Particle3D.htm 17 KB

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  1. <html xmlns:MSHelp="http://msdn.microsoft.com/mshelp" xmlns:msxsl="urn:schemas-microsoft-com:xslt" xmlns:xanx="http://schemas.microsoft.com/developer/xanx/2005"><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><meta name="save" content="history" /><title>Particle 3D Sample</title>
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  260. non-scrolling header region. */
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  282. /* Adds right padding for all blocks in mainBody */
  283. div#mainBody p, div#mainBody ol, div#mainBody ul, div#mainBody dl
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  287. div#mainBody div.alert, div#mainBody div.code, div#mainBody div.tableSection
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  291. div.alert p, div.code p
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  296. /*- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Begin Note Styles - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -*/
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  308. div#mainSection div.alert table td
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  313. img.note
  314. {
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  317. margin-right: 3;
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  319. /*- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - End Note Styles - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -*/
  320. /*- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Begin Non-scrolling Header Region Styles - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -*/
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  335. margin-bottom: 0;
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  342. /* Applies to cells in both tables in the non-scrolling header region. */
  343. div#header table td
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  353. /* Applies to the last row in the upper table of the non-scrolling header region. Text
  354. in this row includes See Also, Constructors, Methods, and Properties. */
  355. div#header table tr#headerTableRow3 td
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  358. padding-top: 5;
  359. padding-left: 15;
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  361. /* Applies to the lower table in the non-scrolling header region. Text in this table
  362. includes Collapse All/Expand All, Language Filter, and Members Options. */
  363. div#header table#bottomTable
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  371. blockquote
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  375. margin-top: .6em;
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  378. sup
  379. {
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  383. a:link
  384. {
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  386. /* font-weight: bold */
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  388. a:visited
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  404. .tl
  405. {
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  408. .atl
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  413. .cfe
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  417. .mini
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  421. .dt
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  425. .indent
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  428. margin-right: 1.9em;
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  430. .product
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  433. color: #333333;
  434. font-size: smaller;
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  442. top: 2;
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  446. .buttonbartable
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  457. /* background color, font for header */
  458. table.buttonbartable td, table.buttonbarshade td
  459. {
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  467. table.buttonbartable td.button1
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  473. cursor: hand;
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  475. table.buttonbartable td.button2
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  478. font-weight: bold;
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  481. table.buttonbartable td.button3
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  484. font-weight: bold;
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  490. font-style: italic;
  491. text-align: left;
  492. }
  493. .version
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  499. font-size: smaller;
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  502. .lang, .ilang
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  533. padding: 4px 4px 8px 26px;
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  538. div.filtered h1, div.filtered h2, div.filtered h3, div.filtered h4
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  541. }
  542. div.filtered span.lang
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  546. }
  547. div.reftip
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  552. visibility: hidden;
  553. border: 1px solid #000000;
  554. background: #ffffd0;
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  556. a.synParam
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  559. /*color: #3F7800;*/
  560. /*color: #8DC54F;*/
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  564. a.synParam:hover
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  569. div.sapop
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  574. width: 100%;
  575. padding: 10px 10px 10px 36px;
  576. visibility: hidden;
  577. border: 1px solid #000000;
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  580. div.footer
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  583. border: none;
  584. background: #ffffff;
  585. margin-top: 18pt;
  586. padding-bottom: 12pt;
  587. color: #0000FF;
  588. /*color: #228B22; */
  589. text-align: center;
  590. font-size: 76%;
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  592. div.preliminary
  593. {
  594. margin-top: 8pt;
  595. padding-bottom: 12pt;
  596. color: #A0A0A0;
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  598. /* A procedure section. eg. 'To create a file', 'To add a value' */
  599. div.proc
  600. {
  601. margin-left: 0.5em;
  602. }
  603. /* The title of a 'procedure' section. */
  604. div.proc h3
  605. {
  606. font-family: Verdana, Arial, Helvetica, sans-serif;
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  608. font-size: 115%;
  609. margin-top: 1em;
  610. margin-bottom: 0.4em;
  611. margin-left: -0.5em;
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  615. {
  616. margin-left: 1.5em;
  617. }
  618. div.proc ol
  619. {
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  621. }
  622. .note
  623. {
  624. margin-left: 14pt;
  625. margin-right: 12pt;
  626. }
  627. .indent1
  628. {
  629. margin-left: 12pt;
  630. }
  631. .indent2
  632. {
  633. margin-left: 24pt;
  634. }
  635. .indent3
  636. {
  637. margin-left: 36pt;
  638. }
  639. p.proch
  640. {
  641. padding-left: 16px;
  642. }
  643. p.proch img
  644. {
  645. position: relative;
  646. vertical-align: top;
  647. left: -18px;
  648. margin-right: -14px;
  649. margin-bottom: -18px;
  650. }
  651. div.clsPlatSpec
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  653. background-color:#FFF8DC;
  654. border-style:solid;
  655. border-width:1pt 0pt 0pt 1pt;
  656. border-color:#ffE4C4;
  657. margin-top:0.6em;
  658. width:100%;
  659. }
  660. /* Applies to the language labels in the Language Filter drop-down list. */
  661. .languageFilter
  662. {
  663. color: #0000FF;
  664. cursor:hand;
  665. text-decoration:underline;
  666. padding-bottom:4;
  667. }
  668. /* Dropdown areas */
  669. #languageSpan {
  670. position: absolute;
  671. visibility: hidden;
  672. border-style: solid;
  673. border-width: 1px;
  674. border-color: #C8CDDE;
  675. background: #d4dfff;
  676. padding: 4px;
  677. font-size: 70%;
  678. }
  679. #membersOptionsSpan {
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  681. visibility: hidden;
  682. border-style: solid;
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  701. </head><body><div id="mainSection"><div id="mainBody">
  702. <h1>Particle 3D Sample</h1>
  703. <p>
  704. This sample shows how to implement an efficient 3D particle system. It animates the particles entirely on the graphics card by using a custom vertex shader, so it can draw large numbers of particles with minimal CPU overhead.
  705. The sample builds on the ideas introduced in the 2D Particle sample, showing how those principles can be extended to work in 3D and optimized through the use of shaders. If you are unfamiliar with the concept of a particle system, you should start with the simpler implementation in the 2D Particle sample.
  706. </p>
  707. <a id="ID2EN" name="ID2EN"> </a><h1 class="heading">Sample Overview</h1><div id="ID2EN" class="hxnx1">
  708. <p>When displaying large numbers of particles, games can easily become bottlenecked by the amount of CPU work involved in updating everything and transferring the latest particle positions across to the GPU for drawing. This sample avoids that by animating particles entirely on the GPU. The CPU overhead remains low regardless of how many particles are active. Moving eye candy to the GPU leaves the CPU free for other things such as gameplay, physics, or AI.</p>
  709. <p>When a new particle is created, the CPU fills a vertex structure with the position, velocity, and time at which the particle was created. After this vertex is uploaded to the GPU, the CPU never needs to touch it again. Every frame, the current time is set as a vertex shader parameter. When the GPU draws the particles, it can work out the age of each one by comparing the creation time (which is stored as part of the vertex data) with the current time. Knowing the starting position, velocity, and age, the shader can then compute the current position and draw a billboard quad at this location.</p>
  710. <p>New particles are always added to the end of the vertex buffer, and old ones are removed from the start. Because all particles last the same amount of time, this means the active particles will always be grouped together in a consecutive region of the buffer, and so can all be drawn in a single call. The CPU is responsible for adding new particle vertices to the end of the buffer, and for retiring old ones from the start, but it does not need to do anything with the active particles in the middle of the buffer. Even games with thousands of particles typically only create and retire a few each frame, so the resulting CPU workload is very low.</p>
  711. <p>Although this sample works in 3D, the same code can be used for efficient 2D particle systems by setting an orthographic matrix as the camera projection.</p>
  712. <a id="ID2EZ" name="ID2EZ"> </a><h2 class="subHeading">Sample Controls</h2><div id="ID2EZ" class="hxnx2">
  713. <p>This sample uses the following keyboard and gamepad controls.</p>
  714. <table>
  715. <tr>
  716. <th>Action</th>
  717. <th>Keyboard control</th>
  718. <th>Gamepad control</th>
  719. </tr>
  720. <tr>
  721. <td>Switch the particle effect</td>
  722. <td>SPACEBAR</td>
  723. <td>
  724. <b>A</b>
  725. </td>
  726. </tr>
  727. <tr>
  728. <td>Rotate the model</td>
  729. <td>
  730. <p>UP ARROW, DOWN ARROW, LEFT ARROW, and RIGHT ARROW</p>
  731. <p>
  732. or <b>W</b>, <b>S</b>, <b>A</b>, and <b>D</b>
  733. </p>
  734. </td>
  735. <td>Right thumb stick</td>
  736. </tr>
  737. <tr>
  738. <td>Zoom</td>
  739. <td>
  740. <b>Z</b> and <b>X</b>
  741. </td>
  742. <td>Triggers</td>
  743. </tr>
  744. <tr>
  745. <td>Reset</td>
  746. <td>
  747. <b>R</b>
  748. </td>
  749. <td>Right thumb stick press</td>
  750. </tr>
  751. <tr>
  752. <td>Exit the sample</td>
  753. <td>ESC or ALT+F4</td>
  754. <td>
  755. <b>BACK</b>
  756. </td>
  757. </tr>
  758. </table>
  759. </div>
  760. </div>
  761. <a id="ID2EWD" name="ID2EWD"> </a><h1 class="heading">How the Sample Works</h1><div id="ID2EWD" class="hxnx1">
  762. <p>
  763. When you add new textures for a particle system, XNA Game Studio defaults them to create a texture with the <b>Color</b> format and without mipmaps. Textures without mipmaps look bad and are inefficient when drawn in 3D. You should change the <b>Texture</b> processor properties on these textures to set <b>Generate Mip Maps</b> to true and <b>Texture Format</b> to <b>DxtCompressed</b>.
  764. </p>
  765. <p>This sample does not sort the particles in any way. That would be too inefficient. The resulting artifacts are usually too subtle to be a problem, but you can see some sorting problems if you look at the smoke plume from certain angles.</p>
  766. </div>
  767. <a id="ID2EME" name="ID2EME"> </a><h1 class="heading">Extending the Sample</h1><div id="ID2EME" class="hxnx1">
  768. <p>
  769. To make the particle systems easier to tweak, the <b>ParticleSettings</b> data could be loaded from an XML configuration file.
  770. </p>
  771. <p>There are no cats in this sample. It would be cool if one could jump through the burning hoop.</p>
  772. </div>
  773. </div><div class="footer" id="footer"><p>© 2010 Microsoft Corporation. All rights reserved.<br />Send feedback to <a href="mailto:[email protected]?subject=Documentation Feedback: Particle 3D Sample">[email protected]</a>.</p></div></div></body></html>