怎么画重复的斜线

Question

我需要使用 opencv-python 以编程方式绘制这样的斜线，并且它必须在倾斜角度和线之间的距离方面相似：

如果使用 OpenCV cv.line() 我需要为函数提供线的起点和终点。
按照 this Whosebug 接受的答案，我想我就能知道这两点，但首先我需要计算线方程本身。

所以我所做的是首先我使用 ai 中的测量工具计算线的倾斜角度（实际图像由平面设计师作为 ai（adobe illustrator）文件给出），我得到 67deg 和我解决了线的梯度。但问题是我不知道如何在行之间获得水平 spacing/distance 。我需要它，所以我可以提供 start.X。我用了illustrator，试着测量线之间的距离，但是如何将它映射到opencv坐标？

总的来说我的想法可行吗？或者有更好的方法来实现这个目标吗？

更新 1：我设法绘制了这个实验图像：

这是代码：

def show_image_scaled(window_name,image,height,width):
    cv2.namedWindow(window_name,cv2.WINDOW_NORMAL)
    cv2.resizeWindow(window_name,width,height)
    cv2.imshow(window_name,image)
    cv2.waitKey(0)
    cv2.destroyAllWindows()

def slanted_lines_background():
    canvas = np.ones((200,300)) * 255
    end_x = 0
    start_y = 0
    m = 2.35
    end_x = 0
    for x in range(0,canvas.shape[1],10):
        start_x = x
        end_y = start_y + compute_length(m,start_x,start_y,end_x)
        cv2.line(canvas,(start_x,start_y),(end_x,end_y),(0,0,0),2)

    show_image_scaled("Slant",canvas,200,300)

def compute_length(m,start_x,start_y,end_x=0):
    c = start_y - (m * start_x)
    length_square = (end_x - start_x)**2 + ((m *end_x) + c - start_y) ** 2
    length = math.sqrt(length_square)
    return int(length)

仍在努力填充矩形的左侧部分

Answer 1

此代码“着色”给定图像中的每个像素以生成您的阴影图案。不用担心数学。 大部分是正确的。我已经检查了细线和宽线的边缘情况。采样并不完全正确，但无论如何没人会注意到，因为缺陷只占像素的一小部分。而且我使用了 numba 来让它变得更快。

import numpy as np
from numba import njit, prange

@njit(parallel=True)
def hatch(im, angle=45, stride=10, dc=None):
    stride = float(stride)
    if dc is None:
        dc = stride * 0.5

    assert 0 <= dc <= stride

    stride2 = stride / 2
    dc2 = dc / 2
    angle = angle / 180 * np.pi
    c = np.cos(angle)
    s = np.sin(angle)

    (height, width) = im.shape[:2]
    for y in prange(height):
        for x in range(width):
            # distance to origin along normal
            dist_origin = c*x - s*y
            
            # distance to center of nearest line
            dist_center = stride2 - abs((dist_origin % stride) - stride2)
            
            # distance to edge of nearest line
            dist_edge = dist_center - dc2
            
            # shade pixel, with antialiasing
            # use edge-0.5 to edge+0.5 as "gradient" <=> 1-sized pixel straddles edge
            # for thick/thin lines, needs hairline handling
            # thin line -> gradient hits far edge of line / pixel may span both edges of line
            # thick line -> gradient hits edge of adjacent line / pixel may span adjacent line
  
            if dist_edge > 0.5: # background
                val = 0

            else: # pixel starts covering line
                val = 0.5 - dist_edge

                if dc < 1: # thin line, clipped to line width
                    val = min(val, dc)

                elif stride - dc < 1: # thick line, little background
                    val = max(val, 1 - (stride - dc))

            im[y,x] = val

canvas = np.zeros((128, 512), 'f4')
hatch(canvas, angle=-23, stride=5, dc=2.5)

# mind the gamma mapping before imshow

怎么画重复的斜线

How to draw repeated slanted lines

python

opencv