Wednesday, October 28, 2009

2.49b Particle Objects

Blender's particle system is flexible and powerful. It can be used for simulating effects like fire, hair, fur, rain. Particles can be emitted from any kind of mesh object. The purpose of this video is to acquaint you with the basic controls for a particle emitter. We'll use the plane, which is the simplest to show. Switch to animation view, with 100 frames.

1) Delete the default cube (Right click, then X, then confirm delete). Add a plane (Space - Add - Mesh - Plane). Subdivide the plane once (W key, then subdivide). Then go to the SR1-Animation view.

2) Go to the Object buttons (F7), then click the Particles button, all the way to the right. We will look at emitter type particles, where the number of particles and their direction change over time. Emitters are good for animating rain and fire, where raindrops and smoke particles move over time. The hair type is for more static simulations, like hair and fur.

3) Particles are emitted from faces of the plane. The default is 1000 particles over 100 frames = 10 particles per frame.

4) Increase the number of particles to 10000. You see that they're emitting from each face by default. Can change to emit from vertices, as well as volume.

5) Particles are most often emitted from the "normals", the direction that's perpendicular from the face. The Normals setting controls how high the particles are emitted. Set the normal to 1 to show how height is controlled. Press F12 to render.

6) Random adds a bit of randomness to the emitting direction. You can mix normals and random and press F12 to rendeer.

7) AccX, AccY, and AccZ can add an extra push in the respective direction. Set AccX to .5, which gives bias in the X direction of .5 blender units. This is good for fire and smoke effects. Press Alt-A to see the path of the animation.

8) Emitting also works in negative direction. For rain, if you float a plane above the scene, and make it a particle emitter, this would be the start of a rain simulation. You can increase the randomness as well. Set Normals to -.5 and AccX to -.3. Properly textured, this could simulate a heavy rainstorm.

9) Start and End are the start and end frames for the particles. Life is how long the particle lives. Increasing the life makes the particles stay around longer. Start can be negative, which means that the particles are alive at the beginning of the animation.

Increase the life to 100. The particles stay around longer. For fireworks, you might want to vary the life and add some randomness to the emitter.

10) Start can be a negative number also. A negative start number means the simulation began before the first frame is rendered, like the fire is already going at frame 1.

11) Go to a frame 41 and press F12 to render. The particles render as halos, and the plane does not render. The emitter does not render by default.

12) Add a material, F5, shading, make the particles red (R=1, G=0, and B=0). Then press F12 render.

13) To change the halo effects, press the Halo button in the Render Pipeline panel. In the Shaders panel, you can change the halo size. You can also customize the halo - Rings, lines, stars.

Render (F12) for
1) Halo with 4 rings and .5 size.
2) Halo with size .1, 3 stars, and 4 lines

14) Many material settings can be animated. Look at Halo Size. Go to IPO window. Select the Material type curves. Then select HaSize. Create an IPO curve, with Control-Left Click, creating IPO points for size. This creates a Bezier curve for the halo size, which will make them emit with different sizes over time. Here's the resulting video.

These are the basic controls and look for emitter type particles, which work well for fire and rain. We've barely scratched the surface. I hope this gives you a good start towards understanding Blender's partcle system. Happy blending!