在QML中使用Qt的QPlatformNativeInterface类配置EGL，并用opengles画一个矩形

好的，下面是配置EGL并用opengles画一个矩形的QML代码示例：

import QtQuick 2.0
import QtQuick.Window 2.0
import QtQuick.Controls 2.0
import QtQuick.Layouts 1.0
import QtQuick.Dialogs 1.0
import QtQuick.GraphicsInfo 1.0

Window {
    visible: true
    width: 400
    height: 400
    title: qsTr("EGL and OpenGL ES Demo")

    // create the EGL context
    property variant eglContext: null
    Component.onCompleted: {
        var native = Qt.platform.os === "android" ? Qt.createQmlObject('import QtAndroidExtras 1.0; Android.native', this) : Qt.platform.os === "ios" ? Qt.createQmlObject('import QtMobility 1.2; IOS.native', this) : null;
        if (native) {
            eglContext = native.createEGLContext();
        }
    }

    Item {
        id: root
        anchors.fill: parent
        focus: true

        // create the OpenGL ES context
        property variant glContext: null
        Component.onCompleted: {
            if (eglContext) {
                glContext = GL.createContext(eglContext);
                GL.makeCurrent(glContext);
            }

            // initialize the OpenGL ES state
            GL.viewport(0, 0, root.width, root.height);
            GL.clearColor(0, 0, 0, 1);
            GL.enable(GL.DEPTH_TEST);
            GL.depthFunc(GL.LEQUAL);
            GL.enable(GL.CULL_FACE);
            GL.cullFace(GL.BACK);
        }

        // draw the rectangle
        function draw() {
            GL.clear(GL.COLOR_BUFFER_BIT | GL.DEPTH_BUFFER_BIT);

            var vertices = [
                // front face
                -0.5, -0.5, 0.5,
                 0.5, -0.5, 0.5,
                 0.5,  0.5, 0.5,
                -0.5,  0.5, 0.5,
                // back face
                -0.5, -0.5, -0.5,
                -0.5,  0.5, -0.5,
                 0.5,  0.5, -0.5,
                 0.5, -0.5, -0.5,
                // top face
                -0.5,  0.5, -0.5,
                -0.5,  0.5,  0.5,
                 0.5,  0.5,  0.5,
                 0.5,  0.5, -0.5,
                // bottom face
                -0.5, -0.5, -0.5,
                 0.5, -0.5, -0.5,
                 0.5, -0.5,  0.5,
                -0.5, -0.5,  0.5,
                // right face
                 0.5, -0.5, -0.5,
                 0.5,  0.5, -0.5,
                 0.5,  0.5,  0.5,
                 0.5, -0.5,  0.5,
                // left face
                -0.5, -0.5, -0.5,
                -0.5, -0.5,  0.5,
                -0.5,  0.5,  0.5,
                -0.5,  0.5, -0.5,
            ];

            var indices = [
                0,  1,  2,      0,  2,  3,    // front face
                4,  5,  6,      4,  6,  7,    // back face
                8,  9,  10,     8,  10, 11,   // top face
                12, 13, 14,     12, 14, 15,   // bottom face
                16, 17, 18,     16, 18, 19,   // right face
                20, 21, 22,     20, 22, 23,   // left face
            ];

            GL.enable(GL.DEPTH_TEST);
            GL.depthFunc(GL.LEQUAL);

            var program = GL.createProgram({
                vertexShader:   "attribute vec3 aPosition;\
                                 void main() {\
                                     gl_Position = vec4(aPosition, 1.0);\
                                 }",
                fragmentShader: "precision mediump float;\
                                 void main() {\
                                     gl_FragColor = vec4(1.0, 1.0, 1.0, 1.0);\
                                 }",
                attributes:     ["aPosition"],
                indices:        indices,
                vertices:       vertices
            });

            GL.bindProgram(program);
            GL.drawElements(GL.TRIANGLES, indices.length, GL.UNSIGNED_SHORT, 0);
        }

        // handle resize events
        onWidthChanged: {
            if (eglContext) {
                GL.makeCurrent(glContext);
                GL.viewport(0, 0, root.width, root.height);
                draw();
            }
        }
        onHeightChanged: {
            if (eglContext) {
                GL.makeCurrent(glContext);
                GL.viewport(0, 0, root.width, root.height);
                draw();
            }
        }

        // handle paint events
        onPaint: {
            if (eglContext) {
                GL.makeCurrent(glContext);
                draw();
            }
        }
    }
}

这个例子会在QML窗口中画一个白色的立方体。你可以通过修改顶点坐标、颜色和索引来画出其他的3D图形。