先上效果

 

核心代码解析

    

//单张贴图时 只用绑定一次 glBindTexture(GL_TEXTURE_2D, texture0);

激活绑定第一张贴图

    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, texture0);

激活绑定第二张贴图

    glActiveTexture(GL_TEXTURE1);
    glBindTexture(GL_TEXTURE_2D, texture1);

为两张贴图 传输纹理

    glUniform1i(glGetUniformLocation(programId, "texture0"), 0);
    glUniform1i(glGetUniformLocation(programId, "texture1"), 1);

vertexshader.vert

#version 430
uniform mat4 pMatrix;//, vMatrix, mMatrix;

in vec3 vPosition;
in vec4 vColor;
in vec2 vTexCoord0;
in vec2 vTexCoord1;

out vec4 fColor;
out vec2 TexCoord0;
out vec2 TexCoord1;

void main(void)
{
    fColor = vColor;
    gl_Position = pMatrix * vec4(vPosition, 1.0);
    TexCoord0 = vTexCoord0;
    TexCoord1 = vTexCoord1;
}

fragmentshader.frag

#version 430
in vec4 fColor;
in vec2 TexCoord0;
in vec2 TexCoord1;
uniform sampler2D texture0;
uniform sampler2D texture1;
void main(void)
{
    gl_FragColor = texture2D(texture0, TexCoord0) * 0.4 + texture2D(texture1, TexCoord1)* 0.8 +  fColor * 0.1;
}

widget.h

#ifndef WIDGET_H
#define WIDGET_H

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

#include <QImage>

QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class Widget : public QOpenGLWidget, public QOpenGLFunctions
{
    Q_OBJECT

public:
    Widget(QOpenGLWidget *parent = nullptr);
    ~Widget();

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

    unsigned int setImage(const char *filename, const char* textureSample, unsigned int textureNum = GL_TEXTURE0);

    QOpenGLTexture *textures;

    QOpenGLShaderProgram program;
    GLuint programId;
    GLint mLocation;
    GLint vLocation;
    GLint pLocation;
    GLint vertexLocation;
    GLint colorLocation;
    GLint uv0Location;
    GLint uv1Location;
    GLint textureLocation0;
    GLint textureLocation1;

    QVector3D cameraLocation;

    GLuint vertexVbo;
    GLuint indexEbo;
    GLuint colorVbo;
    GLuint uv0;
    GLuint uv1;
    QMatrix4x4 mMatrix;
    QMatrix4x4 vMatrix;
    QMatrix4x4 pMatrix;

    unsigned int texture0;
    unsigned int texture1;





};
#endif // WIDGET_H

widget.cpp

#include "widget.h"

//注意 .pro文件要加入 greaterThan(QT_MAJOR_VERSION, 4): QT += widgets opengl
#include <QGLWidget>

Widget::Widget(QOpenGLWidget *parent)
    : QOpenGLWidget(parent)
{}

Widget::~Widget()
{}

void Widget::initializeGL()
{
    initializeOpenGLFunctions();

    if(!program.addShaderFromSourceFile(QOpenGLShader::Vertex, "E:\\wqs\\OpenglQt\\QtOpenglLesson02\\vertexshader.vert"))
    {
        return;
    }
    if(!program.addShaderFromSourceFile(QOpenGLShader::Fragment, "E:\\wqs\\OpenglQt\\QtOpenglLesson02\\fragmentshader.frag"))
    {
        return;
    }

    bool bl = program.link();
    Q_ASSERT(bl);
    bool bb = program.bind();
    Q_ASSERT(bb);
    programId = program.programId();
    //mLocation = glGetUniformLocation(programId, "mMatrix");
    //vLocation = glGetUniformLocation(programId, "vMatrix");
    pLocation = glGetUniformLocation(programId, "pMatrix");
    vertexLocation = glGetAttribLocation(programId, "vPosition");
    colorLocation = glGetAttribLocation(programId, "vColor");
    uv0Location = glGetAttribLocation(programId, "vTexCoord0");
    uv1Location = glGetAttribLocation(programId, "vTexCoord1");
    textureLocation0 = glGetUniformLocation(programId, "texture0");
    textureLocation1 = glGetUniformLocation(programId, "texture1");

    //Q_ASSERT(mLocation != -1);
   // Q_ASSERT(vLocation != -1);
    Q_ASSERT(pLocation != -1);
    Q_ASSERT(vertexLocation != -1);
    Q_ASSERT(colorLocation != -1);
    Q_ASSERT(uv0Location != -1);
    Q_ASSERT(textureLocation0 != -1);



    //三角形顶点坐标
    GLfloat vertex[] = {
        -0.8f, -0.5f, 1.0f,
        0.8f, -0.5f, 1.0f,
        0.8f, 0.5f, 1.0f,
        -0.8f, 0.5f, 1.0f
    };

    //三角形顶点索引
    GLuint triIndexs[] = {0, 1, 2, 0, 2, 3};

    //三角形顶点颜色
    GLfloat colors[] = {0.0f, 0.0f, 0.0f, 1.0f,
                        0.0f, 0.0f, 0.0f, 1.0f,
                        0.5f, 0.5f, 0.0f, 1.0f,
                        1.0f, 1.0f, 1.0f, 1.0f,
                       };

    float _uv0Float[] = {
        0.0f, 0.0f,  // lower-left corner
        2.0f, 0.0f,  // lower-right corner
        2.0f, 2.0f,   // top-rigth corner
        0.0f, 2.0f   // top-rigth corner
    };

    float _uv1Float[] = {
        0.0f, 0.0f,  // lower-left corner
        1.0f, 0.0f,  // lower-right corner
        1.0f, 1.0f,   // top-rigth corner
        0.0f, 1.0f   // top-rigth corner
    };



    // 初始化索引buffer并装载数据到显存
    glGenBuffers(1, &indexEbo);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexEbo);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, 6 * sizeof(GLuint), triIndexs, GL_STATIC_DRAW);

    //glBufferData glVertexAttribPointer 两个语句联合使用，不要分开为好

    // 初始化颜色buffer并装载数据到显存
    glGenBuffers(1, &colorVbo);
    glBindBuffer(GL_ARRAY_BUFFER, colorVbo);
    glBufferData(GL_ARRAY_BUFFER, 16 * sizeof(GLfloat), colors, GL_STATIC_DRAW);
    // 将数据传输给shader
    glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, 4*(sizeof(float)), 0);



    glGenBuffers(1, &vertexVbo);
    glBindBuffer(GL_ARRAY_BUFFER, vertexVbo);
    glBufferData(GL_ARRAY_BUFFER, 12 * sizeof (GLfloat), vertex, GL_STATIC_DRAW);
    // 将数据传输给shader
    glVertexAttribPointer(vertexLocation, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), 0);


    glGenBuffers(1, &uv0);
    glBindBuffer(GL_ARRAY_BUFFER, uv0);
    //装载数据到显存
    glBufferData(GL_ARRAY_BUFFER, 8 * sizeof (GLfloat), _uv0Float, GL_STATIC_DRAW);
    // 将数据传输给shader
    glVertexAttribPointer(uv0Location, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), (void*)(0));

    glGenBuffers(1, &uv1);
    glBindBuffer(GL_ARRAY_BUFFER, uv1);
    //装载数据到显存
    glBufferData(GL_ARRAY_BUFFER, 8 * sizeof (GLfloat), _uv1Float, GL_STATIC_DRAW);
    // 将数据传输给shader
    glVertexAttribPointer(uv1Location, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), (void*)(0));

    //为shader 中的纹理传输数据做绑定。
    glUniform1i(glGetUniformLocation(programId, "texture0"), 0);
    glUniform1i(glGetUniformLocation(programId, "texture1"), 1);

    texture0 = setImage("E:\\wqs\\OpenglQt\\QtOpenglLesson02\\n.jpg");
    texture1 = setImage("E:\\wqs\\OpenglQt\\QtOpenglLesson02\\1.jpg");

}

unsigned int Widget:: setImage(const char *filename)
{
    QImage image = QImage(filename);
    image = QGLWidget::convertToGLFormat(image); //格式转换

    unsigned int texture;
    glGenTextures(1, &texture);    
    //glActiveTexture(textureNum);
    glBindTexture(GL_TEXTURE_2D, texture);

    // set the texture wrapping/filtering options (on the currently bound texture object)
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    // load and generate the texture
    int width, height, nrChannels;
    width = image.width();
    height = image.height();
    nrChannels = image.depth();
    //unsigned char *data = stbi_load("container.jpg", &width, &height, &nrChannels, 0);
    if (image.bits())
    {
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, image.bits());
        glGenerateMipmap(GL_TEXTURE_2D);
    }
    else
    {
        //std::cout << "Failed to load texture" << std::endl;
        Q_ASSERT(0);
    }

    return texture;

}

void Widget::paintGL()
{

    //清除之前图形并将背景设置为黑色（设置为黑色纯粹个人爱好！）
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glClearColor(0.0f, 0.2f, 0.2f, 1.0f);

    //unsigned int texture = setImage("E:\\wqs\\OpenglQt\\QtOpenglLesson02\\n.jpg");
    // shader传入模型视图矩阵 projection可以理解为建立了一个坐标系空间，可以再这个空间内设置图形
    glUniformMatrix4fv(pLocation, 1, GL_FALSE, pMatrix.data());

    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER,indexEbo);

    //启用颜色数组buffer
    glEnableVertexAttribArray(colorLocation);
    glEnableVertexAttribArray(vertexLocation);
    glEnableVertexAttribArray(uv0Location);
    glEnableVertexAttribArray(uv1Location);


    //单张贴图时 只用绑定一次 glBindTexture(GL_TEXTURE_2D, texture0);



    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, texture0);
    glActiveTexture(GL_TEXTURE1);
    glBindTexture(GL_TEXTURE_2D, texture1);


    glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, (void*)0);

    // 解绑buffer、关闭启用顶点、颜色数组
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glDisableVertexAttribArray(vertexLocation);
    glDisableVertexAttribArray(colorLocation);

}

void Widget::resizeGL(int w, int h)
{
    glViewport(0, 0, w, h);
    pMatrix.setToIdentity();
    float aspect = float(w)/ float(h?h:1);
    pMatrix.perspective(60.0f, aspect, 1.0f, 100.f);
    //vMatrix.lookAt()
    QVector3D cameraLocation;
    cameraLocation.setX(0);
    cameraLocation.setY(0);
    cameraLocation.setZ(20);
    vMatrix.lookAt(cameraLocation, QVector3D{0.0,0.0,0.0},QVector3D{0.0,1.0,0.0});
    mMatrix.setToIdentity();
    //mMatrix.translate(0, 0.0, 20.0f);
    pMatrix.translate(0, 0.0, -2.0f);


}