OpenGL-- mirror sphere drawn

effect:

.Gif spherical mirror

See detailed code githup:

MirrorSphere

Realization of ideas:

I have talked about and pay attention to several major points:

Monitor keyboard commands:

Here the upper and lower left and right keyboard monitor several operations, change the position of the respective observer.

void SpeacialKeys(int key,int x,int y)
{
    
    float linear = 0.1f;
    float angular = float(m3dDegToRad(5.0f));
    
    if (key == GLUT_KEY_UP) {
        
        //MoveForward 平移
        cameraFrame.MoveForward(linear);
    }
    
    if (key == GLUT_KEY_DOWN) {
        cameraFrame.MoveForward(-linear);
    }
    
    if (key == GLUT_KEY_LEFT) {
        //RotateWorld 旋转
        cameraFrame.RotateWorld(angular, 0.0f, 1.0f, 0.0f);
    }
    
    if (key == GLUT_KEY_RIGHT) {
        cameraFrame.RotateWorld(-angular, 0.0f, 1.0f, 0.0f);
    }
    
}

Set vertex:

The gif display, to be presented are:
1. The rotation of the large ball
2. The ball revolves around the big pellet
3. Fixed other suspended pellets
4. Floor
mirror effect of various balls (gif under 5. floor , under the floor is in fact the entire pellet was drawn again, mixed with colors, exhibited mirror effect, where the vertex data can be directly reused with a ball, and then to do a translation and inversion about the y-axis, provided no additional vertices ).

//设置大球顶点
void setBigSphereVertex(){
    //60是径向的,80是横向的,都是越大球越圆
    gltMakeSphere(bigSphereBatch, 0.5f, 60, 80);
}
//设置小球顶点
void setSmallSphereVertex(){
    gltMakeSphere(smallSphereBatch, 0.2, 30, 40);
}
//设置龙套小球的顶点
void setOtherSphereVertex(){
    gltMakeSphere(otherSphereBatch, 0.2, 20, 40);
    
    //7.随机小球球顶点坐标数据
    for (int i = 0; i < NUM_SPHERES; i++) {
        
        //y轴不变，X,Z产生随机值
        GLfloat x = ((GLfloat)((rand() % 400) - 200 ) * 0.1f);
        GLfloat y = (GLfloat)((rand() % 4));
        GLfloat z = ((GLfloat)((rand() % 400) - 200 ) * 0.1f);
        
        //在y方向，将球体设置为0.0的位置，这使得它们看起来是飘浮在眼睛的高度
        //对spheres数组中的每一个顶点，设置顶点数据
        spheres[i].SetOrigin(x, y, z);
    }
}
//设置地板顶点
void setFloorVertex(){
    
    GLfloat texSize = 10.0f;
    floorBatch.Begin(GL_TRIANGLE_FAN, 4,1);
    floorBatch.MultiTexCoord2f(0, 0.0f, 0.0f);
    floorBatch.Vertex3f(-20.f, -0.41f, 20.0f);
    
    floorBatch.MultiTexCoord2f(0, texSize, 0.0f);
    floorBatch.Vertex3f(20.0f, -0.41f, 20.f);
    
    floorBatch.MultiTexCoord2f(0, texSize, texSize);
    floorBatch.Vertex3f(20.0f, -0.41f, -20.0f);
    
    floorBatch.MultiTexCoord2f(0, 0.0f, texSize);
    floorBatch.Vertex3f(-20.0f, -0.41f, -20.0f);
    floorBatch.End();
}

Scene rendering

Note that the point has been marked in code comments

//绘制场景
void RenderScene(void)
{
    
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    //这次压栈是为了接收到键盘命令时,移动观察者
    //ps:这个PushMatrix()函数会自动帮我们把栈顶的元素copy一份,然后压入栈中,配合PopMatrix()函数,能让变化只在push和pop之间有效,pop之后恢复原值;这样设计能把不同物体的渲染独立开,不会相互影响.
    modelViewMatrix.PushMatrix();
    M3DMatrix44f mCamera;
    //从cameraFrame取值,然后赋值给矩阵mCamera
    cameraFrame.GetCameraMatrix(mCamera);
    modelViewMatrix.MultMatrix(mCamera);
    
    //绘制镜面开始
    modelViewMatrix.PushMatrix();
    modelViewMatrix.Scale(1.0f, -1.0f, 1.0f);
    modelViewMatrix.Translate(0.0f, 1.0f, -1.0f);
    //指定顺时针为正面,因为物体翻转了,否则看到的是背面
    glFrontFace(GL_CW);
    drawBigSphere();
    drawSmallSphere();
    drawOtherSphere();
    //恢复为逆时针为正面
    glFrontFace(GL_CCW);
    //绘制镜面结束
    modelViewMatrix.PopMatrix();
    
    //开启混合
    glEnable(GL_BLEND);
    //指定glBlendFunc 颜色混合方程式
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    drawFloor();
    //取消混合
    glDisable(GL_BLEND);
    
    //整体上移,否则大球会被地板挡住
    modelViewMatrix.Translate(0.0f, 0.1f, -1.0f);
    drawBigSphere();
    drawSmallSphere();
    drawOtherSphere();
    
    //不能太早pop,这个观察者是针对所有的物体的
    modelViewMatrix.PopMatrix();
    glutSwapBuffers();
    glutPostRedisplay();
}