We’ll light a fuse using fountains for the sparks and smoke. Of course there are more things to solve here: the gradual disappearance of the fuse and the light emitted by the burning fuse.
The Cracker
The cracker can be a cylinder. In this case some subdivision has been applied to round off edges.
The Fuse
The fuse is a path extrusion. It is important to have the points in the path evenly spaced, as this path will be used for animation, and each segment is by default 1 second in the animation.
To have spare paths it is a good idea to copy the path we will use and paste it several times, so there’s always another copy of the path available.
It is very important to begin drawing the path from the end opposite from the cracker. If it is too late, we can always convert the last (red) point into the first (green) point using the Make First Point modeling command.
The fuse is a circle extruded along the path.
Making it disappear
To make the fuse gradually disappear, we’ll use an animated stencil map. Since our path has 5 points, it has 4 segments, and we need to make it disappear in 4 seconds.
The map is generated using Strata 3D, in another scene file. A glowing white square is animated away from view to expose black. It is important to use a linear animation path to obtain constant movement.
The result is this animation.
You can download the animated stencil here.
This animation is now loaded into the stencil channel of a new texture and this texture is applied to the path extrude, making sure to use UV mapping.
Render some preview frames and rotate the map if needed so that the fuse disappears from the correct end, and in the correct direction.
We may have to rotate the stencil map
The light
A powerful, short ranged point light will provide the light of the burning fuse.
We need to make it follow the path, using the Convert to Path tool.
Probably, some keyframe adjustment will be needed to match the stencil and the light. It is desirable that the light is a little behind the fuse to avoid the fuse “swallowing” the light.
In this example, the light starts with zero intensity, and off camera. Quickly it goes to intensity 1000. When the fuse enters the cracker, the intensity drops sharply to zero again.
The Fountains: Sparks and Smoke
We’ll use two fountain FX here: one for the sparks and another for the smoke.
We will attach both fountains to a construction sphere moving along the same path we used for the fuse and the light.
Sparks
Sparks are many, fast and short-lived.
Sparks use a 100% glow orange texture.
Smoke
Smoke uses large spheres, not too fast, with a weight of -1, which allows them to float free from gravity.
A transparent gray texture makes them look like smoke.
Both fountains start at zero amount and in a few frames (say 5) go to the amount shown in the images above. When the fuse goes inside the cracker, they go quickly back to zero. This can be done either moving the playhead to the desired time and editing the Fountain At Current Time, or inputting the time and frame numerically editing the Fountain in custom.
That’s it –at least in theory. There’s tweaking to be done until the animation looks good. The final result should be something like this:
That is the fuse.
We’ll need an explosion soon.
