Python，OpenGL：如何在GPU上存儲頂點數據

Question

我需要在2D中顯示大量的四邊形，使用Python和OpenGL進行設計的最佳方式是什麼？我們的目標是而不是在調用paintGL時將所有數據發送到GPU，因此需要很長時間...我猜想必須存在將頂點數據存儲在GPU上的可能性，以及如何使用Python ？這裏是我的問題的工作示例：

#!/usr/bin/env python 
# -*- coding: utf-8 -*- 

from OpenGL.GL import * 
from PyQt4 import QtGui, QtCore, QtOpenGL 

def get_squares(squareCount, edgeSize): 

    """ 
    Returns vertex list for a matrix of squares 

    squareCount - number of squares on one edge 
    edgeSize - size of the matrix edge 
    """ 

    edgeLength = edgeSize/squareCount/2 
    vertexList = [] 
    x = edgeLength/2 
    y = edgeLength/2 
    z = 0 
    for i in range(squareCount): 
     for j in range(squareCount): 
      vertexList.append([x,y,z]) 
      y += edgeLength 
      vertexList.append([x,y,z]) 
      x += edgeLength 
      vertexList.append([x,y,z]) 
      y -= edgeLength 
      vertexList.append([x,y,z]) 
      x += edgeLength 
     x = edgeLength/2 
     y += 2*edgeLength 
    return vertexList 


class OpenGLWidget(QtOpenGL.QGLWidget): 
    def __init__(self, squareCount = 20, parent = None): 
     QtOpenGL.QGLWidget.__init__(self, parent) 
     self.squares = get_squares(squareCount, 50) 

    def paintGL(self): 
     glBegin(GL_QUADS) 
     for point in self.squares: 
      glVertex3f(*point) 
     glEnd() 

    def resizeGL(self, w, h): 
     glMatrixMode(GL_PROJECTION) 
     glLoadIdentity() 
     glOrtho(0, 50, 0, 50, 0, 1) 
     glViewport(0, 0, w, h) 

    def initializeGL(self): 
     glClearColor(0.0, 0.0, 0.0, 1.0) 
     glClear(GL_COLOR_BUFFER_BIT) 

if __name__ == '__main__': 
    import sys 
    app = QtGui.QApplication([]) 
    w = OpenGLWidget(squareCount = 20) # try increasing that number and resizing the window... 
             # for me at squareCount = 200 (40000 squares) it's really slow 
    w.show() 
    sys.exit(app.exec_()) 

Answer 1

我使用Python-OpenGL和numpy來做到這一點。示例代碼：

import numpy 

Verts = numpy.array([ 
    (-0.5, 0.5, -0.5), # left top rear 
    ( 0.5, 0.5, -0.5), # right top rear 
    ( 0.5, -0.5, -0.5), # right bottom rear 
    (-0.5, -0.5, -0.5), # left bottom rear 
    (-0.5, 0.5, 0.5), # left top front 
    ( 0.5, 0.5, 0.5), # right top front 
    ( 0.5, -0.5, 0.5), # right bottom front 
    (-0.5, -0.5, 0.5), # left bottom front 
], dtype=numpy.float32) 

Faces = numpy.array([ 
    7, 6, 5, 4,  # front 
    6, 2, 1, 5,  # right 
    3, 7, 4, 0,  # left 
    5, 1, 0, 4,  # top 
    3, 2, 6, 7,  # bottom 
    2, 3, 0, 1,  # rear 
], dtype=numpy.int16) 

class Cube (object): 
    "Wireframe cube implemented with VBOs" 

    def __init__ (self, color = (0.0, 1.0, 0.0, 1.0)): 
     self.vert = glGenBuffers(1) 
     self.rgba = glGenBuffers(1) 
     self.idx = glGenBuffers(1) 

     glBindBuffer(GL_ARRAY_BUFFER, self.vert) 
     glBufferData(GL_ARRAY_BUFFER, Verts, GL_STATIC_DRAW) 
     colorTable = numpy.array([color for n in range(0, len(Verts))], dtype=numpy.float32) 
     glBindBuffer(GL_ARRAY_BUFFER, self.rgba) 
     glBufferData(GL_ARRAY_BUFFER, colorTable, GL_STATIC_DRAW) 
     glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, self.idx) 
     glBufferData(GL_ELEMENT_ARRAY_BUFFER, Faces, GL_STATIC_DRAW) 

    def draw (self): 
     glBindBuffer(GL_ARRAY_BUFFER, self.vert) 
     glVertexPointer(3, GL_FLOAT, 0, None) 
     glBindBuffer(GL_ARRAY_BUFFER, self.rgba) 
     glColorPointer(4, GL_FLOAT, 0, None) 
     glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, self.idx) 
     glDrawElements(GL_QUADS, len(Faces), GL_UNSIGNED_SHORT, None)