[游戏开发]Qt opengl 显示单张贴图 Textrue

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

2 。如果是通过索引 绘图 一定不要忘了这句?。

glBindBuffer(GL_ELEMENT_ARRAY_BUFFER,indexEbo);

3 如果有 只有一张贴图的话 加上这句?

glBindTexture(GL_TEXTURE_2D, texture);

#include "widget.h"
#include "ui_widget.h"
#include <QGLWidget>

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

Widget::~Widget()
{}

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

    if(!program.addShaderFromSourceFile(QOpenGLShader::Vertex, "E:\\wqs\\OpenglQt\\QtOpengLesson01\\vertexshader.vert"))
    {
        return;
    }
    if(!program.addShaderFromSourceFile(QOpenGLShader::Fragment, "E:\\wqs\\OpenglQt\\QtOpengLesson01\\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");
    textureLocation = glGetAttribLocation(programId, "vTexCoord");
    ourTextureLocation = glGetUniformLocation(programId, "ourTexture");

    //Q_ASSERT(mLocation != -1);
   // Q_ASSERT(vLocation != -1);
    Q_ASSERT(pLocation != -1);
    Q_ASSERT(vertexLocation != -1);
    Q_ASSERT(colorLocation != -1);
    Q_ASSERT(textureLocation != -1);
    Q_ASSERT(ourTextureLocation != -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 texCoords[] = {
        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, &uv);
    glBindBuffer(GL_ARRAY_BUFFER, uv);
    //装载数据到显存
    glBufferData(GL_ARRAY_BUFFER, 8 * sizeof (GLfloat), texCoords, GL_STATIC_DRAW);
    // 将数据传输给shader
    glVertexAttribPointer(textureLocation, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), (void*)(0));

    setImage("E:\\wqs\\OpenglQt\\QtOpengLesson01\\n.jpg");
}

void Widget:: setImage(const char *filename)
{
    //textures = new QOpenGLTexture(QImage(filename).mirrored());
    QImage image = QImage(filename);
    image = QGLWidget::convertToGLFormat(image); //格式转换

    glGenTextures(1, &texture);
    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);
    }

}

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);


    // 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(textureLocation);

    glBindTexture(GL_TEXTURE_2D, texture);

    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);


}

vertexshader.vert

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


in vec3 vPosition;
in vec4 vColor;
in vec2 vTexCoord;

out vec4 fColor;
out vec2 TexCoord;

void main(void)
{
    fColor = vColor;
    gl_Position = pMatrix * vec4(vPosition, 1.0);
    TexCoord = vTexCoord;
}

fragmentshader.frag

#version 430
in vec4 fColor;
in vec2 TexCoord;
uniform sampler2D ourTexture;
//out vec4 gl_FragColor;

//gl_FragColor = fColor;
void main(void)
{
    //gl_FragColor = texture(ourTexture, TexCoord);
    gl_FragColor = texture2D(ourTexture, TexCoord) + fColor * 0.5;
}