• <ins id="pjuwb"></ins>
    <blockquote id="pjuwb"><pre id="pjuwb"></pre></blockquote>
    <noscript id="pjuwb"></noscript>
          <sup id="pjuwb"><pre id="pjuwb"></pre></sup>
            <dd id="pjuwb"></dd>
            <abbr id="pjuwb"></abbr>

            天行健 君子當自強而不息

            Timing in Animation and Movement(1)

            Games are packed with movement. Characters running here, bullets flying there−basically there's a slew of objects moving about your game world. The smooth motion of these objects is a very important aspect that can't be overlooked. Have you ever thought about the use of movement and animation based on time? Using time−based motion is hot, and to keep up with the rest of the world you must fully understand how it can help your game project. In fact, you need to understand not only using time−based motion, but also motion in general. Do you think only characters move about in your game? Nope, your in−game cinematic cameras need your guidance as well.

             

            Using Time−Based Motion

            Although it might not seem important at first, timing plays a crucial role in your game projects. I'm not talking about the time of day; rather, I'm referring to down−to−the−millisecond timing of animation. This sort of precise timing is required for smooth animation and movement of objects in your project. Although it is a basic topic, it is one that all game programmers should understand quite well.

            When it comes to moving your meshes, time−based motion is the best of the bunch.

            The whole basis of using time−based motion is simple−movement and animation always take the same amount of time to perform on any system, regardless of the computer's actual speed. For example, a 2−GHz system processing a 20−second animation will undoubtedly do so quickly and produce a very smooth motion, whereas the same animation running on a 500−MHz system will be choppy but will still maintain the 20−second animation length.

            More than likely, the slower computer will drop specific frames of the animation to keep up with the speed of the faster computer. Therein lies the secret−slower computers can drop more frames and still maintain a somewhat reasonable representation of the actual motion.

            Okay, I think you're starting to get the idea. As simple as the techniques sound, time−based animation and movement remain a slight mystery to fledgling game programmers. For that reason, I want to introduce (or re−introduce) you to the world of time−based motion. I'll start with a brief look at reading time in Windows.

             

            Reading Time in Windows

            The easiest method of reading time in Windows is by using the timeGetTime function. This function does not take any parameters. As the following code demonstrates, timeGetTime only returns the number of milliseconds that have passed since Windows was started.

            DWORD TimeSinceStarted = timeGetTime();

            What good does this do you? Typically, you call the timeGetTime function once per frame that your game processes. For each frame, you then subtract the time from the last frame processed to obtain the number of milliseconds that have elapsed since your last frame. You can use this elapsed time to compute your time−based motion.

            Storing the time of the last frame update is as easy as using a static variable. At the beginning of your frame's update function, insert a static variable that stores the current time.

            void FrameUpdate()
            {
              static DWORD LastTime = timeGetTime();

            At the end of the FrameUpdate function, you can then store the current time in LastTime.

            LastTime = timeGetTime();

            In this manner (storing the current time at the end of your frame's update function), you have managed to store the time at which the frame update ended. During the next call to FrameUpdate, the LastTime variable will still contain the time at which the last frame update ended. Using this time value, you can calculate the amount of time that has elapsed since you last called FrameUpdate by subtracting LastTime from the current time.

            DWORD ElapsedTime = timeGetTime() − LastTime;

            Now what about those instances when you want to calculate the number of elapsed milliseconds based on a specific time, such as when an animation starts, instead of counting the elapsed time or when the FrameUpdate function was first called?

            Just as you used a static variable to store the last frame's update time, you can store the time at which the function was first called. Using that static variable, you can determine how many milliseconds have passed since the function was first called.

            void FrameUpdate()
            {
              static DWORD StartTime = timeGetTime();
              DWORD ElapsedTime = timeGetTime() − StartTime;

              // ElapsedTime is the number of milliseconds that has passed since you first called FrameUpdate.
            }

            In the same way the previous bit of code tracked the total amount of time that has passed since the first call to the FrameUpdate function, you can embed the starting time of an animation inside your data structures.

            Combined with key frames, time−based animation is a perfect solution for creating smooth animation. Read on to take a closer look at using time−based animation.


            posted on 2008-04-15 15:50 lovedday 閱讀(355) 評論(0)  編輯 收藏 引用

            公告

            導航

            統計

            常用鏈接

            隨筆分類(178)

            3D游戲編程相關鏈接

            搜索

            最新評論

            久久国产欧美日韩精品| 中文国产成人精品久久不卡| 97久久综合精品久久久综合| 国内精品久久久人妻中文字幕| 国产精品久久久久AV福利动漫| 国产99久久久国产精品~~牛| 欧美午夜A∨大片久久| 麻豆AV一区二区三区久久 | 久久天天躁狠狠躁夜夜躁2O2O| 色综合久久综合中文综合网| 久久―日本道色综合久久| 午夜精品久久久久久影视777| 亚洲AV无码成人网站久久精品大| 四虎国产永久免费久久| 亚洲人成伊人成综合网久久久| 久久这里只有精品久久| 国产香蕉久久精品综合网| 久久久91精品国产一区二区三区| 久久天天躁夜夜躁狠狠 | 久久久高清免费视频| 久久99久久99精品免视看动漫| 色婷婷久久久SWAG精品| 久久精品草草草| 漂亮人妻被黑人久久精品| 久久只这里是精品66| 亚洲国产精品久久66| 久久99久久99精品免视看动漫| 午夜精品久久久内射近拍高清| 国产A级毛片久久久精品毛片| 久久精品国产亚洲AV大全| 新狼窝色AV性久久久久久| 要久久爱在线免费观看| 久久久这里有精品中文字幕| 99久久综合国产精品二区| 色综合久久综精品| 久久99精品久久久久久齐齐 | 性高朝久久久久久久久久| 国产午夜精品理论片久久| 国产精品激情综合久久| 国产精品美女久久久网AV| 国产福利电影一区二区三区久久久久成人精品综合 |