Hundred lines of code launch red hearts, why programmers lose their girlfriends!

Qixi is a traditional Chinese folk festival,不同时代、People from different regions give this festival different meanings.在漫长的演变过程中,Tanabata becomes the day when the Cowherd and Weaver Girl meet.Because of this beautiful love legend,Qixi Festival is regarded as the most romantic festival in China、festival of love.Against the backdrop of the west wind,Qixi has become Chinese again“情人节”.

作者 | 许向武       

责编 | 张红月

Since it's Valentine's Day,Romantic programmers always like to come up with tricks,Add some color to a stressful and dull life.今天给各位带来的是3DAnimated Cupid's Sword of Love：A golden cupid love sword stabs a pulsating red heart in slow motion,The hearts of the host will can't control to fall in love withTAfirst person seen.

我猜,The Cowherd and the Weaver Girl must have fallen in love after being shot by Cupid's sword of love,毕竟,They all live in heaven——in western culture,木星（Jupiter）It's Cupid,金星（Venus）Is Venus.

Before Cupid's appearance The Sword of Love,先用matplotlib绘制一个2Dhearts warm up.

import numpy as np
import matplotlib.pyplot as plt


x = np.linspace(-np.pi/2, np.pi/2, 1000)
y1 = np.power(np.cos(x),0.5) * np.cos(200*x) + np.power(np.absolute(x),0.5) - 0.7
y2 = np.power(4-np.power(x, 2), 0.01)


plt.plot(x, y1*y2, c='r')
plt.show()

Heart shape formed by up and down curves

If you zoom in a bit,You will find that the red heart above is actually a curve that fluctuates continuously up and down.red heart below,is a true closed heart,It's just made up of four curves connected end to end.

import numpy as np
import matplotlib.pyplot as plt


x1 = np.linspace(0, 2, 300)
x2 = np.linspace(0, -2, 300)


y11 = (np.power(x1, 2/3) + np.power(np.power(x1, 4/3)-4*np.power(x1, 2)+4, 0.5))/2 - 0.12
y12 = (np.power(x1, 2/3) - np.power(np.power(x1, 4/3)-4*np.power(x1, 2)+4, 0.5))/2
y21 = (np.power(-x2, 2/3) + np.power(np.power(-x2, 4/3)-4*np.power(-x2, 2)+4, 0.5))/2 - 0.12
y22 = (np.power(-x2, 2/3) - np.power(np.power(-x2, 4/3)-4*np.power(-x2, 2)+4, 0.5))/2


plt.plot(x1, y11, c='r')
plt.plot(x1, y12, c='r')
plt.plot(x2, y21, c='r')
plt.plot(x2, y22, c='r')
plt.show()

Heart shape composed of four curves connected end to end

那么,Can you draw a heart shape with one stroke?？当然可以,极坐标方程 r = Arccos(sinθ)just a heart,It's just not perfect.

import numpy as np
import matplotlib.pyplot as plt


theta = np.linspace(0, 2*np.pi, 1000)
x = np.arccos(np.sin(theta)) * np.cos(theta)
y = np.arccos(np.sin(theta)) * np.sin(theta)


plt.plot(x, y, c='r')
plt.show()

心形线

是时候展示3Dred heart.运行下面的代码,除了需要numpy模块,还需要安装wxgl模块——基于PyOpenGL的三维数据绘图工具包.

pip install wxgl

关于wxglModule for more details,Please click to play for ten minutes3D绘图：WxGL完全手册,here is the Chinese document.

下面是3Dversion of red heart drawing code：

import numpy as np
import wxgl.glplot as glt


a = np.linspace(0, 2*np.pi, 500)
b = np.linspace(0.5*np.pi, -0.5*np.pi, 500)
lons, lats = np.meshgrid(a, b)
w = np.sqrt(np.abs(a - np.pi)) * 2
x = 2 * np.cos(lats) * np.sin(lons) * w
y = -2 * np.cos(lats) * np.cos(lons) * w
z = 2 * np.sin(lats)


glt.mesh(x, y, z, color='crimson') # crimson - 绯红
glt.show()

是不是很简单？wxglThe style of use is almost the same asmatplotlib完全一致.拖动鼠标,就可以看到这个3DThe version of the hearts of around before and after.

3D红心

接下来,This code encapsulates the generation of red heart data with a function,Then call the custom model transformation function,This red heart is beating.

import numpy as np
import wxgl.glplot as glt


def red_heart(r, slices=100, thick=2.0, shift=(0,0,0)):
    """Returns the vertex data of hearts"""


    a = np.linspace(0, 2*np.pi, slices)
    b = np.linspace(0.5*np.pi, -0.5*np.pi, slices)
    lons, lats = np.meshgrid(a, b)
    w = np.sqrt(np.abs(a - np.pi)) * thick
    x = r * np.cos(lats) * np.sin(lons) * w + shift[0]
    y = -r * np.cos(lats) * np.cos(lons) * w + shift[1]
    z = r * np.sin(lats) + shift[2]


    return x, y, z


def heart_beat(t):
    """心跳函数"""


    t %= 1000
    if t < 300:
        scale = 1 + t/3000
    elif t > 700:
        scale = 1 + (1000-t)/3000
    else:
        scale = 1.1


    return (scale,)


glt.mesh(*red_heart(2), color='crimson', transform=heart_beat)
glt.show()

Click the play button on the left sidebar,Will according to this red heart60次/heart rate beats in seconds.熟悉了wxgl的使用,It's not hard to read the complete code of Cupid's arrow of love below.

import numpy as np
import wxgl
import wxgl.glplot as glt


def red_heart(r, slices=100, thick=2.0, shift=(0,0,0)):
    """Returns the vertex data of hearts"""


    a = np.linspace(0, 2*np.pi, slices)
    b = np.linspace(0.5*np.pi, -0.5*np.pi, slices)
    lons, lats = np.meshgrid(a, b)
    w = np.sqrt(np.abs(a - np.pi)) * thick
    x = r * np.cos(lats) * np.sin(lons) * w + shift[0]
    y = -r * np.cos(lats) * np.cos(lons) * w + shift[1]
    z = r * np.sin(lats) + shift[2]


    return x, y, z


def heart_beat(t):
    """心跳函数"""


    t %= 1000
    if t < 300:
        scale = 1 + t/3000
    elif t > 700:
        scale = 1 + (1000-t)/3000
    else:
        scale = 1.1


    return (scale,)


def arrow_fly(t):
    """Cupid's Arrow Flight Function"""


    t %= 4000
    if t > 2000:
       return ((0,-2,40-t/100),)
    else:
       return ((0,-2,0),)


def heart_fly(t):
    """Cupid's Arrow Flight Function"""


    t %= 4000
    if t > 2000:
       return ((0,0,1,90), (0,-2,40-t/100))
    else:
       return ((0,0,1,90), (0,-2,0))


glt.figure(azim=50, elev=16, style='gray') # set initial azimuth、高度角、背景色
glt.mesh(*red_heart(2), color='crimson', transform=heart_beat) # Drawing beating hearts


x, y, z = red_heart(0.2, thick=3.0, shift=(0,-8,0)) # Generate Heart Arrow Vertex Data
glt.mesh(x, -z, y, color='crimson', transform=heart_fly) # draw heart arrow


light = wxgl.SunLight(roughness=0, metalness=0, shininess=0.5) # Arrow shaft lights
glt.cylinder((0,0,-8), (0,0,9), 0.1, color='goldenrod', transform=arrow_fly, light=light) # draw arrow shaft


vs = [(-1,1,11), (1,-1,11), (1,-1,6), (-1,1,6),(-1,-1,11), (1,1,11), (1,1,6), (-1,-1,6)] # Nock Vertex Data
texture = wxgl.Texture(r'res\feather.png') # Arrow tail feather texture
texcoord = [(0,1), (0,0), (1,0), (1,1),(0,1), (0,0), (1,0), (1,1)] # nock texture coordinates
light = wxgl.BaseLight() # Arrow tail lights
glt.quad(vs, texture=texture, texcoord=texcoord, transform=arrow_fly, light=light) # draw nocks


glt.show()

wxglThe toolbar provides recordinggif和MP4文件的功能,下面的gif就是使用wxglBuilt-in recording function.

The texture of the feather is used in the code,Please download the pictures,and save to the location specified by the code.

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