3.8 Structural Support【結(jié)構(gòu)性支撐】

This emitter shows how one can produce multistaged emitters.

Splitting an effect up into multiple stages allows one to isolate blocks of complex functionality to the areas where they are needed.

In this case, we place particles and seperate them from each other's volumes. We then create a support structure and pass that off to a third and final runtime emitter. It benefits from all of the preprocessed tasks that were run before it without accumulating their complexity.

【此發(fā)射器展示如果制作多階段發(fā)射器】

【將一個效果拆分成多個階段可將復(fù)雜的功能塊隔離到需要它們的區(qū)域】

【在此示例，我們放置粒子并將它們從彼此的體積中分離出來。然后我們創(chuàng)建一個支撐結(jié)構(gòu)，并傳給最后運行的發(fā)射器。這有利于讓它跳過之前已運行的預(yù)處理任務(wù)，而不用積累它們的復(fù)雜性】

Stage 1: Place particles【階段1：放置粒子】

We would normally kill these particles after a few frames of initialization took place and the particles were duplicated in another emitter. In this case, we retain them for visualization purposes.

【我們通常會在初始化發(fā)生過后再過幾幀就清除粒子，這些粒子會被復(fù)制到另一個發(fā)射器。在此示例，我們?yōu)榱丝梢暬康亩Ａ羲鼈儭?/p>

The global distance field only extends 3500 units outward in the advanced Niagara map so we cull particles that reference it beyond that point.

【在高級Niagara地圖中全局距離場僅向外延伸3500個單位，所以我們剔除超過該距離還引用距離場的粒子】

Init the PBD grid【初始化PBD網(wǎng)格】

Use this as an opportunity to perform as much complex position work that one might want.

【使用這作為一個時機來執(zhí)行獲得想要的更復(fù)雜的位置】

For visualization purposes, we dupe off and offset Particles.Position to a position variable that will be read by the renderer. This is done to make it visually distinct from the other emitters.

【為了可視化目的，我們復(fù)制并偏移粒子位置到一個渲染器讀取的位置變量。這樣做是為了清楚地從其他發(fā)射器外看見粒子】

Ensure that the particles don't clip through each other by running a Position Based Dynamics simulation.

【使用基于位置的物理模擬來確保粒子不會相互重疊】

Stage 2: Create a Heirarchy【階段2：創(chuàng)建層級結(jié)構(gòu)】

Wait a few frames and transfer the particles over to this emitter

【等幾幀后轉(zhuǎn)換粒子到此發(fā)射器】

Generate attribute readers for this emitter and the previous

【生成讀取前發(fā)射器和此發(fā)射器的屬性讀取器】

Spawn the same number of particles as the previous emitter

【生成與前發(fā)射器數(shù)量相同的粒子】

Copy and apply key information from the previous emitter (position, etc.)

【復(fù)制和應(yīng)用前發(fā)射器的關(guān)鍵信息，如粒子位置】

Dupe and offset the render location variable to differential it from the other emitters

【復(fù)制和偏移渲染位置變量到不同的發(fā)射器位置】

Sort and rank neighboring particles based 3 factors.

- How close are they?

- Does the direction from this particle to the other particle line up with the desired direction vector?

- Are the parent-child references non-circular? (Two particles shouldn't point toward each other)

We return 3 particle ids ranked from the best option to the worst. Id 1 being the best.

We then select one of those 3 options and define a "parent id".

【基于3個因素給相鄰粒子排序和分等級】

【它們有多近？】

【是否在搜索向量附近？】

【父級-子級引用是非循環(huán)的？（兩個粒子不應(yīng)該相互指向?qū)Ψ剑?/p>

【我們返回3個由好到差排序的粒子ID。ID1是最好的】

【然后我們選擇其中一個并把它定義為父級ID】

Stage 3：Animate the Particles【階段3：使粒子運動】

Create a larger neighbor grid for this emitter because the particles will travel for longer distances.

【給此發(fā)射器創(chuàng)建一個更大的相鄰網(wǎng)格，因為粒子會漫游更遠距離】

In this example, we perform a number of ops that allow us to find correlations between this emitters particles and the previous emitter's particles. This allows us to recreate the bonds that were formed in the previous emitter.

【在此示例，我們執(zhí)行一些操作，它允許我們找到前發(fā)射器粒子與此發(fā)射器粒子的關(guān)聯(lián)。這允許我們重新建立前發(fā)射器的聯(lián)系】

This module randomly activates a do once which then gets used to detach partcles from their constraints.

【此模組隨機激活一個執(zhí)行一次，這隨后用于分離粒子的限制】

Collide particles against each other

【粒子相互碰撞】

Collide particles against the world

【粒子與場景碰撞】

Propagate detatchment: Each particle reads it's parent's particle supported parameter. If it is false, then this particle also unsupported.

【傳播分離：每個粒子讀取它們的父級粒子的支撐參數(shù)。如果為False，此粒子也不支撐】

"Freeze" supported particles by ignoring their forces, velocity and position updates. Lerp to the actively simulated positions when they are no longer supported.

【通過無視支撐粒子的受力，速度和位置更新來凍結(jié)它們。當(dāng)它們不再支撐時線性插值到激活模擬位置】

Each particle becomes its own parent once it's no longer supported. This is done to avoid drawing lines between detached particles. Note that this occurs in the Set Particles.ParentID module.

【一旦粒子不再支撐，每個粒子變成它們自己父級。這樣做是為了避免分離粒子間畫線。注意此發(fā)生在設(shè)置粒子父級ID模組】

Do Once【執(zhí)行一次】模組

Execute【執(zhí)行】為True持續(xù)一幀，然后一直為False，直到開啟Reset

Trigger Condition【觸發(fā)器狀態(tài)】：為True時才能使Execute為True

Reset【重置】