years, we will be granted with marvellous aircrafts and the world for them to fly.

Cheers!


Bg-09