OpenGL纹理贴图

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方案一：利用opencv库将图片读取为unsigned char

1、用到Opencv将png图片读取到内存，然后转换为GLubyte–unsigned char数据
2、将影像贴图到OpenGL纹理上

#include <stdlib.h>
#include "GL/glut.h"
#include <opencv.hpp>
using namespace cv;
//OpenCV读取图像
Mat I = imread("C://Users//XXX//Desktop//3.png");
//设置长宽  
int width = I.cols;
int height = I.rows;
//设置图像指针
GLubyte* pixels;

GLuint load_texture()
{
   
   
	//OpenGL纹理用整型数表示
	GLuint texture_ID;

	//获取图像指针
	int pixellength = width * height * 3;
	pixels = new GLubyte[pixellength];
	memcpy(pixels, I.data, pixellength * sizeof(char));
	//imshow("OpenCV", I);

	//将texture_ID设置为2D纹理信息
	glGenTextures(2, &texture_ID);
	glBindTexture(GL_TEXTURE_2D, 1);
	//纹理放大缩小使用线性插值
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	//纹理水平竖直方向外扩使用重复贴图
	//glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
	//glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
	//纹理水平竖直方向外扩使用边缘像素贴图(与重复贴图二选一)
	//glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
	//glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);

	//将图像内存用作纹理信息
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_BGR_EXT, GL_UNSIGNED_BYTE, pixels);

	free(pixels);
	return texture_ID;
}

void display()
{
   
   
	// 清除屏幕
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	//获取纹理对象
	GLuint image = load_texture();
	std::cout << image << std::endl;

	//重新设置OpenGL窗口：原点位置为左上角，x轴从左到右，y轴从上到下，坐标值与像素坐标值相同
	glViewport(0, 0, (GLsizei)width, (GLsizei)height);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity