[導(dǎo)讀]我們添加了一個三角形和一個四邊形。也許你認(rèn)為這很簡單，但你已經(jīng)邁出了一大步，要知道任何在OpenGL中繪制的模型都會被分解為這兩種簡單的圖形。lesson1.h#ifndef?LESSON1_H
#d
我們添加了一個三角形和一個四邊形。也許你認(rèn)為這很簡單，但你已經(jīng)邁出了一大步，要知道任何在OpenGL中繪制的模型都會被分解為這兩種簡單的圖形。
lesson1.h
#ifndef?LESSON1_H
#define?LESSON1_H
#include#includeclass?QPainter;
class?QOpenGLContext;
class?QOpenGLPaintDevice;
class?Lesson1?:?public?QWindow,?QOpenGLFunctions_1_0
{
????Q_OBJECT
public:
????explicit?Lesson1(QWindow?*parent?=?0);
????~Lesson1();
????virtual?void?render(QPainter?*);
????virtual?void?render();
????virtual?void?initialize();
public?slots:
????void?renderNow();
protected:
????void?exposeEvent(QExposeEvent?*);
????void?resizeEvent(QResizeEvent?*);
private:
????void?myPerspective(?GLdouble?fov,?GLdouble?aspectRatio,?GLdouble?zNear,?GLdouble?zFar?);
private:
????QOpenGLContext?*m_context;
};
#endif?//?LESSON1_Hlesson1.cpp
#include?"lesson1.h"
#include#include#include#includeLesson1::Lesson1(QWindow?*parent)?:
????QWindow(parent)
??,?m_context(0)
{
????setSurfaceType(QWindow::OpenGLSurface);
}
Lesson1::~Lesson1()
{
}
void?Lesson1::render(QPainter?*painter)
{
????Q_UNUSED(painter);
}
void?Lesson1::myPerspective(?GLdouble?fov,?GLdouble?aspectRatio,?GLdouble?zNear,?GLdouble?zFar?)
{
????//?使用glu庫函數(shù)，需要添加glu.h頭文件
????//?gluPerspective(fov,?aspectRatio,?zNear,?zFar);
????GLdouble?rFov?=?fov?*?3.14159265?/?180.0;
????glFrustum(?-zNear?*?tan(?rFov?/?2.0?)?*?aspectRatio,
???????????????zNear?*?tan(?rFov?/?2.0?)?*?aspectRatio,
???????????????-zNear?*?tan(?rFov?/?2.0?),
???????????????zNear?*?tan(?rFov?/?2.0?),
???????????????zNear,?zFar?);
}
void?Lesson1::render()
{
????glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
????glViewport(0,0,(GLint)width(),(GLint)height());?//?重置當(dāng)前視口
????glMatrixMode(GL_PROJECTION);????????????????????//?選擇投影矩陣
????glLoadIdentity();???????????????????????????????//?重置投影矩陣為單位矩陣
????//?glu庫函數(shù)Qt不支持，但是glu庫函數(shù)是對gl庫函數(shù)的封裝，方便使用。因此我們可以自己
????//?寫一個類似gluPerspective的函數(shù)myPerspective，用于設(shè)置透視。
????//gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.1f,100.0f);
????myPerspective(45.0,(GLfloat)width()/(GLfloat)height(),0.1,100.0);
????glMatrixMode(GL_MODELVIEW);//?選擇模型視圖矩陣
????glLoadIdentity();??????????//?重置模型視圖矩陣為單位矩陣
????glTranslatef(-1.5f,0.0f,-6.0f);
????glBegin(GL_TRIANGLES); //?繪制三角形
????glVertex3f(?0.0f,?1.0f,?0.0f); //?上頂點
????glVertex3f(-1.0f,-1.0f,?0.0f); //?左下
????glVertex3f(?1.0f,-1.0f,?0.0f); //?右下
????glEnd();????????????????????????//?三角形繪制結(jié)束
????glTranslatef(3.0f,0.0f,0.0f);
????glBegin(GL_QUADS); //?繪制正方形
????glVertex3f(-1.0f,?1.0f,?0.0f); //?左上
????glVertex3f(?1.0f,?1.0f,?0.0f); //?右上
????glVertex3f(?1.0f,-1.0f,?0.0f); //?左下
????glVertex3f(-1.0f,-1.0f,?0.0f); //?右下
????glEnd(); ????//?正方形繪制結(jié)束
}
void?Lesson1::initialize()
{
????glShadeModel(GL_SMOOTH);??????????????//?啟用平滑著色
????glClearColor(0.0f,?0.0f,?0.0f,?0.0f);?//?黑色背景
????glClearDepth(1.0f);???????????????????//?設(shè)置深度緩存
????glEnable(GL_DEPTH_TEST);??????????????//?啟用深度測試
????glDepthFunc(GL_LEQUAL);???????????????//?深度測試類型
????//?接著告訴OpenGL我們希望進(jìn)行最好的透視修正。這會十分輕微的影響性能。但使得透視圖看起來好一點。
????glHint(GL_PERSPECTIVE_CORRECTION_HINT,?GL_NICEST);
}
void?Lesson1::renderNow()
{
????if?(!isExposed())
????????return;
????bool?needsInitialize?=?false;
????if?(!m_context)?{
????????m_context?=?new?QOpenGLContext(this);
????????m_context->setFormat(requestedFormat());
????????m_context->create();
????????needsInitialize?=?true;
????}
????m_context->makeCurrent(this);
????if?(needsInitialize)?{
????????initializeOpenGLFunctions();
????????initialize();
????}
????render();
????m_context->swapBuffers(this);
}
void?Lesson1::exposeEvent(QExposeEvent?*event)
{
????Q_UNUSED(event);
????if?(isExposed())
????????renderNow();
}
void?Lesson1::resizeEvent(QResizeEvent?*event)
{
????Q_UNUSED(event);
????if?(isExposed())
????????renderNow();
}main.cpp
#include#includeint?main(int?argc,?char?*argv[])
{
????QGuiApplication?app(argc,?argv);
????QSurfaceFormat?format;
????format.setSamples(16);
????Lesson1?window;
????window.setFormat(format);
????window.resize(640,?480);
????window.show();
????return?app.exec();
}運行效果
源碼中用到的OpenGL庫函數(shù)可以參考：
OpenGL之glViewPort函數(shù)的用法
OpenGL之glLoadIdentity函數(shù)的用法
OpenGL之glMatrixMode函數(shù)的用法
實際上僅用如下代碼就能畫出一個三角形
void?Lesson1::render()
{
????glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
????glViewport(0,0,(GLint)width(),(GLint)height());?//?重置當(dāng)前視口
????glBegin(GL_TRIANGLES); //?繪制三角形
????glVertex3f(?0.0f,?1.0f,?0.0f); //?上頂點
????glVertex3f(-1.0f,-1.0f,?0.0f); //?左下
????glVertex3f(?1.0f,-1.0f,?0.0f); //?右下
????glEnd();????????????????????????//?三角形繪制結(jié)束
}
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