diff options
Diffstat (limited to 'main.c')
| -rw-r--r-- | main.c | 15 |
1 files changed, 13 insertions, 2 deletions
@@ -103,9 +103,10 @@ swap(int *a, int *b) void bresenham(Memimage *dst, Point p0, Point p1, Memimage *src) { - int steep = 0, Δe, e; + int steep = 0, Δe, e, Δy; Point p, dp; + /* transpose the points */ if(abs(p0.x-p1.x) < abs(p0.y-p1.y)){ steep = 1; swap(&p0.x, &p0.y); @@ -121,6 +122,7 @@ bresenham(Memimage *dst, Point p0, Point p1, Memimage *src) dp = subpt(p1, p0); Δe = 2*abs(dp.y); e = 0; + Δy = p1.y > p0.y? 1: -1; for(p = p0; p.x <= p1.x; p.x++){ if(steep) swap(&p.x, &p.y); @@ -129,13 +131,21 @@ bresenham(Memimage *dst, Point p0, Point p1, Memimage *src) e += Δe; if(e > dp.x){ - p.y += p1.y > p0.y? 1: -1; + p.y += Δy; e -= 2*dp.x; } } } void +triangle(Memimage *dst, Point p0, Point p1, Point p2, Memimage *src) +{ + bresenham(dst, p0, p1, src); + bresenham(dst, p1, p2, src); + bresenham(dst, p2, p0, src); +} + +void redraw(void) { lockdisplay(display); @@ -211,6 +221,7 @@ threadmain(int argc, char *argv[]) bresenham(fb, Pt(40,40), Pt(300,300), red); bresenham(fb, Pt(80,80), Pt(100,200), red); bresenham(fb, Pt(80,80), Pt(200,100), red); + triangle(fb, Pt(30,10), Pt(45, 45), Pt(5, 100), red); display->locking = 1; unlockdisplay(display); |