1 //参照FreeImage官网给出的CTextrueManager写的加载函数
2 //官方给的例子是用opengl3.0以下的旧GL写的，没有使用glGenerateMipmap(GL_TEXTURE_2D)来产生mipmap
3 //在GL3.0以后，渲染时默认是开启了MIPMAP的，如果不调用glGenerateMipmap来生成MIPMAP，则渲染出的贴图一片黑色
//另外要注意freeimage的颜色分量顺序是gbr,不知为什么，故这里fmt应传GL_BGR
4 GLuint CResMgr::LoadTextrue(const char* texFile, GLenum fmt, GLuint ifmt, GLuint level, GLuint border) {
5 FREE_IMAGE_FORMAT fifmt = FreeImage_GetFileType(texFile, 0);
6 if (fifmt == FIF_UNKNOWN) {
7 fifmt = FreeImage_GetFIFFromFilename(texFile);
8 if (fifmt == FIF_UNKNOWN) {
9 xsMsg(texFile, "图片加载失败:未知的格式", MB_ICONERROR);
10 return 0;
11 }
12 }
13
14 if (!FreeImage_FIFSupportsReading(fifmt)) {
15 xMsg(texFile, "freeImage不支持该文件格式的读取", MB_ICONERROR);
16 return 0;
17 }
18
19 FIBITMAP* dib = FreeImage_Load(fifmt, texFile);
20 if (!dib) {
21 xMsg(texFile, "freeImage_load失败", MB_ICONERROR);
22 return 0;
23 }
24
25 BYTE* bits = FreeImage_GetBits(dib);
26 GLuint width = FreeImage_GetWidth(dib);
27 GLuint height = FreeImage_GetHeight(dib);
28
29 if (!bits || width == 0 || height == 0) {
30 xMsg(texFile, "freeImage_getbits, getwidth, getheight-failed", MB_ICONERROR);
31 return 0;
32 }
33
34 GLuint texId;
35 glGenTextures(1, &texId);
36 glBindTexture(GL_TEXTURE_2D, texId);
37 glTexImage2D(GL_TEXTURE_2D, level, ifmt, width, height, border, fmt, GL_UNSIGNED_BYTE, bits);
38
39 glGenerateMipmap(GL_TEXTURE_2D); //注意，不加这句渲染出的贴图是一片黑色，
40 FreeImage_Unload(dib);
41 return texId;
42 }