Function rasterizeTriangle

primitive/triangle.go:111–135

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

}

func rasterizeTriangle(x1, y1, x2, y2, x3, y3 int, buf []Scanline) []Scanline {
	if y1 > y3 {
		x1, x3 = x3, x1
		y1, y3 = y3, y1
	}
	if y1 > y2 {
		x1, x2 = x2, x1
		y1, y2 = y2, y1
	}
	if y2 > y3 {
		x2, x3 = x3, x2
		y2, y3 = y3, y2
	}
	if y2 == y3 {
		return rasterizeTriangleBottom(x1, y1, x2, y2, x3, y3, buf)
	} else if y1 == y2 {
		return rasterizeTriangleTop(x1, y1, x2, y2, x3, y3, buf)
	} else {
		x4 := x1 + int((float64(y2-y1)/float64(y3-y1))*float64(x3-x1))
		y4 := y2
		buf = rasterizeTriangleBottom(x1, y1, x2, y2, x4, y4, buf)
		buf = rasterizeTriangleTop(x2, y2, x4, y4, x3, y3, buf)
		return buf
	}
}

func rasterizeTriangleBottom(x1, y1, x2, y2, x3, y3 int, buf []Scanline) []Scanline {
	s1 := float64(x2-x1) / float64(y2-y1)