Function rasterizeTriangleTop

primitive/triangle.go:155–171

(x1, y1, x2, y2, x3, y3 int, buf []Scanline)

}

func rasterizeTriangleTop(x1, y1, x2, y2, x3, y3 int, buf []Scanline) []Scanline {
	s1 := float64(x3-x1) / float64(y3-y1)
	s2 := float64(x3-x2) / float64(y3-y2)
	ax := float64(x3)
	bx := float64(x3)
	for y := y3; y > y1; y-- {
		ax -= s1
		bx -= s2
		a := int(ax)
		b := int(bx)
		if a > b {
			a, b = b, a
		}
		buf = append(buf, Scanline{y, a, b, 0xffff})
	}
	return buf
}