为什么改变模型矩阵会改变 OpenGL 中错误对象的大小？

Question

缩放 model2 矩阵后。 model2 矩阵是网格矩阵

之前

我想增加网格而不是立方体的大小。为什么会这样？为什么缩放立方体的 y 为 0？错误在哪里？下面是我的所有代码。

查看draw_canvas.cpp paintGL 函数，有一个名为'model2' 的缩放矩阵。这一行 model2.scale(10.0f,0.0f,10.0f)。为什么这种缩放会改变我的立方体？

 QMatrix4x4 model2(1.0f, 0.0f, 0.0f, 0.0f,
                     0.0f, 1.0f, 0.0f, 0.0f,
                     0.0f, 0.0f, 1.0f, 0.0f,
                     0.0f, 0.0f, 0.0f, 1.0f);
    unsigned int modelID2 = gridShaderProgram->uniformLocation("model");
    
    model2.translate(QVector3D(0.0f, 0.0f, 0.0f)); 
    model2.scale(10.0f, 0.0f, 10.0f);

draw_canwas3D.h


#pragma once
#include <QOpenGLWidget>
#include <QOpenGLVertexArrayObject>
#include <QOpenGLBuffer>
#include <QOpenGLShaderProgram>
#include <QOpenGLShader>
#include <list>


class Canvas3D : public QOpenGLWidget
{
public:
    Canvas3D(QWidget *parent = nullptr) : QOpenGLWidget(parent) { };
    ~Canvas3D();
private:
    QOpenGLVertexArrayObject m_vao;
    QOpenGLBuffer m_vbo;
    QOpenGLShaderProgram* m_program;
    QOpenGLShaderProgram* gridShaderProgram;
    QOpenGLShaderProgram* shLightprogram;
        
    QVector3D cameraPos {0.0f, 0.0f, 3.0f};
    QVector3D cameraFront{0.0f, 0.0f, -1.0f};
    QVector3D cameraUp{0.0f, 1.0f, 0.0f};
    float yaw = -90.0f;
    float pitch = 0.0f;
    float lastX = 400, lastY = 300;
    float Zoom = 45.0;
    unsigned int gridVAO;
    unsigned int gridEBO;
    GLuint lenght = 0;
    //std::list<Object*>
protected:
    void initializeGL() override;

    void resizeGL(int w, int h) override;

    void paintGL() override;

    void keyPressEvent(QKeyEvent *ev) override;
    
    bool eventFilter(QObject *obj, QEvent *event);

};

draw_canvas3D.cpp

#include "draw_canvas3D.h"
#include "src/common/geometry/shapes3D/cube.h"
#include <iostream>
#include <QOpenGLContext>
#include <QOpenGLFunctions>
#include <QOpenGLExtraFunctions>
#include <QMatrix4x4>
#include <QVector3D>
#include <QtMath>
#include <QKeyEvent>


void Canvas3D::initializeGL()
{
    connect(this, SIGNAL(frameSwapped()), this, SLOT(update()));
    auto functions = this->context()->functions();
    functions->glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
    this->setGeometry(100, 100, 800, 600);
    functions->glViewport(this->geometry().x(),
                  this->geometry().y(),
                  this->geometry().width(),
                  this->geometry().height());

    m_program = new QOpenGLShaderProgram(this);
    QOpenGLShader vxShader(QOpenGLShader::Vertex);
    vxShader.compileSourceFile("/main/stage/home/andreyp/fork_invar/invar/shaders/shader.vs");
    QOpenGLShader frShader(QOpenGLShader::Fragment);
    frShader.compileSourceFile("/main/stage/home/andreyp/fork_invar/invar/shaders/shader.fs");
    m_program->addShader(&vxShader);
    m_program->addShader(&frShader);
    m_program->link();
    functions->glEnable(GL_DEPTH_TEST);
    this->installEventFilter(this);
    
    functions->glEnable(GL_POLYGON_SMOOTH);
    functions->glHint(GL_LINE_SMOOTH_HINT, GL_NICEST);
    functions->glHint(GL_POLYGON_SMOOTH_HINT, GL_NICEST);
    
    /*GRID*/ //Create Class
   auto additionalFunctions = this->context()->extraFunctions(); 
   unsigned int gridVBO;

   std::vector<QVector3D> vertices;
  std::vector<unsigned int> indices;
  int slices = 10;
  for(int j=0; j<=slices; ++j) {
    for(int i=0; i<=slices; ++i) {
      float x = (float)i/(float)slices;
      float y = 0;
      float z = (float)j/(float)slices;
      vertices.push_back(QVector3D(x, y, z));
    }
  }

  for(int j=0; j<slices; ++j) {
    for(int i=0; i<slices; ++i) {

      int row1 =  j * (slices+1);
      int row2 = (j+1) * (slices+1);

      indices.push_back(row1+i); indices.push_back(row1+i+1); indices.push_back(row1+i+1); indices.push_back(row2+i+1);
      indices.push_back(row2+i+1); indices.push_back(row2+i); indices.push_back(row2+i); indices.push_back(row1+i);

    }
  }
  lenght = (GLuint)indices.size()*4;
   /*std::vector<QVector3D> vecLines;
   std::vector<unsigned int> vecLinesIdx;*/
   /*for(unsigned int nHorizontalLines = 0; nHorizontalLines < 10; ++nHorizontalLines)
   {
       vecLines.push_back(QVector3D(0.0f, 0.0, -(float)nHorizontalLines));
       vecLines.push_back(QVector3D(9.0f, 0.0, -(float)nHorizontalLines));
   }
   
  
   for(unsigned int nVerticalLines = 0; nVerticalLines < 10; ++nVerticalLines)
   {
       vecLines.push_back(QVector3D((float)nVerticalLines, 0.0f, 0.0f));
       vecLines.push_back(QVector3D((float)nVerticalLines, 0.0f, -9.0f));
   }
   for(unsigned int j = 0; j < 39; j+=2)
   {
       vecLinesIdx.push_back(j);
       vecLinesIdx.push_back(j+1);
   }*/
   

   functions->glGenBuffers(1, &gridEBO);
   functions->glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, gridEBO);
   functions->glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size()*sizeof(unsigned int), indices.data(), GL_STATIC_DRAW);
  
   functions->glGenBuffers(1, &gridVBO);
   additionalFunctions->glGenVertexArrays(1, &gridVAO);
   additionalFunctions->glBindVertexArray(gridVAO);
   functions->glBindBuffer(GL_ARRAY_BUFFER, gridVBO);
   functions->glBufferData(GL_ARRAY_BUFFER, vertices.size()*sizeof(QVector3D), vertices.data(), GL_STATIC_DRAW);
   
   functions->glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3*sizeof(float), nullptr);
   functions->glEnableVertexAttribArray(0);
   gridShaderProgram = new QOpenGLShaderProgram(this);
   QOpenGLShader vxShader2(QOpenGLShader::Vertex);
   vxShader2.compileSourceFile("/main/stage/home/andreyp/fork_invar/invar/shaders/shaderGrid.vs");
   QOpenGLShader frShader2(QOpenGLShader::Fragment);
   frShader2.compileSourceFile("/main/stage/home/andreyp/fork_invar/invar/shaders/shaderGrid.fs");
   gridShaderProgram->addShader(&vxShader2);
   gridShaderProgram->addShader(&frShader2);
   gridShaderProgram->link();
    /*GRID END*/
   
   
}


void Canvas3D::resizeGL(int w, int h)
{
    auto functions = this->context()->functions();
    functions->glViewport(0,
                  0,
                  this->geometry().width(),
                  this->geometry().height());
    
}

void Canvas3D::paintGL()
{
    auto functions = this->context()->functions();
    //auto additionalFunctions = this->context()->extraFunctions();
    functions->glClearColor(0.0f / 255.0f, 25.0f / 255.0f, 53.0f / 255.0f, 1.0f);
    functions->glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    
    QMatrix4x4 projection;
    projection.perspective(Zoom, 800.0f / 600.0f, 0.1f, 100.0f);

    QMatrix4x4 view; 
    view.lookAt(cameraPos,
                cameraPos + cameraFront,
                cameraUp);
   
    unsigned int viewID = m_program->uniformLocation("view");
    functions->glUniformMatrix4fv(viewID, 1, GL_FALSE, view.constData());
    
    unsigned int projectionID = m_program->uniformLocation("projection");
    functions->glUniformMatrix4fv(projectionID, 1, GL_FALSE, projection.constData());
    
    QVector3D cubePositions[] = {
        QVector3D(0.0f, 0.0, 0.0),
        QVector3D( 0.5f, 0.0f, 0.5f),
        QVector3D( 2.0f, 0.0f, 3.0f),
        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)
    };
    

    for(unsigned int i = 0; i < 2; i++)
    {
       
        QMatrix4x4 model(1.0f, 0.0f, 0.0f, 0.0f,
                         0.0f, 1.0f, 0.0f, 0.0f,
                         0.0f, 0.0f, 1.0f, 0.0f,
                         0.0f, 0.0f, 0.0f, 1.0f);
        unsigned int modelID = m_program->uniformLocation("model");
        
        model.translate(cubePositions[i]);
        functions->glUniformMatrix4fv(modelID, 1, GL_FALSE, model.constData());
        
        auto cube3d = new invar::geometry3D::Cube(cubePositions[i], 1*qSqrt(3), m_program);
  

        cube3d->Draw();
    }
    auto additionalFunctions = this->context()->extraFunctions();
    additionalFunctions->glBindVertexArray(0);
    /*GRID*/
    unsigned int viewID2 = gridShaderProgram->uniformLocation("view");
    functions->glUniformMatrix4fv(viewID2, 1, GL_FALSE, view.constData());
    
    unsigned int projectionID2 = gridShaderProgram->uniformLocation("projection");
    functions->glUniformMatrix4fv(projectionID2, 1, GL_FALSE, projection.constData());
    
    QMatrix4x4 model2(1.0f, 0.0f, 0.0f, 0.0f,
                     0.0f, 1.0f, 0.0f, 0.0f,
                     0.0f, 0.0f, 1.0f, 0.0f,
                     0.0f, 0.0f, 0.0f, 1.0f);
    unsigned int modelID2 = gridShaderProgram->uniformLocation("model");
    //model2.scale(10.0f, 0.0f, 10.0f); ------ THIS SCALING
    model2.translate(QVector3D(0.0f, 0.0f, 0.0f)); 
    
    functions->glUniformMatrix4fv(modelID2, 1, GL_FALSE, model2.constData());
    gridShaderProgram->bind();
    
    additionalFunctions->glBindVertexArray(gridVAO);
    functions->glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, gridEBO);
    functions->glDrawElements(GL_LINES, lenght, GL_UNSIGNED_INT, 0);

    /*GRID END*/
}

void Canvas3D::keyPressEvent(QKeyEvent *ev)
{
    const float cameraSpeed = 0.25f;
    if(ev->key() == Qt::Key_W)
        cameraPos += cameraSpeed * cameraFront;
    else if(ev->key() == Qt::Key_S)
        cameraPos -= cameraSpeed * cameraFront;
    else if(ev->key() == Qt::Key_A)
        cameraPos -= QVector3D(QVector3D::crossProduct(cameraFront, cameraUp)) * cameraSpeed;
    else if(ev->key() == Qt::Key_D)
        cameraPos += QVector3D(QVector3D::crossProduct(cameraFront, cameraUp)) * cameraSpeed;
    else if(ev->key() == Qt::Key_Q)
    {
        /*Rotate camera*/
    }
    else if(ev->key() == Qt::Key_E)
    {
        /*Rotate camera*/
    }

}   

bool Canvas3D::eventFilter(QObject *obj, QEvent *event)
{
    
  if (event->type() == QEvent::MouseButtonPress)
  {
    QMouseEvent *mouseEvent = static_cast<QMouseEvent*>(event);
    lastX = mouseEvent->pos().x();
    lastY = mouseEvent->pos().y();
  }
  if (event->type() == QEvent::MouseMove)
  {
    QMouseEvent *mouseEvent = static_cast<QMouseEvent*>(event); 
    float xoffset = mouseEvent->pos().x() - lastX;
    float yoffset = lastY - mouseEvent->pos().y();
    lastX = mouseEvent->pos().x();
    lastY = mouseEvent->pos().y();
    float sensitivity = 0.1f;
    xoffset *= sensitivity;
    yoffset *= sensitivity;
    yaw += xoffset;
    pitch += yoffset;
    if(pitch > 89.0f)
        pitch = 89.0f;
    if(pitch < -89.0f)
        pitch = -89.0f;
    QVector3D direction;
    direction.setX(qCos(qDegreesToRadians(yaw)) * qCos(qDegreesToRadians(pitch)));
    direction.setY(qSin(qDegreesToRadians(pitch)));
    direction.setZ(qSin(qDegreesToRadians(yaw)) * qCos(qDegreesToRadians(pitch)));
    cameraFront = direction.normalized();
  }
  else if (event->type() == QEvent::Wheel)
  {
    QWheelEvent *wheelEvent = static_cast<QWheelEvent*>(event);
    QPoint numDegrees = wheelEvent->angleDelta();
    if (numDegrees.y() < 0 && Zoom < 45.0f)
        Zoom += 1.0f;
    if (numDegrees.y() > 0 && Zoom > 1.0f)  
        Zoom -= 1.0f;
  }
  return false;
}

Canvas3D::~Canvas3D()
{
    //delete f;
}

cube.cpp


#include "src/common/geometry/shapes3D/cube.h"
#include <QOpenGLExtraFunctions>
#include <QOpenGLWidget>
#include <QOpenGLContext>
#include <QtMath>
#include <iostream>

namespace invar::geometry3D
{
void Cube::Draw()
{
    auto context = QOpenGLContext::currentContext();
    auto functions = context->functions();
    auto additionalFunctions = context->extraFunctions();
    m_program->bind();
    additionalFunctions->glBindVertexArray(VAO);
    functions->glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
    int size;    
    functions->glGetBufferParameteriv(GL_ELEMENT_ARRAY_BUFFER, GL_BUFFER_SIZE, &size);
    functions->glDrawElements(GL_TRIANGLES, size/sizeof(float), GL_UNSIGNED_INT, 0);
    
}

void Cube::setupShape()
{
    auto context = QOpenGLContext::currentContext();
    auto functions = context->functions();
    auto additionalFunctions = context->extraFunctions();
    
    float vertices[] = {
 
        -0.5f,0.5f,-0.5f,   0.0f, 0.0f, 0.0f,//Point A 0
        -0.5f,0.5f,0.5f,    0.0f, 0.0f, 1.0f,//Point B 1
        0.5f,0.5f,-0.5f,    0.0f, 1.0f, 0.0f,//Point C 2
        0.5f,0.5f,0.5f,     0.0f, 1.0f, 1.0f,//Point D 3
         
        -0.5f,-0.5f,-0.5f,  1.0f, 0.0f, 0.0f,//Point E 4
        -0.5f,-0.5f,0.5f,   1.0f, 0.0f, 1.0f,//Point F 5
        0.5f,-0.5f,-0.5f,   1.0f, 1.0f, 0.0f,//Point G 6
        0.5f,-0.5f,0.5f,    1.0f, 1.0f, 1.0f//Point H 7
 
    };
    
    unsigned int indices[] = {
        0,1,2,
        1,2,3,
 
        4,5,6,
        5,6,7,
        
        0,1,5,
        0,4,5,
        
        2,3,7,
        2,6,7,
    
        0,2,6,
        0,4,6,
       
        1,5,7,
        1,3,7
    };
   functions->glGenBuffers(1, &EBO);
   functions->glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
   functions->glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
   
   unsigned int VBO;
   functions->glGenBuffers(1, &VBO);
   additionalFunctions->glGenVertexArrays(1, &VAO);
   additionalFunctions->glBindVertexArray(VAO);
   functions->glBindBuffer(GL_ARRAY_BUFFER, VBO);
   functions->glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
   
   functions->glEnableVertexAttribArray(0);/*Check if need to normilize*/
   functions->glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float),(void*)0);
   
   functions->glEnableVertexAttribArray(1);
   functions->glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float),
                                       (void*)(3*sizeof(float)));
   
   additionalFunctions->glBindVertexArray(0);
   
}

Cube::Cube(QVector3D pos, float diagonal, QOpenGLShaderProgram* m_program):
           pos(pos), diagonal(diagonal), m_program(m_program)
{
    this->setupShape();
}

}

cube.h

#pragma once
#include "shape3D.h"
#include <QOpenGLContext>
#include <QVector3D>
#include <QOpenGLShaderProgram>

namespace invar::geometry3D
{
class Cube
{

public:
    Cube(QVector3D pos, float diagonal, QOpenGLShaderProgram* program);
    void Draw();
private:
    unsigned int VAO;
    unsigned int EBO;
    QVector3D pos;
    float diagonal;
    QOpenGLShaderProgram* m_program;
    void setupShape();
};
}

着色器很简单

shaderGrid.fs


#version 130
out vec4 FragColor;

void main()
{
FragColor = vec4(0, 1.0, 1.0, 1.0);
}

shaderGrid.vs

#version 130

in vec3 aPos;
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;

void main()
{
    gl_Position = projection * view * model * vec4(aPos, 1.0);
}

shader.fs //--- 立方体片段着色器

#version 130
out vec4 FragColor;
in vec3 ourColor;
void main()
{
FragColor = vec4(ourColor, 1.0);
}

shader.vs //--- 立方体顶点着色器


#version 130

in vec3 aPos;
in vec3 aColor;
out vec3 ourColor;
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;

void main()
{
gl_Position = projection * view * model * vec4(aPos, 1.0);
ourColor = aColor;
}

Answer 1

glUniform* 更改当前安装的着色器程序的制服。因此，在设置制服之前必须安装（bind）程序：

gridShaderProgram->bind();    // <--- INSERT

unsigned int viewID2 = gridShaderProgram->uniformLocation("view");
functions->glUniformMatrix4fv(viewID2, 1, GL_FALSE, view.constData());

unsigned int projectionID2 = gridShaderProgram->uniformLocation("projection");
functions->glUniformMatrix4fv(projectionID2, 1, GL_FALSE, projection.constData());

QMatrix4x4 model2(1.0f, 0.0f, 0.0f, 0.0f,
                    0.0f, 1.0f, 0.0f, 0.0f,
                    0.0f, 0.0f, 1.0f, 0.0f,
                    0.0f, 0.0f, 0.0f, 1.0f);
unsigned int modelID2 = gridShaderProgram->uniformLocation("model");
//model2.scale(10.0f, 0.0f, 10.0f); ------ THIS SCALING
model2.translate(QVector3D(0.0f, 0.0f, 0.0f)); 

functions->glUniformMatrix4fv(modelID2, 1, GL_FALSE, model2.constData());

// gridShaderProgram->bind();     <--- DELETE

为什么改变模型矩阵会改变 OpenGL 中错误对象的大小？

Why changing model matrix change size of wrong object in OpenGL?

c++

qt

matrix

opengl