| 摘要 |
PURPOSE:To omit the calculation of luminance on a vertex every change of a visual face and to shorten a processing time by deciding a front face or a rear face in accordance with the appearance order of vertexes. CONSTITUTION:A vertex having the minimum Y-coordinate value out of respective vertexes is found out as B and a vertex having the maximum Y-coordinate value is found out as T. An angle DBT formed by a vector connecting the vertexes B, T and a horizontal line and an angle DBP formed by a vector connecting the vertex B and a vertex P appearing next to the B and the horizontal line are found out. Both the angles BBT, BBP are compared with each other to decide a clockwise direction or a counterclockwise direction, and DBT>=DBP and DBT< DBP are respectively decided as the counterclockwise direction and the clockwise direction. In case of setting up the surface as the counterclockwise direction, rear face display is decided. When the front/rear face luminance data are utilized on the terminal side, luminance calculation every change of a visual direction can be omitted.
|
