Draw rotated rectangle in opencv c++ - c++

Question

I want to draw a rotated rectangle in opencv with c++. I use "rectangle" function like bellow:
rectangle(RGBsrc, vertices[0], vertices[2], Scalar(0, 0, 0), CV_FILLED, 8, 0);
but this function draw an rectangle with 0 angle. How can i draw rotated rectangle with special angle in opencv with c++?

Answer 1

Since you want a filled rectangle, you should use fillConvexPoly:
// Include center point of your rectangle, size of your rectangle and the degrees of rotation
void DrawRotatedRectangle(cv::Mat& image, cv::Point centerPoint, cv::Size rectangleSize, double rotationDegrees)
{
cv::Scalar color = cv::Scalar(255.0, 255.0, 255.0); // white
// Create the rotated rectangle
cv::RotatedRect rotatedRectangle(centerPoint, rectangleSize, rotationDegrees);
// We take the edges that OpenCV calculated for us
cv::Point2f vertices2f[4];
rotatedRectangle.points(vertices2f);
// Convert them so we can use them in a fillConvexPoly
cv::Point vertices[4];
for(int i = 0; i < 4; ++i){
vertices[i] = vertices2f[i];
}
// Now we can fill the rotated rectangle with our specified color
cv::fillConvexPoly(image,
vertices,
4,
color);
}

Answer 2

The sample below demonstrates how to draw rotated rectangle in opencv c++.
Mat test_image(200, 200, CV_8UC3, Scalar(0));
RotatedRect rRect = RotatedRect(Point2f(100,100), Size2f(100,50), 30);
Point2f vertices[4];
rRect.points(vertices);
for (int i = 0; i < 4; i++)
line(test_image, vertices[i], vertices[(i+1)%4], Scalar(0,255,0), 2);
Rect brect = rRect.boundingRect();
rectangle(test_image, brect, Scalar(255,0,0), 2);
imshow("rectangles", test_image);
waitKey(0);
The result is :
Reference:
OpenCV docs