texture.cpp
#include "texture.h" #include "utils.h" unsigned char* DecodeBMP(unsigned char*bmpFileData, int&width, int&height) { if (0x4D42==*((unsigned short*)bmpFileData)) { printf("yes"); int pixelDataOffset = *((int*)(bmpFileData + 10)); width = *((int*)(bmpFileData+18)); height = *((int*)(bmpFileData + 22)); unsigned char*pixelData = bmpFileData + pixelDataOffset; //bgr bgr bgr .... //rgb rgb rgb for (int i=0;i<width*height*3;i+=3) { unsigned char temp = pixelData[i]; pixelData[i] = pixelData[i+2]; pixelData[i+2]=temp; } return pixelData; } else { printf("no"); return nullptr; } } void Texture::Init(const char*imagePath) { //load image file from disk to memory unsigned char*imageFileContent = LoadFileContent(imagePath); //decode image int width = 0, height = 0; unsigned char* pixelData = DecodeBMP(imageFileContent, width, height); //generate an opengl texture glGenTextures(1, &mTextureID); glBindTexture(GL_TEXTURE_2D, mTextureID); /*glGenTextures(GLsizei n, GLuint *textures)函数说明 百度百科： n：用来生成纹理的数量 textures：存储纹理索引的第一个元素指针 glGenTextures函数根据纹理参数返回n个纹理索引。纹理名称集合不必是一个连续的整数集合。 （glGenTextures就是用来产生你要操作的纹理对象的索引的，比如你告诉OpenGL，我需要5个纹理对象，它会从没有用到的整数里返回5个给你） glBindTexture实际上是改变了OpenGL的这个状态，它告诉OpenGL下面对纹理的任何操作都是对它所绑定的纹理对象的，比如glBindTexture(GL_TEXTURE_2D,1)告诉OpenGL下面代码中对2D纹理的任何设置都是针对索引为1的纹理的。 产生纹理函数假定目标纹理的面积是由glBindTexture函数限制的。先前调用glGenTextures产生的纹理索引集不会由后面调用的glGenTextures得到，除非他们首先被glDeleteTextures删除。你不可以在显示列表中包含glGenTextures。*/ //operation on current texture 可以解决绝大多数问题 glTexParameteri:http://blog.csdn.net/d04421024/article/details/5089641 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, pixelData); glBindTexture(GL_TEXTURE_2D, 0); delete imageFileContent; } texture.h #pragma once #include <windows.h> #include <gl/GL.h> class Texture { public: GLuint mTextureID;//gpu void Init(const char*imagePath); };加载文件 #include "utils.h" unsigned char* LoadFileContent(const char*filePath) { unsigned char* fileContent = nullptr; FILE*pFile = fopen(filePath, "rb"); if (pFile) { //read fseek(pFile,0,SEEK_END); int nLen = ftell(pFile); if (nLen>0) { rewind(pFile); fileContent = new unsigned char[nLen+1]; fread(fileContent,sizeof(unsigned char),nLen,pFile); fileContent[nLen]='\0'; } fclose(pFile); } return fileContent; }utlis.h #pragma once #include <stdio.h> unsigned char* LoadFileContent(const char*filePath);
texture.cpp
