基于Qt的OpenGL学习（9）—— 材质、光照贴图

简介

要学习OpenGL的话，强烈安利这个教程JoeyDeVries的learnopengl，这里是中文翻译好的版本。教程中使用OpenGL是通过GLFW这个库，而在Qt中对OpenGL封装得很好，并且和GUI以及IO相关的处理Qt更便捷，学习起来更轻松。这里就对每篇教程，在Qt在分别直接使用OpenGL的函数和Qt封装好的类以作对比。
教程中使用的OpenGL版本为3.3，在Qt中需要使用此版本的OpenGL只需要继承类QOpenGLFunctions_3_3_Core即可。如果为了在不同设备上都能用OpenGL的话，Qt提供了类QOpenGLFunctions，这个类包含了大部分公共的函数，可能会有个别函数不能用。

对比说明

教程地址

原教程-材质，原教程-光照贴图，相关知识可以点击链接学习。
我的工程地址，每篇教程一个commit，教程-材质代码 git checkout v2.3，教程-光照贴图代码 git checkout v2.4，喜欢就点个Star吧~

不同点 (仅列出新增)

之后对于增量型的教程可能就多篇合成一篇了，可自行切换commit查看，修改文件只贴出最后版。

运行结果

材质运行结果

光照贴图结果

修改的文件

QtFunctionWidget.h

#ifndef QTFUNCTIONWIDGET_H
#define QTFUNCTIONWIDGET_H

#include <QOpenGLWidget>
#include <QOpenGLShaderProgram>
#include <QOpenGLFunctions>
#include <QOpenGLVertexArrayObject>
#include <QOpenGLBuffer>
#include <QOpenGLTexture>

#include "Camera.h"

class QtFunctionWidget : public QOpenGLWidget, protected QOpenGLFunctions
{
public:
    QtFunctionWidget(QWidget *parent = nullptr);
    ~QtFunctionWidget() Q_DECL_OVERRIDE;

protected:
    virtual void initializeGL() Q_DECL_OVERRIDE;
    virtual void resizeGL(int w, int h) Q_DECL_OVERRIDE;
    virtual void paintGL() Q_DECL_OVERRIDE;

    void keyPressEvent(QKeyEvent *event) Q_DECL_OVERRIDE;
    void keyReleaseEvent(QKeyEvent *event) Q_DECL_OVERRIDE;
    void mousePressEvent(QMouseEvent *event) Q_DECL_OVERRIDE;
    void mouseReleaseEvent(QMouseEvent *event) Q_DECL_OVERRIDE;
    void mouseMoveEvent(QMouseEvent *event) Q_DECL_OVERRIDE;
    void wheelEvent(QWheelEvent *event) Q_DECL_OVERRIDE;

private:
    bool createShader();
    QOpenGLTexture* loadTexture(const QString& path);

private:
    QOpenGLShaderProgram lightingShader, lampShader;
    QOpenGLBuffer vbo;
    QOpenGLVertexArrayObject cubeVAO, lightVAO;
    QOpenGLTexture* m_pDiffuseMap = nullptr;
    QOpenGLTexture* m_pSpecularMap = nullptr;

    QTimer* m_pTimer = nullptr;
    int     m_nTimeValue = 0;

    // camera
    std::unique_ptr<Camera> camera;
    bool m_bLeftPressed;
    QPoint m_lastPos;
};

#endif // QTFUNCTIONWIDGET_H

QtFunctionWidget.cpp

#include "QtFunctionWidget.h"
#include <QDebug>
#include <QTimer>

// lighting
static QVector3D lightPos(1.2f, 1.0f, 2.0f);

QtFunctionWidget::QtFunctionWidget(QWidget *parent) : QOpenGLWidget (parent),
    vbo(QOpenGLBuffer::VertexBuffer)
{
    camera = std::make_unique<Camera>(QVector3D(0.0f, 0.0f, 3.0f));
    m_bLeftPressed = false;

    m_pTimer = new QTimer(this);
    connect(m_pTimer, &QTimer::timeout, this, [=]{
        m_nTimeValue += 1;
        update();
    });
    m_pTimer->start(40);//25 fps
}

QtFunctionWidget::~QtFunctionWidget(){
    makeCurrent();

    lightVAO.destroy();
    cubeVAO.destroy();
    vbo.destroy();

    if (m_pDiffuseMap) {
        delete m_pDiffuseMap;
    }

    if (m_pSpecularMap) {
        delete m_pSpecularMap;
    }

    doneCurrent();
}

void QtFunctionWidget::initializeGL(){
    this->initializeOpenGLFunctions();

    createShader();

    // set up vertex data (and buffer(s)) and configure vertex attributes
    // ------------------------------------------------------------------
    float vertices[] = {
        // positions          // normals           // texture coords
        -0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  0.0f, 0.0f,
         0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  1.0f, 0.0f,
         0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  1.0f, 1.0f,
         0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  1.0f, 1.0f,
        -0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  0.0f, 1.0f,
        -0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  0.0f, 0.0f,

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

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

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

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

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

    vbo.create();
    vbo.bind();
    vbo.allocate(vertices, sizeof(vertices));

    {
        QOpenGLVertexArrayObject::Binder vaoBind(&cubeVAO);

////        position attribute
//        int attr = -1;
//        attr = lightingShader.attributeLocation("aPos");
//        lightingShader.setAttributeBuffer(attr, GL_FLOAT, 0, 3, sizeof(GLfloat) * 6);
//        lightingShader.enableAttributeArray(attr);
//        attr = lightingShader.attributeLocation("aNormal");
//        lightingShader.setAttributeBuffer(attr, GL_FLOAT, sizeof(GLfloat) * 3, 3, sizeof(GLfloat) * 6);
//        lightingShader.enableAttributeArray(attr);

        glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
        glEnableVertexAttribArray(0);
        glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
        glEnableVertexAttribArray(1);
        glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
        glEnableVertexAttribArray(2);
    }

    {
        QOpenGLVertexArrayObject::Binder vaoBind(&lightVAO);

////        position attribute
//        int attr = -1;
//        attr = lightingShader.attributeLocation("aPos");
//        lightingShader.setAttributeBuffer(attr, GL_FLOAT, 0, 3, sizeof(GLfloat) * 6);
//        lightingShader.enableAttributeArray(attr);

        glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
        glEnableVertexAttribArray(0);
    }

    // load textures (we now use a utility function to keep the code more organized)
    // -----------------------------------------------------------------------------
    m_pDiffuseMap = loadTexture(":/container2.png");
    m_pSpecularMap = loadTexture(":/container2_specular.png");

    // shader configuration
    // --------------------
    lightingShader.bind();
    lightingShader.setUniformValue("material.diffuse", 0);
    lightingShader.setUniformValue("material.specular", 1);
    lightingShader.release();

    vbo.release();

    // configure global opengl state
    // -----------------------------
    glEnable(GL_DEPTH_TEST);
}

void QtFunctionWidget::resizeGL(int w, int h){
    glViewport(0, 0, w, h);
}

void QtFunctionWidget::paintGL(){
    // input
    // -----
    camera->processInput(0.5f);//speed

    // render
    // ------
    glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    // be sure to activate shader when setting uniforms/drawing objects
    lightingShader.bind();
    lightingShader.setUniformValue("light.position", lightPos);
    lightingShader.setUniformValue("viewPos", camera->position);

    // light properties
    lightingShader.setUniformValue("light.ambient", QVector3D(0.2f, 0.2f, 0.2f));
    lightingShader.setUniformValue("light.diffuse", QVector3D(0.5f, 0.5f, 0.5f));
    lightingShader.setUniformValue("light.specular", QVector3D(1.0f, 1.0f, 1.0f));

    // material properties
    lightingShader.setUniformValue("material.shininess", 64.0f);

    // view/projection transformations
    QMatrix4x4 projection;
    projection.perspective(camera->zoom, 1.0f * width() / height(), 0.1f, 100.0f);
    QMatrix4x4 view = camera->getViewMatrix();
    lightingShader.setUniformValue("projection", projection);
    lightingShader.setUniformValue("view", view);

    // world transformation
    QMatrix4x4 model;
    lightingShader.setUniformValue("model", model);

    // bind diffuse map
    glActiveTexture(GL_TEXTURE0);
    m_pDiffuseMap->bind();

    // bind specular map
    glActiveTexture(GL_TEXTURE1);
    m_pSpecularMap->bind();

    {// render the cube
        QOpenGLVertexArrayObject::Binder vaoBind(&cubeVAO);
        glDrawArrays(GL_TRIANGLES, 0, 36);
    }
    lightingShader.release();


    // also draw the lamp object
    lampShader.bind();
    lampShader.setUniformValue("projection", projection);
    lampShader.setUniformValue("view", view);
    model = QMatrix4x4();
    model.translate(lightPos);
    model.scale(0.2f); // a smaller cube
    lampShader.setUniformValue("model", model);
    {
        QOpenGLVertexArrayObject::Binder vaoBind(&lightVAO);
        glDrawArrays(GL_TRIANGLES, 0, 36);
    }
    lampShader.release();
}

void QtFunctionWidget::keyPressEvent(QKeyEvent *event)
{
    int key = event->key();
    if (key >= 0 && key < 1024)
        camera->keys[key] = true;
}

void QtFunctionWidget::keyReleaseEvent(QKeyEvent *event)
{
    int key = event->key();
    if (key >= 0 && key < 1024)
        camera->keys[key] = false;
}

void QtFunctionWidget::mousePressEvent(QMouseEvent *event)
{
    if(event->button() == Qt::LeftButton){
        m_bLeftPressed = true;
        m_lastPos = event->pos();
    }
}

void QtFunctionWidget::mouseReleaseEvent(QMouseEvent *event)
{
    Q_UNUSED(event);

    m_bLeftPressed = false;
}

void QtFunctionWidget::mouseMoveEvent(QMouseEvent *event)
{
    if (m_bLeftPressed) {
        int xpos = event->pos().x();
        int ypos = event->pos().y();

        int xoffset = xpos - m_lastPos.x();
        int yoffset = m_lastPos.y() - ypos;
        m_lastPos = event->pos();
        camera->processMouseMovement(xoffset, yoffset);
    }
}

void QtFunctionWidget::wheelEvent(QWheelEvent *event)
{
    QPoint offset = event->angleDelta();
    camera->processMouseScroll(offset.y()/20.0f);
}

bool QtFunctionWidget::createShader()
{
    bool success = lightingShader.addShaderFromSourceFile(QOpenGLShader::Vertex, ":/lighting_maps.vert");
    if (!success) {
        qDebug() << "shaderProgram addShaderFromSourceFile failed!" << lightingShader.log();
        return success;
    }

    success = lightingShader.addShaderFromSourceFile(QOpenGLShader::Fragment, ":/lighting_maps.frag");
    if (!success) {
        qDebug() << "shaderProgram addShaderFromSourceFile failed!" << lightingShader.log();
        return success;
    }

    success = lightingShader.link();
    if(!success) {
        qDebug() << "shaderProgram link failed!" << lightingShader.log();
    }

    success = lampShader.addShaderFromSourceFile(QOpenGLShader::Vertex, ":/lamp.vert");
    if (!success) {
        qDebug() << "shaderProgram addShaderFromSourceFile failed!" << lampShader.log();
        return success;
    }

    success = lampShader.addShaderFromSourceFile(QOpenGLShader::Fragment, ":/lamp.frag");
    if (!success) {
        qDebug() << "shaderProgram addShaderFromSourceFile failed!" << lampShader.log();
        return success;
    }

    success = lampShader.link();
    if(!success) {
        qDebug() << "shaderProgram link failed!" << lampShader.log();
    }

    return success;
}

QOpenGLTexture *QtFunctionWidget::loadTexture(const QString &path)
{
    QOpenGLTexture* pTexture = new QOpenGLTexture(QImage(path), QOpenGLTexture::GenerateMipMaps);
    if(!pTexture->isCreated()){
        qDebug() << "Failed to load texture";
    }
    // set the texture wrapping parameters
    pTexture->setWrapMode(QOpenGLTexture::DirectionS, QOpenGLTexture::Repeat);  //glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    pTexture->setWrapMode(QOpenGLTexture::DirectionT, QOpenGLTexture::Repeat);  //glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    // set texture filtering parameters
    pTexture->setMinificationFilter(QOpenGLTexture::Linear);   //glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    pTexture->setMagnificationFilter(QOpenGLTexture::Linear);

    return pTexture;
}

GLSL

lighting_maps.vert

#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aNormal;
layout (location = 2) in vec2 aTexCoords;

out vec3 FragPos;
out vec3 Normal;
out vec2 TexCoords;

uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;

void main()
{
    FragPos = vec3(model * vec4(aPos, 1.0));
    Normal = mat3(transpose(inverse(model))) * aNormal;  
    TexCoords = aTexCoords;
    
    gl_Position = projection * view * vec4(FragPos, 1.0);
}

lighting_maps.frag

#version 330 core
out vec4 FragColor;

struct Material {
    sampler2D diffuse;
    sampler2D specular;    
    float shininess;
}; 

struct Light {
    vec3 position;

    vec3 ambient;
    vec3 diffuse;
    vec3 specular;
};

in vec3 FragPos;  
in vec3 Normal;  
in vec2 TexCoords;
  
uniform vec3 viewPos;
uniform Material material;
uniform Light light;

void main()
{
    // ambient
    vec3 ambient = light.ambient * texture(material.diffuse, TexCoords).rgb;
    
    // diffuse 
    vec3 norm = normalize(Normal);
    vec3 lightDir = normalize(light.position - FragPos);
    float diff = max(dot(norm, lightDir), 0.0);
    vec3 diffuse = light.diffuse * diff * texture(material.diffuse, TexCoords).rgb;  
    
    // specular
    vec3 viewDir = normalize(viewPos - FragPos);
    vec3 reflectDir = reflect(-lightDir, norm);  
    float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess);
    vec3 specular = light.specular * spec * texture(material.specular, TexCoords).rgb;  
        
    vec3 result = ambient + diffuse + specular;
    FragColor = vec4(result, 1.0);
}

最后编辑于：2019.08.15 10:53:14

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