文章目录
- Qt的OpenGL窗口
- GLSL的实现
- 摄像机类的实现
- 简单的漫游器
Qt的OpenGL窗口
Qt主要是使用QOpenGLWidget来实现opengl的功能。
QOpenGLWidget 提供了三个便捷的虚函数，可以重载，用来重新实现典型的OpenGL任务：
- paintGL：渲染OpenGL场景。widget 需要更新时调用。
- resizeGL：设置OpenGL视口、投影等。widget 调整大小（或首次显示）时调用。
- initializeGL：设置OpenGL资源和状态。第一次调用 resizeGL() / paintGL() 之前调用一次。
- 如果需要从paintGL()以外的位置触发重新绘制（典型示例是使用计时器设置场景动画），则应调用widget的update()函数来安排更新。
- 调用paintGL()、resizeGL()或initializeGL()时，widget 的OpenGL呈现上下文将变为当前。如果需要从其他位置（例如，在 widget 的构造函数或自己的绘制函数中）调用标准OpenGL API函数，则必须首先调用makeCurrent()。
- QOpenGLFunctions_X_X_Core 提供OpenGL X.X版本核心模式的所有功能。是对OpenGL函数的封装：
- initializeOpenGLFunctions：初始化OpenGL函数，将Qt里的函数指针指向显卡的函数。
#include <QOpenGLWidget>
#include <QOpenGLFunctions_3_3_Core> class MyOpenGLWidget : public QOpenGLWidget,QOpenGLFunctions_3_3_Core
{
Q_OBJECT
public:
explicit MyOpenGLWidget (QWidget *parent = nullptr);
protected:
virtual void initializeGL();
virtual void resizeGL(int w, int h);
virtual void paintGL();
};
void MyOpenGLWidget::initializeGL()
{initializeOpenGLFunctions();
}
void MyOpenGLWidget::resizeGL(int w, int h)
{Q_UNUSED(w);Q_UNUSED(h);
}
void MyOpenGLWidget::paintGL()
{glClearColor(0.2f, 0.3f, 0.3f, 1.0f);glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
}
以上是最简单的实现版本。
GLSL的实现
由于是最简单的漫游器，所以我们实现的版本只需要一个顶点着色器和一个片段着色器即可。
shapes.vert
#version 330 core
layout(location = 0) in vec3 aPos;
layout(location = 1) in vec2 aTexCoord;out vec2 texCoord;
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;void main(){gl_Position = projection * view * model * vec4(aPos, 1.0f);texCoord = aTexCoord;
}shapes.frag
#version 330 core
out vec4 FragColor;
in vec2 texCoord;uniform sampler2D texturewall;
uniform sampler2D texturesmile;
uniform sampler2D textureSmall;uniform float ratio;
void main(){FragColor = mix(texture(texturewall,texCoord),texture(texturesmile,texCoord),ratio);
}摄像机类的实现
这边实现了一个可以对模型进行上下左右移动，移动视角，放大缩小的操作。
摄像机类初始化了几个变量
// 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;
偏航角默认为90度，灵敏度主要用于控制鼠标移动时视角的变化量。
#ifndef CAMERA_H
#define CAMERA_H#include<QMatrix4x4>#include <vector>// 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 AttributesQVector3D Position;QVector3D Front;QVector3D Up;QVector3D Right;QVector3D WorldUp;// euler Anglesfloat Yaw;float Pitch;// camera optionsfloat MovementSpeed;float MouseSensitivity;float Zoom;// constructor with vectorsCamera(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 valuesCamera(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 MatrixQMatrix4x4 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, bool 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 vectorfloat 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 vectorRight = 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简单的漫游器
漫游器的实现主要是通过Qt的窗口事件触发后将触发产生的位置偏量给摄像机类进行计算，从摄像机类中得到视图矩阵将模型的位置进行改变。
myopenglwidget.h
#ifndef MYOPENGLWIDGET_H
#define MYOPENGLWIDGET_H#include <QOpenGLWidget>
#include <QOpenGLFunctions_3_3_Core>
#include <QOpenGLShaderProgram>
#include <QOpenGLTexture>
#include <QTimer>
#include <QElapsedTimer>
#include "camera.h"class MyOpenGLWidget : public QOpenGLWidget,QOpenGLFunctions_3_3_Core
{Q_OBJECT
public:enum Shape{None,Circle,Rect,Triangle};explicit MyOpenGLWidget(QWidget *parent = nullptr);~MyOpenGLWidget();void DrawShape(Shape shape);void setWireFrameMode(bool enterWireframe);void onTimeout();
protected:virtual void initializeGL();virtual void resizeGL(int w, int h);virtual void paintGL();
signals:
private:Shape m_shape;QOpenGLShaderProgram shaderProgram;QOpenGLTexture *textureWall;QOpenGLTexture *textureSmile;QOpenGLTexture *textureSmall;QTimer *m_timer;QElapsedTimer m_time;Camera m_camera;// QWidget interface
protected:void keyPressEvent(QKeyEvent *event) override;void mouseMoveEvent(QMouseEvent *event) override;void wheelEvent(QWheelEvent *event) override;
};#endif // MYOPENGLWIDGET_Hmyopenglwidget.cpp
#include "myopenglwidget.h"
#include <QImage>
#include <QKeyEvent>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
};QVector<QVector3D> cubePositions= {QVector3D( 0.0f, 0.0f, 0.0f),QVector3D( 2.0f, 5.0f, -15.0f),QVector3D(-1.5f, -2.2f, -2.5f),QVector3D(-3.8f, -2.0f, -12.3f),QVector3D( 2.4f, -0.4f, -3.5f),QVector3D(-1.7f, 3.0f, -7.5f),QVector3D( 1.3f, -2.0f, -2.5f),QVector3D( 1.5f, 2.0f, -2.5f),QVector3D( 1.5f, 0.2f, -1.5f),QVector3D(-1.3f, 1.0f, -1.5f)
};#define TIMEOUT 100unsigned int indices[] = { // note that we start from 0!0, 1, 3, // first triangle1, 2, 3 // second triangle
};unsigned int VBO, VAO ,EBO;float ratio = 0.5;
QPoint deltaPos;MyOpenGLWidget::MyOpenGLWidget(QWidget *parent): QOpenGLWidget{parent}
{setFocusPolicy(Qt::StrongFocus);setMouseTracking(true);m_timer = new QTimer(this);connect(m_timer,&QTimer::timeout,this,&MyOpenGLWidget::onTimeout);m_timer->start(TIMEOUT);m_time.start();m_camera.Position = QVector3D(0.0,0.0,3.0);
}MyOpenGLWidget::~MyOpenGLWidget()
{if(!isValid()) return;makeCurrent();glDeleteBuffers(1,&VBO);glDeleteBuffers(1,&EBO);glDeleteVertexArrays(1,&VAO);doneCurrent();
}void MyOpenGLWidget::DrawShape(Shape shape)
{m_shape=shape;update();
}void MyOpenGLWidget::setWireFrameMode(bool enterWireframe)
{makeCurrent();if(enterWireframe)glPolygonMode(GL_FRONT_AND_BACK,GL_LINE);elseglPolygonMode(GL_FRONT_AND_BACK,GL_FILL);update();doneCurrent();
}void MyOpenGLWidget::onTimeout()
{update();
}void MyOpenGLWidget::initializeGL()
{initializeOpenGLFunctions();//创建VBO和VAO对象，并赋予IDglGenVertexArrays(1,&VAO);glGenBuffers(1,&VBO);//绑定VAO和VBO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);//告知显卡如何解析缓冲里的属性值glVertexAttribPointer(1,2,GL_FLOAT,GL_FALSE,5*sizeof(float),(void *)(3*sizeof(float)));//开启VAO管理的第三个属性值glEnableVertexAttribArray(1);glBindBuffer(GL_ARRAY_BUFFER,0);bool success;shaderProgram.addShaderFromSourceFile(QOpenGLShader::Vertex,":Shaders/shapes.vert");shaderProgram.addShaderFromSourceFile(QOpenGLShader::Fragment,":Shaders/shapes.frag");success = shaderProgram.link();if(!success){qDebug()<<"Error:"<<shaderProgram.log();}shaderProgram.bind();shaderProgram.setUniformValue("ratio",ratio);shaderProgram.setUniformValue("texturewall",0);shaderProgram.setUniformValue("texturesmile",1);shaderProgram.setUniformValue("textureSmall",2);unsigned int EBO;glGenBuffers(1, &EBO);glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);glEnable(GL_BLEND);glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);textureWall = new QOpenGLTexture(QImage(":Images/images/wall.jpg").mirrored());textureSmile = new QOpenGLTexture(QImage(":Images/images/awesomeface.png").mirrored());textureSmall = new QOpenGLTexture(QImage(":Images/images/small.png").mirrored());glBindVertexArray(0);}void MyOpenGLWidget::resizeGL(int w, int h)
{Q_UNUSED(w);Q_UNUSED(h);
}void MyOpenGLWidget::paintGL()
{QMatrix4x4 model;QMatrix4x4 view;QMatrix4x4 projection;view=m_camera.GetViewMatrix();glClearColor(0.2f, 0.3f, 0.3f, 1.0f);glEnable(GL_DEPTH_TEST);glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);shaderProgram.bind();projection.perspective(m_camera.Zoom,(float)width()/(height()),0.1,100.0);shaderProgram.setUniformValue("projection", projection);shaderProgram.setUniformValue("view", view);glBindVertexArray(VAO);//glDrawArrays(GL_TRIANGLES, 0, 3);switch(m_shape){case Rect:textureWall->bind(0);textureSmile->bind(1);textureSmall->bind(2);//glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);foreach (auto item, cubePositions){model.setToIdentity();model.translate(item);shaderProgram.setUniformValue("model", model);glDrawArrays(GL_TRIANGLES,0,36);}break;case None:break;case Triangle:break;case Circle:break;}}void MyOpenGLWidget::keyPressEvent(QKeyEvent *event)
{float deltatime=TIMEOUT / 1000.0;switch(event->key()){case Qt::Key_Up:ratio += 0.1;break;case Qt::Key_Down:ratio -= 0.1;break;case Qt::Key_W: m_camera.ProcessKeyboard(FORWARD,deltatime);break;case Qt::Key_S: m_camera.ProcessKeyboard(BACKWARD,deltatime);break;case Qt::Key_D: m_camera.ProcessKeyboard(RIGHT,deltatime);break;case Qt::Key_A: m_camera.ProcessKeyboard(LEFT,deltatime);break;}if(ratio > 1) ratio = 1;if(ratio < 0) ratio = 0;makeCurrent();shaderProgram.bind();shaderProgram.setUniformValue("ratio",ratio);update();doneCurrent();
}void MyOpenGLWidget::mouseMoveEvent(QMouseEvent *event)
{static QPoint lastPos(width()/2,height()/2);auto currentPos=event->pos();deltaPos=currentPos-lastPos;lastPos=currentPos;m_camera.ProcessMouseMovement(deltaPos.x(),-deltaPos.y());update();
}void MyOpenGLWidget::wheelEvent(QWheelEvent *event)
{ m_camera.ProcessMouseScroll(event->angleDelta().y()/120);update();
}完整代码链接
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