Digital Differential Analyzer (DDA) algorithm

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Digital Differential Analyzer (DDA) algorithm
The Cartesian slope-intercept equation for a straight line is
with m representing the slope of the line and b as they intercept. Given that the two
endpoints of the segment at positions (x, y,) and (x, y), we can determine values for the
slope m and y intercept b with the following calculations
Algorithms for displaying straight lines are based on the line equation 3-1 and the
calculations given in Eqs. 3-2 and 3-3.
For any given x interval along a line, we can compute the corresponding y interval
from Eq. 3-2 as
2
Similarly, we can obtain the x interval
Line DDA algorithm is the simple line generation algorithm which is explained step by step here.
LineDDA algorithm
Step 1 ? Get the input of two end points (X0,Y0) and (X1,Y1)
Step 2 ? Calculate the difference between two end points.
dx = X1 - X0
dy = Y1 - Y0
Step 3 ? Based on the calculated difference in step-2, you need to identify the number of steps to
put pixel. If dx > dy, then you need more steps in x coordinate; otherwise in y coordinate.
if (dx > dy) then Steps = absolute(dx);
else Steps = absolute(dy);
Step 4 ? Calculate the increment in x coordinate and y coordinate.
Xincrement = dx / (float) steps;
Yincrement = dy / (float) steps;
Step 5 ? Put the pixel by successfully incrementing x and y coordinates accordingly and
complete the drawing of the line.
X=X0, Y=Y0
For I=1 to step do
Plot(X,Y,color)
X=X+Xincrement
Y=Y+Yincremen
Square1 algorithm
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2)X2,y( ,)X1,Y1(in square Get the input of two points Step 1 ? Call LinDDA(X1,Y1,X2,y1,color)Step 2 ? Call LinDDA(X2,Y1,X2,y2,color)Step 3 ? Call LinDDA(X2,Y2,X1,y2,color)Step 4 ?
Step 5 ? Call LinDDA(X1,Y2,X1,y1,color)
lgorithma 2