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Lesson 0: Bresenham's Line Drawing Algorithm—Fifth attempt

--- a/main.c

+++ b/main.c

@@ -103,8 +103,7 @@

 void

 bresenham(Memimage *dst, Point p0, Point p1, Memimage *src)

 {

-	int steep = 0;

-	double t;

+	int steep = 0, Δe, e;

 	Point p, dp;

 	if(abs(p0.x-p1.x) < abs(p0.y-p1.y)){

@@ -120,18 +119,19 @@

 	}

 	dp = subpt(p1, p0);

+	Δe = 2*abs(dp.y);

+	e = 0;

 	for(p = p0; p.x <= p1.x; p.x++){

-		t = (double)(p.x-p0.x)/(p1.x-p0.x);

-		p.y = flerp(p0.y, p1.y, t);

-

-		if(steep)

-			swap(&p.x, &p.y);

-

+		if(steep) swap(&p.x, &p.y);

 		pixel(dst, p, src);

+		if(steep) swap(&p.x, &p.y);

-		if(steep)

-			swap(&p.x, &p.y);

+		e += Δe;

+		if(e > dp.x){

+			p.y += p1.y > p0.y? 1: -1;

+			e -= 2*dp.x;

+		}

 	}

 }