Update bresneham line drawing algorithm.cpp

Author: Senor101

bresneham line drawing algorithm.cpp

@@ -4,48 +4,44 @@
 
 void bresenham(float x1, float y1, float x2, float y2)
 {
-    float x, y, xincr, yincr;
+    float x=x1, y=y1, xincr, yincr;
     int p, dx, dy;
-    dx = x2 - x1;
-    dy = y2 - y1;
-    if(dx<0)    xincr = -1;
-    if(dy<0)    yincr = -1;
-    dx = abs(dx);
-    dy = abs(dy);
-
-    if(dx < dy)
+    dx = abs(x2 - x1);
+    dy = abs(y2 - y1);
+    if(dx>0)  xincr = 1; else  xincr = -1;
+    if(dy>0)  yincr = 1; else  yincr = -1;
+    putpixel(x, y, WHITE);
+    if(dx > dy)
     {
-        putpixel(x, y, WHITE);
         p =2*dy-dx;
         int k = 0;
-        while(k < dx)
+        while(k <= dx)
         {
             if(p < 0){
-                x += 1;
+                x += xincr;
                 p += 2*dy;
             }else{
-                x += 1;
-                y += 1;
+                x += xincr;
+                y += yincr;
                 p += 2*dy - 2*dx;
             }
             k++;
             putpixel(x, y, WHITE);
         }
     }
     else{
-        putpixel(x, y, WHITE);
-        p = 2*dy-dx;
+        p = 2*dx-dy;
         int k = 0;
 
-        while(k < dy)
+        while(k <= dy)
         {
             if(p < 0){
-                y += 1;
+                y += yincr;
                 p += 2*dx;
             }
             else{
-                x += 1;
-                y += 1;
+                x += xincr;
+                y += yincr;
                 p += 2*dx -2*dy;
             }
             k++;
@@ -63,4 +59,5 @@ int main()
     bresenham(300, 200, 100, 50);
     getch();
     closegraph();
+    return 0;
 }