Cg7_2013

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Unformatted text preview: a line F(x,y) = ax + by + c = 0. If b < 0, F > 0 if the line is above the point F < 0 if the line is below the point Summary of mid-point algorithm ● ● ● ● Start point is simply first endpoint (xl,yl). Calculate the initial value for d Choose between 2 pixels at each step based upon the sign of a decision variable. Update the decision variable based upon which pixel is chosen. ●No floating point arithmetic needed Midpoint algorithm void MidpointLine(int x1,y1,x2,y2) { int dx=x2-x1; int dy=y2-y1; int d=2*dy-dx; int increE=2*dy; int incrNE=2*(dy-dx); x=x1; y=y1; WritePixel(x,y); while (x < x2) { if (d<= 0) { d+=incrE; x++ } else { d+=incrNE; x++; y++; } WritePixel(x,y); } } * Overview Rasterization •Line Rasterization •Polygon Rasterization ●Scanline Algorithm ●Rasterizing triangles Edge walking ●Interpolation by barycentric coordinates ● •Mean value coordinates •Dividing polygons into triangles Scanline algorithm A traditional approach of rasterization Filling in the pixels within the polygon along the scan line Scanline algorithm For each scan line: 1.Find the intersections of the scan   line with all edges of th...
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This document was uploaded on 03/26/2014.

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