在Qt中使用两个texture

在上一篇博客<<利用QOpenGLWidget glDrawArrays()实现纹理贴图>>中，我介绍了如何利用QOpenGLWidget + glDrawArrays()绘制纹理。本篇博文在上一篇的基础上，介绍如何使用两个纹理。

头文件：

#ifndef MAINWINDOW_H#define MAINWINDOW_H#include <QOpenGLWidget>#include <QOpenGLFunctions>class GLWidget : public QOpenGLWidget, protected QOpenGLFunctions{    Q_OBJECTpublic:    GLWidget(QWidget *parent = 0);    ~GLWidget();    GLuintm_arrID[2];    unsigned char               m_arrData1[1024];    unsigned char               m_arrData2[1024];protected:    void initializeGL() Q_DECL_OVERRIDE;    void paintGL() Q_DECL_OVERRIDE;    void resizeGL(int width, int height) Q_DECL_OVERRIDE;};#endif // MAINWINDOW_H

cpp文件：

#include "glwidget.h"#include <QImage>#include "math3d.h"GLWidget::GLWidget(QWidget *parent)    : QOpenGLWidget(parent){    int iVal = 0;    for(int iIndex = 0;iIndex < 4; iIndex++)    {            if(0 == iVal)            {                iVal = 255;            }            else            {                iVal = 0;            }            memset(m_arrData1 + 32 * 8 * iIndex, iVal, 32 * 8);            memset(m_arrData2 + 32 * 8 * iIndex, 255 - iVal, 32 * 8);    }}GLWidget::~GLWidget(){    glDeleteTextures(2, m_arrID);}void GLWidget::initializeGL(){    initializeOpenGLFunctions();//这句必须有，否则程序会崩溃    glGenTextures(2, m_arrID);    glEnable(GL_TEXTURE_2D);    glBindTexture(GL_TEXTURE_2D, m_arrID[0]);    //这下面的两句是必要的，否则在绘制区的像素数和纹理的像素数不等时，图案不能正常显示    glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);    glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);    glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, 32, 32, 0, GL_LUMINANCE,//GL_INTENSITY,                 GL_UNSIGNED_BYTE, m_arrData1);glDisable(GL_TEXTURE_2D);    //再初始化第二个texture    glEnable(GL_TEXTURE_2D);    glBindTexture(GL_TEXTURE_2D, m_arrID[1]);    //这下面的两句是必要的，否则在绘制区的像素数和纹理的像素数不等时，图案不能正常显示    glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);    glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);    glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, 32, 32, 0, GL_LUMINANCE,//GL_INTENSITY,                 GL_UNSIGNED_BYTE, m_arrData2);glDisable(GL_TEXTURE_2D);}void GLWidget::paintGL(){    M3DVector2farrVetex1[4] = {{0.0,0.0}, {50.0, 0.0}, {50.0, 100.0}, {0.0, 100.0}};//M3DVector2f是math3d.h定义的类型M3DVector2farrVetex2[4] = {{50.0,0.0}, {100.0, 0.0}, {100.0, 100.0}, {50.0, 100.0}};//M3DVector2f是math3d.h定义的类型    float arrTex[8] = {0.0,0.0,1.0, 0.0,1.0, 1.0, 0.0, 1.0};    glBindTexture(GL_TEXTURE_2D, m_arrID[0]);    glEnable(GL_TEXTURE_2D);    glEnableClientState(GL_VERTEX_ARRAY);    glEnableClientState(GL_TEXTURE_COORD_ARRAY);    glTexCoordPointer(2, GL_FLOAT, 0, arrTex);    glVertexPointer(2, GL_FLOAT, 0, &arrVetex1[0]);    glDrawArrays(GL_TRIANGLE_FAN, 0, 4);    glDisableClientState(GL_VERTEX_ARRAY);    glDisableClientState(GL_TEXTURE_COORD_ARRAY);    glBindTexture(GL_TEXTURE_2D, 0);    glDisable(GL_TEXTURE_2D);    glBindTexture(GL_TEXTURE_2D, m_arrID[1]);    glEnable(GL_TEXTURE_2D);    glEnableClientState(GL_VERTEX_ARRAY);    glEnableClientState(GL_TEXTURE_COORD_ARRAY);    glTexCoordPointer(2, GL_FLOAT, 0, arrTex);    glVertexPointer(2, GL_FLOAT, 0, &arrVetex2[0]);    glDrawArrays(GL_TRIANGLE_FAN, 0, 4);    glDisableClientState(GL_VERTEX_ARRAY);    glDisableClientState(GL_TEXTURE_COORD_ARRAY);    glBindTexture(GL_TEXTURE_2D, 0);    glDisable(GL_TEXTURE_2D);}void GLWidget::resizeGL(int width, int height){    glViewport(0,0,width,height);    glMatrixMode(GL_PROJECTION);    glLoadIdentity();    glOrtho(0.0, 100.0, 0.0, 100.0, -1.0, 1.0);    glMatrixMode(GL_MODELVIEW);}

效果：