#include "widget.h"
#include "ui_widget.h"

GLuint VBO, VAO, EBO;

Widget::Widget()
{
    cameraPos = QVector3D(0.0f, 0.0f, 3.0f);
    cameraFront = QVector3D(0.0f, 0.0f, -1.0f);
    cameraUp = QVector3D(0.0f, 1.0f, 0.0f);
    deltaTime = 0.0f;
    lastFrame = 0.0f;

    firstMouse = true;
    yaw = -90.0f;
    pitch = 0.0f;
    lastX = 800.0f / 2.0;
    lastY = 600.0 / 2.0;
    fov = 45.0f;
}

Widget::~Widget()
{
    delete ourShader;
    core->glDeleteVertexArrays(1, &VAO);
    core->glDeleteBuffers(1, &VBO);
    core->glDeleteBuffers(1, &EBO);
    texture1->destroy();
    texture2->destroy();
}

void Widget::initializeGL()
{
    //着色器部分
    core = QOpenGLContext::currentContext()->versionFunctions<QOpenGLFunctions_3_3_Core>();
    if (!core) {
          qWarning() << "Could not obtain required OpenGL context version";
          exit(1);
    }
    ourShader = new Shader(":/shader/vertexshadersource.vert", ":/shader/fragmentshadersource.frag");

    //VAO，VBO数据部分
    float vertices[] = {
        -0.5f, -0.5f, -0.5f,  0.0f, 0.0f,
         0.5f, -0.5f, -0.5f,  1.0f, 0.0f,
         0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
         0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
        -0.5f,  0.5f, -0.5f,  0.0f, 1.0f,
        -0.5f, -0.5f, -0.5f,  0.0f, 0.0f,

        -0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
         0.5f, -0.5f,  0.5f,  1.0f, 0.0f,
         0.5f,  0.5f,  0.5f,  1.0f, 1.0f,
         0.5f,  0.5f,  0.5f,  1.0f, 1.0f,
        -0.5f,  0.5f,  0.5f,  0.0f, 1.0f,
        -0.5f, -0.5f,  0.5f,  0.0f, 0.0f,

        -0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
        -0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
        -0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
        -0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
        -0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
        -0.5f,  0.5f,  0.5f,  1.0f, 0.0f,

         0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
         0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
         0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
         0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
         0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
         0.5f,  0.5f,  0.5f,  1.0f, 0.0f,

        -0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
         0.5f, -0.5f, -0.5f,  1.0f, 1.0f,
         0.5f, -0.5f,  0.5f,  1.0f, 0.0f,
         0.5f, -0.5f,  0.5f,  1.0f, 0.0f,
        -0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
        -0.5f, -0.5f, -0.5f,  0.0f, 1.0f,

        -0.5f,  0.5f, -0.5f,  0.0f, 1.0f,
         0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
         0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
         0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
        -0.5f,  0.5f,  0.5f,  0.0f, 0.0f,
        -0.5f,  0.5f, -0.5f,  0.0f, 1.0f
    };

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


    core->glGenVertexArrays(1, &VAO);
    core->glGenBuffers(1, &VBO);
    core->glGenBuffers(1, &EBO);

    core->glBindVertexArray(VAO);

    core->glBindBuffer(GL_ARRAY_BUFFER, VBO);
    core->glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

//    core->glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
//    core->glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
    //position attribute
    core->glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5*sizeof(GLfloat), nullptr);
    core->glEnableVertexAttribArray(0);
    //texture coord attribute
    core->glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5*sizeof(GLfloat), (void*)(3 * sizeof(float)));
    core->glEnableVertexAttribArray(1);
    //纹理1
    texture1 = new QOpenGLTexture(QImage(":/image/box.jpg").mirrored(), QOpenGLTexture::GenerateMipMaps); //直接生成绑定一个2d纹理, 并生成多级纹理MipMaps
    if(!texture1->isCreated()) {
        qDebug()<<"Failed to load texture" << endl;
    }
    texture1->setWrapMode(QOpenGLTexture::DirectionS, QOpenGLTexture::Repeat);
    texture1->setWrapMode(QOpenGLTexture::DirectionT, QOpenGLTexture::Repeat);

    texture1->setMinificationFilter(QOpenGLTexture::Linear);
    texture1->setMagnificationFilter(QOpenGLTexture::Linear);
    texture1->setFormat(QOpenGLTexture::RGBFormat);

    texture2 = new QOpenGLTexture(QImage(":/image/smile.png").mirrored(), QOpenGLTexture::GenerateMipMaps); //直接生成绑定一个2d纹理, 并生成多级纹理MipMaps
    if(!texture2->isCreated()) {
        qDebug()<<"Failed to load texture" << endl;
    }
    texture2->setWrapMode(QOpenGLTexture::DirectionS, QOpenGLTexture::Repeat);
    texture2->setWrapMode(QOpenGLTexture::DirectionT, QOpenGLTexture::Repeat);

    texture2->setMinificationFilter(QOpenGLTexture::Linear);
    texture2->setMagnificationFilter(QOpenGLTexture::Linear);
    texture2->setFormat(QOpenGLTexture::RGBFormat);
    ourShader->use();
    ourShader->shaderProgram.setUniformValue("texture1", 0);
    ourShader->shaderProgram.setUniformValue("texture2", 1);
    mtime.start();

    core->glEnable(GL_DEPTH_TEST);
}

QVector3D cubePositions[] = {
    QVector3D(0.0f,  0.0f,  0.0f),
    QVector3D( 2.0f,  5.0f, -15.0f),
    QVector3D(-1.5f, -2.2f, -2.5f),
    QVector3D(-3.8f, -2.0f, -12.3f),
    QVector3D( 2.4f, -0.4f, -3.5f),
    QVector3D(-1.7f,  3.0f, -7.5f),
    QVector3D( 1.3f, -2.0f, -2.5f),
    QVector3D( 1.5f,  2.0f, -2.5f),
    QVector3D( 1.5f,  0.2f, -1.5f),
    QVector3D(-1.3f,  1.0f, -1.5f)
};


void Widget::paintGL()
{
    deltaTime = (GLfloat)mtime.elapsed()/100 - lastFrame;
    lastFrame = (GLfloat)mtime.elapsed()/100;

    core->glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
    core->glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    ourShader->use();
    core->glActiveTexture(GL_TEXTURE1);
    texture2->bind();
    core->glActiveTexture(GL_TEXTURE0);
    texture1->bind();    

    QMatrix4x4 view, projection;
    view.translate(QVector3D(0.0f, 0.0f, -3.0f));
    projection.perspective(fov, (GLfloat)width()/(float)height(), 0.1f, 100.0f);
    ourShader->use();
    ourShader->shaderProgram.setUniformValue("view", view);
    ourShader->shaderProgram.setUniformValue("projection", projection);

//    ourShader->use();
    view.lookAt(cameraPos, cameraPos+cameraFront, cameraUp);
    ourShader->shaderProgram.setUniformValue("view", view);
    core->glBindVertexArray(VAO);

    for(unsigned int i=0;i<10;i++) {
        QMatrix4x4 model;
        model.translate(cubePositions[i]);
        if(i%3 == 0) {
            float angle = 20.0f*i + (float)mtime.elapsed()/10;
            model.rotate(angle, QVector3D(0.5f, 1.0f, 0.0f));
        }
        ourShader->shaderProgram.setUniformValue("model", model);
        core->glDrawArrays(GL_TRIANGLES, 0, 36);
    }

    update();
}

void Widget::resizeGL(int w, int h)
{
    core->glViewport(0, 0, w, h);
}

void Widget::keyPressEvent(QKeyEvent *event)
{
    GLfloat cameraSpeed = 2.5 * deltaTime;
    if(event->key() == Qt::Key_W) {
        cameraPos -= cameraFront * cameraSpeed;
    }

    if(event->key() == Qt::Key_S) {
        cameraPos += cameraFront * cameraSpeed;
    }

    if(event->key() == Qt::Key_A) {
        cameraPos -= (QVector3D::crossProduct(cameraFront, cameraUp).normalized()) * cameraSpeed;
    }

    if(event->key() == Qt::Key_D) {
        cameraPos += (QVector3D::crossProduct(cameraFront, cameraUp).normalized()) * cameraSpeed;
    }
    if(event->key() == Qt::Key_E) {
        cameraPos += cameraUp * cameraSpeed;
    }
    if(event->key() == Qt::Key_Q) {
        cameraPos -= cameraUp * cameraSpeed;
    }
}

void Widget::mouseMoveEvent(QMouseEvent *event)
{
    GLfloat xpos = event->pos().x();
    GLfloat ypos = event->pos().y();
    if (firstMouse) {
        lastX = event->pos().x();
        lastY = event->pos().y();
        firstMouse = false;
    }

    GLfloat xoffset = xpos - lastX;
    GLfloat yoffset = lastY - ypos; // reversed since y-coordinates go from bottom to top
    lastX = xpos;
    lastY = ypos;

    GLfloat sensitivity = 0.01f; // change this value to your liking
    xoffset *= sensitivity;
    yoffset *= sensitivity;

    yaw += xoffset;
    pitch += yoffset;

    // make sure that when pitch is out of bounds, screen doesn‘t get flipped
    if (pitch > 89.0f)
        pitch = 89.0f;
    if (pitch < -89.0f)
        pitch = -89.0f;

    QVector3D front(cos(yaw) * cos(pitch), sin(pitch), sin(yaw) * cos(pitch));
    cameraFront = front.normalized();
}

void Widget::wheelEvent(QWheelEvent *event)
{
    QPoint offset = event->angleDelta();
    if(fov >= 1.0f && fov <=45.0f)
        fov -= ((GLfloat)offset.y())/20;
    if(fov < 1.0f)
        fov = 1.0f;
    if(fov > 45.0f)
        fov = 45.0f;
}

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QGLWidget>
#include <QOpenGLShader>
#include <QOpenGLShaderProgram>
#include <QDebug>
#include <QOpenGLFunctions>
#include <QOpenGLFunctions_3_3_Core>
#include <QTime>
#include <QtMath>
#include <QTimer>
#include <QOpenGLTexture>
#include <QKeyEvent>

#include "shader.h"

namespace Ui {
class Widget;
}

class Widget : public QGLWidget
{
    Q_OBJECT

public:
    Widget();
    ~Widget();
public slots:

protected:
    virtual void initializeGL();
    virtual void paintGL();
    virtual void resizeGL(int w, int h);
    virtual void keyPressEvent(QKeyEvent *event);
    virtual void mouseMoveEvent(QMouseEvent *event);
    virtual void wheelEvent(QWheelEvent *event);

private:
    QOpenGLFunctions_3_3_Core *core;
    QOpenGLTexture *texture1, *texture2;
    Shader *ourShader;
    QTimer updateTimer;
    QTime mtime;
    QVector3D cameraPos;
    QVector3D cameraFront;
    QVector3D cameraUp;
    GLfloat deltaTime;
    GLfloat lastFrame;

    GLboolean firstMouse;
    GLfloat yaw;
    GLfloat pitch;
    GLfloat lastX;
    GLfloat lastY;
    GLfloat fov;
};

#endif // WIDGET_H