OpenGL with QtWidgets：投光物、多光源
2024-06-03 17:03:46
（本文是LearnOpenGL的学习笔记， 教程中文翻译地址https://learnopengl-cn.github.io/（备用地址https://learnopengl-cn.readthedocs.io/zh/latest/），写于 2021-10-2）
0.前言
上一节学习了材质和光照贴图（https://gongjianbo1992.blog.csdn.net/article/details/120397134），教程接下来讲了投光物和多光源。
1.知识点
投光物就是在基础光照的内容上进行扩展，之前的光照都是拟定一个点，现实世界中，我们有很多种类的光照，每种的表现都不同。将光投射(Cast)到物体的光源叫做投光物(Light Caster)。教程讲了三种投光物：定向光(Directional Light)，点光源(Point Light)，聚光(Spotlight)。
平行光：当一个光源处于很远的地方时，来自光源的每条光线就会近似于互相平行。（相对于之前基础光照的点光源，简化了光照方向的计算，只需要固定值，而不是计算光源指向物体表面顶点的向量）
点光源：前面基础光照用的就是点光源，某个点的光源朝着所有方向散射光线。只是前面课程没有进行衰减模拟计算，距离越远光照强度越弱。
聚光：聚光是位于环境中某个位置的光源，它只朝一个特定方向而不是所有方向照射光线（手电筒/聚光灯的效果）。相当于以一个方向为基准，夹角超过一定就不进行光照计算。
2.实现代码
（项目git链接：https://github.com/gongjianbo/OpenGLwithQtWidgets.git）
多光源实现效果：
#pragma once
#include <QOpenGLWidget>
#include <QOpenGLFunctions_3_3_Core>
#include <QOpenGLShaderProgram>
#include <QOpenGLVertexArrayObject>
#include <QOpenGLBuffer>
#include <QOpenGLTexture>
#include <QVector3D>
#include <QMatrix4x4>
#include <QQuaternion>
#include <QTimer>//多光源
//QOpenGLWidget窗口上下文
//QOpenGLFunctions访问OpenGL接口，可以不继承作为成员变量使用
class GLMultipleLights: public QOpenGLWidget, protected QOpenGLFunctions_3_3_Core
{Q_OBJECT
public:explicit GLMultipleLights(QWidget *parent = nullptr);~GLMultipleLights();protected://【】继承QOpenGLWidget后重写这三个虚函数//设置OpenGL资源和状态。在第一次调用resizeGL或paintGL之前被调用一次void initializeGL() override;//渲染OpenGL场景，每当需要更新小部件时使用void paintGL() override;//设置OpenGL视口、投影等，每当尺寸大小改变时调用void resizeGL(int width, int height) override;private:void initShader();QOpenGLTexture *initTexture(const QString &imgpath);private://着色器程序QOpenGLShaderProgram lightingShader,lampShader;//顶点数组对象QOpenGLVertexArrayObject lightingVao,lampVao;//顶点缓冲QOpenGLBuffer vbo;//纹理QOpenGLTexture *diffuseMap{ nullptr };QOpenGLTexture *specularMap{ nullptr };//QTimer timer;int rotate{ 0 };
};#include "GLMultipleLights.h"
#include <cmath>
#include <QtMath>
#include <QDebug>GLMultipleLights::GLMultipleLights(QWidget *parent): QOpenGLWidget(parent)
{connect(&timer,&QTimer::timeout,this,[this](){rotate+=1;if(isVisible()){update();}});timer.setInterval(50);
}GLMultipleLights::~GLMultipleLights()
{//initializeGL在显示时才调用，释放未初始化的会异常if(!isValid())return;//QOpenGLWidget//三个虚函数不需要makeCurrent，对应的操作已由框架完成//但是释放时需要设置当前上下文makeCurrent();vbo.destroy();lightingVao.destroy();lampVao.destroy();delete diffuseMap;delete specularMap;doneCurrent();
}void GLMultipleLights::initializeGL()
{//为当前上下文初始化OpenGL函数解析initializeOpenGLFunctions();initShader();//方块的顶点、法向量、纹理坐标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=QOpenGLBuffer(QOpenGLBuffer::VertexBuffer);vbo.create();//light vaolightingVao.create();lightingVao.bind();vbo.bind();vbo.allocate(vertices,sizeof(vertices));//setAttributeBuffer(int location, GLenum type, int offset, int tupleSize, int stride = 0)lightingShader.setAttributeBuffer(0, GL_FLOAT, sizeof(GLfloat) * 0, 3, sizeof(GLfloat) * 8);lightingShader.enableAttributeArray(0);lightingShader.setAttributeBuffer(1, GL_FLOAT, sizeof(GLfloat) * 3, 3, sizeof(GLfloat) * 8);lightingShader.enableAttributeArray(1);lightingShader.setAttributeBuffer(2, GL_FLOAT, sizeof(GLfloat) * 6, 2, sizeof(GLfloat) * 8);lightingShader.enableAttributeArray(2);vbo.release();lightingVao.release();//lamp vaolampVao.create();lampVao.bind();vbo.bind();//setAttributeBuffer(int location, GLenum type, int offset, int tupleSize, int stride = 0)lampShader.setAttributeBuffer(0, GL_FLOAT, 0, 3, sizeof(GLfloat) * 8);lampShader.enableAttributeArray(0);vbo.release();lampVao.release();//纹理diffuseMap = initTexture(":/container2.png");specularMap = initTexture(":/container2_specular.png");//shader configurationlightingShader.bind();lightingShader.setUniformValue("material.diffuse", 0);lightingShader.setUniformValue("material.specular", 1);lightingShader.release();//timer.start();
}//绘制多个盒子
static QVector3D cubePositions[] = {QVector3D( 0.0f, 0.0f, 0.0f),QVector3D( 0.0f, -4.0f, 0.0f),QVector3D( 0.0f, 4.0f, 0.0f),QVector3D( 1.0f, -5.0f, 1.0f),QVector3D(-1.5f, -2.2f, -2.5f),QVector3D(-3.8f, -2.0f, -7.3f),QVector3D( 2.4f, -0.4f, -3.5f),QVector3D(-1.7f, -3.0f, -6.5f),QVector3D( 5.3f, -2.0f, -2.5f),QVector3D(-1.3f, 1.0f, -1.5f)
};//多个光源
static QVector3D pointLightPositions[] = {QVector3D( 0.0f, 2.0f, 0.0f),QVector3D( 2.3f, -3.0f, -1.0f),QVector3D(-3.0f, 2.0f, 0.5f),QVector3D( 2.0f, 3.0f, 2.0f)
};void GLMultipleLights::paintGL()
{glClearColor(0.2f, 0.3f, 0.3f, 1.0f);//清除深度缓冲glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);//Z缓冲(Z-buffer),深度缓冲(Depth Buffer)。glEnable(GL_DEPTH_TEST);//draw lightinglightingShader.bind();QMatrix4x4 view; //观察矩阵view.translate(0.0f, 0.0f, -10.0f);view.rotate(45, QVector3D(1.0f, 0.8f, 0.0f));lightingShader.setUniformValue("view", view);QMatrix4x4 projection; //透视投影projection.perspective(45.0f, 1.0f * width() / height(), 0.1f, 100.0f);lightingShader.setUniformValue("projection", projection);// Directional lightlightingShader.setUniformValue("dirLight.direction", -0.2f, -1.0f, -0.3f);lightingShader.setUniformValue("dirLight.ambient", 0.05f, 0.05f, 0.05f);lightingShader.setUniformValue("dirLight.diffuse", 0.2f, 0.2f, 0.2f);lightingShader.setUniformValue("dirLight.specular", 0.5f, 0.5f, 0.5f);QVector3D ambient_color(0.05f, 0.05f, 0.05f);QVector3D diffuse_color(0.0f, 0.0f, 0.4f);QVector3D specular_color(0.0f, 0.0f, 1.0f);// Point light 1lightingShader.setUniformValue("pointLights[0].position", pointLightPositions[0]);lightingShader.setUniformValue("pointLights[0].ambient", ambient_color);lightingShader.setUniformValue("pointLights[0].diffuse", diffuse_color);lightingShader.setUniformValue("pointLights[0].specular", specular_color);lightingShader.setUniformValue("pointLights[0].constant", 1.0f);lightingShader.setUniformValue("pointLights[0].linear", 0.09f);lightingShader.setUniformValue("pointLights[0].quadratic", 0.032f);// Point light 2lightingShader.setUniformValue("pointLights[1].position", pointLightPositions[1]);lightingShader.setUniformValue("pointLights[1].ambient", ambient_color);lightingShader.setUniformValue("pointLights[1].diffuse", diffuse_color);lightingShader.setUniformValue("pointLights[1].specular", specular_color);lightingShader.setUniformValue("pointLights[1].constant", 1.0f);lightingShader.setUniformValue("pointLights[1].linear", 0.09f);lightingShader.setUniformValue("pointLights[1].quadratic", 0.032f);// Point light 3lightingShader.setUniformValue("pointLights[2].position", pointLightPositions[2]);lightingShader.setUniformValue("pointLights[2].ambient", ambient_color);lightingShader.setUniformValue("pointLights[2].diffuse", diffuse_color);lightingShader.setUniformValue("pointLights[2].specular", specular_color);lightingShader.setUniformValue("pointLights[2].constant", 1.0f);lightingShader.setUniformValue("pointLights[2].linear", 0.09f);lightingShader.setUniformValue("pointLights[2].quadratic", 0.032f);// Point light 4lightingShader.setUniformValue("pointLights[3].position", pointLightPositions[3]);lightingShader.setUniformValue("pointLights[3].ambient", ambient_color);lightingShader.setUniformValue("pointLights[3].diffuse", diffuse_color);lightingShader.setUniformValue("pointLights[3].specular", specular_color);lightingShader.setUniformValue("pointLights[3].constant", 1.0f);lightingShader.setUniformValue("pointLights[3].linear", 0.09f);lightingShader.setUniformValue("pointLights[3].quadratic", 0.032f);// SpotLightQMatrix4x4 model;//模型矩阵model.translate(pointLightPositions[0]);model.scale(0.2f);QVector3D light_pos = model.map(QVector3D(0.0f, 0.0f, 0.0f));QVector3D direction_pos = QVector3D(0.0f, -20.0f, 0.0f);lightingShader.setUniformValue("spotLight.direction", direction_pos);lightingShader.setUniformValue("spotLight.position", light_pos);lightingShader.setUniformValue("spotLight.ambient", 0.0f, 0.0f, 0.0f);lightingShader.setUniformValue("spotLight.diffuse", 0.3f, 1.0f, 0.3f);lightingShader.setUniformValue("spotLight.specular", 0.3f, 1.0f, 0.3f);lightingShader.setUniformValue("spotLight.constant", 1.0f);lightingShader.setUniformValue("spotLight.linear", 0.09f);lightingShader.setUniformValue("spotLight.quadratic", 0.032f);lightingShader.setUniformValue("spotLight.cutOff", (float)std::cos(qDegreesToRadians(12.5)));lightingShader.setUniformValue("spotLight.outerCutOff", (float)std::cos(qDegreesToRadians(15.0)));//材质-material properties//shininess影响镜面高光的散射/半径lightingShader.setUniformValue("material.shininess", 32.0f);lightingVao.bind();//绑定2d纹理//bind diffuse mapglActiveTexture(GL_TEXTURE0);diffuseMap->bind();//bind specular mapglActiveTexture(GL_TEXTURE1);specularMap->bind();//glDrawArrays(GL_TRIANGLES, 0, 36);//多个盒子便于对比for (unsigned int i = 0; i < 10; i++) {//模型矩阵QMatrix4x4 box_model;//平移box_model.translate(cubePositions[i]);float angle = 20.0f * i;//旋转box_model.rotate(angle, QVector3D(1.0f, 0.3f, 0.5f));//传入着色器并绘制lightingShader.setUniformValue("model", box_model);glDrawArrays(GL_TRIANGLES, 0, 36);}lightingVao.release();lightingShader.release();//draw lamplampShader.bind();lampShader.setUniformValue("view", view);lampShader.setUniformValue("projection", projection);lampVao.bind();for (unsigned int i = 0; i < 4; i++) {//模型矩阵QMatrix4x4 lamb_model;lamb_model.translate(pointLightPositions[i]);lamb_model.scale(0.2f);//传入着色器并绘制lampShader.setUniformValue("model", lamb_model);glDrawArrays(GL_TRIANGLES, 0, 36);}lampVao.release();lampShader.release();
}void GLMultipleLights::resizeGL(int width, int height)
{glViewport(0, 0, width, height);
}void GLMultipleLights::initShader()
{//lingting shader//in输入，out输出,uniform从cpu向gpu发送const char *lighting_vertex=R"(#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);
})";const char *lighting_fragment=R"(#version 330 core
struct Material {sampler2D diffuse;sampler2D specular;float shininess;
};struct DirLight {vec3 direction;vec3 ambient;vec3 diffuse;vec3 specular;
};struct PointLight {vec3 position;float constant;float linear;float quadratic;vec3 ambient;vec3 diffuse;vec3 specular;
};struct SpotLight {vec3 position;vec3 direction;float cutOff;float outerCutOff;float constant;float linear;float quadratic;vec3 ambient;vec3 diffuse;vec3 specular;
};#define NR_POINT_LIGHTS 4in vec3 FragPos;
in vec3 Normal;
in vec2 TexCoords;out vec4 color;uniform vec3 viewPos;
uniform DirLight dirLight;
uniform PointLight pointLights[NR_POINT_LIGHTS];
uniform SpotLight spotLight;
uniform Material material;// Function prototypes
vec3 CalcDirLight(DirLight light, vec3 normal, vec3 viewDir);
vec3 CalcPointLight(PointLight light, vec3 normal, vec3 fragPos, vec3 viewDir);
vec3 CalcSpotLight(SpotLight light, vec3 normal, vec3 fragPos, vec3 viewDir);void main()
{// Propertiesvec3 norm = normalize(Normal);vec3 viewDir = normalize(viewPos - FragPos);// == ======================================// Our lighting is set up in 3 phases: directional, point lights and an optional flashlight// For each phase, a calculate function is defined that calculates the corresponding color// per lamp. In the main() function we take all the calculated colors and sum them up for// this fragment's final color.// == ======================================// Phase 1: Directional lightingvec3 result = CalcDirLight(dirLight, norm, viewDir);// Phase 2: Point lightsfor(int i = 0; i < NR_POINT_LIGHTS; i++)result += CalcPointLight(pointLights[i], norm, FragPos, viewDir);// Phase 3: Spot lightresult += CalcSpotLight(spotLight, norm, FragPos, viewDir);color = vec4(result, 1.0);
}// Calculates the color when using a directional light.
vec3 CalcDirLight(DirLight light, vec3 normal, vec3 viewDir)
{vec3 lightDir = normalize(-light.direction);// Diffuse shadingfloat diff = max(dot(normal, lightDir), 0.0);// Specular shadingvec3 reflectDir = reflect(-lightDir, normal);float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess);// Combine resultsvec3 ambient = light.ambient * vec3(texture(material.diffuse, TexCoords));vec3 diffuse = light.diffuse * diff * vec3(texture(material.diffuse, TexCoords));vec3 specular = light.specular * spec * vec3(texture(material.specular, TexCoords));return (ambient + diffuse + specular);
}// Calculates the color when using a point light.
vec3 CalcPointLight(PointLight light, vec3 normal, vec3 fragPos, vec3 viewDir)
{vec3 lightDir = normalize(light.position - fragPos);// Diffuse shadingfloat diff = max(dot(normal, lightDir), 0.0);// Specular shadingvec3 reflectDir = reflect(-lightDir, normal);float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess);// Attenuationfloat distance = length(light.position - fragPos);float attenuation = 1.0f / (light.constant + light.linear * distance + light.quadratic * (distance * distance));// Combine resultsvec3 ambient = light.ambient * vec3(texture(material.diffuse, TexCoords));vec3 diffuse = light.diffuse * diff * vec3(texture(material.diffuse, TexCoords));vec3 specular = light.specular * spec * vec3(texture(material.specular, TexCoords));ambient *= attenuation;diffuse *= attenuation;specular *= attenuation;return (ambient + diffuse + specular);
}// Calculates the color when using a spot light.
vec3 CalcSpotLight(SpotLight light, vec3 normal, vec3 fragPos, vec3 viewDir)
{vec3 lightDir = normalize(light.position - fragPos);// Diffuse shadingfloat diff = max(dot(normal, lightDir), 0.0);// Specular shadingvec3 reflectDir = reflect(-lightDir, normal);float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess);// Attenuationfloat distance = length(light.position - fragPos);float attenuation = 1.0f / (light.constant + light.linear * distance + light.quadratic * (distance * distance));// Spotlight intensityfloat theta = dot(lightDir, normalize(-light.direction));float epsilon = light.cutOff - light.outerCutOff;float intensity = clamp((theta - light.outerCutOff) / epsilon, 0.0, 1.0);// Combine resultsvec3 ambient = light.ambient * vec3(texture(material.diffuse, TexCoords));vec3 diffuse = light.diffuse * diff * vec3(texture(material.diffuse, TexCoords));vec3 specular = light.specular * spec * vec3(texture(material.specular, TexCoords));ambient *= attenuation * intensity;diffuse *= attenuation * intensity;specular *= attenuation * intensity;return (ambient + diffuse + specular);
})";//将source编译为指定类型的着色器，并添加到此着色器程序if(!lightingShader.addCacheableShaderFromSourceCode(QOpenGLShader::Vertex,lighting_vertex)){qDebug()<<"compiler vertex error"<<lightingShader.log();}if(!lightingShader.addCacheableShaderFromSourceCode(QOpenGLShader::Fragment,lighting_fragment)){qDebug()<<"compiler fragment error"<<lightingShader.log();}//使用addShader()将添加到该程序的着色器链接在一起。if(!lightingShader.link()){qDebug()<<"link shaderprogram error"<<lightingShader.log();}//lamp shaderconst char *lamp_vertex=R"(#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, 1.0f);
})";const char *lamp_fragment=R"(#version 330 core
out vec4 FragColor;
void main()
{
FragColor = vec4(1.0);
})"; // set alle 4 vector values to 1.0if(!lampShader.addCacheableShaderFromSourceCode(QOpenGLShader::Vertex,lamp_vertex)){qDebug()<<"compiler vertex error"<<lampShader.log();}if(!lampShader.addCacheableShaderFromSourceCode(QOpenGLShader::Fragment,lamp_fragment)){qDebug()<<"compiler fragment error"<<lampShader.log();}if(!lampShader.link()){qDebug()<<"link shaderprogram error"<<lampShader.log();}
}QOpenGLTexture *GLMultipleLights::initTexture(const QString &imgpath)
{QOpenGLTexture *texture = new QOpenGLTexture(QImage(imgpath), QOpenGLTexture::GenerateMipMaps);if(!texture->isCreated()){qDebug() << "Failed to create texture";}//set the texture wrapping parameters//等于glTexParameteri(GLtexture_2D, GLtexture_WRAP_S, GL_REPEAT);texture->setWrapMode(QOpenGLTexture::DirectionS, QOpenGLTexture::Repeat);texture->setWrapMode(QOpenGLTexture::DirectionT, QOpenGLTexture::Repeat);////set texture filtering parameters//等价于glTexParameteri(GLtexture_2D, GLtexture_MIN_FILTER, GL_LINEAR);texture->setMinificationFilter(QOpenGLTexture::Linear);texture->setMagnificationFilter(QOpenGLTexture::Linear);return texture;
}
3.参考
LearnOpenGL：https://learnopengl-cn.github.io/02%20Lighting/05%20Light%20casters/
LearnOpenGL：https://learnopengl-cn.github.io/02%20Lighting/06%20Multiple%20lights/
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