Add lights, reflections, refractions, and shadows

Lighting effects are an essential element of animation. You can render particles with several lighting techniques that are commonly used for conventional surfaces.

Add reflections, refractions, and shadows

You can turn on reflections, refractions, and shadows when you software render Clouds, Tubes, and Blobby Surfaces.

To turn on reflections, refractions, and shadows

1. Select the particle object.
2. In the Render Stats section of the Attribute Editor, turn on:
   • Visible In Reflections
   • Visible In Refractions
   • Casts Shadows

   You must use ray tracing to create reflections and refractions. You can use ray tracing or depth map shadows to create shadows. See Rendering for details.

   Tip: If you’ve created clouds, tubes, or blobby surfaces in your scene and are not currently working with them, you can speed up software test rendering by selecting the particle object and turning off Primary Visibility.

Use lights with moving particles

By default, all particles are evenly lit, regardless of where you place lights in the scene. For some effects, you might want moving particles to drift in or out of the lighting, disappearing when not illuminated.

For example, you might want cigar smoke rising under a lamp to show only when it passes through the lighting. Or, you might want rain to show only when it passes beneath a street light or in front of the headlights of a car.

If you use Streak, Point, MultiStreak, and Multipoint render types, you can use lights to create these effects.

To use scene lighting with particles

1. Add a spot light, point light, or directional light to your scene. A spotlight gives the most obvious effect. See Create a Maya light source for details on adding lights.
2. Aim the light at the particles.
3. Select Lighting > Use All Lights.
4. Select Shading > Smooth Shade All.
5. Select the particle object you want to light.
6. In the Attribute Editor, set the Particle Render Type to Streak, Point, MultiStreak, or Multipoint.
7. Click the Add Attributes For Current Render Type button.

   The default render attributes are displayed in the Attribute Editor.

8. In the Render Attributes section, turn on Use Lighting.
9. To maximize particle illumination, set Normal Dir as follows:
   • Set to 1 if most or all particles are moving towards the light. Example: smoke rising toward a light.
   • Set to 2 if most or all particles are stationary or passing in front of the light. Examples: rain passing in front of headlights, or stationary particles creating a glow around a point light.
   • Set to 3 if most or all particles are moving away from the light. Example: rain falling down past a street light.
10. From the Hardware Render Buffer window, select Render > Attributes.
11. In the Render Modes section of the Attribute Editor, select All Lights from the Lighting Mode pull-down menu.
12. Hardware render the scene to see the effect.
    Note: Sometimes, unlit particles may appear brighter than lit ones when viewed in the hardware renderer. To fix this problem, substitute the particle type with small radius spheres.
    
    Tip: If the particles aren’t illuminated as expected, make sure the light points at the particles. Also, position and rotate the camera so your view of the particles is from behind the light. Because changing the Normal Dir setting is convenient, it’s often fastest to simply try each setting and see which looks best. If you use stationary particles with Normal Dir set to 1 or 3, the particles won’t be displayed.

Apply shadow casting to particles

Maya supports shadow casting for hardware-rendered particle types Point, MultiPoint, and Sphere. The particles will also cast shadows on themselves (self-shadow). Due to the limited resolution of the depth map, particles may cast rough or pixelated shadows.