qt opengl 3d基本形状--圆环

 画圆环体的方法为，用一个小圆绕y轴一定半径转一周，这样就能形成一个圆环，其生成顶点的公式如下

       其纹理坐标可以使用上一节圆柱的方法，将圆环体剪开，再水平剪开，就能还原为一个矩形。所以纹理坐标计算方式为，当大圆周每转过一定角度时，用这个角度除以360就能得到纹理x坐标，将小圆周角度除以360就能得到纹理y坐标。

我实现的圆环体效果如下

 

 其渲染器实现如下

 

#ifndef TORUSRENDER_H
#define TORUSRENDER_H

#include 
#include 
#include 
#include 
#define PI 3.14159265f
class TorusRender
{
public:
    TorusRender() = default;
    void initsize(float rBig,float rSmall,int nCol,int nRow,QImage &img);
    void initsize(float rBig,float rSmall,int nCol,int nRow);
    void render(QOpenGLExtraFunctions *f,QMatrix4x4 &pMatrix,QMatrix4x4 &vMatrix,QMatrix4x4 &mMatrix);

private:
    QOpenGLShaderProgram program_;
    QOpenGLBuffer vbo_;
    QVector vertPoints_,textPoints_;
    QOpenGLTexture *texture_{nullptr};
    bool userTexture_ = false;
};

#endif // TORUSRENDER_H

#include 
#include "torusrender.h"

void TorusRender::initsize(float rBig, float rSmall, int nCol, int nRow, QImage &img)
{
    userTexture_ = true;
    program_.addCacheableShaderFromSourceFile(QOpenGLShader::Vertex,"vsrc.vert");
    program_.addCacheableShaderFromSourceFile(QOpenGLShader::Fragment,"fsrc.frag");
    program_.link();

    float angdegColSpan = 360.0/nCol;
    float angdegRowSpan = 360.0/nRow;
    float A = (rBig - rSmall)/2;
    float D = rSmall + A;
    QVector originVertPoints,originTextPoints;
    for(float angdegCol=0;::ceil(angdegCol)<360+angdegColSpan;angdegCol+=angdegColSpan)	{//对小圆按照等角度间距循环
        double a=angdegCol * PI / 180;//当前小圆弧度
        float t=angdegCol/360;//当前角度对应的t坐标
        for(float angdegRow=0;::ceil(angdegRow)<360+angdegRowSpan;angdegRow+=angdegRowSpan)
        {//对大圆按照等角度间距循环
            double u=angdegRow * PI / 180;//当前大圆弧度
            float y=(float) (A*::cos(a));//按照公式计算当前顶点
            float x=(float) ((D+A*::sin(a))*::sin(u));	//的X、Y、Z坐标
            float z=(float) ((D+A*::sin(a))*::cos(u));
            //将计算出来的X、Y、Z坐标放入原始顶点列表
            originVertPoints << x << y << z;

            float s=angdegRow/360;//当前角度对应的s坐标
            originTextPoints << s << t;
        }
    }

    for(int i=0;i vboVec;
    vboVec << vertPoints_ << textPoints_;
    vbo_.create();
    vbo_.bind();
    vbo_.allocate(vboVec.data(),vboVec.count() * sizeof(GLfloat));

    texture_ = new QOpenGLTexture(img);
    texture_->setWrapMode(QOpenGLTexture::ClampToEdge);
    texture_->setMinMagFilters(QOpenGLTexture::NearestMipMapNearest,QOpenGLTexture::LinearMipMapNearest);
}

void TorusRender::initsize(float rBig, float rSmall, int nCol, int nRow)
{
    userTexture_ = false;
    program_.addCacheableShaderFromSourceFile(QOpenGLShader::Vertex,"lvsrc.vert");
    program_.addCacheableShaderFromSourceFile(QOpenGLShader::Fragment,"lfsrc.frag");
    program_.link();

    float angdegColSpan = 360.0/nCol;
    float angdegRowSpan = 360.0/nRow;
    float A = (rBig - rSmall)/2;
    float D = rSmall + A;
    QVector originVertPoints,originColorPoints;
    for(float angdegCol=0;::ceil(angdegCol)<360+angdegColSpan;angdegCol+=angdegColSpan)	{//对小圆按照等角度间距循环
        double a=angdegCol * PI / 180;//当前小圆弧度
        for(float angdegRow=0;::ceil(angdegRow)<360+angdegRowSpan;angdegRow+=angdegRowSpan)
        {//对大圆按照等角度间距循环
            double u=angdegRow * PI / 180;//当前大圆弧度
            float y=(float) (A*::cos(a));//按照公式计算当前顶点
            float x=(float) ((D+A*::sin(a))*::sin(u));	//的X、Y、Z坐标
            float z=(float) ((D+A*::sin(a))*::cos(u));
            //将计算出来的X、Y、Z坐标放入原始顶点列表
            originVertPoints << x << y << z;
            originColorPoints << 1.0 << 1.0 << 1.0 << 1.0;
        }
    }

    for(int i=0;i vboVec;
    vboVec << vertPoints_ << textPoints_;
    vbo_.create();
    vbo_.bind();
    vbo_.allocate(vboVec.data(),vboVec.count() * sizeof(GLfloat));
}

void TorusRender::render(QOpenGLExtraFunctions *f, QMatrix4x4 &pMatrix, QMatrix4x4 &vMatrix, QMatrix4x4 &mMatrix)
{
    f->glEnable(GL_DEPTH_TEST);
    f->glEnable(GL_CULL_FACE);
    program_.bind();
    vbo_.bind();
    if(userTexture_){
        f->glActiveTexture(GL_TEXTURE0);
        program_.setUniformValue("uPMatrix",pMatrix);
        program_.setUniformValue("uVMatrix",vMatrix);
        program_.setUniformValue("uMMatrix",mMatrix);
        program_.setUniformValue("sTexture",0);

        program_.enableAttributeArray(0);
        program_.enableAttributeArray(1);
        program_.setAttributeBuffer(0,GL_FLOAT,0,3,3*sizeof(GLfloat));
        program_.setAttributeBuffer(1,GL_FLOAT,vertPoints_.count() * sizeof(GLfloat),2,2*sizeof(GLfloat));
        texture_->bind();
        f->glDrawArrays(GL_TRIANGLES,0,vertPoints_.count() / 3);
        program_.disableAttributeArray(0);
        program_.disableAttributeArray(1);

        texture_->release();
    }else{
        program_.setUniformValue("uPMatrix",pMatrix);
        program_.setUniformValue("uVMatrix",vMatrix);
        program_.setUniformValue("uMMatrix",mMatrix);

        program_.enableAttributeArray(0);
        program_.enableAttributeArray(1);
        program_.setAttributeBuffer(0,GL_FLOAT,0,3,3*sizeof(GLfloat));
        program_.setAttributeBuffer(1,GL_FLOAT,vertPoints_.count() * sizeof(GLfloat),4,4*sizeof(GLfloat));
        f->glDrawArrays(GL_LINE_STRIP,0,vertPoints_.count() / 3);
        program_.disableAttributeArray(0);
        program_.disableAttributeArray(1);
    }
    vbo_.release();
    program_.release();
    f->glDisable(GL_CULL_FACE);
    f->glDisable(GL_DEPTH_TEST);
}

 shader实现如下，带纹理图片

#version 330
uniform mat4 uPMatrix,uVMatrix,uMMatrix;
layout (location = 0)in vec3 aPosition;
layout (location = 1)in vec2 aTexture;
smooth out vec2 vTexture;

void main(void)
{
    gl_Position = uPMatrix * uVMatrix * uMMatrix * vec4(aPosition,1);
    vTexture = aTexture;
}

#version 330
uniform sampler2D sTexture;
in vec2 vTexture;
out vec4 fragColor;

void main(void)
{
    fragColor = texture2D(sTexture,vTexture);
}

shader不带纹理图片

#version 330
uniform mat4 uPMatrix,uVMatrix,uMMatrix;
layout (location = 0)in vec3 aPosition;
layout (location = 1)in vec4 aColor;
smooth out vec4 vColor;

void main(void)
{
    gl_Position = uPMatrix * uVMatrix * uMMatrix * vec4(aPosition,1);
    vColor = aColor;
}

#version 330
in vec4 vColor;
out vec4 fragColor;

void main(void)
{
    fragColor = vColor;
}

其实现方法和前面一样

#ifndef WIDGET_H
#define WIDGET_H

#include 
#include 
#include "torusrender.h"
class Widget : public QOpenGLWidget
{
    Q_OBJECT

public:
    Widget(QWidget *parent = 0);
    ~Widget();

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

private:
    QTimer tm_;
    TorusRender render_;
    QMatrix4x4 pMatrix_;
    QVector3D camera_;
    qreal angleX_ = 0,angleY_ = 0,angleZ_ = 0;

private slots:
    void slotTimeout();
};

#endif // WIDGET_H

#include "widget.h"

Widget::Widget(QWidget *parent)
    : QOpenGLWidget(parent)
{
    connect(&tm_,SIGNAL(timeout()),this,SLOT(slotTimeout()));
    tm_.start(60);
}

Widget::~Widget()
{

}

void Widget::initializeGL()
{
//    render_.initsize(0.9,0.7,13,30,QImage("texture.png"));
    render_.initsize(0.9,0.7,13,30);
    camera_.setX(0);
    camera_.setY(0);
    camera_.setZ(3);
}

void Widget::resizeGL(int w, int h)
{
    pMatrix_.setToIdentity();
    pMatrix_.perspective(45,float(w)/h,0.01f,100.0f);
}

void Widget::paintGL()
{
    QOpenGLExtraFunctions *f = QOpenGLContext::currentContext()->extraFunctions();
    f->glClearColor(0.0f,0.0f,0.0f,0.0f);
    f->glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    QMatrix4x4 vMatrix;
    vMatrix.lookAt(camera_,QVector3D(0.0,0.0,0.0),QVector3D(0.0,1.0,0.0));

    QMatrix4x4 mMatrix;
    mMatrix.rotate(angleX_,1,0,0);
    mMatrix.rotate(angleY_,0,1,0);
    mMatrix.rotate(angleZ_,0,0,1);
    render_.render(f,pMatrix_,vMatrix,mMatrix);
}

void Widget::slotTimeout()
{
    angleX_ += 5;
    angleY_ += 5;
    angleZ_ += 5;
    update();
}

 到此结束。