Rendering

Here we are in the rendering module of the main loop. In this module, we draw the cube’s lines and points in the frame, and then fill in the faces.

In this module we are dealing with the following code snippet of the Engine Loop:

main method

def main(self):

    ...

        self.camera_model.draw_all_cube_lines(clipped_triangles)
        if self.window.show_points:
            self.camera_model.draw_all_cube_points(clipped_triangles)
        if self.window.show_planes:
            self.camera_model.fill_cube_faces(clipped_triangles)
        ...

draw_all_cube_points(triangles: List) → None
Draws all points of the cube on the camera image.

Note

This method handles only the triangle points; the actual drawing will be performed in the draw_camera_image_point method.

Parameters:

triangles: A list of triangles representing the cube.
draw_all_cube_points method
def draw_all_cube_points(self, triangles: List) -> None:

    for triangle in triangles:
        for point in triangle.camera_points:
            self.draw_camera_image_point(point)

draw_camera_image_point(C_point: np.array) → None
Draws a single point on the camera image using the camera coordinates from the draw_all_cube_points method.

Parameters:

C_point: The point in camera coordinates.
draw_camera_image_point method
def draw_camera_image_point(self, C_point: np.array) -> None:
    I_point = np.matmul(self.I_T_C, C_point)
    u = int(I_point[0] / I_point[2])
    v = int(I_point[1] / I_point[2])
    cv.circle(self.camera_image, (u, v), 5, (255, 0, 0), 2)

draw_all_cube_lines(triangles: List) → None
Draws all edges of the cube on the camera image.

Note

This method handles only the triangle points; the actual drawing will be performed in the draw_camera_image_line method.

Parameters:

triangles: A list of triangles representing the cube.
draw_all_cube_lines method
def draw_all_cube_lines(self, triangles : List) -> None:

    for triangle in triangles:
        for i in range(3):
            C_point0 = triangle.camera_points[i]
            C_point1 = triangle.camera_points[(i + 1) % 3]
            self.draw_camera_image_line(C_point0, C_point1)

draw_camera_image_line(C_point0: np.array, C_point1: np.array) → None
Draws a line between two points on the camera image using the camera coordinates given by the draw_all_cube_lines method.

Parameters:

C_point0: The first point in camera coordinates.

C_point1: The second point in camera coordinates.
draw_camera_image_line method
def draw_camera_image_line(self, C_point0: np.array, C_point1: np.array) -> None:
    I_point0 = np.matmul(self.I_T_C, C_point0)
    I_point1 = np.matmul(self.I_T_C, C_point1)

    u0 = int(I_point0[0] / I_point0[2])
    v0 = int(I_point0[1] / I_point0[2])

    u1 = int(I_point1[0] / I_point1[2])
    v1 = int(I_point1[1] / I_point1[2])

    cv.line(self.camera_image, (u0, v0), (u1, v1), (0, 0, 0), 1)

draw_camera_image_arrow(C_point0: np.array, C_point1: np.array) → None

Draws an arrow from one point to another on the camera image.

Parameters:

C_point0: The starting point in camera coordinates.
C_point1: The ending point in camera coordinates.

draw_camera_image_arrow method

def draw_camera_image_arrow(self, C_point0: np.array, C_point1: np.array) -> None:
    try:
        I_point0 = np.matmul(self.I_T_C, C_point0)
        I_point1 = np.matmul(self.I_T_C, C_point1)

        u0 = int(I_point0[0] / I_point0[2])
        v0 = int(I_point0[1] / I_point0[2])

        u1 = int(I_point1[0] / I_point1[2])
        v1 = int(I_point1[1] / I_point1[2])

        cv.arrowedLine(self.camera_image, (u0, v0), (u1, v1), (0, 255, 0), 2)
    except:
        raise ValueError(f"Could draw normal {C_point0}, {C_point1}")

fill_cube_faces(triangles: List) → None

Fills the faces of the cube with a specified color on the camera image.

Parameters:

triangles: A list of triangles representing the cube.

fill_cube_faces method

def fill_cube_faces(self, triangles: List) -> None:
    for triangle in triangles:
        I_points = []

        for C_point in triangle.camera_points:
            I_point = np.matmul(self.I_T_C, C_point)

            u = int(I_point[0] / I_point[2])
            v = int(I_point[1] / I_point[2])

            I_points.append((u, v))

        Poly_Points = np.array(I_points, np.int32)
        cv.fillPoly(self.camera_image, [Poly_Points], triangle.color)

draw_poly(points: List[np.array]) → None

Draws a polygon defined by a list of points on the camera image. Parameters:

points: A list of points representing the polygon.

draw_poly method

def draw_poly(self, points: List[np.array]) -> None:

    I_points = []

    for point in points:

        I_point = np.matmul(self.I_T_C, point)

        u = int(I_point[0] / I_point[2])
        v = int(I_point[1] / I_point[2])

        I_points.append((u, v))

    Poly_Points = np.array(I_points, np.int32)
    hull = cv.convexHull(Poly_Points)
    cv.fillPoly(self.camera_image, [hull], (50,50,50))