Autodesk 62205-051408-9001 User Guide - Page 364

Size Over Life, Velocity Over Life, Motion, Randomness Over Life, and Bounce Over

Page 364 highlights

14 Creating Particle Effects This range of percentages is shown in the Timeline and has no correlation to the frames in the project. Keyframes can be added as usual, but you cannot add keyframes before 0% or after 100%. The Size Over Life graph shown below changes at each third of the lifetime. Size Over Life, Velocity Over Life, Motion Randomness Over Life, and Bounce Over Life-These four properties all work the same way. The values along the Y-axis are scaling factors that are applied to the basic property. For example, if the Size Over Life graph in the Timeline is a horizontal line at 200, the particle is the same size its whole life. If the horizontal line is at 80, the particle is still the same size its entire life, but it is smaller. However, if the Size Over Life graph is set to 80 at birth (0%) and 200 at death (100%), the size increases over the particle's lifetime. Use the over-life properties together for complex effects. For example, to make particles appear to fly at the camera, increase the Velocity Over Life and Size Over Life toward the end of the life (usually more rapidly toward the end). Or increase Velocity Over Life and Motion Randomness to make the particles scatter as they get older. Weight Over Life and Spin Over Life-Unlike the other four over-life properties, weight and spin have both negative and positive values. For both, the possible values range from -100 to 100. If you set the birth value in the Weight Over Life graph to a negative number, and set the death value to a positive number, the particles are light at first (so they float), and they get heavier as they get older. Note that a negative value in the Weight Over Life graph reverses the basic Weight value. For example, if the basic Weight value is positive (so the particle falls), setting the birth value in the Weight Over Life graph to a negative number makes the particle rise initially. Conversely, if the basic Weight value is negative (so the particle rises instead), then a negative initial keyframe in the Weight Over Life graph makes the particle fall. Although the Timeline graphs for the six over-life properties are special, you can still use the regular Timeline features such as math operations to modify the graphs. For example, you can reverse a complex Size Over Life graph horizontally to convert it from a growing effect to a shrinking effect. To do this, select the Size Over Life channel (to select all its keyframes), and click Math Operations. In the Math Operations dialog, select Reverse and click OK. Over Life Graph in the Timeline 348

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Creating Particle Effects
14
348
This range of percentages is shown in the Timeline
and has no correlation to the frames in the project.
Keyframes can be added as usual, but you cannot
add keyframes before 0% or after 100%.
The Size Over Life graph shown below changes at
each third of the lifetime.
Size Over Life, Velocity Over Life, Motion
Randomness Over Life, and Bounce Over
Life
—These four properties all work the same way.
The values along the Y-axis are scaling factors that
are applied to the basic property.
For example, if the Size Over Life graph in the
Timeline is a horizontal line at 200, the particle is the
same size its whole life. If the horizontal line is at 80,
the particle is still the same size its entire life, but it is
smaller. However, if the Size Over Life graph is set to
80 at birth (0%) and 200 at death (100%), the size
increases over the particle’s lifetime.
Use the over-life properties together for complex
effects. For example, to make particles appear to fly
at the camera, increase the Velocity Over Life and
Size Over Life toward the end of the life (usually
more rapidly toward the end). Or increase Velocity
Over Life and Motion Randomness to make the
particles scatter as they get older.
Weight Over Life and Spin Over Life
—Unlike
the other four over-life properties, weight and spin
have both negative and positive values. For both, the
possible values range from –100 to 100.
If you set the birth value in the Weight Over Life
graph to a negative number, and set the death value
to a positive number, the particles are
light
at first (so
they float), and they get heavier as they get older.
Note that a negative value in the Weight Over Life
graph
reverses
the basic Weight value. For example, if
the basic Weight value is positive (so the particle
falls), setting the birth value in the Weight Over Life
graph to a negative number makes the particle rise
initially. Conversely, if the basic Weight value is
negative (so the particle rises instead), then a
negative initial keyframe in the Weight Over Life
graph makes the particle fall.
Although the Timeline graphs for the six over-life
properties are special, you can still use the regular
Timeline features such as math operations to modify
the graphs.
For example, you can reverse a complex Size Over
Life graph horizontally to convert it from a growing
effect to a shrinking effect. To do this, select the Size
Over Life channel (to select all its keyframes), and
click Math Operations. In the Math Operations
dialog, select Reverse and click OK.
Over Life Graph in the Timeline