Canadian visiting other countries prior to Vietnam

Hi, I'm a Canadian citizen. I'm planning to tour Asia this December and my destinations include Hong Kong, Beijing and Vietnam. I will be flying to these other destinations before arriving in Vietnam. (example: Canada to Hong Kong for 1 week, then Hong Kong to Vietnam for another week, with the remaining week flying from Vietnam to Beijing. Are the visa's to Vietnam based on the location I arrived from? or is it based solely on my country of citizenship? Is the visa all I need to access Vietnam? or would I need to fill out other forms because i will be arriving from a different location (other than directly from Canada) Thanks, Kevin.