QT+OpenGL纹理与颜色混合

标签：颜色混合 1.0 QT OpenGL 0.0 void TEXTURE 纹理 GL

一、概述

　　使用OpenGL将纹理与颜色混合输出。ps：此处并无实际的意义只是单纯的为了好玩。

　　步骤：

　　1.定义顶点坐标、颜色、纹理及顶点索引

float vertices[] = {
    //     ---- 位置 ----  -----颜色-----          - 纹理坐标 -
         1.0f,  1.0f, 0.0f,  1.0f, 0.0f, 0.0f,  1.0f, 1.0f,   // 右上
         1.0f, -1.0f, 0.0f,  0.0f, 1.0f, 0.0f, 1.0f, 0.0f,   // 右下
        -1.0f, -1.0f, 0.0f,  0.0f, 0.0f, 1.0f, 0.0f, 0.0f,   // 左下
        -1.0f,  1.0f, 0.0f,   1.0f, 1.0f, 0.0f, 0.0f, 1.0f    // 左上
};

　顶点索引　

unsigned int indices[] = {
   0, 1, 3, // first triangle
   1, 2, 3  // second triangle
};

　　2.创建及绑定VAO、VBO、EBO

//创建VAO、VBO、EBO
glGenVertexArrays(1, &VAO);
glGenBuffers(1, &VBO);
glGenBuffers(1, &EBO);
glBindVertexArray(VAO);

////顶点数据存入缓冲区
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

////EBO
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);

　　3.告知显卡应该如何解析vertices中定义的数据

////告知显卡顶点数据如何解析
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);

////告知显卡颜色坐标如何解析
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(1);

////告知显卡纹理坐标如何解析
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
glEnableVertexAttribArray(2);

　　4.创建纹理、绑定纹理、并将纹理数据发送给GPU

////创建纹理
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
//设置纹理环绕方式
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
//设置纹理过滤方式
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

stbi_set_flip_vertically_on_load(true);
//生成纹理
int width, height, mChannels;
QString path = getTexturePath("similing_face.png");
unsigned char* data = stbi_load(path.toStdString().c_str(), &width, &height, &mChannels, 0);
if (data) {
    qDebug() << "图片加载成功,width=" << width << ",height=" << height;
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
    glGenerateMipmap(GL_TEXTURE_2D);
}
else {
    qDebug() << "图像数据加载失败";
}
stbi_image_free(data);

　　5.定义顶点着色器及片元着色器代码

//顶点着色器
#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aColor;
layout (location = 2) in vec2 aTexCoord;
out vec2 ourTexCoord;
out vec3 ourColor;
void main(void)
{
    gl_Position = vec4(aPos,1.0f);
    ourTexCoord = aTexCoord;
    ourColor = aColor;
}
//片元着色器
#version 330 core
out vec4 FragColor;
in vec2 ourTexCoord;
in vec3 ourColor;
uniform sampler2D ourTexture;
void main()
{
    FragColor = texture(ourTexture,ourTexCoord)*vec4(ourColor,1.0f);
}

　　6.编译着色器代码

GLuint BaseOpenGLWindow::buildAttachShaderAndReturnProgramId(QString vertexResPath, QString fragmentResPath) {
    //编译顶点着色器和片元着色器
    GLuint vertexShader = getShaderId(GL_VERTEX_SHADER, vertexResPath);
    GLuint fragmentShader = getShaderId(GL_FRAGMENT_SHADER, fragmentResPath);
    GLuint programId = glCreateProgram();
    glAttachShader(programId, vertexShader);
    glAttachShader(programId, fragmentShader);
    glLinkProgram(programId);
    getLinkProgramErrorInfo(programId);

    glDeleteShader(vertexShader);
    glDeleteShader(fragmentShader);
    return programId;
}
void BaseOpenGLWindow::getLinkProgramErrorInfo(GLuint programId) {
    int success;
    char infoLog[512];
    glGetProgramiv(programId, GL_LINK_STATUS, &success);
    if (!success) {
        glGetProgramInfoLog(programId, 512, NULL, infoLog);
        qDebug() << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog;
    }
}
GLuint BaseOpenGLWindow::getShaderId(GLenum shaderType, QString resPath) {
    //创建顶点着色器
    unsigned int shaderId = glCreateShader(shaderType);
    QFile vertexShaderFile(resPath);
    if (!vertexShaderFile.open(QIODevice::ReadOnly)) {
        qDebug() << "Cannot open vertex shader file for reading";
    }
    QString verQStr = vertexShaderFile.readAll();
    std::string verStdStr = verQStr.toStdString();
    const char* vertexStr = verStdStr.c_str();
    qDebug() << "vertexStr-------------" << vertexStr;
    vertexShaderFile.flush();
    vertexShaderFile.close();
    glShaderSource(shaderId, 1, &vertexStr, NULL);
    glCompileShader(shaderId);
    getCompileShaderErrorInfo(shaderId);
    return shaderId;
}
void BaseOpenGLWindow::getCompileShaderErrorInfo(GLuint shaderId) {
    int success;
    char infoLog[512];
    glGetShaderiv(shaderId, GL_COMPILE_STATUS, &success);
    if (!success)
    {
        glGetShaderInfoLog(shaderId, 512, NULL, infoLog);
        qDebug() << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog;
    }
}

　　7.绘制

void GLTextureColorWindow::paintGL() {

    glBindVertexArray(VAO);
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, texture);
    glUseProgram(programId);
    //glUniform1i(glGetUniformLocation(programId, "ourTexture"), 0);

    glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
}

二、完整代码示例

　　1.GLTextureColorWindow.h

#pragma once
#include "BaseOpenGLWindow.h"
#ifndef STB_IMAGE_H
#define STB_IMAGE_H
#include "../../stb_image.h"
#endif // STB_IMAGE_H

class GLTextureColorWindow : public BaseOpenGLWindow
{
    Q_OBJECT

public:
    GLTextureColorWindow(QWidget *parent = nullptr);
    ~GLTextureColorWindow();

protected:
    virtual void initializeGL();//初始化OpenGL
    virtual void resizeGL(int w, int h);//ResizeWindow大小
    virtual void paintGL();//绘制OpenGL
private:
    unsigned int VAO, VBO, EBO;
    unsigned int texture, texture1, texture2;
    GLuint programId;
};

　　2.GLTextureColorWindow.cpp

#include "GLTextureColorWindow.h"

GLTextureColorWindow::GLTextureColorWindow(QWidget *parent)
    : BaseOpenGLWindow(parent)
{
    this->setWindowTitle("贴图与颜色混合");
}
void GLTextureColorWindow::initializeGL() {
    this->initializeOpenGLFunctions();
    glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    float vertices[] = {
        //     ---- 位置 ----  -----颜色-----          - 纹理坐标 -
             1.0f,  1.0f, 0.0f,  1.0f, 0.0f, 0.0f,  1.0f, 1.0f,   // 右上
             1.0f, -1.0f, 0.0f,  0.0f, 1.0f, 0.0f, 1.0f, 0.0f,   // 右下
            -1.0f, -1.0f, 0.0f,  0.0f, 0.0f, 1.0f, 0.0f, 0.0f,   // 左下
            -1.0f,  1.0f, 0.0f,   1.0f, 1.0f, 0.0f, 0.0f, 1.0f    // 左上
    };
    unsigned int indices[] = {
       0, 1, 3, // first triangle
       1, 2, 3  // second triangle
    };
    //创建VAO、VBO、EBO
    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);
    glGenBuffers(1, &EBO);
    glBindVertexArray(VAO);

    ////顶点数据存入缓冲区
    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

    ////EBO
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);

    ////告知显卡顶点数据如何解析
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);

    ////告知显卡颜色坐标如何解析
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
    glEnableVertexAttribArray(1);

    ////告知显卡纹理坐标如何解析
    glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
    glEnableVertexAttribArray(2);


    ////创建纹理
    glGenTextures(1, &texture);
    glBindTexture(GL_TEXTURE_2D, texture);
    //设置纹理环绕方式
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    //设置纹理过滤方式
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    stbi_set_flip_vertically_on_load(true);
    //生成纹理
    int width, height, mChannels;
    QString path = getTexturePath("similing_face.png");
    unsigned char* data = stbi_load(path.toStdString().c_str(), &width, &height, &mChannels, 0);
    if (data) {
        qDebug() << "图片加载成功,width=" << width << ",height=" << height;
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
        glGenerateMipmap(GL_TEXTURE_2D);
    }
    else {
        qDebug() << "图像数据加载失败";
    }
    stbi_image_free(data);

    //小程序
    programId = buildAttachShaderAndReturnProgramId(":/QtForOpenCV4Tool/shader/texture_color.vert",
        ":/QtForOpenCV4Tool/shader/texture_color.frag");
}
void GLTextureColorWindow::resizeGL(int w, int h) {
    glViewport(0, 0, w, h);
}
void GLTextureColorWindow::paintGL() {

    glBindVertexArray(VAO);
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, texture);
    glUseProgram(programId);
    //glUniform1i(glGetUniformLocation(programId, "ourTexture"), 0);

    glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
}

GLTextureColorWindow::~GLTextureColorWindow()
{
}

标签：颜色混合,1.0,QT,OpenGL,0.0,void,TEXTURE,纹理,GL
From： https://www.cnblogs.com/tony-yang-flutter/p/18376618

QT+OpenGL纹理与颜色混合

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