本文主要内容是关于QOpenGLWidget的使用。此控件用于代替旧的QGLWidget类。关于此类的使用方法可以参考Qt帮助相关内容。
- glDrawArrays(...)函数参数说明：OpenGL 理解GL_TRIANGLE_STRIP、GL_TRIANGLE_FAN等绘制三角形序列的三种方式_匆忙拥挤repeat的博客-CSDN博客
- 变量修饰符说明：shader三种变量类型修饰（uniform，attribute和varying） - 知乎 (zhihu.com)。除此之外还有其它修饰符，如：highp，mediump，lowp，in，out等，读者可以自行查找相关资料
下面将从简到繁给出3个例子带读者入门Qt3D的世界。以下代码开发平台是VS2017和Qt5.9。
一、绘制曲面和颜色
本代码实现了一个沿着x轴旋转的彩色曲面。头文件：
class QOpenGLShaderProgram;
//---------------------------------------------------------------------------------------
// 显示彩虹色
//---------------------------------------------------------------------------------------
class MyOpenGLWidget : public QOpenGLWidget, private QOpenGLFunctions
{
Q_OBJECT
public:
MyOpenGLWidget(QWidget* parent = 0);
private:
void initializeGL() override;
void paintGL() override;
void resizeGL(int w, int h) override;
private:
QOpenGLShaderProgram* program;
int iter;
};
CPP文件：
MyOpenGLWidget::MyOpenGLWidget(QWidget* parent) :
QOpenGLWidget(parent), iter(0)
{
QSurfaceFormat surface;
surface.setSamples(4);
setFormat(surface);
QTimer* timer = new QTimer(this);
connect(timer, &QTimer::timeout, this, QOverload<>::of(&MyOpenGLWidget::update));
timer->setInterval(100);
timer->start();
}
void MyOpenGLWidget::initializeGL()
{
initializeOpenGLFunctions();
glEnable(GL_DEPTH_TEST);
QOpenGLShader* vshader = new QOpenGLShader(QOpenGLShader::Vertex, this);
const char* vsrc = R"(
in vec4 vposition;
in vec4 vcolor;
out vec4 ocolor;
uniform mat4 trans;
void main() {
gl_Position = trans * vposition;
ocolor = vcolor;
})";
vshader->compileSourceCode(vsrc);
QOpenGLShader* fshader = new QOpenGLShader(QOpenGLShader::Fragment, this);
const char* fsrc = R"(
in vec4 ocolor;
void main() {
gl_FragColor = ocolor;
})";
fshader->compileSourceCode(fsrc);
program = new QOpenGLShaderProgram(this);
program->addShader(vshader);
program->addShader(fshader);
program->link();
program->bind();
delete vshader;
delete fshader;
}
void MyOpenGLWidget::paintGL()
{
GLfloat vertices[] =
{
-0.8f, 0.8f, 0.2f,
-0.8f, -0.8f, -0.3f,
0.8f, 0.8f, 0.0f,
0.8f, -0.8f, 0.5f,
};
GLfloat colors[] =
{
0.9f, 0.7f, 0.1f,
0.2f, 0.7f, 0.3f,
0.8f, 0.0f, 0.5f,
0.1f, 0.1f, 0.9f,
};
QMatrix4x4 matrix;
matrix.perspective(60.0f, 1.0f, 1.0f, 100.0f);
matrix.translate(0, 0, -3);
matrix.rotate(iter * 1.0f, 1, 0, 0);
program->setUniformValue("trans", matrix);
program->enableAttributeArray("trans");
iter++;
program->setAttributeArray("vposition", vertices, 3);
program->enableAttributeArray("vposition");
program->setAttributeArray("vcolor", colors, 3);
program->enableAttributeArray("vcolor");
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
}
void MyOpenGLWidget::resizeGL(int w, int h)
{
}
程序运行效果如下图：
二、绘制曲面和贴图
本代码实现了一个沿着z轴旋转的曲面，曲面上贴了图片。头文件：
class QOpenGLTexture;
//---------------------------------------------------------------------------------------
// 显示图片
//---------------------------------------------------------------------------------------
class MzOpenGLWidget : public QOpenGLWidget, private QOpenGLFunctions
{
Q_OBJECT
public:
MzOpenGLWidget(QWidget* parent = 0);
private:
void initializeGL() override;
void paintGL() override;
void resizeGL(int w, int h) override;
private:
QOpenGLShaderProgram* program;
QOpenGLTexture *texture;
int iter;
};
CPP文件：
MzOpenGLWidget::MzOpenGLWidget(QWidget* parent) :
QOpenGLWidget(parent), iter(0)
{
QSurfaceFormat surface;
surface.setSamples(4);
setFormat(surface);
QTimer* timer = new QTimer(this);
connect(timer, &QTimer::timeout, this, QOverload<>::of(&MyOpenGLWidget::update));
timer->setInterval(100);
timer->start();
}
void MzOpenGLWidget::initializeGL()
{
initializeOpenGLFunctions();
glEnable(GL_DEPTH_TEST);
program = new QOpenGLShaderProgram(this);
const char* vsrc = R"(
in vec4 pos;
in vec2 itextCoor;
out vec2 otextCoor;
uniform mat4 trans;
void main() {
gl_Position = trans * pos;
otextCoor = itextCoor;
})";
program->addShaderFromSourceCode(QOpenGLShader::Vertex, vsrc);
const char* fsrc = R"(
uniform sampler2D image;
in vec2 otextCoor;
void main() {
gl_FragColor = texture2D(image, otextCoor);
})";
program->addShaderFromSourceCode(QOpenGLShader::Fragment, fsrc);
texture = new QOpenGLTexture(QImage(u8"F:/Mr.Duu/ProjectM/QtTest/QtTest/1.bmp"));
texture->setMinificationFilter(QOpenGLTexture::LinearMipMapNearest); /* 缩小图片插值方法 */
texture->setMagnificationFilter(QOpenGLTexture::LinearMipMapLinear); /* 放大图片插值方法 */
texture->setWrapMode(QOpenGLTexture::Repeat);
program->link();
program->bind();
}
void MzOpenGLWidget::paintGL()
{
GLfloat vertices[] =
{
-0.8f, 0.8f, 0.2f,
-0.8f, -0.8f, -0.3f,
0.8f, 0.8f, 0.0f,
0.8f, -0.8f, 0.5f,
};
GLfloat coors[] = /* 此数组和vertices数组一一对应 */
{
0.0f, 0.0f,
0.0f, 2.2f,
2.2f, 0.0f,
2.2f, 2.2f,
};
QMatrix4x4 matrix;
matrix.perspective(60.0f, 1.0f, 1.0f, 100.0f);
matrix.translate(0, 0, -3);
matrix.rotate(iter * 1.0f, 0, 1, 0);
program->setUniformValue("trans", matrix);
program->enableAttributeArray("trans");
iter++;
program->setAttributeArray("pos", vertices, 3);
program->enableAttributeArray("pos");
program->setAttributeArray("itextCoor", coors, 2);
program->enableAttributeArray("itextCoor");
program->setUniformValue("image", 0);
texture->bind(0);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
}
void MzOpenGLWidget::resizeGL(int w, int h)
{
}
程序运行效果如下：
三、绘制立体图形和颜色
立体图形其实也是曲面，只不过首尾点相同把曲面连接成了封闭的图形。下面给出一个绘制三棱锥的例子。头文件：
class QOpenGLTexture;
//---------------------------------------------------------------------------------------
// 显示图片
//---------------------------------------------------------------------------------------
class MxOpenGLWidget : public QOpenGLWidget, private QOpenGLFunctions
{
Q_OBJECT
public:
MxOpenGLWidget(QWidget* parent = 0);
private:
void initializeGL() override;
void paintGL() override;
void resizeGL(int w, int h) override;
private:
QOpenGLShaderProgram* program;
int iter;
};
CPP文件：
MxOpenGLWidget::MxOpenGLWidget(QWidget* parent) :
QOpenGLWidget(parent), iter(0)
{
QSurfaceFormat surface;
surface.setSamples(4);
setFormat(surface);
QTimer* timer = new QTimer(this);
connect(timer, &QTimer::timeout, this, QOverload<>::of(&MyOpenGLWidget::update));
timer->setInterval(100);
timer->start();
}
void MxOpenGLWidget::initializeGL()
{
initializeOpenGLFunctions();
glEnable(GL_DEPTH_TEST);
program = new QOpenGLShaderProgram(this);
const char* vsrc = R"(
in vec4 pos;
in vec4 itextCoor;
out vec4 otextCoor;
uniform mat4 trans;
void main() {
gl_Position = trans * pos;
otextCoor = itextCoor;
})";
program->addShaderFromSourceCode(QOpenGLShader::Vertex, vsrc);
const char* fsrc = R"(
in vec4 otextCoor;
void main() {
gl_FragColor = otextCoor;
})";
program->addShaderFromSourceCode(QOpenGLShader::Fragment, fsrc);
program->link();
program->bind();
}
void MxOpenGLWidget::paintGL()
{
GLfloat vertices[] =
{
-0.8f, -0.4f, 0.3f,
0.8f, -0.4f, 0.3f,
0.0f, 0.8f, 0.0f,
0.0f, -0.4f, -0.5f,
-0.8f, -0.4f, 0.3f,
0.8f, -0.4f, 0.3f,
};
GLfloat colors[] =
{
0.0f, 0.0f, 1.0f,
0.0f, 1.0f, 0.0f,
1.0f, 0.0f, 0.0f,
0.0f, 1.0f, 1.0f,
1.0f, 0.0f, 1.0f,
1.0f, 1.0f, 0.0f,
};
QMatrix4x4 matrix;
matrix.perspective(60.0f, 1.0f, 1.0f, 100.0f);
matrix.translate(0, 0, -2);
matrix.rotate(iter * 1.0f, 0, 1, 0);
program->setUniformValue("trans", matrix);
program->enableAttributeArray("trans");
iter++;
program->setAttributeArray("pos", vertices, 3);
program->enableAttributeArray("pos");
program->setAttributeArray("itextCoor", colors, 3);
program->enableAttributeArray("itextCoor");
glDrawArrays(GL_TRIANGLE_STRIP, 0, 6);
}
void MxOpenGLWidget::resizeGL(int w, int h)
{
}
程序运行效果如下图：
标签：0.8,1.0,Qt,例程,0.0,void,int,program,3D From： https://www.cnblogs.com/mengxiangdu/p/17672585.html