..::dragon fire::..

Note from the author: This article was written with 3ds max 4.x in mind. Due to software improvements, bug fixes, user interface amendments and added features, some items listed below may not apply to 3ds max after version 4.x...

Creating realistic looking and flowing fire is tricky without some fancy third-party plugin. So here we will try to do just that with 3ds max 4’s own toolkit. Up for the challenge?

Fire effects are one of the most awkward elements to simulate in 3D. Normally, an artist would have to resort to stock footage, pass the task to a compositor to merge the fire element into the scene or purchase a third party plugin to generate the effect. Granted, this can give a very nice result, but what if you can’t afford these materials? Creating fire in 3D can be challenging, but one of the most enjoyable, with one simple value change can alter the fire’s behaviour from a simple flame to a force to be reckoned with. Depending on the situation and combustible material, fire can take on many forms; from tendril and flickering shapes through to rolling clouds. Here we are going to attempt to introduce a realistic turbulent fire cloud into our scene to add some extra drama, kind of like a flamethrower, being shot out of our dragon’s mouth. All of the scene elements have been previously created, so all we need to concentrate on is the fire, it’s appearance and motion and how it interacts with the rest of the scene.

	Firstly, we will load the scene: Dragon_hall.max . The scene is lit using several Omni lights from each chandelier to create the right ambient effect, which as a downside, will increase your rendering time, so feel free to remove some lights from each chandelier and increase the multiplier of the others (which are all instanced).
	As this tutorial is based on the fire effect, we won’t concentrate on the animation of the beasty with the bad breath. Note though the dummy object around it’s head; this will be used later on to align and position the fire emitter and any additional lighting we require.
	Create a Geosphere primitive anywhere in the scene. Set the radius to 300 with 7 segments. Ensure the Geodesic Base Type is set to Icosa. This is a relatively high segment count for a particle system, so when working within the viewport, you may wish to reduce the number of segments, but increase it back when rendering.
	Assign a UVW Map modifier to the sphere and set the Map ID spinner to 2. We are using Map ID 2 as when the sphere is referenced by the particle system, the particle system itself uses Map ID 1 which can cause conflicts.
	To add some irregular motion and shape to the particle, assign a Noise modifier to the sphere. We can then animate these settings if required to make the fire ripple and contort more, depending on our requirements. As this modifier is positioned after the UVW modifier, it will therefore also deform the map.
	Turn on Animate Noise in the Noise modifier’s Animation Rollout and amend the Frequency spinner to 0.5. This will increase the rate of the Noise modifier’s animation. Turn on Fractal and increase the Roughness to 0.3 set all X Y and Z Strength spinners to 100.
	Create a SuperSpray particle system and set the Icon size to 1000 so we can see it clearly and use it as a sense of proportion. Select the Align tool and click on the Select By Name icon (or press H). Select the Dragon Mouth Dummy object as the object to align to.
	In the Align pop-up box, check on X Y and Z position align and also check on local X Y and Z Align Orientation. Clicking OK will automatically position and rotate the particle system exactly where we want it to be, directly inside the dragon’s mouth.
	With the particle system still selected, expand the Command Panel by pulling it out from the left hand side to the right. The particle system has a lot of rollouts and settings that we need to amend, so viewing all of them at once helps the process and aids our workflow. Select the particle system’s properties and turn off Cast and Receive Shadows.
	In the particle system’s Basic Parameters rollout, change the Particle Formation Off Axis Spread to 10 degrees and the Off Plane Spread to 90 degrees. Change the Viewport Display to Mesh and the Percentage of Particles to 100 to view the entire particle system.
	In the Particle Generation Rollout, amend the Speed spinner value to 500 with 20% variation. In the Particle Timing section, set the Emit Start spinner to 1 and the Emit Stop and Life spinners to 100 with 20 variation.
	In the Particle Size section, set the Size spinner to 5 with 20% variation, amend the Grow For value to 30 and set the Fade for value to 0. These set the general physical size of the particles. They don’t have to be increased as much as normal due to the particle type is to be set as Instanced Geometry.
	Under the Particle Type rollout, set the Particle Type to Instanced Geometry. In the Instancing Parameters section, click on the Pick Object button and choose the Geosphere. Under Animation Offset Keying, check the Birth radio icon. This makes the particle begin animating the Noise modifier when a particle is born, adding more variation to the particle appearance.
	In the Rotation and Collision rollout, set the Spin time to 20 with 50% variation. Under the Object Motion Inheritance rollout, set the Influence spinner to 0. So if the SuperSpray emitter is moved or rotated, the particles don’t move or rotate to follow but continue on the same path.
	Scrubbing the timeline forward, we should now see the particles being emitted from the dragon’s mouth in a linear motion; further still, we will see them intersect the floor and continue downwards. Create a large (about 80000 square) Deflector SpaceWarp slightly larger than the ground, and position it just slightly above the ground and tiles.
	Set the Bounce to 0.2 and the Chaos to 10%. Bind the particle system to the SpaceWarp. We should now see the particles reflect back up, although half of the particle still remaining below the ground and Deflector. This is normal as max’s particle collision detection is set to the center of the particle.
	To add some more random motion to the fire effect, create a Wind SpaceWarp and rotate it so the direction arrow is pointing vertically up at the Scene’s arched roof. Set the Wind’s Strength to 0.3 (only a slight breeze!) and the Turbulence to 2. Bind this SpaceWarp to the particle system.
	We shall now create the fire material. The material is comprised of several elements; the main billowing fire effect, the smoke cloud material, the combination of the above and a transparent element to mask out any harsh edges of the particles. Combined with this, the use of material ID’s to add a post glow effect.
	We shall start with the main fire material. Create a new standard material labelled Fireball and change it’s shading type to Oren-Nayar-Blinn. Check on Self-Illumination. Set the Specular Level and Glossiness spinners to 0. In the Extended Parameters rollout, set the Falloff Amt spinner to 65.
	In the Diffuse Color slot, create a new Smoke map and label it White. Set the Size spinner to 0.5, the # Iterations spinner to 10 and the Exponent to 0.4. Select the Color #2 swatch and set it to White (RGB 255,255,255). Set the Source to Explicit Map Channel and the Map Channel to 2.
	In the Color #1 slot, create a new Smoke map and label it Yellow. Set the Size spinner to 0.5, the # Iterations to 10 and the Exponent to 1.3. Set the Source to Explicit Map Channel and the Map Channel to 2.
	Create a new Smoke map in the Color #1 slot and label it Red & Black. Set the Size to 0.5, the # Iterations to 10 and the Exponent to 0.5. Set the Source to Explicit Map Channel and the Map Channel to 2. In the Color #2 slot, create a new Gradient Ramp map and label it Orange & Red. Change the mapping to Planar from Object XYZ and set the Y Angle spinner to –90.
	In the Gradient Ramp Parameters rollout, set the Interpolation type to Ease In Out. Design the Gradient as shown, with keys at 100 (RGB 255,163,0), 63 (RGB 255,0,0) and 0 (RGB 255,0,0).
	In the Yellow Smoke map, create a Gradient Ramp map in Color #2 and label it White Yellow & Orange. Change the mapping to Planar from Object XYZ and set the Y Angle spinner to –90. Change the Interpolation type to Ease In Out and design the gradient as shown with keys at 100 and 92 (255,255,255) 73 (255,255,0) 40 and 0 (255,163,0)
	Diffuse Color slot to the Diffuse Level and Diffuse Roughness slots. Create a new Smoke map in the Bump slot and label it Xtra Bump. Set the Source to Explicit Map Channel and the Map Channel to 2.
	Instance copy the White Smoke map tree into the Color #1 slot and make the Color #2 swatch black. Set the size to 0.5, the Iterations to 10 and the Exponent to 0.6. Back at the top of the material, set the Bump spinner to 60, create a new Falloff map in the Self-Illumination slot and label it Outer & Inner Glow.
	Instance copy the Yellow Smoke map into the first slot and set the second swatch to RGB 252,220,0. Amend the Mix curve at the bottom of the map so that it resembles the screenshot. Back at the top of the material, create a new Falloff map in the Opacity slot and label it Opaque Inner.
	Set black as the 2nd swatch colour and instance the Yellow smoke map into the 1st slot. Amend the mix and output curves to those displayed in the screenshot. We have now completed the main fire material. The rest of the material structure consists of more simple materials…
	Create a new Standard material and label it Smoke. Set the Diffuse swatch to black, Specular and Glossiness to 0, change the Advanced Transparency type to Out and set it’s spinner to 100. In the Opacity slot, create a new Falloff map, set the type to Fresnel and flip the white and black colours.
	Create a new Standard material and label it Transparent. Set the Specular, Glossiness and Opacity spinners to 0 to create a completely transparent material. That’s all the materials created, so next we’ll put them all together…
	Create a new Shellac Material and instance copy the Smoke material to the Base Material slot. Instance copy the Fireball material to the Shellac Material slot and set the Shellac Color Blend spinner to 340. Label this material Smoke & Fireball Mix.
	Create a new Blend Material, label it Fireball End Mix and assign a Material ID of 1 to it. Instance copy the Transparent material to the Material 1 slot and the Smoke & Fireball Mix Shellac material to the Material 2 slot. Create a Falloff map in the Mask slot and set the type to Fresnel. Flip the black and white colours and amend the Mix curve to the one displayed.
	Assign this material to the Sphere and in the particle system under Mat’l Mapping and Source, check on Instanced Geometry and click on the Get Material From: button. Create a new Omni light and set the colour swatch to 255,245,87. Ensure shadows are checked on and amend the Multiplier to 5.
	Set the Contrast and Soften Diff. Edge values to 50 and check on Use and Show under Far Attenuation. Set the Start spinner to 0 and the End to 30000. Under the Shadow Map Params rollout, set the Bias to 0.01, the Size to 1024 and the Sample Range to 20. As with the particle system, align this to the Dummy object.
	In the Environment window, check Ambient is set to 0,0,0. In the Effects window, create a new Lens Effects effect. Add a Glow effect and name it Fire Glow. In the Glow Element rollout, set the Size to 0.1, the Intensity, Occlusion and Use Source Color to 100. In the Options tab, ensure Effects ID is checked and set to 1.
	Create a new Glow effect and label it Illumination Glow. In the Glow Element rollout, set the Size to 3, Intensity to 200, Occlusion and Use Source Color to 100. In the Options tab, ensure Effects ID is checked and set to 1. Hide the Sphere, select the particle system and add 0.5 of image motion blur. Voila.
	Due to the nature of the particle system, the geometry count, the number of lights and the resolution of the image, it may take a white to render even a single frame. Consider lowering the particle birth rate if you find it’s taking too long, or reduce the detail of the referenced sphere. You may also wish to animate the phase of the smoke material to add more chaos to the fire effect. Should you decide to render out the scene at a size other than the default (640x480), you may wish to adjust the Glow settings as they will appear more or less intense depending on the image size.
	Download the max file & maps!
	The resulting rendered animation.

..::additional tips::..

Fire Plugins: As mentioned, additional 3rd party plugins could be used to add more realism to the fire effect. Most effective ones for the fire appearance are Afterburn, Pyrocluster, Outburst and Phoenix, with the first three generating volumetric fire and smoke, with Phoenix designed to generate tendril-like fire. Cebas’ Pro-Optic Suite could also be used in conjunction with Pyrocluster (of which it contains) to enhance the glow effect to add more effective intensity to the fire.

Particle Systems: Max’s particle system and corresponding SpaceWarps as it stands has it’s limitations. To create any real convincing fire simulation, the particle system must interact with the scene. In which case you may want to look into the use of particle dynamics and / or the use of an additional particle system such as Particle Studio or Thinking Particles which allows you to design the particle system to the relevant needs of the scene.

Materials: Due to the nature of our fire simulation, we have to use several mixed and composited materials to create the desired result. Because of this, you will find that render times in the scene will increase dramatically. The main culprit behind this is the Shellac material, which could be replaced with a Composite material, additive transparency or having two particle systems; one with the bare fire material and the other with the dark smoke effect.

Illumination: Max currently does not have any geometric-based lighting system. Therefore, the fire cannot accurately illuminate the scene depending on it’s intensity so we have to simulate this with a Glow post effect. The Omni light positioned in or near to the dragon’s mouth is the main light source for the fire illumination, which could be cloned, reduced in intensity, moved further along the particle trail and animated to illuminate the scene as the particles pass over it.

Particle Trails: Our fire setup currently behaves as clouds. More tendril-like effects can be created by amending the material settings slightly, assigning them to a new and smaller reference sphere, and turn on Particle Spawning in the SuperSpray particle system. By choosing Spawn Trails, each born particle will generate an additional few particles, and by tweaking the settings, we can get it to move erratically, spawn the new reference sphere for it to die abruptly like a tendril.

Interparticle Collision: With the amount of particle chaos in the scene, particles do often collide but have no effect on one another. To make the fire motion more realistic, turn on Inter-particle collision, and increase it’s value spinner to detect collisions at a sub-frame value, but not too high as geometry updates will be slow.

Particle Motion: Currently, the particles just simply emit from the dragon’s mouth. To generate a more realistic motion, try animating the speed of the particle from 0 up to the set value. Also animate the birth rate from 1 up to the set value. With these values animating over a short time, coupled with Inter-Particle collision, we can see smaller particles being forced through the larger particles as the fire’s full velocity is achieved.

Particle Age Map: In the tutorial, we haven’t taken the particle’s appearance as it dies in to consideration. This is due to the nature of the material setup and the inability to assign a Particle Age map to the referenced sphere as the Particle Age material has to be directly assigned to the particle system and not to instanced geometry. If we assigned the fire material directly to the particle system, we would not be able to lock the material to the individual particle, and as a result would have the particles “passing under” the fire material.

Other Material Methods: Depending on the “design” of your fire, you may wish to create the particles and materials differently. Facing particles with a fire material set to face map and additive transparency keeps render times down and gives an effective result, but does not generate the fireball-type effect generated in this tutorial with the darker patches of fire and smoke.

Fire Motion: To add more dramatic motion to the fire, try rotating the dragon, Omni light and SuperSpray particle system so the particles just clip a close pillar by about 25%. Create UDeflector and Cylindrical Decay SpaceWarps (to form the particles around the pillar) and adjust their settings and position accordingly to react with the pillar. Note that once the SpaceWarps have been bound to the SuperSpray system, the Viewport update time increases. To stop particle updates in the Viewport, simply hit the Escape key.

Initially published: Computer Arts Special magazine, Issue 27, December 2001.

Copyright © Pete Draper, December 2001. Reproduction without permission prohibited.

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