initial commit

Implemented two line drawing algorithms
 - BLD - Bresenham Line drawing algorithm (for |m| < 1)
 - DDA - Digital Differential Analyser algorithm

Changes to be committed:
new file:   .gitignore
new file:   line.c

.gitignore

+a.out
+.vscode/*

line.c

+/**
+ * line drawing algorithms
+ * BLD - Bresenham Line Drawing algorithm (for |m| < 1)
+ * DDA - Digital Differential Analyser algorithm
+ */
+#include <graphics.h>
+#include <stdlib.h>
+#include <stdio.h>
+#define WHITE 15
+
+/**
+ * function to return max of two float values
+   max(a, b);
+ * @param float
+ * @param float
+ */
+float max(float a, float b){
+    return (a>b)
+            ? a
+            : b;
+}
+
+/**
+ * function to draw line given two end points in Cartesian co-ordinate system
+ * with Basic Bresenham Line Drawing algorithm supporting lines with |m| < 1
+   drawlineBLD(x1, y1, x2, y2);
+ * @param int abscissa of starting point
+ * @param int ordinate of starting point
+ * @param int abscissa of ending point
+ * @param int oridante of ending point
+ */
+void drawlineBLD(int x1,int y1, int x2, int y2){
+    int dx, dy, p, x, y;
+
+    dx = x2 - x1;
+    dy = y2 - y1;
+
+    x = x1;
+    y = y1;
+
+    p=2*dy-dx;
+
+    while(x<x2)
+    {
+        putpixel(x,y,WHITE);
+        if(p>=0) {
+            y=y+1;
+            p=p+2*dy-2*dx;
+        } else {
+            p=p+2*dy;
+        }
+        x=x+1;
+    }
+}
+
+/**
+ * function to draw line given two end points in Cartesian co-ordinate system
+ * with Digital Differential Analyser algorithm
+   drawlineDDA(x1, y1, x2, y2);
+ * @param float abscissa of starting point
+ * @param float ordinate of starting point
+ * @param float abscissa of ending point
+ * @param float oridante of ending point
+ */
+void drawlineDDA(float x1, float y1, float x2, float y2){
+    float x, y, dx, dy, step, xinc, yinc;
+    int k;
+
+    dx = x2 - x1;
+    dy = y2 - y1;
+
+    x = x1;
+    y = y1;
+
+    step = max(abs(dx),abs(dy));
+    xinc = dx / step;
+    yinc = dy / step;
+    for (k=0; k<step; ++k) {
+        putpixel(x, y, WHITE);
+        x += xinc;
+        y += yinc;
+    }
+}
+
+int main()
+{
+
+   /* request autodetection */
+   int gdriver = DETECT, gmode, errorcode;
+   int xmax, ymax;
+
+   /* initialize graphics and local variables */
+   initgraph(&gdriver, &gmode, "");
+
+   xmax = getmaxx();
+   ymax = getmaxy();
+
+   /* draw line BLD*/
+   drawlineBLD(0,0,xmax,ymax);
+
+   /* draw line DDA*/
+   drawlineDDA(0,ymax,xmax,0);
+
+   /* clean up */
+   getchar();
+   closegraph();
+   return 0;
+}