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
原教程地址，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，可以切换着看，查看本篇代码 git checkout v2.2，喜欢就点个Star吧~
不同点 (仅列出新增)
- 主要是着色器中光照的各种计算，看原教程慢慢理解。
运行结果
运行结果
修改的文件
QtFunctionWidget.h
#ifndef QTFUNCTIONWIDGET_H
#define QTFUNCTIONWIDGET_H
#include
#include
#include
#include
#include
#include
#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();
private:
QOpenGLShaderProgram lightingShader, lampShader;
QOpenGLBuffer vbo;
QOpenGLVertexArrayObject cubeVAO, lightVAO;
QTimer* m_pTimer = nullptr;
int m_nTimeValue = 0;
// camera
std::unique_ptr camera;
bool m_bLeftPressed;
QPoint m_lastPos;
};
#endif // QTFUNCTIONWIDGET_H
QtFunctionWidget.cpp
#include "QtFunctionWidget.h"
#include
#include
// lighting
static QVector3D lightPos(1.2f, 1.0f, 2.0f);
QtFunctionWidget::QtFunctionWidget(QWidget *parent) : QOpenGLWidget (parent),
vbo(QOpenGLBuffer::VertexBuffer)
{
camera = std::make_unique(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();
doneCurrent();
}
void QtFunctionWidget::initializeGL(){
this->initializeOpenGLFunctions();
createShader();
// set up vertex data (and buffer(s)) and configure vertex attributes
// ------------------------------------------------------------------
float vertices[] = {
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
-0.5f, 0.5f, 0.5f, -1.0f, 0.0f, 0.0f,
-0.5f, 0.5f, -0.5f, -1.0f, 0.0f, 0.0f,
-0.5f, -0.5f, -0.5f, -1.0f, 0.0f, 0.0f,
-0.5f, -0.5f, -0.5f, -1.0f, 0.0f, 0.0f,
-0.5f, -0.5f, 0.5f, -1.0f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, -1.0f, 0.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 0.0f, 0.0f,
0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 0.0f,
0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f,
0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f,
0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f,
0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f
};
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);
// position attribute
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
// normal attribute
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(1);
}
{
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, 6 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
}
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("objectColor", QVector3D(1.0f, 0.5f, 0.31f));
lightingShader.setUniformValue("lightColor", QVector3D(1.0f, 1.0f, 1.0f));
lightingShader.setUniformValue("lightPos", lightPos);
lightingShader.setUniformValue("viewPos", camera->position);
// 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);
{// 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, ":/basic_lighting.vert");
if (!success) {
qDebug() << "shaderProgram addShaderFromSourceFile failed!" << lightingShader.log();
return success;
}
success = lightingShader.addShaderFromSourceFile(QOpenGLShader::Fragment, ":/basic_lighting.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;
}
GLSL
basic_lighting.vert
#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aNormal;
out vec3 FragPos;
out vec3 Normal;
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;
void main()
{
FragPos = vec3(model * vec4(aPos, 1.0));
Normal = mat3(transpose(inverse(model))) * aNormal;
gl_Position = projection * view * vec4(FragPos, 1.0);
}
basic_lighting.frag
#version 330 core
out vec4 FragColor;
in vec3 Normal;
in vec3 FragPos;
uniform vec3 lightPos;
uniform vec3 viewPos;
uniform vec3 lightColor;
uniform vec3 objectColor;
void main()
{
// ambient
float ambientStrength = 0.1;
vec3 ambient = ambientStrength * lightColor;
// diffuse
vec3 norm = normalize(Normal);
vec3 lightDir = normalize(lightPos - FragPos);
float diff = max(dot(norm, lightDir), 0.0);
vec3 diffuse = diff * lightColor;
// specular
float specularStrength = 0.5;
vec3 viewDir = normalize(viewPos - FragPos);
vec3 reflectDir = reflect(-lightDir, norm);
float spec = pow(max(dot(viewDir, reflectDir), 0.0), 32);
vec3 specular = specularStrength * spec * lightColor;
vec3 result = (ambient + diffuse + specular) * objectColor;
FragColor = vec4(result, 1.0);
}