Echo Method


The echo method attribute indicates how primitives are to be echoed and unechoed. PEXlib defines the following echo methods:

PEXEchoDestructiveColor -
Echoes a primitive by drawing it in the color defined by the echo color renderer attribute. This color overrides the primitive's color. Lighting, shading, depth cueing, transparency, texture mapping, and data mapping are not applied to the primitive. The color is applied to both the front-facing and back-facing facets of surface primitives. (See Surfaces - General Attributes.)

This method is destructive, meaning the image rendered in echo mode PEXEcho cannot be redrawn correctly in echo mode PEXUnEcho. The image must be cleared and re-rendered to be restored. (5.2)

PEXEchoNonDestructiveColor -
This method is identical to method PEXEchoDestructiveColor except that the image is redrawn correctly in echo mode PEXUnEcho. (5.2)

PEXEchoXORColor - Echo a primitive by performing the logical XOR operation on the pixel values in the frame buffer that the primitive modifies with the pixel value obtained by applying the renderer's current color approximation to the renderer's echo color renderer attribute. The resulting pixels are stored back in the frame buffer, overriding the primitive's color. Lighting, shading, depth cueing, transparency, texture mapping, and data mapping are not applied to the primitive. The color is applied to both the front-facing and back-facing facets of surface primitives. (See Surfaces - General Attributes.)

The pipeline state's drawing function is forced to behave like function GXcopy when echo method PEXEchoXORColor is enabled.

This method is non-destructive, meaning the image rendered in echo mode PEXEcho is redrawn correctly in echo mode PEXUnEcho. (5.2)

Whether primitives are to be echoed is controlled by the echo mode renderer attribute.

The complete list of renderer attributes is listed in the Renderer Attributes Table.

For an overview about Renderers, see General Information. For a list of all Renderer functions and related topics, see Rendering.