Forest Fires

Overview

New as of rel2022.1+, the main purpose of this feature is to enable pc-nova to render a forest fire fighting simulation. As a whole, "fire fighting" covers a number of integrated pieces based on contractual requirements and these are summarized below:

• Forest fire and smoke effects.
• Multiple definable areas of trees that may be burnt
• A content library of "burned" tree models that can be swapped with normal trees they are mapped to.
• Blackened terrain in the clipmap over burned areas
• Water dump effect with tunable spray dynamics.
• AW-139 & 500-gal BAMBI bucket models which execute the water dump.

Configuration

Optional Tokens

1. ConfigBurntTreeInstancedLib → DB_OVERLAY\DB_GLOBAL_DOD_V20\RELEASE\V20_1\R2P\DB_FEATURES\GENERIC\TREE_LIB\instancedlib_burnedtrees.cfg
   1. See burnt trees section below for a detailed example of the BurntTreeInstancedLib and .hie formats.

Required Data

AW-139 & BAMBI Bucket Models:

• • Using a post re-org database, you should be loading the AW-139 & BAMBI models into specific indices.
    Note: This will enable the keyboard shortcut "E" (requires token "ControlKeyboard Advanced" in override file) to have all the pieces it needs to setup the models & parenting. Press E 6 times as an alternative shortcut to enable turning on the forest fire icds.

    AW-139 & Bambi Bucket

    CODE

    list_type ASIGN_AER
    {
    7 COMMON/RELEASE/V1/DB/DB_MOVING_MODELS/MILITARY/HELICOPTER/AW_139/AW_139_AM.hie COMMON/RELEASE/V1/DB/DB_MOVING_MODELS/MILITARY/HELICOPTER/AW_139/AW_139_AM.fx
    }
    
    list_type ASIGN_SLING
    {
    3 COMMON/RELEASE/V1/DB/DB_MOVING_MODELS/ELEMENTS/SLING_LOAD/BAMBI_BUCKET_500gal/BAMBI_BUCKET_500gal.hie COMMON/RELEASE/V1/DB/DB_MOVING_MODELS/ELEMENTS/SLING_LOAD/BAMBI_BUCKET_500gal/BAMBI_BUCKET_500gal.fx
    }

Burnt Trees

Burnt trees refer to alternative textures for trees, which are swapped in when an area is in a burnt region defined in the forest_burn_hv packet.

• • The config token ConfigBurntTreeInstancedLib above points to a file which is used to load burnt tree textures and geostates. This file is NOT required to render the burnt trees.
  • Below is a BurntTreeInstancedLib file example.

  • BurntTreeInstancedLib Example

    TEXT

    # FORMAT: <instance #> <GST path without extension>
      1 R2P/DB_FEATURES/GENERIC/TREE_LIB/SHRUB_6FT_BURNT/SHRUB_6FT_BURNT
      2 R2P/DB_FEATURES/GENERIC/TREE_LIB/DECIDUOUS_46FT_BURNT/DECIDUOUS_46FT_BURNT

Trees that have alternative burnt textures should have two switch nodes in the .hie, with the first being SW_BURNT OFF and the second SW_BURNT ON.

• • Below the ON (burnt) branch is a geo node similar to the X-Tree geo node in the OFF branch except with a burnt tree geostate. The OFF branch is simply the old non-burnable tree structure.

  • Burnable Tree Hie Example

    CODE

    NAMEDSW SW_BURNT OFF 1
    {
      LOD LO_WALNUT_EUROPEAN_COLUMNAR_34FT C 0.0 0.0 0.0 R (0.0 384.0 65000.0)
      {
        GEO WALNUT_EUROPEAN_COLUMNAR_34FT_ANIM
        {
            CFILE WALNUT_EUROPEAN_COLUMNAR_34FT_ANIM.cpto GST_WALNUT_EUROPEAN_COLUMNAR_34FT
        }
        GEO WALNUT_EUROPEAN_COLUMNAR_34FT
        {
          CFILE WALNUT_EUROPEAN_COLUMNAR_34FT.cpto GST_WALNUT_EUROPEAN_COLUMNAR_34FT
        }
      }
    }
    NAMEDSW SW_BURNT ON 1
    {
      GEO WALNUT_EUROPEAN_COLUMNAR_34FT
      {
          CFILE WALNUT_EUROPEAN_COLUMNAR_34FT.cpto GST_DECIDUOUS_46FT_BURNT
      }
    }

General Usage

ICD interface

The forest fire and forest burn ICDs support a total of 20 fire regions and 10 burn regions respectively. The water spray effect is controlled independently via its own ICD struct.  The blocks below generally summarize what each entity is capable of through the ICD structure.

forest_fire_hv[]

ICD.dat_hst.forest_fire_hv[i].fire_enable     = 0 or 1 -> enable/disable
ICD.dat_hst.forest_fire_hv[i].smoke_enable    = 0 or 1 -> enable/disable
ICD.dat_hst.forest_fire_hv[i].fire_intensity  = 0.0 - 1.0 -> Intensity scalar
ICD.dat_hst.forest_fire_hv[i].smoke_intensity = 0.0 - 1.0 -> Intensity scalar
ICD.dat_hst.forest_fire_hv[i].radius          = region radius in m
ICD.dat_hst.forest_fire_hv[i].position[0]     = lat component of region pos
ICD.dat_hst.forest_fire_hv[i].position[1]     = long component of region pos

forest_burn_hv[]

ICD.dat_hst.forest_burn_hv[i].enabled        = 0 or 1 -> enable/disable
ICD.dat_hst.forest_burn_hv[i].radius         = burned area in m
ICD.dat_hst.forest_burn_hv[i].position[0]    = lat component of region pos
ICD.dat_hst.forest_burn_hv[i].position[1]    = long component of region pos

fire_fighting_water_dump_hv

ICD.dat_hst.fire_fighting_water_dump_hv.enable                  = 0 or 1 -> enable/disable
ICD.dat_hst.fire_fighting_water_dump_hv.trigger                 = incremental triger (++) for spray dump
ICD.dat_hst.fire_fighting_water_dump_hv.parent.type             = parent entity type
ICD.dat_hst.fire_fighting_water_dump_hv.parent.id               = id of entity parented to
ICD.dat_hst.fire_fighting_water_dump_hv.parent.attachment_point = attach point for pairing water spray
ICD.dat_hst.fire_fighting_water_dump_hv.size                    = spray size scalar (0 is default size)
ICD.dat_hst.fire_fighting_water_dump_hv.speed[0]                = X component of water spray speed
ICD.dat_hst.fire_fighting_water_dump_hv.speed[1]                = y component of water spray speed
ICD.dat_hst.fire_fighting_water_dump_hv.speed[2]                = z component of water spray speed
ICD.dat_hst.fire_fighting_water_dump_hv.position[0]                = X component of water spray position (relative or absolute)
ICD.dat_hst.fire_fighting_water_dump_hv.position[1]                = y component of water spray position (relative or absolute)
ICD.dat_hst.fire_fighting_water_dump_hv.position[2]                = z component of water spray position (relative or absolute)

Runtime Operation

Basic end-to-end process for operating a small forest fire, then extinguishing it.

Changing Number of Fires in Region

The actual number of individual fire and smoke column sprites are by default determined by the radius of the fire region. This can be quickly summarized like so:

• • At radius < 75, one region will be populated by a singular fire and smoke sprite.
    At radius >= 75, one region will have up to 5 fire and smoke sprites spread out over its area.
    At radius > 200, one region will have up to 15 fire and smoke sprites spread out over its area.

From left to right, the pictures in the section below demonstrate how the fire sprites multiply according to these rules. 

Animating the BAMBI bucket

While animation of the bambi bucket is not required to trigger the fire fighting water dump, it has a bit of nice granularity between states and adds additional realism to the scene.

Adding Forest Fire Haze

In larger forest fires, it is common for a brown/orange haze to form which envelops the entire area in low visibility. Typically this happens because wildfire smoke scatters the sunlight, making the brownish red colors, which have the longest wavelength of light, appear more prominently. This is why in pc-nova we represent both the wildfire smoke, and the forest_fire_haze as the same color.

To use the forest fire haze, we interact with the fog ICD. A quick guide below:

NOTE: The left picture is comparison to a real world stock image of forest fire haze, the right is how we represent this in pc-nova

Optional Fx Tuning

The following files contain relevant FX tokens which act as knobs to tune various elements of the forest fires, burn regions and water spray.

• • Forest_Fire_base.fx → Tunes most fire related params. The following tokens will have the greatest visual impact if testing.
    • FIRE_SIZE_SCALE → positive values scale size
    • FIRE_HEIGHT_OFFSET → negative values brings fire above terrain
•  
  • Fire_Fighting_Water_Dump_base.fx → Tunes most water dump related params.
    • No need to tweak much in most test cases
•  
  • Smoke_base.fx → Can tweak global smoke settings which should also affect forest fire smoke. Some useful fx tokens below.
    • SMOKE_SIZE_SCALE → positive values scale puff size
    • SMOKE_FADE_TIME → Controls smoke fade
    • SMOKE_WIND_SCALE → Controls wind effect of smoke.

Forest Fires CIGI Control

The Forest Fire and Water Dump Effect are controlled through a mixture of Entity Control and Component Control Packets.  The necessary packets are outlined below along with their mapping to the ICD variables described above.

Forest Fires CIGI Controls

Forest Fire Entity Control

Forest Fire Component Control - Fire

Forest Fire Component Control - Smoke

Fire Fighting Water Dump CIGI Controls

Fire Fighting Water Dump Entity Control

Fire Fighting Water Dump Component Control - Size

Fire Fighting Water Dump Component Control - Speed

Fire Fighting Water Dump Component Control - Attachment Point

Forest Burn CIGI Controls

Forest Burn Entity Control

Forest Burn Component Control - Size

Forest Fire Haze CIGI Control

Forest Fire Haze Component Control - Enable

Example Path

You can download the path below for a basic example scene.

fireFighting_basic.pth