题目地址

LeetCode#791 Custom Sort String

题目描述

  S and T are strings composed of lowercase letters. In S, no letter occurs more than once.

  S was sorted in some custom order previously. We want to permute the characters of T so that they match the order that S was sorted. More specifically, if x occurs before y in S, then x should occur before y in the returned string.

  Return any permutation of T (as a string) that satisfies this property.

  在学习了OpenGL最初步的一些内容，包括三维图形，摄像机，鼠标键盘操作后，不由得有了拿这些东西做个小练习的想法。之后又是自然而然的想到了小时候就开始玩的FPS游戏，FPS（First Person Shooter第一人称射击游戏）是可以对之前学到的东西进行综合利用的练习项目。

题目地址

LeetCode#788 Rotated Digits

题目描述

  X is a good number if after rotating each digit individually by 180 degrees, we get a valid number that is different from X. A number is valid if each digit remains a digit after rotation. 0, 1, and 8 rotate to themselves; 2 and 5 rotate to each other; 6 and 9 rotate to each other, and the rest of the numbers do not rotate to any other number.

参考教程

【中文版】基础光照

【英文版】Basic Lighting

学习心得

  终于是开始接触一些较为复杂的东西了，这篇主要是讲解光照实现的原理（漫反射光和镜面光）以及他们的计算方式。

参考教程

【中文版】摄像机

【英文版】Camera

学习心得

  在开始这一篇之前，我们需要清楚OpenGL中的坐标系规则，OpenGL采用右手坐标系，即伸出右手，让大拇指指向右方，食指向上，剩下手指弯曲90度指向自己，这即是X，Y，Z三轴。