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講到香港迪士尼嘅Projection Show, 雖然到樂園十周年嘅時候園方先為星夢奇緣加入投影效果, 但其實再早多五年之前, 喺11年前, 即2010年嘅Halloween 活動, 樂園已經出現咗一個萬聖節版本嘅Pyrotechnics show, 以Maleficent 為主題嘅魔咒焚城. 採用投影技術喺城堡上. 雖然當年香港嘅projection mapping 技術仲未成熟, 但假如完全冇對過位嘅話Maleficent 嘅影像並唔會喺城堡不同位置出現.
https://youtu.be/XKi0csmmfz8
即使唔講城堡, 大街兩旁建築物喺夜光鬼魅巡遊嘅年代已經有Halloween 版本嘅projection mapping 全晚無間斷播放, 有蜘蛛有蛇等等嘅動畫配合大街建築物嘅外觀輪廓.
https://youtu.be/RokNq8anx2E
We Love Mickey 並無用到咩嶄新前衛嘅技術. 喺Projection Mapping 呢方面, 香港迪士尼有好多年嘅經驗, 亦都相比其他Disney Parks 走得更前.
📜 [專欄新文章] Gas Efficient Card Drawing in Solidity
✍️ Ping Chen
📥 歡迎投稿： https://medium.com/taipei-ethereum-meetup #徵技術分享文 #使用心得 #教學文 #medium
Assign random numbers as the index of newly minted NFTs
Scenario
The fun of generative art NFT projects depends on randomness. The industry standard is “blind box”, where both the images’ serial number and the NFTs’ index are predetermined but will be shifted randomly when the selling period ends. (They call it “reveal”) This approach effectively solves the randomness issue. However, it also requires buyers to wait until the campaign terminates. What if buyers want to know the exact card right away? We’ll need a reliable onchain card drawing solution.
The creator of Astrogator🐊 isn’t a fan of blind boxes; instead, it thinks unpacking cards right after purchase is more interesting.
Spec
When initializing this NFT contract, the creator will determine the total supply of it. And there will be an iterable function that is randomly picking a number from the remaining pool. The number must be in range and must not collide with any existing ones.
Our top priority is accessibility/gas efficiency. Given that gas cost on Ethereum is damn high nowadays, we need an elegant algorithm to control gas expanse at an acceptable range.
Achieving robust randomness isn’t the primary goal here. We assume there’s no strong financial incentive to cheat, so the RNG isn’t specified. Implementers can bring their own source of randomness that they think is good enough.
Implementation
Overview
The implementation is pretty short and straightforward. Imagine there’s an array that contains all remaining(unsold) cards. When drawIndex() is called, it generates a (uniform) random seed to draw a card from the array, shortens the array, and returns the selected card.
Algorithm
Drawing X cards from a deck with the same X amount of cards is equal to shuffling the deck and dealing them sequentially. It’s not a surprise that our algorithm is similar to random shuffling, and the only difference is turning that classic algo into an interactive version.
A typical random shuffle looks like this: for an array with N elements, you randomly pick a number i in (0,N), swap array[0] and array[i], then choose another number i in (1,N), swap array[1] and array[i], and so on. Eventually, you’ll get a mathematically random array in O(N) time.
So, the concept of our random card dealing is the same. When a user mints a new card, the smart contract picks a number in the array as NFT index, then grabs a number from the tail to fill the vacancy, in order to keep the array continuous.
Tweak
Furthermore, as long as the space of the NFT index is known, we don’t need to declare/initialize an array(which is super gas-intensive). Instead, assume there’s such an array that the n-th element is n, we don’t actually initialize it (so it is an array only contains “0”) until the rule is broken.
For the convenience of explanation, let’s call that mapping cache. If cache[i] is empty, it should be interpreted as i instead of 0. On the other hand, when a number is chosen and used, we’ll need to fill it up with another unused number. An intuitive method is to pick a number from the end of the array, since the length of the array is going to decrease by 1.
By doing so, the gas cost in the worst-case scenario is bound to be constant.
Performance and limitation
Comparing with the normal ascending index NFT minting, our random NFT implementation requires two extra SSTORE and one extra SLOAD, which cost 12600 ~ 27600 (5000+20000+2600) excess gas per token minted.
Theoretically, any instantly generated onchain random number is vulnerable. We can restrict contract interaction to mitigate risk. The mitigation is far from perfect, but it is the tradeoff that we have to accept.
ping.eth
Gas Efficient Card Drawing in Solidity was originally published in Taipei Ethereum Meetup on Medium, where people are continuing the conversation by highlighting and responding to this story.
👏 歡迎轉載分享鼓掌
40年來，學者相信2200年前的兵馬俑青銅兵器之所以能保存完好，是因為鍍有鉻。新研究指出：並非如此。
我們花整個童年(甚至到現在)學習中文，何況是第二外語！！
這支影片簡單分享考題方向和幾個單字撇步，
✏ 時間有限，就先背高頻率出現單字
✏ 情境式記憶，利用Word mapping增加印象
✏ 多益很狡猾，同義字/反義字要一起看
其他像是利用發音、音節記憶，字首、字根的運用，
詞語搭配都是hen棒的方法。歡迎底下分享妳都是怎麼記單字的。
市面上絕對沒看過的影音解析🔥
多益第一回 https://bit.ly/3AVOcF1
多益第二回 https://bit.ly/3CZmJEc
喜歡我也記得追蹤這些 🔎
♥ FB：https://www.facebook.com/msgingerme
♥ IG：https://www.instagram.com/gingerliu50
作業厨は昔のバージョンに篭ってるから最新版の知識が圧倒的に足りてない
実は村にドラゴン飛ばしたり、色々する計画はあったんですが
10時間じゃ足りませんでしたねぇ。。。
計画段階で試作されたドラゴン君はそのうち沈没世界でつくるかも(かも)
▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬
他の人の動画を含む今回の企画の再生リスト
https://www.youtube.com/playlist?list=PLRvO41EShTHOQ_fjGhCJsJPFo84kr8hTx
使用させていただいたもの
Wingless Seraph 様(http://wingless-seraph.net/ )
おんたま 様(http://ontama-m.com/ )
ShaderPack
Builders QOL Shaders ( https://www.minecraftforum.net/forums/mapping-and-modding-java-edition/minecraft-mods/2778752-builders-quality-of-life-shaders )
バイオームを見つけるやつ
https://chunkbase.com
這支影片是黃標嗎？＃對這支影片是黃標
如果你覺得它不應該被黃標
歡迎留言 ＃ItDeservesGreenMark ＃這應該綠標
和我們一起協助 YouTube 建立一個更完善、更精準的AI判別系統！
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＃塔利班 ＃阿富汗
各節重點：
00:00 前導
01:19「簡訊設計片頭動畫製作」廣告段落
02:04 戰亂的起點：蘇聯入侵阿富汗
03:22 塔利班的崛起
04:19 塔利班席捲全國
04:58 塔利班時期的阿富汗
05:58 塔利班與賓拉登
07:19 重新崛起的塔利班
08:28 阿富汗的未來？
09:17 我們的觀點
11:28 提問
11:46 結尾
【 製作團隊 】
｜企劃：宇軒
｜腳本：宇軒
｜編輯：土龍
｜剪輯後製：絲繡
｜剪輯助理：歆雅
｜演出：志祺
——
【 本集參考資料 】
→Mapping the advance of the Taliban in Afghanistan：https://bbc.in/2XyWsMy
→Mapping the advance of the Taliban in Afghanistan：https://bbc.in/2W3WPOx
→塔利班何以控制今日的阿富汗？誕生自美蘇冷戰的怪物政權崛起之路 - 故事：https://bit.ly/2WcdwHL
→入侵阿富汗的40年傷口：俄羅斯為何重返「帝國墳場」？：https://bit.ly/2W5pHpE
→不死神學士（上）：阿富汗「軍閥亂鬥」下的塔利班崛起 - 轉角國際：https://bit.ly/3mjH1T4
→不死神學士（下）：塔利班是怎麼捲入「恐怖主義」？ - 轉角國際：https://bit.ly/3y56d1w
→阿富汗局勢評論國際深度 喀布爾陷落，塔利班閃電奪權：阿富汗政府為何快速崩盤？：https://bit.ly/3j4svw4
→為什麼這麼快？不到一週塔利班全面奪權 阿富汗如何牽動國際局勢？：https://bit.ly/3B2VVBf
→原來塔利班早與世界打交道！「阿富汗變天」竟因美國長達20年的政治誤判？：https://bit.ly/3gf2zfp
→塔利班首場喀布爾記者會 承諾和平及尊重女權[影]：https://bit.ly/380rU8E
→中國成為塔利班的新朋友 中俄印如何面對阿富汗「改朝換代」：https://bbc.in/3mmFFGW
→莫斯科稱是否承認塔利班政權將根據新政權的作為來決定：https://bit.ly/3gj1YJH
→阿富汗歷史-Wiki：https://bit.ly/385EfIp
【 延伸閱讀 】
→9-11 事件的起點其實是來自上一世紀，冷戰時美蘇在西亞對峙的產物：https://bit.ly/3z2TJJm
→What We, the Taliban, Want：https://nyti.ms/2WaSs46
→記者手記：「在阿富汗戰場上多年的採訪，迫使我質疑國際媒體扮演的角色」：https://bit.ly/3kaeIn9
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map · n.[C]. 地圖；天體圖 · vt. 繪製……的地圖，在地圖上表示出；（為製地圖而）勘測 ... ... <看更多>
中國大陸譯名: 映射. 以mapping 進行詞彙精確檢索結果. 出處/學術領域, 英文詞彙, 中文詞彙. ... <看更多>
mapping 在 mapping中文(繁體)翻譯：劍橋詞典 的相關結果
mapping 翻譯：製作地圖, 製作代表…的圖表, 對基因在染色體上位置的描述, （用以發現大腦的那一部分用來執行某一任務的）定位。了解更多。 ... <看更多>