to the right of the Transparency color sliders. From the menu, select a texture shader.
You can use a picture to define areas of transparency on your object. The alpha channel or RGB intensity of the picture file is used and a factor is applied to map a pattern of varying degrees of transparency on the object’s material.
You can create a transparency map by connecting a texture to a surface shader’s transparency parameter.
1. Select the object to which you want to apply a transparency map.
Make sure your object has a surface shader applied to it. If it doesn’t, you can quickly apply one by choosing Get > Material > Phong.
2. Open the surface shader’s property editor by choosing Modify > Shader from the Render toolbar. Lock the property editor open by clicking the lock icon in its title bar.
3. On the Transparency/Reflection tab, click the connection icon to the right of the Transparency color sliders. From the menu, select a texture shader.
Once selected, the texture is connected to the Transparency color parameter of the surface shader and the render region displays a transparency map on the selected object.
4. The texture shader’s property editor opens. Define a texture projection for it from the Texture tab.
5. Close the texture’s property editor. From the Transparency/Reflection tab of the surface shader’s property editor, adjust the following options as necessary:
- Select the Use Alpha option to use only the texture’s alpha channel to control the transparency.
- Select Invert to invert the transparency map.
This is useful when you are using a black-and-white image or an image’s alpha channel (matte) to control transparency. In a typical matte, the black areas are transparent and the white areas are opaque. For surface shaders, on the other hand, the reverse is true: black areas are opaque and white areas are transparent. Inverting the transparency gives you the correct transparency defined by the matte.
- Use the Scale value to adjust the overall intensity of the transparency.
If you don’t see the effect, try increasing the Ray Depth values in the render region setup (Render > Regions > All Options or Active Viewport Options) or the render options (Render > Render > Options).
Using the Color at Vertices feature, you can paint an alpha channel onto any polygon mesh in your scene and use it as a transparency map. For example, if you have a polygon mesh model of a house and want to make the window polygons transparent, you could use the Color at Vertices paint tool to paint certain polygons with an alpha.
For information on how to use the Color at Vertices feature, see Vertex Colors.
To paint an alpha onto a polygon mesh object
1. Select the object on which you want to paint transparency and choose Get > Property > Color at Vertices from the Render toolbar.
This applies a vertex coloring support so you can paint directly on the object’s surface.
2. Select Ctrl+w to open the Brush Properties property editor.
3. On the Vertex Color Painting tab, select Alpha from the Color Paint Mode menu to paint an alpha channel onto the object.
The Opacity slider defines the gray with which you paint the alpha channel.
4. Press Shift+w to activate the Paint Vertex Color tool.
The 3D view you paint in automatically changes to Constant viewing mode. Click or drag the brush tool over the areas that you want to paint.
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If you wish to see how the Color at Vertices property affects the transparency in the rendered image, use the same camera view in a second 3D view and draw a render region in it. Keep in mind, though, that this slows performance. Note: For the paint effect to be visible in the render region, you must first apply the Vertex_RGBA shader to the object. To do this in the render tree, choose Nodes > Texture > Vertex RGBA and connect this node’s output to the material node’s Displacement input. Then open the Vertex RGBA node’s property editor, and select the Color at Vertices property that you applied to the object (from the Vertex Property menu). |
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Because the camera does not display the alpha channel by default, you need to activate it to see a painted alpha channel. To do this, open the Camera Display property editor by choosing Display Options from the Display Type of the 3D view in which you are painting. From the Display Options tab, set the property editor and choose Properties. Set the Shaded Mode > Vertex Color option to Show Alpha. |
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