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pyopenglをブラウザで表示する(python + eel)

Last updated at Posted at 2020-05-19

#はじめに
ブラウザで、OpenGLだと既にWebGLがある。だけど、compute shaderと他のshaderが使えない。文法も違う。だけど、GUIが圧倒的にWebGLの方が良い。手軽さも良い。
pyopenglは、ほぼ使ってる人がいないと思う。GUIが、どうにもならないからだと思う。いつかブラウザでpyopenglをやりたいと思っていた。
最近、EELをはじめて、情報を漁っていたら、
【OpenCV】OpenCVの画像をEelに表示する 
を見つけた。これは、やるしかないでしょう。CVとか知識がなかったから、かなりハマったけど、できた。

#ソースコード

main.py
import eel
from OpenGL.GL import *
from OpenGL.WGL import *
from ctypes import *
from ctypes.wintypes import *
import numpy as np
import cv2
import base64
import time
import atexit

kernel32 = windll.kernel32
user32 = windll.user32
winmm = windll.winmm 
    
# window init
XRES, YRES = user32.GetSystemMetrics(0), user32.GetSystemMetrics(1)
WS_OVERLAPPEDWINDOW = 0xcf0000
hWnd = user32.CreateWindowExA(0,0xC018,0,WS_OVERLAPPEDWINDOW,0,0,XRES,YRES,0,0,0,0)
hdc = user32.GetDC(hWnd)   
user32.SetForegroundWindow(hWnd)

# GL context init
PFD_SUPPORT_OPENGL = 32
PFD_DOUBLEBUFFER = 1
pfd = PIXELFORMATDESCRIPTOR(0,1,PFD_SUPPORT_OPENGL|PFD_DOUBLEBUFFER,32,0,0,0,0,0,0,0,0,0,0,0,0,0,32,0,0,0,0,0,0,0)
SetPixelFormat(hdc, ChoosePixelFormat(hdc, pfd), pfd)
hGLrc = wglCreateContext(hdc)
wglMakeCurrent(hdc, hGLrc)

def finish():
    # GL context finish
    wglMakeCurrent(0, 0)
    wglDeleteContext(hGLrc)
    # windoe finish
    user32.ReleaseDC(hWnd, hdc)
    user32.PostQuitMessage(0)
    user32.DestroyWindow(hWnd)
    #print("finish")
atexit.register(finish)


def main():
    vsh = """
#version 430

layout(location = 0) in vec2 p;

void main(){
    gl_Position = vec4(p, 0, 1);
}
"""

    fsh = """
#version 430

out vec4 fragColor;

uniform vec2 resolution;
uniform float time;

void main() {
    vec2 p = (2.0 * gl_FragCoord.xy - resolution.xy) / resolution.y;
    p += vec2(cos(time), sin(time)) * 0.5;
    float g = exp(-1.5 * dot(p,p));
    fragColor = vec4(g*.3, g*.5, g, 1)+.3;
}
"""

    width = 640
    height = 350


    # GL init
    glClearColor(0, 0, 0, 1)
    glEnable(GL_CULL_FACE)
    glCullFace(GL_BACK)
    glEnable(GL_DEPTH_TEST)
    glDepthFunc(GL_LEQUAL)
    glViewport(0,0,width,height)
    
    program = glCreateProgram()
    for s, t in zip((vsh, fsh), (GL_VERTEX_SHADER, GL_FRAGMENT_SHADER)):    
        shader = glCreateShader(t)
        glShaderSource(shader, s)
        glCompileShader(shader)
        if glGetShaderiv(shader, GL_COMPILE_STATUS) != GL_TRUE:
            raise RuntimeError(glGetShaderInfoLog(shader).decode())
        glAttachShader(program, shader)
    glLinkProgram(program)
    glUseProgram(program)
    glUniform2f(glGetUniformLocation(program, "resolution"), width,height)
    vertices = np.array([-1,-1,1,-1,-1,1,1,1], np.float32)
    glBindBuffer(GL_ARRAY_BUFFER, glGenBuffers(1))
    glBufferData(GL_ARRAY_BUFFER, vertices.nbytes, (c_float*len(vertices))(*vertices), GL_STATIC_DRAW)
    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, None)
    glEnableVertexAttribArray(0)
    
    pixels = np.zeros((height,width,3), np.uint8)
    st = time.time()
    while True:
        eel.sleep(0.01)
        elapsedTime = time.time()-st
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
        glUniform1f(glGetUniformLocation(program, "time"), elapsedTime)
        glDrawArrays(GL_TRIANGLE_STRIP, 0, 4)
        glReadPixels(0, 0, width,height, GL_BGR, GL_UNSIGNED_BYTE, pixels)
        _, image = cv2.imencode('.jpg', np.flipud(pixels))
        eel.set_base64image("data:image/jpg;base64," + base64.b64encode(image).decode())
        eel.set_elapsedtime(round(elapsedTime,1))

if __name__ == '__main__':
    eel.init('web')
    eel.start('index.html', block=False)
    main()

index.html
<!doctype html>
<html>
    <head>
        <meta charset="utf-8">
        <script type="text/javascript" src="/eel.js"></script>

        <script>
            eel.expose(set_elapsedtime);
            function set_elapsedtime(elapsedtime0) {
                document.getElementById("elapsedtime").innerHTML = "elapsedtime:" + elapsedtime0 + "s";
            }
            eel.expose(set_base64image);
            function set_base64image(img) {
                document.getElementById("python_video").src = img;
            }
        </script>
    </head>
    <body>
        <div id="elapsedtime">elapsedtime</div>
        <img id="python_video" >
    </body>
</html>

#おわりに
python + eelで実現してます。詳しい事は、python,eelで検索してください。
OpenGLの終了処理も無難に書いておきました。pythonでやっているので、いらないかもしれません。このあたりのことは、よくわかりません。
マニアック過ぎて、見る人もいないと思いますが、自分の忘備録を兼ねてます。

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