Choosing a Shape Type

Since shapes are either Color or Gray, and use one or more frames, there are four shape types, each with its own icon in the shape library.

When you use a multi-frame shape for a particle type, a few extra controls become available in the Particles controls. See Random Start Frame, Start At, and Hold for more information.

The different color depths affect the result and the amount of memory required:

• A Color shape is 32-bit because it has RGB and alpha channels.
• A Gray shape is 8-bit because it has one channel used for both the grayscale image data and transparency. This means the pixel value always represents the transparency (black is transparent, gray is semi-transparent, and white is opaque).

Note: The Particles operator uses a bit depth of 8 bits per channel. Color depth refers to the total number of bits for the shape image, not just one channel. Thus, Color is 32-bit because it has four 8-bit channels.

Gray shapes are suitable for most particles, and they are recommended because they use less memory. Using Gray shapes does not limit the particles to be grayscale; color can be added by the particle type or emitter.

Note: You can still use the alpha channel for a Gray shape—the alpha channel is added to the color channels, and the resulting grayscale image is used for the Gray shape.

Also note that particles that use Color shapes can still have their color changed. See Changing Particle Colors for more information. You should use Color shapes if you want the colors of the image to be preserved in the shape.

Color shapes use more memory than Gray shapes, and multi-frame shapes use more memory than single frame shapes. The way OpenGL card texture memory is used can affect the performance of the Particles operator.