OpenGL（QT平台）学习与实战（十五）

创建一个光照场景

框架搭建

新建项目



设置窗口名称

设置窗口icon

选择图片即可

设置样式


添加相应的action

拖动到工具栏处

添加openglwidget

设置openglwidget填充整个窗口

接着要重载QopenGLWidget中的一些函数，因此我们新建一个子类去继承它：


修改相关代码

将OpenGJWidget提升为自定义类


至此，通用的框架已经搭建完毕。

绘制背景颜色

void ZJJOpenGJWidget::paintGL()
{
    glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
    glEnable(GL_DEPTH_TEST);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
}

添加着色器

添加资源文件


添加文件

其中着色器文件代码：
顶点着色器：

#version 330 core
layout (location = 0) in vec3 aPos;
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;
void main()
{
   gl_Position = projection * view * model * vec4(aPos, 1.0);
}

片段着色器：

#version 330 core
out vec4 FragColor;
uniform vec3 objectColor;
uniform vec3 lightColor;
void main()
{
   FragColor = vec4(lightColor * objectColor, 1.0);
}

添加顶点数据

float vertices[] = {
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f,
 0.5f, -0.5f, -0.5f, 1.0f, 0.0f,
 0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
 0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f,

-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,

-0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 0.0f,

 0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
 0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
 0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
 0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
 0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
 0.5f, 0.5f, 0.5f, 1.0f, 0.0f,

-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
 0.5f, -0.5f, -0.5f, 1.0f, 1.0f,
 0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
 0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,

-0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
 0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
 0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
 0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f
};

定义VAO,VBO以及光源的属性

unsigned int VAO,VBO,lightVAO; 
QVector3D lightPos(1.2f, 1.0f, 2.0f); 
QVector3D lightColor(1.0f, 1.0f, 1.0f); 
QVector3D objectColor(1.0f, 0.5f, 0.31f);

配置OpenglWidget的状态

void ZJJOpenGJWidget::initializeGL()
{
    initializeOpenGLFunctions();

    //创建VBO和VAO对象，并赋予ID
    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO); //绑定VBO和VAO对象
    glBindVertexArray(VAO);
    glBindBuffer(GL_ARRAY_BUFFER, VBO); //为当前绑定到target的缓冲区对象创建一个新的数据存储。
    //如果data不是NULL，则使用来自此指针的数据初始化数据存储
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW); //告知显卡如何解析缓冲里的属性值
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
    //开启VAO管理的第一个属性值
    glEnableVertexAttribArray(0);
    bool success;
    m_shaderProgram.addShaderFromSourceFile(QOpenGLShader::Vertex,":/shaders/shaders/shapes.vert");
    m_shaderProgram.addShaderFromSourceFile(QOpenGLShader::Fragment,":/shaders/shaders/shapes.frag");
    success=m_shaderProgram.link();
    if(!success) qDebug()<<"ERR:"<<m_shaderProgram.log();
    m_shaderProgram.bind();
    m_shaderProgram.setUniformValue("objectColor",lightColor);
    m_shaderProgram.setUniformValue("lightColor",objectColor);
}

析构函数补充：

ZJJOpenGJWidget::~ZJJOpenGJWidget()
{
    makeCurrent();
    glDeleteBuffers(1,&VBO);
    glDeleteVertexArrays(1,&VAO);
    doneCurrent();
}

新建一个Camera类（只需要添加头文件即可）：

#ifndef CAMERA_H
#define CAMERA_H


#include
#include
#include 

// 移动方向枚举量. 是一种抽象，以避开特定于窗口系统的输入方法
// 我们这里是WSAD
enum Camera_Movement {
    FORWARD,
    BACKWARD,
    LEFT,
    RIGHT
};

// 默认值
const float YAW         = -90.0f;
const float PITCH       =  0.0f;
const float SPEED       =  2.5f;
const float SENSITIVITY =  0.1f;
const float ZOOM        =  45.0f;


// 一个抽象的camera类，用于处理输入并计算相应的Euler角度、向量和矩阵，以便在OpenGL中使用
class Camera
{
public:
    // camera Attributes
    QVector3D Position;
    QVector3D Front;
    QVector3D Up;
    QVector3D Right;
    QVector3D WorldUp;
    // euler Angles
    float Yaw;
    float Pitch;
    // camera options
    float MovementSpeed;
    float MouseSensitivity;
    float Zoom;

    // constructor with vectors
    Camera(QVector3D position = QVector3D(0.0f, 0.0f, 0.0f), QVector3D up = QVector3D(0.0f, 1.0f, 0.0f), float yaw = YAW, float pitch = PITCH) : Front(QVector3D(0.0f, 0.0f, -1.0f)), MovementSpeed(SPEED), MouseSensitivity(SENSITIVITY), Zoom(ZOOM)
    {
        Position = position;
        WorldUp = up;
        Yaw = yaw;
        Pitch = pitch;
        updateCameraVectors();
    }
    // constructor with scalar values
    Camera(float posX, float posY, float posZ, float upX, float upY, float upZ, float yaw, float pitch) : Front(QVector3D(0.0f, 0.0f, -1.0f)), MovementSpeed(SPEED), MouseSensitivity(SENSITIVITY), Zoom(ZOOM)
    {
        Position = QVector3D(posX, posY, posZ);
        WorldUp = QVector3D(upX, upY, upZ);
        Yaw = yaw;
        Pitch = pitch;
        updateCameraVectors();
    }

    // returns the view matrix calculated using Euler Angles and the LookAt Matrix
    QMatrix4x4 GetViewMatrix()
    {
        QMatrix4x4 theMatrix;
        theMatrix.lookAt(Position, Position + Front, Up);
        return theMatrix;
    }

    // 处理从任何类似键盘的输入系统接收的输入。接受摄像机定义枚举形式的输入参数（从窗口系统中提取）
    void ProcessKeyboard(Camera_Movement direction, float deltaTime)
    {
        float velocity = MovementSpeed * deltaTime;
        if (direction == FORWARD)
            Position += Front * velocity;
        if (direction == BACKWARD)
            Position -= Front * velocity;
        if (direction == LEFT)
            Position -= Right * velocity;
        if (direction == RIGHT)
            Position += Right * velocity;
    }

    // 处理从鼠标输入系统接收的输入。需要x和y方向上的偏移值。
    void ProcessMouseMovement(float xoffset, float yoffset, GLboolean constrainPitch = true)
    {
        xoffset *= MouseSensitivity;
        yoffset *= MouseSensitivity;

        Yaw   += xoffset;
        Pitch += yoffset;

        // 确保当投球超出边界时，屏幕不会翻转
        if (constrainPitch)
        {
            if (Pitch > 89.0f)
                Pitch = 89.0f;
            if (Pitch < -89.0f)
                Pitch = -89.0f;
        }

        // 使用更新的Euler角度更新前、右和上矢量
        updateCameraVectors();
    }

    // 处理从鼠标滚轮事件接收的输入。仅需要在垂直车轮轴上输入
    void ProcessMouseScroll(float yoffset)
    {
        Zoom -= (float)yoffset;
        if (Zoom < 1.0f)
            Zoom = 1.0f;
        if (Zoom > 75.0f)
            Zoom = 75.0f;
    }

private:
    // 根据相机的（更新的）Euler角度计算前矢量
    void updateCameraVectors()
    {
        // calculate the new Front vector
        float PI=3.1415926;
        QVector3D front;
        front.setX(cos(Yaw*PI/180.0) * cos(Pitch*PI/180.0));
        front.setY( sin(Pitch*PI/180.0));
        front.setZ(sin(Yaw*PI/180.0) * cos(Pitch*PI/180.0));
        front.normalize();
        Front = front;
        // also re-calculate the Right and Up vector
        Right = QVector3D::crossProduct(Front, WorldUp);
        // 标准化向量，因为向上或向下看得越多，向量的长度就越接近0，这会导致移动速度变慢。
        Right.normalize();
        Up    = QVector3D::crossProduct(Right, Front);
        Up.normalize();
    }
};
#endif

结果：