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Qt+OpenGL-part4

作者：盐析白兔 | 2024-04-11 16:39:52

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Qt+OpenGL-part4

1-5练习_哔哩哔哩_bilibili

添加更多顶点到数据中，使用glDrawElements，尝试绘制两个彼此相连的三角形 

  1. #include "openglwidget.h"
  2. #include <QDebug>
  3.  
  4. unsigned int VBO,VAO,EBO;
  5. unsigned int shaderProgram;
  6.  
  7. //顶点着色器
  8. const char* vertexShaderSource="#version 330 core\n"
  9.         "layout(location=0) in vec3 aPos;\n"
  10.         "void main()\n"
  11.         "{\n"
  12.         "gl_Position=vec4(aPos.x,aPos.y,aPos.z,1.0);\n"
  13.         "}\0";
  14. //片段着色器
  15. const char* fragmentShaderSource="#version 330 core\n"
  16.         "out vec4 FragColor;\n"
  17.         "void main()\n"
  18.         "{\n"
  19.         "FragColor=vec4(0.3f,0.5f,0.2f,0.2f);\n"
  20.         "}\0";
  21.  
  22. OpenGLWidget::OpenGLWidget(QWidget *parent) : QOpenGLWidget(parent)
  23. {
  24.  
  25. }
  26.  
  27. void OpenGLWidget::initializeGL()
  28. {
  29.     initializeOpenGLFunctions();
  30.  
  31.     float vertices[] = {
  32.         0.5f, 0.5f, 0.0f,   // 右上角
  33.         0.5f, -0.5f, 0.0f,  // 右下角
  34.         -0.5f, -0.5f, 0.0f, // 左下角
  35.         -0.5f, 0.4f, 0.0f,   // 左上角
  36.         -0.5f, 0.8f, 0.0f,   //另一个左上角
  37.     };
  38.  
  39.     unsigned int indices[] = {
  40.         // 注意索引从0开始!
  41.         // 此例的索引(0,1,2,3)就是顶点数组vertices的下标，
  42.         // 这样可以由下标代表顶点组合成矩形
  43.         0, 1, 4, // 第一个三角形
  44.         1, 2, 3  // 第二个三角形
  45.     };
  46.     //顶点数组
  47.     glGenVertexArrays(1,&VAO);
  48.     //顶点缓冲对象
  49.     glGenBuffers(1,&VBO);
  50.     glGenBuffers(1,&EBO);
  51.  
  52.     //绑定顶点数组
  53.     glBindVertexArray(VAO);
  54.     //绑定顶点缓冲对象
  55.     glBindBuffer(GL_ARRAY_BUFFER,VBO);
  56.     glBindBuffer(GL_ELEMENT_ARRAY_BUFFER,EBO);
  57.  
  58.     //把相关数据复制到缓冲内存中
  59.     glBufferData(GL_ARRAY_BUFFER,sizeof(vertices),vertices,GL_STATIC_DRAW);
  60.     //第二个参数：数据的大小（字节为单位）
  61.     //第三个参数：数据指针
  62.     glBufferData(GL_ELEMENT_ARRAY_BUFFER,sizeof(indices),indices,GL_STATIC_DRAW);
  63.  
  64.  
  65.     glVertexAttribPointer(0,3,GL_FLOAT,GL_FALSE,3*sizeof(float),(void *)0);
  66.     glEnableVertexAttribArray(0);
  67.  
  68.     glBindBuffer(GL_ARRAY_BUFFER,0);//解除绑定
  69.     glBindVertexArray(0);
  70.  
  71.  
  72.     unsigned int vertexShader=glCreateShader(GL_VERTEX_SHADER);
  73.     glShaderSource(vertexShader,1,&vertexShaderSource,NULL);
  74.     glCompileShader(vertexShader);
  75.  
  76.     int  success;
  77.     char infoLog[512];
  78.     glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
  79.  
  80.     if(!success)
  81.     {
  82.         glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
  83.         qDebug() << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog;
  84.     }
  85.  
  86.     unsigned int fragmentShader=glCreateShader(GL_FRAGMENT_SHADER);
  87.     glShaderSource(fragmentShader,1,&fragmentShaderSource,NULL);
  88.     glCompileShader(fragmentShader);
  89.  
  90.     shaderProgram=glCreateProgram();
  91.     glAttachShader(shaderProgram,vertexShader);
  92.     glAttachShader(shaderProgram,fragmentShader);
  93.     glLinkProgram(shaderProgram);
  94.  
  95.     glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);
  96.     if(!success) {
  97.         glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
  98.         qDebug() << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog;
  99.     }
  100.  
  101.     glDeleteShader(vertexShader);
  102.     glDeleteShader(fragmentShader);
  103.  
  104.     glPolygonMode(GL_FRONT_AND_BACK,GL_LINE);//使用线条填充
  105.  
  106.  
  107. }
  108.  
  109. void OpenGLWidget::resizeGL(int w, int h)
  110. {
  111.  
  112. }
  113.  
  114. void OpenGLWidget::paintGL()
  115. {
  116.     glClearColor(0.2f,0.3f,0.3f,1.0f);
  117.     glClear(GL_COLOR_BUFFER_BIT);
  118.  
  119.     glUseProgram(shaderProgram);
  120.  
  121.     glBindVertexArray(VAO);
  122.     //VAO知道VBO和EBO的情况
  123.  
  124.     glDrawElements(GL_TRIANGLES,6,GL_UNSIGNED_INT,0);
  125. }

添加更多顶点到数据中，使用glDrawArrays，尝试绘制两个彼此相连的三角形 

  1. #include "openglwidget.h"
  2. #include <QDebug>
  3.  
  4. unsigned int VBO,VAO,EBO;
  5. unsigned int shaderProgram;
  6.  
  7. //顶点着色器
  8. const char* vertexShaderSource="#version 330 core\n"
  9.         "layout(location=0) in vec3 aPos;\n"
  10.         "void main()\n"
  11.         "{\n"
  12.         "gl_Position=vec4(aPos.x,aPos.y,aPos.z,1.0);\n"
  13.         "}\0";
  14. //片段着色器
  15. const char* fragmentShaderSource="#version 330 core\n"
  16.         "out vec4 FragColor;\n"
  17.         "void main()\n"
  18.         "{\n"
  19.         "FragColor=vec4(0.3f,0.5f,0.2f,0.2f);\n"
  20.         "}\0";
  21.  
  22. OpenGLWidget::OpenGLWidget(QWidget *parent) : QOpenGLWidget(parent)
  23. {
  24.  
  25. }
  26.  
  27. void OpenGLWidget::initializeGL()
  28. {
  29.     initializeOpenGLFunctions();
  30.  
  31.     float vertices[] = {
  32.         0.5f, 0.5f, 0.0f,
  33.         0.5f, -0.5f, 0.0f,
  34.         -0.5f, 0.8f, 0.0f,
  35.         -0.5f, 0.5f, 0.0f,
  36.         0.3f, -0.5f, 0.0f,
  37.         -0.5f, 0.8f, 0.0f,
  38.     };
  39.  
  40.     //顶点数组
  41.     glGenVertexArrays(1,&VAO);
  42.     //顶点缓冲对象
  43.     glGenBuffers(1,&VBO);
  44.     glGenBuffers(1,&EBO);
  45.  
  46.     //绑定顶点数组
  47.     glBindVertexArray(VAO);
  48.     //绑定顶点缓冲对象
  49.     glBindBuffer(GL_ARRAY_BUFFER,VBO);
  50.     glBindBuffer(GL_ELEMENT_ARRAY_BUFFER,EBO);
  51.  
  52.     //把相关数据复制到缓冲内存中
  53.     glBufferData(GL_ARRAY_BUFFER,sizeof(vertices),vertices,GL_STATIC_DRAW);
  54.     //第二个参数：数据的大小（字节为单位）
  55.     //第三个参数：数据指针
  56.     glBufferData(GL_ELEMENT_ARRAY_BUFFER,sizeof(indices),indices,GL_STATIC_DRAW);
  57.  
  58.  
  59.     glVertexAttribPointer(0,3,GL_FLOAT,GL_FALSE,3*sizeof(float),(void *)0);
  60.     glEnableVertexAttribArray(0);
  61.  
  62.     glBindBuffer(GL_ARRAY_BUFFER,0);//解除绑定
  63.     glBindVertexArray(0);
  64.  
  65.  
  66.     unsigned int vertexShader=glCreateShader(GL_VERTEX_SHADER);
  67.     glShaderSource(vertexShader,1,&vertexShaderSource,NULL);
  68.     glCompileShader(vertexShader);
  69.  
  70.     int  success;
  71.     char infoLog[512];
  72.     glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
  73.  
  74.     if(!success)
  75.     {
  76.         glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
  77.         qDebug() << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog;
  78.     }
  79.  
  80.     unsigned int fragmentShader=glCreateShader(GL_FRAGMENT_SHADER);
  81.     glShaderSource(fragmentShader,1,&fragmentShaderSource,NULL);
  82.     glCompileShader(fragmentShader);
  83.  
  84.     shaderProgram=glCreateProgram();
  85.     glAttachShader(shaderProgram,vertexShader);
  86.     glAttachShader(shaderProgram,fragmentShader);
  87.     glLinkProgram(shaderProgram);
  88.  
  89.     glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);
  90.     if(!success) {
  91.         glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
  92.         qDebug() << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog;
  93.     }
  94.  
  95.     glDeleteShader(vertexShader);
  96.     glDeleteShader(fragmentShader);
  97.  
  98.     glPolygonMode(GL_FRONT_AND_BACK,GL_LINE);//使用线条填充
  99.  
  100.  
  101. }
  102.  
  103. void OpenGLWidget::resizeGL(int w, int h)
  104. {
  105.  
  106. }
  107.  
  108. void OpenGLWidget::paintGL()
  109. {
  110.     glClearColor(0.2f,0.3f,0.3f,1.0f);
  111.     glClear(GL_COLOR_BUFFER_BIT);
  112.  
  113.     glUseProgram(shaderProgram);
  114.  
  115.     glBindVertexArray(VAO);
  116.     //VAO知道VBO和EBO的情况
  117.     glDrawArrays(GL_TRIANGLES,0,6);
  118. }

创建两个三角形，对它们的数据使用不同的VAO和VBO 

  1. #include "openglwidget.h"
  2. #include <QDebug>
  3.  
  4. unsigned int VBOs[2],VAOs[2];
  5. unsigned int shaderProgram;
  6.  
  7. //顶点着色器
  8. const char* vertexShaderSource="#version 330 core\n"
  9.         "layout(location=0) in vec3 aPos;\n"
  10.         "void main()\n"
  11.         "{\n"
  12.         "gl_Position=vec4(aPos.x,aPos.y,aPos.z,1.0);\n"
  13.         "}\0";
  14. //片段着色器
  15. const char* fragmentShaderSource="#version 330 core\n"
  16.         "out vec4 FragColor;\n"
  17.         "void main()\n"
  18.         "{\n"
  19.         "FragColor=vec4(0.3f,0.5f,0.2f,0.2f);\n"
  20.         "}\0";
  21.  
  22. OpenGLWidget::OpenGLWidget(QWidget *parent) : QOpenGLWidget(parent)
  23. {
  24.     
  25. }
  26.  
  27. void OpenGLWidget::initializeGL()
  28. {
  29.     initializeOpenGLFunctions();
  30.  
  31.     float firstTriangle[]={
  32.         -0.9f,-0.5f,0.0f,
  33.         -0.0f,-0.5f,0.0f,
  34.         -0.45f,0.5f,0.0f
  35.     };
  36.  
  37.     float secondTriangle[]={
  38.         -0.0f,-0.5f,0.0f,
  39.         0.9f,-0.5f,0.0f,
  40.         0.45f,0.5f,0.0f
  41.     };
  42.     unsigned int indices[] = {
  43.         // 注意索引从0开始!
  44.         // 此例的索引(0,1,2,3)就是顶点数组vertices的下标，
  45.         // 这样可以由下标代表顶点组合成矩形
  46.         0, 1, 4, // 第一个三角形
  47.         1, 2, 3  // 第二个三角形
  48.     };
  49.     //顶点数组
  50.     glGenVertexArrays(2,VAOs);
  51.     //顶点缓冲对象
  52.     glGenBuffers(2,VBOs);
  53.  
  54.     //绑定顶点数组
  55.     glBindVertexArray(VAOs[0]);
  56.     //绑定顶点缓冲对象
  57.     glBindBuffer(GL_ARRAY_BUFFER,VBOs[0]);
  58.  
  59.     //把相关数据复制到缓冲内存中
  60.     glBufferData(GL_ARRAY_BUFFER,sizeof(firstTriangle),firstTriangle,GL_STATIC_DRAW);
  61.     //第二个参数：数据的大小（字节为单位）
  62.     //第三个参数：数据指针
  63.  
  64.     glVertexAttribPointer(0,3,GL_FLOAT,GL_FALSE,3*sizeof(float),(void *)0);
  65.     glEnableVertexAttribArray(0);
  66.  
  67.  
  68.     //绑定顶点数组
  69.     glBindVertexArray(VAOs[1]);
  70.     //绑定顶点缓冲对象
  71.     glBindBuffer(GL_ARRAY_BUFFER,VBOs[1]);
  72.  
  73.     //把相关数据复制到缓冲内存中
  74.     glBufferData(GL_ARRAY_BUFFER,sizeof(secondTriangle),secondTriangle,GL_STATIC_DRAW);
  75.     //第二个参数：数据的大小（字节为单位）
  76.     //第三个参数：数据指针
  77.  
  78.     glVertexAttribPointer(0,3,GL_FLOAT,GL_FALSE,3*sizeof(float),(void *)0);
  79.     glEnableVertexAttribArray(0);
  80.  
  81.  
  82.  
  83.     glBindBuffer(GL_ARRAY_BUFFER,0);//解除绑定
  84.     glBindVertexArray(0);
  85.  
  86.     unsigned int vertexShader=glCreateShader(GL_VERTEX_SHADER);
  87.     glShaderSource(vertexShader,1,&vertexShaderSource,NULL);
  88.     glCompileShader(vertexShader);
  89.  
  90.     int  success;
  91.     char infoLog[512];
  92.     glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
  93.  
  94.     if(!success)
  95.     {
  96.         glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
  97.         qDebug() << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog;
  98.     }
  99.  
  100.     unsigned int fragmentShader=glCreateShader(GL_FRAGMENT_SHADER);
  101.     glShaderSource(fragmentShader,1,&fragmentShaderSource,NULL);
  102.     glCompileShader(fragmentShader);
  103.  
  104.     shaderProgram=glCreateProgram();
  105.     glAttachShader(shaderProgram,vertexShader);
  106.     glAttachShader(shaderProgram,fragmentShader);
  107.     glLinkProgram(shaderProgram);
  108.  
  109.     glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);
  110.     if(!success) {
  111.         glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
  112.         qDebug() << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog;
  113.     }
  114.  
  115.     glDeleteShader(vertexShader);
  116.     glDeleteShader(fragmentShader);
  117.  
  118.     glPolygonMode(GL_FRONT_AND_BACK,GL_LINE);//使用线条填充
  119.  
  120.  
  121. }
  122.  
  123. void OpenGLWidget::resizeGL(int w, int h)
  124. {
  125.  
  126. }
  127.  
  128. void OpenGLWidget::paintGL()
  129. {
  130.     glClearColor(0.2f,0.3f,0.3f,1.0f);
  131.     glClear(GL_COLOR_BUFFER_BIT);
  132.  
  133.     glUseProgram(shaderProgram);
  134.  
  135.     glBindVertexArray(VAOs[0]);
  136.     glDrawArrays(GL_TRIANGLES,0,3);
  137.  
  138.     glBindVertexArray(VAOs[1]);
  139.     glDrawArrays(GL_TRIANGLES,0,3);
  140. }

创建两个着色器程序，第二个程序使用一个不同的片段着色器。

  1. #include "openglwidget.h"
  2. #include <QDebug>
  3.  
  4. unsigned int VBOs[2],VAOs[2];
  5. unsigned int shaderProgram,shaderProgram2;
  6.  
  7. //顶点着色器
  8. const char* vertexShaderSource="#version 330 core\n"
  9.         "layout(location=0) in vec3 aPos;\n"
  10.         "void main()\n"
  11.         "{\n"
  12.         "gl_Position=vec4(aPos.x,aPos.y,aPos.z,1.0);\n"
  13.         "}\0";
  14. //片段着色器
  15. const char* fragmentShaderSource="#version 330 core\n"
  16.         "out vec4 FragColor;\n"
  17.         "void main()\n"
  18.         "{\n"
  19.         "FragColor=vec4(0.3f,0.5f,0.2f,0.2f);\n"
  20.         "}\0";
  21. const char* fragmentShader2Source="#version 330 core\n"
  22.         "out vec4 FragColor;\n"
  23.         "void main()\n"
  24.         "{\n"
  25.         "FragColor=vec4(0.8f,0.8f,1.0f,0.2f);\n"
  26.         "}\0";
  27.  
  28. OpenGLWidget::OpenGLWidget(QWidget *parent) : QOpenGLWidget(parent)
  29. {
  30.  
  31. }
  32.  
  33. void OpenGLWidget::initializeGL()
  34. {
  35.     initializeOpenGLFunctions();
  36.  
  37.     float firstTriangle[]={
  38.         -0.9f,-0.5f,0.0f,
  39.         -0.0f,-0.5f,0.0f,
  40.         -0.45f,0.5f,0.0f
  41.     };
  42.  
  43.     float secondTriangle[]={
  44.         -0.0f,-0.5f,0.0f,
  45.         0.9f,-0.5f,0.0f,
  46.         0.45f,0.5f,0.0f
  47.     };
  48.  
  49.     //顶点数组
  50.     glGenVertexArrays(2,VAOs);
  51.     //顶点缓冲对象
  52.     glGenBuffers(2,VBOs);
  53.  
  54.     //绑定顶点数组
  55.     glBindVertexArray(VAOs[0]);
  56.     //绑定顶点缓冲对象
  57.     glBindBuffer(GL_ARRAY_BUFFER,VBOs[0]);
  58.  
  59.     //把相关数据复制到缓冲内存中
  60.     glBufferData(GL_ARRAY_BUFFER,sizeof(firstTriangle),firstTriangle,GL_STATIC_DRAW);
  61.     //第二个参数：数据的大小（字节为单位）
  62.     //第三个参数：数据指针
  63.  
  64.     glVertexAttribPointer(0,3,GL_FLOAT,GL_FALSE,3*sizeof(float),(void *)0);
  65.     glEnableVertexAttribArray(0);
  66.  
  67.  
  68.     //绑定顶点数组
  69.     glBindVertexArray(VAOs[1]);
  70.     //绑定顶点缓冲对象
  71.     glBindBuffer(GL_ARRAY_BUFFER,VBOs[1]);
  72.  
  73.     //把相关数据复制到缓冲内存中
  74.     glBufferData(GL_ARRAY_BUFFER,sizeof(secondTriangle),secondTriangle,GL_STATIC_DRAW);
  75.     //第二个参数：数据的大小（字节为单位）
  76.     //第三个参数：数据指针
  77.  
  78.     glVertexAttribPointer(0,3,GL_FLOAT,GL_FALSE,3*sizeof(float),(void *)0);
  79.     glEnableVertexAttribArray(0);
  80.  
  81.  
  82.     glBindBuffer(GL_ARRAY_BUFFER,0);//解除绑定
  83.     glBindVertexArray(0);
  84.  
  85.     unsigned int vertexShader=glCreateShader(GL_VERTEX_SHADER);
  86.     glShaderSource(vertexShader,1,&vertexShaderSource,NULL);
  87.     glCompileShader(vertexShader);
  88.  
  89.     int  success;
  90.     char infoLog[512];
  91.     glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
  92.  
  93.     if(!success)
  94.     {
  95.         glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
  96.         qDebug() << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog;
  97.     }
  98.  
  99.     unsigned int fragmentShader=glCreateShader(GL_FRAGMENT_SHADER);
  100.     glShaderSource(fragmentShader,1,&fragmentShaderSource,NULL);
  101.     glCompileShader(fragmentShader);
  102.  
  103.     unsigned int fragmentShader2=glCreateShader(GL_FRAGMENT_SHADER);
  104.     glShaderSource(fragmentShader2,1,&fragmentShader2Source,NULL);
  105.     glCompileShader(fragmentShader2);
  106.  
  107.     shaderProgram=glCreateProgram();
  108.     glAttachShader(shaderProgram,vertexShader);
  109.     glAttachShader(shaderProgram,fragmentShader);
  110.     glLinkProgram(shaderProgram);
  111.  
  112.     glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);
  113.     if(!success) {
  114.         glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
  115.         qDebug() << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog;
  116.     }
  117.  
  118.     shaderProgram2=glCreateProgram();
  119.     glAttachShader(shaderProgram2,vertexShader);
  120.     glAttachShader(shaderProgram2,fragmentShader2);
  121.     glLinkProgram(shaderProgram2);
  122.  
  123.     glDeleteShader(vertexShader);
  124.     glDeleteShader(fragmentShader);
  125.     glDeleteShader(fragmentShader2);
  126.     glPolygonMode(GL_FRONT_AND_BACK,GL_LINE);//使用线条填充
  127.  
  128.  
  129. }
  130.  
  131. void OpenGLWidget::resizeGL(int w, int h)
  132. {
  133.  
  134. }
  135.  
  136. void OpenGLWidget::paintGL()
  137. {
  138.     glClearColor(0.2f,0.3f,0.3f,1.0f);
  139.     glClear(GL_COLOR_BUFFER_BIT);
  140.  
  141.     glUseProgram(shaderProgram);
  142.     glBindVertexArray(VAOs[0]);
  143.     glDrawArrays(GL_TRIANGLES,0,3);
  144.  
  145.     glUseProgram(shaderProgram2);
  146.     glBindVertexArray(VAOs[1]);
  147.     glDrawArrays(GL_TRIANGLES,0,3);
  148. }

 

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