Shade 10 Particle Physics

From ShadeCamp

Particle Physics

Particle Physics Overview

Particle Physics is a plug-in used especially for explosions, fountain effects, smoke, flames and similar amorphous objects. Physics-based collision detection can also be used in scenes with particles. Particle Physics in included in Shade Standard and Professional.

Creating Particles

Generating Particles

1. Select Particle Physics > Particle Emitter from the Create tool. The particle emitter is the source that generates the particles.

2. Click and drag upwards in the front view like shown below.

3. Click OK in the warning dialog that appears. For an explanation of the warning dialog see “Rendering Particles.”

4. Open the Motion window by selecting View > Motion. Click Play to watch the particles be generated from the particle emitter.

Generating Particles from Objects

1. Select Rectangle from the Create tool and create a rectangle as shown below.

2. Select Particle Physics > Particle Emitter from the Create tool.

3. Click and drag upwards from the rectangle as shown below.

4. In the Browser you will see several parts inside the emitter part. Move the rectangle (“Closed line”) you just created inside the objects part.

5. Open the Motion window by seleting View > Motion. Click Play to watch the particles be emitted from the rectangle with a movement similar to smoke.

Using Wind Objects

Cross Wind

1. Create a particle emitter following the steps in Generating Particles.

2. Select Particle Physics > Cross Wind from the Create tool.

3. In the Front view of the Figure window click and drag diagonally up and to the right as shown below.

A cross wind object with the direction and range of influence is created.

4. In the Motion window, click the Play button to watch the movement of the particles.

The particles are affected by the cross wind object and move in the direction the cross wind object is facing.

Turbulent Wind

1. Create a particle emitter following the steps in Generating Particles.

2. Select Particle Physics > Turbulent Wind from the Create tool.

3. In the Front view of the Figure window click and drag a box around the particle emitter as shown below.

4. In the Motion window, click Play to watch the movement of the particles.

The particles are affected by the turbulent wind object and move randomly inside the turbulent wind object.

Tornado Wind

1. Create a particle emitter following the steps in Generating Particles.

2. Select Particle Physics > Tornado Wind from the Create tool.

3. In the front view of the Figure window click and drag upwards as shown below.

4. In the Motion window, click Play to watch the movement of the particles.

The particles are affected by the tornado wind object and move in an upwards swirling motion.

Gravitational Pull

1. Create a particle emitter following the steps in Generating Particles.

2. Select Particle Physics > Gravitational Pull from the Create tool.

3. In the front view of the Figure window click and drag across the particle emitter as shown below.

4. In the Motion window, click Play to watch the movement of the particles.

The particles are affected by the gravitational pull object and move toward the it as if they are being sucked in.

Collision Detection

Physics-based collision detection can be used in scenes with particles. Physics calculations are done for the particles and objects in the scene and the mutual effects based on their interactivity are determined.

Collision Detection Settings

1. Create a particle emitter following the steps in Generating Particles.

2. Select Particle Physics > Physical Object Initialization from the Create menu. A new Particle Physics (Physics Object) part is created in the Browser.

3. Select Sphere from the Create menu and draw a sphere in the Figure window.

Move the sphere inside the Physics Object part in the Browser.

4. With the sphere selected, select Physics Settings from the Custom tool. The Object Physics Settings dialog appears.

The Material pull-down menu lists the available materials for the object. Select Air.

5. In the Motion window, click Play to watch the movement of the particles.

By setting the sphere’s material to Air in the Physics Settings dialog, the collision detection causes it to float upwards. If you set the sphere’s material to Wood instead, it moves downward as if falling.

Collision Detection for Bounces

1. Open the sample file PM_particlephysics01. shd from the Documentation - Sample tab in ShadeExplorer.

2. Select Particles Physics > Physical Object Initialization from the Create tool. Next move the sphere and closed line objects in the scene inside the newly created Physical Object part.

3. Select all the closed line objects that make up the walls and floor, and select Physics Settings from the Custom tool. In the Object Physics Settings dialog turn off Receive Force and click OK.

4. Now select the sphere in the Figure window and again select Physics Settings from the Custom tool. From the Basic Shape pull-down menu choose Sphere, and from the Material pull-down menu choose Wood.

5. In the Motion window, click Play to watch the movement of the particles. Because the walls and floor were set not to receive the force of other objects, they stand rigid when the sphere collides into them. On the other hand, the sphere receives the force of the walls and bounces off them.

Collision Detection Using Initial Velocity

1. Open the sample file PM_particlephysics02.shd.

2. Select Particle Physics > Physical Object Initialization from the Create tool. Now move all the line objects and the sphere inside the newly created Physics Object part.

3. Select the closed line object that functions as the floor in the Figure window, and select Physics Settings from the Custom tool. Clear the Receive Force checkbox and click OK.

4. Now select the sphere in the Figure window and again select Physics Settings from the Custom tool. From the Basic Shape pull-down menu choose Sphere, and from the Material pull-down menu choose Wood. Set the Initial Velocity to 0, 3 and 5 from left to right. These values are the velocity, in meters per second, of the object’s initial velocity in the X, Y and Z directions respectively.

5. In the Motion window, click Play to watch the movement of the particles. Because we set the initial velocity of the sphere, its speed at the start of the animation causes it to collide with the blocks as if being thrown.

Turning the Physics Preview On/Off

The Particle Preview checkbox on the control bar can be cleared if you do not wish to draw the wireframe preview for physics calculations. The Particle Preview checkbox does not affect rendering.

Rendering Particles

In order for Particles Physics to be rendered properly, the correct rendering settings need to be specified. When creating a particle emitter, a dialog appears asking you whether you wish to enable Particle Physics rendering. Click OK to automatically apply the necessary rendering settings.

If you click Cancel in the above dialog, you will need to make the following rendering settings:

1. Open the Image window by selecting View > Image window.

2. Click the triangle button to open the rendering settings. On the Effects tab, select Particle Physics from the Effector pull-down menu.

Both still and animation rendering will now work for Particle Physics as for normal rendering.

Particle Physics Applications

Applying Motion Blur

Motion blur adds an after-image (blur) effect along the path of particles set in the Billboard. Motion Blur is applied in the Image window. To apply Motion Blur, on the Effects tab select Particle Physics from the Effector pull-down menu. Click the Set button to open the Particle Physics Effector Settings dialog.

Enable motion blur by turning the Motion Blur checkbox on, then choose the number of frames, from 1 to 16, you wish to blur from the Frames pulldown menu.

Left: No blur. Right: Motion blur applied to 8 frames

Adding Images to the Billboard

By assigning a custom image set in the Billboard as a particle, you can use any image you like as a Billboard.

The original image is a 128 x 128 pixel RGBA image

Using Meta Particles (Shade Professional)

Choose Particle Physics > Meta Particle from the Create tool to create a sphere that can be used with the Meta Particle Renderer. The Meta Particle Renderer supports Ray Tracing and Path Tracing.

By placing the Meta Particle sphere inside the Particle Emitter part, the sphere will be rendered as a blob particle.

To add physics calculations for a part that is already applied to the Meta Particle Renderer, place that part inside the Physics Object - Particle Physics part. By doing so the sphere inside the part will be rendered as a Meta Particle. In this case, physics settings must be applied to the sphere inside the Meta Particle part.

Converting Particles to Objects

To convert particles into standard polygon mesh objects, first select the “Emitter - Particle Physics” part in the Browser. Then choose Convert to Polygon Mesh from the Custom tool or from the Attributes pull-down menu in the Browser.

Particle Physics Reference

Here each of the Particle Physics settings and functionality are explained.

Particle Emitter Settings Dialog

The Particle Emitter Settings dialog is accessible from the Custom tool by selecting Particle Emitter Settings when the Particle Physics emitter part is selected in the Browser.

Preview Checkbox

Displays particle motion set in the Motion window in the Figure window. Particles are shown as an aggregation of spheres.

Render Checkbox

The particles are rendered along with other objects.

Basic Settings Tab

Emission Angle Slider and Textbox

Sets the angle at which the particles are emitted. The axis passing through the center of the particle emitter cone is considered 0.0.

Number Textbox

Sets the number of particles emitted in one second. In a 30 frames-per-second animation, this number divided by 30 will be the number of particles emitted per frame.

Emission Velocity Textbox

Sets the initial velocity of the particles in meters per second (m/s).

Variation Slider and Textbox

Varies the life and emission velocity of each particle for a more natural look.

False Start Textbox

Delays the emission of the particles by the specified number of seconds.

Animation Tab

Size Textbox

Sets the maximum initial size of the particles, in meters. The graph measures 0 to 100%, making it possible to animate the particles’ size.

Life Textbox

Sets the lifetime of the particle from its generation until it disappears, in seconds.

Gradation Bar

Sets the color variation of the emitted particles. Up to six new markers can be added by clicking on the gradation bar. To move a marker, click and drag it along the gradation bar. To delete a marker, click and drag it up or down, away from the gradation bar. The markers on each end cannot be moved or deleted.

Markers

Marks the thresholds along the gradation bar for the color, size, transparency and glow.

Lifecycle Graph

Displays the size, transparency and glow of the particles over time. The markers are represented by points on the graph.

Color Picker Box

Click on the box to select a new color for the currently selected marker.

Size Slider and Textbox

Sets the size ratio.

Transparency Slider and Textbox

Sets the transparency ratio.

Glow Slider and Textbox

Sets the glow ratio. 0.0 means no glow, 1.0 means the particle will be the specified color.

Effects Tab

Receive Light Checkbox

Sets the particle emitter to receive light. When off, the particles are not affected by lights in the scene and keep the color set by the billboard. Objects set as particles do not receive light.

Blend Glow Checkbox

Blends the particles set by the billboard with the glow values set in the Animation tab using an addition blend. Creates a sparkling effect.

Drop Shadow Checkbox

Drops shadows from a light source. Distant lights, point lights and spot lights are supported. Objects set as particles do not drop shadows.

Wind Settings Dialog

Settings for all the wind effects (Cross Wind, Turbulent Wind, Tornado Wind and Gravitational Pull) can be made from the Wind Settings dialog. Wind settings can be previewed in the Figure window. To open the Wind Settings dialog, select the Wind Particle Physics part, and select Wind Settings from the Custom tool.