OpenGL 着色器程序的保存和加载（二进制）

背景

为了提高OpenGL 着色器程序的编译和链接速度，我们可以将程序保存为二进制进行加载，可以大幅度提升加载效率。

方法

以下是加载和保存二进制程序的方法。

// 加载着色器程序的二进制文件到已创建的着色器程序中
bool loadPragram(const std::string& programFilePath, unsigned int programId)
{// Load binary from filestd::ifstream inputStream(programFilePath, std::ios::binary);if (!inputStream.is_open()){inputStream.close();WARN_LOG(" gl program binary file not exist! programfile:%s", programFilePath.c_str());return false;}unsigned int format = 0;inputStream.read(reinterpret_cast<char*>(&format), sizeof(GLenum));inputStream.seekg(sizeof(GLenum));std::istreambuf_iterator<char> startIt(inputStream), endIt;std::vector<char> buffer(startIt, endIt);  // Load fileinputStream.close();// Install shader binaryglProgramBinary(programId, format, buffer.data(), buffer.size());int success;glGetProgramiv(programId, GL_LINK_STATUS, &success);if (!success){WARN_LOG("Install gl program failed.program file:%s,program id:%d ,format:%d", programFilePath.c_str(), programId, format);return false;}INFO_LOG("load gl program success.program name:%s", programFilePath.c_str());return true;
}
// 保存着色器的二进制信息到文件中
void saveProgram(const std::string& programFilePath,unsigned int programId)
{GLint length = 0;glGetProgramiv(programId, GL_PROGRAM_BINARY_LENGTH, &length);// Retrieve the binary codestd::vector<GLubyte> buffer(length + sizeof(GLenum));GLenum format = 0;glGetProgramBinary(programId, length, NULL, &format, buffer.data());// Write the binary to a file.std::ofstream out(programFilePath, std::ios::binary);out.write(reinterpret_cast<char*>(buffer.data()), length);out.close();INFO_LOG("save gl program success.program name:%s,binary format:%d", programFilePath.c_str(), format);
}