Tutorial Autodesk Maya Lighting

Here’s where  the fun begins. To create  the effect of the light traveling along  the length of the neon  tube,  you’ll attach a ramp  to the incandescence channel  of a Blinn shader.

1.     Open  the Hypershade to find the shader  named  neonGlassBlinn. This is a simple

shader  that  has already  been set up to create  the look  of the neon  glass. Select the shader, and MMB  drag it on top of the vacancyNeonGeo in the Perspective view.

2.    In the Hypershade, select the neonGlassBlinn shader, and open  its settings  in the Attribute Editor. Click the checkered box to the right  of the Incandescence chan- nel to open  the Create  Texture Node  panel.

3.    Select the 2D Textures category on the left side of the panel,  and click Ramp  to create  a ramp  node  (see Figure 1.5).  Hold  the mouse  pointer over the Perspective view, and press the 6 hotkey  to switch  to textured view. Make  sure that  the Renderer panel  in the viewport window is set to High  Quality Rendering; otherwise, you won’t  see the ramp  texture update properly as it’s applied  to the geometry.

In Perspective  view, the rainbow pattern of the ramp  appears on the neon  tube, but it is a repeating pattern that  looks  more  festive than  demonic. To fix this, you can adjust  the UVs of the vacancyNeonGeo node.

Figure 1.5   Use the Create Render node panel to attach a ramp                                      texture to the Incandescence channel of the neon-

                                                                                                    GlassBlinn material.

4.     Select the vacancyNeonGeo node,  and choose  Window c UV Texture Editor.

If you zoom  out (waaaaay out),  you’ll see that  the UVs are a long vertical  strip. In the UV Texture Editor’s  menu  panel,  expand the Textures menu,  and select vacancyNeonGeo|blinn2SG|ramp1 so that  the ramp  appears in the UV Texture Editor.

As you can see, the rainbow colors  of the ramp  appear in the upper  quadrant of the UV Texture Editor. What  you don’t  see is that  outside  of this area,  the ramp texture repeats  over and over to infinity,  which  is what  the colors  on the neon tube continually repeat;  the UVs for the tube continue well outside  of that  upper quadrant (see Figure 1.6).

Figure 1.6   The UV Texture Editor shows that the UV texture coordinates of the neon sign geometry go well beyond the upper quadrant of the texture space. The result is that the ramp texture repeats along the length of the glass tube.

5.   Right-click the UVs, and select UV from the marking menu.   Select some of the UV coordinates in the editor  (the selected coordinates will be highlighted in green). Hold  the Ctrl key, right-click again  above  the selected UVs, and choose To Shell from the marking menu.  This selects all of the connected UVs of the glass tube geometry.

6.    From  within  the UV Texture Editor, choose  Polygons  c Normalize. This forces the UVs to fit within  the upper-right quadrant of the UV texture space. Now  the ramp  is no longer  repeating. The UV coordinates will look  fairly dense in the

UV Texture Editor, but in Perspective  view, you’ll see that  the ramp  goes from red to green to blue across  the length  of the sign.

7.   Select the ramp1 node  on the Textures tab of Hypershade, and open  its settings in the Attribute Editor.

8.   Click the x at the top of the ramp  to delete the blue color  at the top of the ramp.         Set the middle  color  to black;  then set Interpolation to None.

9.   Set the bottom color  to a devilish shade  of red.

10.  Try dragging the circle for the black  color  up and down;  you’ll see the light move

      along  the neon  tube (see Figure 1.7).  Name  the ramp  node  neonLight.

Figure 1.7   Move the black color of the ramp up and down; the color updates on the tube geometry in Perspective view.

To make  the sign easier to read,  you can apply  a separate dark  shader  to the parts  of the tube that  connect  the letters.  This replicates the way actual  neon signs are constructed in the real world, adding  an extra  touch  of realism.

11.     Right-click the vacancyNeonGeo geometry in Perspective  view, and choose Face. Carefully select the individual faces connecting the V and the A. Once they are selected,  switch  to the Rendering menu  set, and choose  Lighting/ Shading  c Assign Favorite Material c Lambert. This creates  a new Lambert shader  and applies  it to the selected faces. Do the same for the other  parts  of the sign. Assign the same Lambert shader  to these selected faces (you can use

Lighting/Shading c Assign Existing  Material to do this easily). Figure 1.8 shows the result.

Figure 1.8

12.     Select sparkEmitter in the Outliner. In the Set Driven  Key panel,  click Load

Driven.  lightControlHandle should  still be loaded  as the driver.

13.     Use the Set Driven  Key panel  to keyframe the emitter  so that  when  lightControl- Handle is all the way to the left, the Rate attribute of the emitter  is 0, and when lightControlHandle is all the way to the right,  the emitter’s  Rate attribute is 100. You can use the same technique that  you used in steps 9 and 10 to do this.

14.     This is probably a good  point  at which  to save your  scene file.