Rendering Attributes

• A RenderingAttributes node component controls:

  • Depth buffer use and write enable

  • Alpha buffer test enable

  • Alpha buffer function

  • Visibility flag

The RenderingAttributes object defines common rendering attributes for all primitive types. The rendering attributes are:* Alpha test function - used to compare the alpha test value with each per-pixel alpha value. If the test passes, the pixel is written, otherwise the pixel is not written. The alpha test function is set with the setAlphaTestFunction method. The alpha test function is one of the following:* ALWAYS - pixels are always drawn, irrespective of the alpha value. This effectively disables alpha testing. This is the default setting.
* NEVER - pixels are never drawn, irrespective of the alpha value.
* EQUAL - pixels are drawn if the pixel alpha value is equal to the alpha test value.
* NOT_EQUAL - pixels are drawn if the pixel alpha value is not equal to the alpha test value.
* LESS - pixels are drawn if the pixel alpha value is less than the alpha test value.
* LESS_OR_EQUAL - pixels are drawn if the pixel alpha value is less than or equal to the alpha test value.
* GREATER - pixels are drawn if the pixel alpha value is greater than the alpha test value.
* GREATER_OR_EQUAL - pixels are drawn if the pixel alpha value is greater than or equal to the alpha test value.* Alpha test value - the test value used by the alpha test function. This value is compared to the alpha value of each rendered pixel. The alpha test value is set with the setAlphaTestValue method. The default alpha test value is 0.0.
* Raster operation - the raster operation function for this RenderingAttributes component object. The raster operation is set with the setRasterOp method. The raster operation is enabled or disabled with the setRasterOpEnable method. The raster operation is one of the following:* ROP_COPY - DST = SRC. This is the default operation.
* ROP_XOR - DST = SRC ^ DST.* Vertex colors - vertex colors can be ignored for this RenderingAttributes object. This capability is set with the setIgnoreVertexColors method. If ignoreVertexColors is false, per-vertex colors are used, when present in the associated geometry objects, taking precedence over the ColoringAttributes color and Material diffuse color. If ignoreVertexColors is true, per-vertex colors are ignored. In this case, if lighting is enabled, the Material diffuse color will be used as the object color. if lighting is disabled, the ColoringAttributes color is used. The default value is false.
* Visibility flag - when set, invisible objects are not rendered (subject to the visibility policy for the current view), but they can be picked or collided with. This flag is set with the setVisible method. By default, the visibility flag is true.
* Depth buffer - can be enabled or disabled for this RenderingAttributes component object. The setDepthBufferEnable method enables or disabled the depth buffer. The setDepthBufferWriteEnable method enables or disables writing the depth buffer for this object. During the transparent rendering pass, this attribute can be overridden by the depthBufferFreezeTransparent attribute in the View object. Transparent objects include BLENDED transparent and antialiased lines and points. Transparent objects do not include opaque objects or primitives rendered with SCREEN_DOOR transparency. By default, the depth buffer is enabled and the depth buffer write is enabled.