Advanced Features (3D Vertex Array Screen Objects); Overview; Triangle Strips - PRG MBOX User Manual

ADVANCED FEATURES (3D VERTEX ARRAY SCREEN OBJECTS)

Overview

The following section covers Triangle Strips and Fans. Use of these items goes beyond typical rectangular screen
objects for image remapping. If unsure about how to use these features, contact Mbox support for assistance.

Triangle Strips

In order to support non-rectangular shapes, standard screen objects may be converted to Triangle Strip screen objects.
Standard screen objects are referenced by their origin and their width and height. Triangle strips are referenced by their
vertices.
To convert a screen object to a triangle strip or fan, select the screen object in the listbox on the main window. Then
click on the Add button at the top-left of the window and select "Convert to Strip" or "Convert to Fan" from the list.
CAUTION! Once a screen object has been converted to a triangle strip or fan, the change cannot be undone.
Triangle strips are the simpler of the triangle-based screen objects. The standard rectangular screen object is converted
to a screen object made from two triangles, placed side by side x`as in the second illustration below. Four vertices are
created, one for each corner of the screen object. Texture coordinates for all four vertices are also be created.
The two illustrations below show the coordinate data for the standard screen object and the triangle strip screen object:
The simple screen object only needs one coordinate, the "top, left" coordinate that specifies its origin. The coordinates
for the other three corners are implied by the width and height.
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