Fire Environment Effect

Use Fire to produce animated fire, smoke, and explosion effects. Possible uses for Fire effects include campfires, torches, fireballs, clouds, and nebula.

Scene using fire

You can add any number of fire effects to a scene. The order of effects is important because effects near the bottom of the list are layered in front of effects near the top of the list.

Each effect has its own parameters. When you select a fire effect in the Effects list, its parameters appear in the Environment dialog.

Fire renders only in Camera or Perspective views. Orthographic or User views don’t render Fire effects.

Tip: Fire doesn't support completely transparent objects. Set the transparency of Fire objects accordingly. Use visibility rather than transparency to make Fire objects disappear.
Note: The Fire effect does not cast any light or shadows in the scene. To simulate illumination, you must also create lights. To cast shadows, you need to go to the Shadows Parameters rollout of your lights, and turn on Atmosphere Shadows.

Procedures

To create fire effects:

  1. Create one or more atmospheric apparatus objects to locate the fire effect in your scene.
  2. Define one or more fire atmospheric effects on the Environment panel.
  3. Assign atmospheric apparatus objects to the fire effects.

    Sample fire effects

Example: To create a campfire:

  1. Click Helpers on the Create panel and choose Atmospheric Apparatus from the subcategory list.
  2. Click Sphere Gizmo. Drag the cursor in the Top viewport to define an apparatus radius of about 20 units. Turn on the Hemisphere checkbox in Sphere Gizmo Parameters.
  3. Click Non-Uniform Scale. Click Yes in the Warning dialog (this warning doesn't apply to atmospheric gizmos), and scale the apparatus 250 percent along its local Z axis only. You can then model logs, embers, and rocks around the base of the apparatus.
  4. Open the Modify panel of the Sphere Gizmo. On the Atmosphere rollout, click Add and choose Fire from the Add Atmosphere dialog.
  5. Highlight Fire in the Atmospheres list under the Atmospheres & Effects rollout. Click Setup.
  6. Set the following parameters under Shape and Characteristics:
    • Flame Type=Tendril
    • Stretch=0.8
    • Flame Size=18.0
    • Flame Density=30.0
  7. Turn on (Auto Key) and advance to the end of the animation.
  8. Set the following parameters under Motion:
    • Phase=300.0
    • Drift=200.0

The Fire effect doesn’t cast any light in the scene. If you want to simulate illumination from the fire effect, you must create lights as well.

Example model with fire

Interface

Fire Gizmo

You create a fire apparatus, or "gizmo," to position the effect in your scene and to define the maximum boundaries of the effect. The apparatus is a Helper object found in the Atmospheric Apparatus subcategory.

There are three kinds of apparatus: BoxGizmo, SphereGizmo, and CylGizmo.

You can move, rotate, and scale the apparatus, but you cannot apply modifiers.

Using non-uniform scale is a good way to change the shape of the apparatus for effects. (You will see a warning when you use this transform. Because you don't modify atmospheric apparatus, you can safely ignore the warning.)

Fire Parameters rollout

Gizmos group

You must assign an atmospheric apparatus to a fire effect before you can render the effect. Use buttons in the Gizmos area to manage the list of apparatus objects.

Gizmo for the fire in the scene shown at the beginning of this topic

Pick Gizmo
Click to enter Pick mode and click an atmospheric apparatus in the scene. The apparatus displays the fire effect when you render. The name of the apparatus is added to the apparatus list.

Multiple apparatus objects can display the same fire effect. For example, torches on a wall can all use the same effect. Assign a different seed to each apparatus to vary the effect.

You can assign single apparatus to multiple fire effects. For example, one apparatus can display both a fireball and a tendril flame effect.

You can choose multiple gizmos. Click Pick Gizmo and press H. This opens the Pick Object dialog, which lets you choose multiple objects from the list.

Remove Gizmo
Removes the gizmo selected in the gizmo list. The gizmo remains in your scene but it no longer displays the fire effect.
[gizmo drop-down list]
Lists apparatus objects assigned to the fire effect.

Colors group

You can set three color properties for a fire effect using the color swatches under Colors. Click a color swatch to display the 3ds Max Color Selector.

Inner Color
Sets the color of the densest part of the effect. For a typical fire, this color represents the hottest part of the flame.
Outer Color
Sets the color of the sparsest part of the effect. For a typical fire, this color represents the cooler, dissipating edge of the flame.

The fire effect is colored using a gradient between the inner and outer colors. The dense areas of the effect use the inner color and gradually blend to the outer color near the edges of the effect.

Smoke Color
Sets the color of smoke for use with the Explosion option.

If you turn on Explosion and Smoke, the inner and outer colors animate to the smoke color. If you turn off Explosion or Smoke, the smoke color is ignored.

Shape group

You control the shape, scale, and pattern of flames within the fire effect using controls under Shape.

Flame Type

Sets the direction and general shape of flames.

  • Tendril Creates directional pointed flames with veins along their center. The flames orient along the local Z axis of the fire apparatus. Tendril creates campfire-like flames.
  • Fireball Creates round puffy flames. Fireballs are well suited for explosions.
Stretch
Scales flames along the Z axis of the apparatus. Stretch works best with Tendril flames, but you can use it to give Fireballs an oval shape.

Values less than 1.0 compress flames, making them shorter and thicker.

Values greater than 1.0 stretch flames, making them long and skinny.

You can combine Stretch with non-uniform scaling of the apparatus. Use non-uniform scale to change the boundary of the effect and scale the shape of the flames.

Use the Stretch parameter to scale only the flames inside the apparatus. You can also use Stretch values to reverse the effect that scaling the apparatus had on the flames.

Effect of changing Stretch

Value=0.5, 1.0, 3.0

Non-uniform scaling of an apparatus

Stretch=0.5, 1.0, 3.0

Regularity
Modifies how the flames fill the apparatus. Range=1.0 to 0.0.

A value of 1.0 completely fills the apparatus. The effect fades near the edges of the apparatus, but the overall shape is still very noticeable.

A value of 0.0 produces a very irregular effect that might occasionally reach the boundary of the apparatus, but usually gets trimmed back and is smaller.

Effect of changing Regularity

Value=0.2, 0.5, 1.0

Characteristics group

You set the size and appearance of flames using parameters under Characteristics. All of these parameters depend on the apparatus size and are interdependent on each other. Changing one parameter affects the behavior of the other three.

Flame Size
Sets the size of individual flames inside the apparatus. The size of the apparatus affects the flame size. A larger apparatus requires a larger flame size. Use a range from 15.0 to 30.0 for the best results.

Large values work best for Fireballs.

Small values work best for Tendrils.

If the flame size is very small, you might need to increase Samples to see individual flames.

Effect of changing Flame Size

Value=15.0, 30.0, 50.0

Radius of apparatus=30.0

Flame Detail
Controls the amount of color change and edge sharpness seen within each flame. Range=0.0 to 10.0.

Low values produce smooth, fuzzy flames and render faster.

High values produce patterned, sharp flames and render slower.

Use higher detail values for large flame sizes. If the detail value is greater than 4, you might need to increase Samples to capture the detail.

Effect of changing Flame Detail

Value=1.0, 2.0, 5.0

Density
Sets the opacity and brightness of the fire effect. The size of the apparatus affects the density. A large apparatus with the same density as a small apparatus appears more opaque and brighter because of its larger size.

Low values make the effect less opaque and use more of the outer color. High values make the effect more opaque and brighten the effect by gradually replacing the inner color with white. The higher the value, the more white the center of the effect is.

If you turn on Explosion, Density animates from 0.0 at the start of the explosion to the set density value at the peak of the explosion.

Effect of changing Flame Density

Value=10, 60, 120

Samples
Sets the rate at which the effect is sampled. Higher values produce more accurate results but take longer to render.

You might consider raising the samples value under the following conditions:

  • Flame Size is small.
  • Flame Detail is greater than 4.
  • Any time you see color banding in the effect. The chance of color banding increases if a flat surface intersects the fire effect.
    Note: 100 percent transparent objects that intersect the effect become partially visible. To use particles with Fire, consider using 3D particles instead of opacity-mapped particles.

Motion group

Use the parameters in the Motion group to animate the churning and rise of flames.

Phase
Controls the rate of change for the fire effect. Turn on (Auto Key) and change the phase value at different times.
Drift
Sets how flames are rendered along the Z axis of the fire apparatus. The value is the amount of rise in units.

Low values give a slow-burning, cool fire.

High values give a fast-burning, hot fire.

For the best fire effects, drift should be a multiple of the height of the fire apparatus.

You can also animate the location and size of the fire apparatus and most of the fire parameters. For example, a fire effect can animate color, size, and density.

Explosion group

Use the parameters in the Explosion group to automatically animate explosions.

Explosion
Animates size, density, and color automatically based on the animation of the Phase value.
Smoke
Controls whether or not the explosion creates smoke.

When on, fire colors change to smoke between Phase values 100 to 200. Smoke clears between Phase values 200 to 300. When off, fire colors remain at full density between Phase values 100 to 200. Fire fades away between Phase values 200 to 300.

Fury
Varies the churning effect of the Phase parameter.

Values greater than 1.0 cause faster churning. Values less than 1.0 cause slower churning.

Set Up Explosion
Displays the Set Up Explosion Phase Curve dialog. You enter a start time and end time, and then click OK. The Phase value animates automatically for a typical explosion effect.
Parent topic: Environment and Exposure Settings