将OpenGl代码用于FreeCAD COIN3D场景？

Question

我希望能够使用OpenGL内部的QuarterWidget，FreeCAD用胶水Coin3D到OpenCascade场景。我可以通过python检索以下对象：

    def GetQuarterWidget(self): #From FreeCAD forum
       views = []
       self.mainWindow=Gui.getMainWindow()
       for w in self.mainWindow.findChild(QtGui.QMdiArea).findChildren(QtGui.QWidget):
           if w.inherits("SIM::Coin3D::Quarter::QuarterWidget"):
               views.append(w)
       return views

    def getMdiWindow(self)  #From FreeCAD forum
        mw = Gui.getMainWindow()
        mdi = mw.findChild(PySide2.QtWidgets.QMdiArea)

但是我不知道如何用OpenGL代码来画场景.打个招呼世界代码(只画一个三角形)？

我的目标是能够链接到场景，这样我就可以直接使用OpenGL，而不是COIN3D，或者使用SDL2库..etc来绘制我所有的新对象。

我很感激任何能做到这一点的暗示。我使用python，但我也接受获得cpp代码。

非常感谢

编辑:我在场景中画了个世界三角。密码有多好？我还不确定。下面是密码。

from OpenGL.GL import *
from OpenGL.GLU import *
import PySide2
import FreeCADGui as Gui
import pivy.coin as coin
import PySide.QtCore as QtCore
import PySide.QtGui as QtGui
from PySide2.QtOpenGL import * #as QtOPENGL
from OpenGL.WGL import *

def drawOpenGl(arg1,arg2):
    glTranslatef(-2.5, 0.5, -6.0)
    glColor3f( 1.0, 1.5, 0.0 )
    glPolygonMode(GL_FRONT, GL_FILL)
    glBegin(GL_TRIANGLES)
    glVertex3f(2.0,-1.2,0.0)
    glVertex3f(2.6,0.0,0.0)
    glVertex3f(2.9,-1.2,0.0)
    glEnd()

def drawsomething():
    w_view = Gui.ActiveDocument.ActiveView
    Root_SceneGraph = w_view.getSceneGraph()
    calback_=coin.SoCallback()
    calback_.setCallback(drawOpenGl)
    Root_SceneGraph.addChild(calback_)

drawsomething()

请注意，通过运行freecad的python，您需要在FreeCAD中安装pyopengl (而不是pc/linux/mac版本的pip或python)。

FREECAD_DIR/bin/Scripts/pip install pyopengl

Answer 1

您的代码看起来非常类似于逆变器导师中的样本书。我认为您应该使用glPushMatrix和glPopMatrix存储当前状态。否则，转换的行为可能会不正确。

def drawOpenGl(arg1,arg2):
    glPushMatrix()
    glTranslatef(-2.5, 0.5, -6.0)
    glColor3f( 1.0, 1.5, 0.0 )
    glPolygonMode(GL_FRONT, GL_FILL)
    glBegin(GL_TRIANGLES)
    glVertex3f(2.0,-1.2,0.0)
    glVertex3f(2.6,0.0,0.0)
    glVertex3f(2.9,-1.2,0.0)
    glEnd()
    glPopMatrix()

不确定这对您是否有任何用处，但是有一个C++示例，它混合了一个纯OpenGL几何(一个矩形)和一个Coin3D几何(一个圆锥体)，并使用了四分之一：

#include <QApplication>
#include <Inventor/nodes/SoBaseColor.h>
#include <Inventor/nodes/SoCone.h>
#include <Inventor/nodes/SoSeparator.h>
#include <Inventor/nodes/SoCallback.h>
#include <Quarter/Quarter.h>
#include <Quarter/QuarterWidget.h>
#include <GL/gl.h>

using namespace SIM::Coin3D::Quarter;

// Callback routine to render using OpenGL
void
myCallbackRoutine(void *, SoAction *)
{
   glPushMatrix();
   glTranslatef(0.0, -3.0, 0.0);
   glColor3f(1.0, 0.0, 0.0);
   glDisable(GL_LIGHTING);  // so we don't have to set normals
    glBegin(GL_POLYGON);
        glVertex3f(0.0, 0.0, 0.0);
        glVertex3f(0.5, 0.0, 0.0);
        glVertex3f(0.5, 0.5, 0.0);
        glVertex3f(0.0, 0.5, 0.0);
    glEnd();
    glEnable(GL_LIGHTING);
   glPopMatrix();
}

int
main(int argc, char ** argv)
{
    QApplication app(argc, argv);
    // Initializes Quarter library (and implicitly also the Coin and Qt
    // libraries).
    Quarter::init();
    // Make a dead simple scene graph by using the Coin library, only
    // containing a single yellow cone under the scenegraph root.
    SoSeparator * root = new SoSeparator;
    root->ref();
    SoBaseColor * col = new SoBaseColor;
    col->rgb = SbColor(1, 1, 0);
    root->addChild(col);
    root->addChild(new SoCone);
    
    SoCallback *myCallback = new SoCallback;
    myCallback->setCallback(myCallbackRoutine);
    root->addChild(myCallback);
    
    // Create a QuarterWidget for displaying a Coin scene graph
    QuarterWidget * viewer = new QuarterWidget;
    viewer->setSceneGraph(root);
    // make the viewer react to input events similar to the good old
    // ExaminerViewer
     viewer->setNavigationModeFile(QUrl("coin:///scxml/navigation/examiner.xml"));
    // Pop up the QuarterWidget
    viewer->show();
    // Loop until exit.
    app.exec();
    // Clean up resources.
    root->unref();
    delete viewer;
    Quarter::clean();
    return 0;
}