diff --git a/tinyrender/main.cpp b/tinyrender/main.cpp
index 7b0819c..55d0e70 100644
--- a/tinyrender/main.cpp
+++ b/tinyrender/main.cpp
@@ -3,9 +3,48 @@
 const TGAColor white = TGAColor(255, 255, 255, 255);
 const TGAColor red = TGAColor(255, 0, 0, 255);
 
+
+void line(int x0, int y0, int x1, int y1, TGAImage& image, TGAColor color) {
+	bool steep = false;
+	if (std::abs(x0-x1) < std::abs(y0-y1)) // 交换次序
+	{
+		std::swap(x0, y0);
+		std::swap(x1, y1);
+		steep = true;
+	}
+	if (x0 > x1)
+	{
+		std::swap(x0, x1);
+		std::swap(y0, y1);
+	}
+	int dx = x1 - x0;
+	int dy = y1 - y0;
+	int derror2 = std::abs(dy) * 2;
+	int error2 = 0;
+	int y = y0;
+	for (int x = x0; x <=x1; x++)
+	{
+		if (steep) 
+		{
+			image.set(x, y, color);
+		}
+		else
+		{
+			image.set(x, y, color);
+		}
+		error2 += derror2;
+		if (error2 > dx) // 误差值，提供从当前位置到最佳直线的距离
+		{
+			y += (y1 > y0 ? 1 : -1);
+			error2 -= dx * 2;
+		}
+	}
+}
+
+
 int main(int argc, char** argv) {
 	TGAImage image(100, 100, TGAImage::RGB);
-	image.set(52, 41, red);
+	line(52, 41,90,70,image ,red);
 	image.flip_vertically(); // i want to have the origin at the left bottom corner of the image
 	image.write_tga_file("output.tga");
 	return 0;