Applying a Car Paint Material

This task explains how to apply the Car Paint material giving metallic textures with reflective-particle effects to your model. This advanced material is hard-coded and delivered with your Version 5 product.
The Car Paint material is available on Windows and SGI only.
Moreover, bear in mind that this shader is not taken into account when computing rendered images.
To be able to use this advanced material, you need to download the OpenGL Shader development kit if you are working on IRIX (only versions earlier than 6.5.20) or on Windows. To do so, browse the following site:

then send an e-mail to the Strategic Partner Manager (click its name on the page) to ask for the required elements.

  Open the Hood.CATProduct document.
  1. Select the Tools > Options > General > Display > Performance tab then select the Enable OpenGL Shader check box in the Miscellaneous area (this option appears only once the necessary elements are downloaded):

  2. Select the Chroma material in the specification tree.

  3. Select Edit > Properties or right-click and select Properties to open the Properties dialog box.

    The material properties can also be accessed by right-clicking the object onto which the material has been applied then selecting Material > Edit Material
    This avoids selecting the material in the specification tree and is especially useful when working in Full Screen mode, for instance.

    You can also manipulate the object (i.e. zooming in/out, etc.) directly in the geometry area while displaying the Properties dialog box either by double-clicking the material in the specification tree or by right-clicking the material then selecting xxx object > Definition.
    The Car Paint advanced material supports standard light sources (defined via View > Lighting) as well as spot and directional light sources defined in the Real Time Rendering workbench.
    When using the above-mentioned light sources, you can modify the specular, ambient and diffuse coefficients as needed.


  4. Click the Rendering tab, then select Texture tab and select Car Paint from the Type list:

    The shader is applied to your model as shown below: 
  5. Use the Paint Color box to define the color of the texture either using the slider or the box.

    You can also click ... to define more precisely the color to be applied. This opens the Color chooser:

    Click in the preview area to choose the color, or even key in the exact value of the desired color. You can enter a value comprised between 0 and 255 for any of these boxes.

    As you can see in the above picture, two color system models are used:

    • HLS (Hue, Saturation, Luminance) model is an intuitive, easy to use tool for describing or modifying a color.
      Hue is the "color" of the color. It is the name by which the color is designated and is used to define the desired color.
      Saturation is the intensity of the color. The higher the number, the more intense the color. It is used to tune the purity of the color. 
      Luminance is the brightness of the color, i.e. the degree to which the pure color is diluted by white or black. The larger the number, the lighter the color. It is used to adjust intensity.
    • RGB (Red, Green and Blue) model is a more physical model. It is based on the tri-stimulus theory of the human perception system. This model is usually used to define, with a high precision, the three primary components of the color.

    Once satisfied with the color, click OK to validate and go back to the Properties dialog box.

  6. The Particle Brightness box lets you define the contrast, i.e. the intensity of light diffused by particles when lit by light sources.

    You can choose a value comprised between 0 and 1.
    For instance, "0" means that there are no particles at all as shown below:

    Particle  brightness = 0 Particle brightness = 1
  7. Use the Particle Density box to set the size of the particles. The higher the value, the smaller the particles:

    Particle density = 1 Particle density = 3
  8. The Reflectivity box enables you to define the degree of reflectivity of the particles. The higher the value, the more reflective the particles. You can enter a value comprised between 0 and 1.

    Set to a high value, the object reflects its environment.
    Reflectivity = 0  Reflectivity = 0.5
    When setting the Reflectivity parameter, you can also click ... to set advanced reflection settings if you wish to use a customized environment image for environment reflections:
    For more information, refer to Defining Reflection Settings in this guide. Note that, when using the Car Paint shader, the Advanced Reflection Settings dialog box slightly differs from the usual one (the Reflection Type, Transparency Width and Transparency Height boxes are not displayed) but works the same way.

    When finished, click OK to validate and go back to the Properties dialog box.

  9. Use the Roughness box to set the size of the specular spot.

    Set the value to a maximum to generate very sharp highlights on very shiny surfaces. Set the roughness to a lower value to generate large specular spots creating a duller effect.

    Roughness = 0.2    Roughness = 0.4
  10. Click OK or Apply and OK to validate your parameters.

  11. Close the Properties dialog box.