Apparatus of and method for drawing graphics, and computer program product

Abstract

An apparatus of drawing graphics includes an edge coefficient calculator calculating, from vertex data on vertices of a triangle, edge coefficients of edge functions used to determine whether a pixel is present in an inside region of the triangle, and a bounding box calculator calculating a bounding box of projected images of the triangle on a projection plane based on the edge coefficients. The apparatus also includes a starting point determiner and a traverser. The starting point determiner classifies the projected images of the triangle based on a combination of the edge coefficients for respective sides of the triangle, and determines a scan starting point from a corner of the bounding box based on classification of the projected images. The traverser generates pixel data used in rasterization by scanning the bounding box from the scan starting point.

1 . An apparatus of drawing graphics, comprising:
 an edge coefficient calculator calculating, from vertex data on vertices of a triangle, edge coefficients of edge functions used to determine whether a pixel is present in an inside region of the triangle;   a bounding box calculator calculating a bounding box of projected images of the triangle on a projection plane based on the edge coefficients;   a starting point determiner classifying the projected images of the triangle based on a combination of the edge coefficients for respective sides of the triangle, and determining a scan starting point from a corner of the bounding box based on classification of the projected images; and   a traverser generating pixel data used in rasterization by scanning the bounding box from the scan starting point,   wherein the starting point determiner classifies the projected images of the triangle based on a combination of a sign of one of the edge coefficients in an X-axis direction and a sign of one of the edge coefficients in a Y-axis direction on the projection plane for each side, and determines the scan starting point based on classification of the projected images.   
   
   
       2 . An apparatus of drawing graphics, comprising:
 an edge coefficient calculator calculating, from vertex data on vertices of a triangle, edge coefficients of edge functions used to determine whether a pixel is present in an inside region of the triangle;   a bounding box calculator calculating a bounding box of projected images of the triangle on a projection plane based on the edge coefficients;   a starting point determiner classifying the projected images of the triangle based on a combination of the edge coefficients for respective sides of the triangle, and determining a scan starting point from a corner of the bounding box based on classification of the projected images; and   a traverser generating pixel data used in rasterization by scanning the bounding box from the scan starting point,   wherein the starting point determiner classifies the projected images of the triangle based on a combination of a sign of one of the edge coefficients in an X-axis direction and a sign of one of the edge coefficients in a Y-axis direction on the projection plane for each side, and based on a classification bit table that presets bits indicating classification of the edge coefficients, and determines the scan starting point based on the classification bit table.   
   
   
       3 . An apparatus of drawing graphics, comprising:
 edge coefficient calculating means for calculating, from vertex data on vertices of a triangle, edge coefficients of edge functions used to determine whether a pixel is present in an inside region of the triangle;   bounding box calculating means for calculating a bounding box of projected images of the triangle on a projection plane based on the edge coefficients;   starting point determining means for classifying the projected images of the triangle based on a combination of the edge coefficients for respective sides of the triangle, and determining a scan starting point from a corner of the bounding box based on classification of the projected images; and   traversing means for generating pixel data used in rasterization by scanning the bounding box from the scan starting point,   wherein the starting point determining means classifies the projected images of the triangle based on a combination of a sign of one of the edge coefficients in an X-axis direction and a sign of one of the edge coefficients in a Y-axis direction on the projection plane for each side, and determines the scan starting point based on classification of the projected images.