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    February 07

    Gamebryo限制4层材质

    由于地形贴图尺寸很大,所以无法使用全局贴图。而是把多层Tiling 的纹理使用alpha通道互相融合起来。诸如WOW[1],天堂2 等大型室外地形渲染多采用此技术。此技术在每一层Tiling 贴图依然用到了一张全局alpha 贴图。以及一张全地形唯一的静态光影贴图。在multitexture 中根据显卡的multitexture 处理单元数量,进行multi-pass 和multitexture 的混合渲染。
    比如,混合绿草,土路,野花的一块室外地形,需要至少3 层地表贴图。分别是一块256x256 的草贴图,128x128 的土路贴图,和128x128 的野花贴图。每层纹理使用Tiling 模式进行绘制,在绘制的同时,每层纹理带有一张ALPHA 灰度图(第一层不用)。用来表明本层纹理在融合中所占的比重。把3 张地表贴图,2 张ALPHA 贴图,以及一张LIGHTMAP贴图混合起来,就有如下地表效果。可以看出土路和草地之间的均匀过渡。

    如果进行优化,4 层ALPHA 可以混合称为一张贴图。Lightmap 一张。那么也至少需要2 张全局贴图进行地表绘制。

    --------------------------------------------------------------------------------------------------------------------------------------------摘自 ID TECH 5

    所以限制4层纹理一般是因为对于一个纹元RGBA,RGB 能代表3 个alpha。而alpha 通道代表阴影。再加上第一层的基础纹理不需要alpha值
    alpha值放入到一张纹理图中,不会因为LOD,而降低混合效果这也是一些引擎限制4层材质的原因。wow 也是4层材质的

    October 10

    杂事两三件

    使用左(右)手拇指指向坐标轴正向,握住坐标轴,4指环绕方向为正方向

    不管是左手右手,行向量还是列向量。矩阵存储基本都是[row][col]形式

    这时该如何建立矩阵呢?
    答案就是区分你用的是行向量还是列向量.

    也许有人会问为什么不区分是左手坐标系还是右手坐标系呢?
    因为矩阵M可以变换到矩阵M1, 那么他们一定是同在左手坐标系或右手坐标系,变换只能在可以互相转换的坐标系之间进行。 这也是为什么gamebryo摄像机朝向X.但最终dx 还是z值判断深度。这也是矩阵变换的结果

    如果你用的是行向量:由于行向量只能左乘矩阵(注意乘与乘以的区别)

    gamebryo 默认模型朝向-Y轴。摄像机看向X轴方向。上方向为Y. 当然变换后的矩阵在z向上世界坐标里面是看向Y轴。

    gamebryo 矩阵和dx矩阵相乘方向相同 Rx * Ry * Rz 先执行Rx,然后 Ry,最后Rz。

    在全屏调试下程序crash原因非常麻烦。设置断点也会导致全屏情况不能切换回桌面。这个有个简单办法就是在断点前加入一个MessageBox操作。通过弹出对话框,从全屏状态恢复到窗口状态。后面就是你的断点了。cool~

    对于NiNode代表的场景图。要节省效率可以做2个场景图。一个放入静态对象。这些对象不需要Update更新。另一个放入动画对象。这个场景图需要一直更新。
    同理对于实体-场景架构也可以用这个办法,但不包括大范围运动物体,如玩家和大范围寻路npc之类。这样会拉大其所在结点的包围体大小

    注意GameBryo 使用的场景图是一种包围体层次结构BHV,这种结构退化的表现就是八叉树。但注意不同于八叉树。可以参考3D游戏编程大师技巧上面的说明。这本书上说包围体层次结构建立可以使用分而治之或者集群技术算法。但GameBryo 并没有使用算法来确定树结构,所以通过程序Node attach 结点方法建立起来的包围体层次结构效率会非常差。而在3dmax里面是通过美术人员手动 group 一下相关网格来组成一个节点层次结构。如果遇到经验不足的,直接所有mesh挂在根结点下。效率也会非常差。不过还好3dmax很多很多操作会自动产生节点,所以通过group相关的(主要是空间相关、效果相关,可参考mout)节点在一起可以提高效能。

    softparticles 写深度到另一个rendertarget
    MeshCreation 使用了floodgate. 波浪由 floodgate 产生
    StandardMaterial 展示了标准的shader

    material 只是引用了 shader 。
    有很多使用光源方法。投射光源等等。

    scene graph bounding Spheres是用摄影机进行裁切。地表系统用了quadtree。

    NiMesh 比 NiGeomentry 有什么不同

    因为floodgate 等的使用,要提供一个更有弹性的系统。 NiMesh 取代之。更多东西可以在Mesh上分享。还有如GPU Instancing等功能。以前有三角形 ,线条等。现在统一为NiMesh

    gamebryo2.5 支持1024*1024地形大小。由于gb对应max是1:1的,这样相当于1平方公里. lightspeed 版本好像没有限制了。这个也可以不是1平方公里。就像魔兽世界一个地形网格代表的是3.333的样子。也不是1.就是说max人物建筑之类的可以缩小到1/3放入地形场景。这样地形就大了。如果要求不太高还可以缩小。
    地形支持4层材质(不是纹理。材质可以是很多纹理的混合。bump map. light map. 等等一个材质信息要丰富很多。如魔兽4个纹理的地形,可能就相当于一个材质如MOUT中的地形材质)。

    RenderStep 相当于一个effect. 如:hdr,dof 等等,游戏场景也是一个effect.相当于 dx 的 d3deffect. 负责 rendertargetgroup

    renderclick 是一个单独的渲染pass.可以设置摄像机和 culler.  一个renderstep的多个renderclick,操作的是相同的rendertargetgroup
    renderview 为 renderclick 提供一些列需要渲染的几何体数据

    对于 .fx 之外的 shader 一般需要一个 .nsf 描述文件,来描述shader文件中的外部变量。在程序中动态更新某个shader内变量如下:

    NiShaderFactory::UpdateGlobalShaderConstant("LightDiffuse",sizeof(afLightDiffuse), &afLightDiffuse);
    如果没有用nsf描述外部变量,可以通过NiShaderFactory::RegisterGlobalShaderConstant()函数来注册 shader 脚本中的外部变量

    注意 NiAplhaAccumulate 对物体是从后向前排序的,这样适合绘制alpha物体,但对于无alpha物体应该从前到后排序,这样减少像素值重复覆盖次数。就像bsp树的做法。 orion 例子里面的 Accumulate 就是这种做法

    NiSortAdjustNode 可以让引擎按节点下面网格顺序来draw alpha 物体而不进行排序操作,但还不清楚在3dmax中这些子网格是如何附加到这个虚拟体上的

    July 11

    Gamebryo/Artist's Guides/Gamebryo 3ds max Plug in/Geometry and Performance

    Introduction to Geometry, Performance, and 3ds Max
    A basic geometric question facing all real-time 3D artists is "How should I construct my scene so that I can maintain great real-time rendering speed?"
    There are numerous factors that affect performance, including how many triangles to use, the number of textures applied to a single surface, and the target platform. The sections that follow discuss these issues in more detail.

    对所有实时3D美工人员面对的基本的几何学问题是"为了维持良好实时渲染速度,我应该怎么构建我的场景?"
    这里有很多因素可能影响性能,包括使用了多少三角形,应用到一个单独平面的纹理贴图的数量,以及目标平台。接下来的章节我们将详细讨论这些问题。

    Terminology
    术语

    The Triangle/Mesh Ratio
    Triangle / Mesh 比值

    Transform-Rate, Fill-Rate
    转换率,填充率

    Clipping & Culling
    剪切和剔除

    Triangle/Mesh Ratios vs. Clipping and Culling
    Triangle/Mesh 比值与剪切和剔除比较

    Grouping
    群组

    Skinning & Morphing
    蒙皮 & 变形

    Cloning and Instancing
    克隆和实例化

    Multi/Sub-Object and Triangle/Mesh Ratios
    Multi/Sub-Object 物体 和 Triangle/Mesh 比值

    Multiple UVs, Smoothing Groups and Vertices
    多重 UVs,光滑群组和定点

    Precache Custom Attributes
    预先缓存定制属性

    Terminology
    术语

    The following section will introduce key terms and phrases that you should understand before discussing geometry.
    接下来的章节将在讨论几何体之前介绍一下你应该理解的一些关键术语和惯用语

    Stripification
    条带化

    This term describes an operation in which a list of independent triangles is transformed into a list of triangles that are linked together in a chain. Although this operation can increase performance, it is mutually exclusive with the Vertex Cache optimization which only operates on triange lists. Vertex cache optimization generally gives better performance results.

    这个术语描述了一个操作,在这个操作中一系列独立的三角被转化成一个三角形条带。尽管这个操作可以提高性能,但它和三角形列表上的顶点缓存优化是互斥的,而顶点缓存优化通常能带来更高的性能。(而且条带化要条带足够长才能优化,而很多三角形不能形成很好的条带)

    Mesh (or NiMesh)
    网格

    This term describes the Gamebryo representation of geometry. A mesh contains all of the per-vertex information about a piece of geometry, including vertex positions, normals, vertex colors, and UV sets. A mesh is usually composed of independent triangle primitives, but if the mesh has been stripified it will be composed of a set of triangle strips.
    这个术语描述了Gamebryo如何表示几何体。一个网格包括一块几何体的所有顶点数据信息,包括顶点位置,发现,颜色,和UV集合。一个网格通常由独立的三角形图元组成,但如果网格被条带化,那么它将由一套三角形条带组成。

    The Triangle/Mesh Ratio

    The triangle to mesh ratio is the most important geometric metric for game performance. The issue with triangles and meshes is that when rendering an mesh, Gamebryo must do a fixed amount of work on the CPU (property-state setup, texture swapping, etc.) each time it passes down the set of triangles, no matter how big. You should, thus, try to pack as many triangles as possible into each mesh.
    三角形对网格的比值对游戏的性能是一个非常重要几何度量。三角形和网格的问题是:当渲染一个网格时,无论每次处理的三角形集合多大,Gamebryo在CPU上必须做固定负荷的工作(属性设置,纹理交换等等) 。一次你应尽可能向每个网格打包更多的的三角形。

    In general, a game should never have fewer than 20 triangles per mesh. You don't have to increase the number of triangles just to improve the triangle/mesh ratio, but if doing so will improve vertex lighting or some geometric detail, it won't hurt the performance. Another way to tackle improving the ratio is to collapse similar meshes with the same materials that are close together in a scene. This collapsed mesh will be converted to a single mesh instead of several separate meshes, thus improving the overall ratio.
    总的来说,一个游戏每个网格不能少于20个三角形。你不需要为了提高三角形/网格比率而特意增加三角形个数,虽然这么做可以提高顶点光照和几何体细节,但不要让他损害性能。另一个途径是折叠在场景中相邻并使用的相同材质的网格。这样折叠的网格将转换成一个单独的网格而不是几个分散的网格,这样将改善原来所有单独网格的比值,让比率获得全面的提高。

    The importance of a large triangle/mesh ratio (i.e. a lot of triangles per mesh) is increased on hardware transform and lighting cards (high-end graphics cards). Hardware transform and lighting cards perform vertex transformation, lighting, and rasterization on the graphics card. Earlier cards could only perform the rasterization while the CPU was forced to do the vertex transformation and lighting.
    增大三角形/网格比率的价值(例如,一个网格拥有大量三角形)随着硬件变换和光照显卡(高端图形显卡??很多年前喽)出现而变得重要。硬件变换和光照(T&L)显卡在显卡端执行顶点变换,光照和光栅化。而早前的显卡只能执行光栅化而cpu被迫执行顶点变换和光照的计算。

    Hardware transform and lighting cards both free the CPU of this task and perform it faster than the CPU ever could. This division of labor decreases the time required to render an individual polygon but leaves the fixed amount of work that Gamebryo must do for each mesh (discussed earlier) unchanged. In a low triangle/mesh situation the CPU will become the bottleneck (doing the rendering setup) and the full rendering capabilities of the graphics card will not be used. In contrast, a high triangle/mesh ratio will allow the graphics card to draw as many polygons as possible and leave the CPU free to perform other operations.
    硬件T&L显卡减少了CPU的这项任务而且比CPU处理的更加迅速。这种分工减少了渲染一个单独多边形的时间,但是留给Gamebryo的每个网格的工作量没有改变。在三角形/网格第比值的较低情况下CPU将变成瓶颈(执行渲染设置操作),而显卡的全部渲染能力没有被用到。相反,三角形/网格高比值将允许显卡尽可能多的绘制三角形从而留给CPU空闲去执行其他工作
    尽可能把相同材质多边形放入同一个网格,而不是无尽的增加网格的三角形面数

    Performance Metrics
    性能标准

    Performance analysis done at nVidia and ATI revealed that on a 1 GHz CPU, you can render 25,000 objects per second before you spend all of your time on the CPU, a circumstance you wish to avoid at almost all costs.
    根据nVida 和 ATI 透漏的性能分析数据,在1GHz CPU 上,当你花费CPU全部时间,你可以每秒钟渲染25000个对象,而这种全部花费的情况是你希望避免的

    What do these statistics mean to an artist? For performance of 60 fps on a 1 GHz CPU, try to keep the number of visible objects in any given scene below 417 objects. In other words, make every object count!
    这个统计对于美工意味着什么呢?为了在1Hz CPU 上保持60fps的性能,应该在场景中控制可见对象少于417个。注意每个物体都要计算

    As the CPU speed of the target machine increases, the number of visible objects that may be rendered per frame will correspondingly increase.
    The following sections will discuss how art content issues could increase or decrease the Triangle/Mesh ratio.
    随着cpu的速度越来越快,每一帧渲染的物体数量也会相对增加。下一章将讨论美工内容如何提高或者减少三角形/网格比值

    Transform-Rate, Fill-Rate
    变换速率,填充速率

    Transform-Rate

    The transform-rate is the number of vertices a graphics card can process in a given time period. When the number of vertices to be transformed (moved, rotated, and lit) per time period exceeds the graphics card's capabilities, an application is said to be "transform limited."

    The following table shows the maximum T&L rate for various PC graphics hardware:
    变换率是指图形显卡在给定的时间周期内处理顶点的个数,如一个周期内变换(平移,旋转,照明)的顶点个数超过显卡的能力,可以说应用程序到达了"变换上限"。下列表格列出了不同的PC显卡最大的T&L的速率:

    Manufacturer & Card

     

    T&L - million vertex/sec

    nVidia GeForce 3

    40

    nVidia GeForce 4 Ti

    136

    NVidia GeForce FX

    200

    nVidia GeForce 6800

    600

    ATI Radeon 8500

    75

    ATI Radeon 9700

    300

    ATI Radeon X800

    780

    These values are, of course, theoretical peaks and do not represent real-world game situations. However, these numbers can be useful in examining performance. If you wish to achieve 60 fps on a GeForce 3, the absolute top amount of vertices you can transform in a frame is 666,666. Let's say that every object you render requires two passes. The theoretical top you could transform is now halved to 333,333 vertices. Mind you, these vertices all belong to one object and are untextured and flat shaded, drawn as optimally as possible with absolutely nothing else happening in the application. No interesting game could ever hope to achieve this situation.
    当然这些理论峰值并且不能代表真实游戏世界情况。但这些数字可以用来检查性能。如果你希望在GeForce 3上达到60fps.能够变换的一帧相对最大顶点数量是666,666。每个对象你需要渲染两次。能够变换顶点的理论最大值将减半为333,333. 注意:这些顶点都属于一个还未纹理化和平坦着色的对象,尽可能优化而且应用程序无任何情况发生。任何游戏都不可能发生这种情况。

    Fill-Rate
    填充率

    Not only is a graphics card limited in the number of vertices it can transform, it is also limited in the number of pixels it can write to the backbuffer per second. The backbuffer is the portion of a graphics card's memory that is used as a scratch pad while the final image is being assembled. When this process of writing to the backbuffer exceeds the graphics card's capability, an application is described as being "fill-rate limited."
    The following chart shows the maximum fill rate for various PC graphics hardware:

    显卡不仅仅在变换顶点的数量方面受到限制, 而且每秒填充到后缓冲区的像素个数也受到了限制。后备缓冲区是显卡显存的一部分,做为正在组装的最终图像便签。当写入后备缓冲区操作超出显卡能力时,应用程序称为"填充率上限"
    下图显示了不同PC显卡最大的填充率

    Manufacturer & Card

     

    Pixel fillrate - million pixel/sec

    nVidia GeForce 3

    800

    nVidia GeForce 4 Ti

    1200

    nVidia GeForce FX

    2000

    nVidia GeForce 6800

    6400

    ATI Radeon 8500

    1100

    ATI Radeon 9700

    2600

    ATI Radeon X800

    8300

    These values are, of course, theoretical peaks and do not represent real-world game situations. However, these numbers can be useful in examining performance. Let's see what we can do with a GeForce 3 at a display resolution of 1024 by 768. We'll assume for the moment that transformation and lighting comes for free (which it never does). 1024 by 768 resolution is 786,432 pixels. We'd like to run at 60 fps, so that involves rendering that 1024 by 768 image 60 times for a grand total of 47.19 million pixels. Assuming each pixel is drawn more than once, the maximum number of pixel writes we can do on each pixel is roughly 17. This, of course, assumes that all operations that write a pixel cost the same. Multitexturing and the complexity of pixel shaders quickly lower this number. Overuse of complex pixel shaders can quickly make an application fill rate limited.
    当然这些理论峰值并且不能代表真实游戏世界情况.但这些数字可以用来检查性能. 让我们看看我们在显示器分辨率1024*768的GeForce 3上能做什么。我们假定此时变换和光照操作免费(这不可能发生)。1024×768 分辨率表示786,432 个像素。我们希望以60fps运行。所以渲染1024×768分辨率图像60次将达到47.19 百万像素。假定每个像素被渲染不止一次,假定所有写入一个像素操作花费相同时间,我们在每个像素上写入的最大次数大约是17次 (800/47)。多纹理和复杂的像素shaders会降低这个数量。过度使用复杂的像素着色器会快速的达到应用程序填充率上限。

    Clipping & Culling
    裁剪和剔除

    The clipping/culling behavior of Gamebryo is another issue that must be kept in mind when creating scene geometry.
    当创建场景几何体时Gamebryo的裁切/剔除行为是另一个需要记在头脑中的问题

    Clipping is the process of dividing polygons into only the fragments that will appear on screen.
    裁切是将多边形分开成可以在屏幕上显示的片断的过程。

    Culling is an attempt to avoid clipping by rejecting whole NiMesh objects if no part of them appears on the screen. In general, culling is preferable to clipping because clipping is vastly more expensive than culling.
    如果物体的任何部分都不出现在屏幕上通过拒绝整个NiMesh对象显示来避免裁切就是剔除。总的来说,剔除比裁切更可取,因为裁切比剔除操作更加昂贵。

    You can structure your scenes to improve culling by limiting the volume of space an NiMesh occupies. A small NiMesh is more likely to be completely off screen while a very large one (e.g. a huge floor) is likely to be, at least, partially on screen all the time.
    通过限制NiMesh占据的空间体积,你可以在构造场景是提高剔除效率。一个小的NiMesh更可能完全离开屏幕而一个非常大的(例如巨型地板)很有可能,至少一部分一直在场景中。

    Triangle/Mesh Ratios vs. Clipping & Culling
    三角形/网格比值 VS 裁切和剔除

    These two issues, the triangle/mesh ratio and the culling/clipping behavior, place somewhat contradictory demands on you. To improve the triangle/mesh ratio you must have the most triangles in a mesh possible (mesh collapsing, increasing the number of triangles in the mesh, etc.). Simultaneously, the meshes must be kept compact to allow for efficient culling. There is no simple solution to this problem and you must constantly balance the two constraints. In general, triangles should be grouped into meshes so that culling will still be effective, but the meshes should contain the most triangles possible.

    For example, when modeling the four walls of a room, if the walls are relatively complex, each wall should be in its own mesh. Having all the walls in a single mesh would improve the triangle/mesh ratio but would force clipping on all the geometry. By dividing the walls into four meshes, two of them will usually be culled leaving the other two to be clipped. However, if the walls were very simple (i.e. 2 triangles each) then it might make sense to clump all the wall triangles together to avoid having several 2 triangle meshes.

    In modern hardware, side plane clipping is avoided as much as possible through various tricks. Near plane clipping remains a problem, however.

    对于这两个问题,三角形/网格比值和裁切/剔除形为,对于你来说处于某种对立的位置。为了改善三角形/网格比值,你必须尽可能让更多的三角形在一个网格中(折叠网格,增加网格中三角形的数量等等)。同时地,网格必须保持紧凑的以允许有效的剔除。对这个问题没有一个简单的解决办法,你必须自己在两个限制间找平衡。总的来说,三角形应该被组合到网格中,这样剔除仍然高效,但网格应该包含尽可能多的三角形。

    例如,当为一个屋子的4面墙壁建模,如果墙壁相对较复杂,每个墙壁应该有它自己的网格。把所有的墙壁放入一个单独的网格中可以改善三角形/网格比值,但是将强迫裁切所有的几何体。通过将墙壁分成4个网格,它们中的两个将总是执行剔除操作,而留下另外两个执行裁切。然而,如果墙壁是非常简单的 (比如每个2个三角形)那么可以考虑将整个墙壁整合起来以避免出现几个拥有两个三角形的网格。

    在现代的硬件中,侧平面(side plane)裁切可以通过多种多样的窍门尽可能避免,然而,近平面(near plane)裁切仍然是一个问题。

    Gamebryo/Artist's Guides/Gamebryo 3ds max Plug in/Geometry and Performance(II)

    Grouping and 3ds Max
    群组和3ds Max

    As with Multi/Sub-Object materials, grouping should be used with care. Everything in a scene in Max has a corresponding node in its scene graph. In Gamebryo, that node is called an NiNode. An NiMesh represents a group of triangles while an NiNode contains a list of children and a list of transforms. Whenever a collection of objects in Max is grouped, the Gamebryo 3ds max plug-in has to add another NiNode to group them together in Gamebryo.

    Indiscriminate use of grouping can have a significant effect on the triangle/mesh ratio. In general, a high-triangle single object has much better frame-rate performance then many objects grouped together.

    同使用Multi/Sub-Object材质一样,群组应该小心使用。在Max场景中的每个东西都有一个对应的节点在它的场景图中。在Gamebryo中,这个节点称为NiNode。一个NiMesh描述了一组三角形而一个 NiNode 包含了一个子结点列表以及一个变换列表。无论何时物体的集合在Max中被群组化,Gamebryo 3ds max插件必须加入另一个NiNode 将它们在Gamebryo中组合起来。

    不加选择的应用群组会对triangle/mesh ratio比率产生重大的影响。总的来说,一个复杂三角形单一对象比许多对象群组在一起,在帧速率上可以获得更好的性能。

    Skinning & Morphing with 3ds Max

    Skinning for Artists

    There are a few important bits of hardware knowledge that a character animator and modeler should be aware of before jumping into skinning a character. The hardware skinning pipeline is broken into two important numbers, the maximum number of bones the hardware can handle and the maximum number of bones that can influence a vertex. Each number has an important role to play in determining how your skinned character will perform in a game.

    The maximum number of bones the hardware can handle by default for most platforms is four. What exactly does this mean? Four is a really small number for a character. Behind the scenes, Gamebryo will break the skinned mesh apart into pieces that obey this limit. These pieces are referred to as skin partitions. For each partition we generate, we have to render the partition's geometry in a separate rendering call. For instance, a skinned character with 28 bones could be broken into 23 partitions in order to obey the maximum bone limit. This means that we are rendering the model in 23 separate pieces. Furthermore, each partition can only be composed of the vertices that use only those bones. If you're not careful in your weight assignments, you could end up with a partition with only one triangle!

    The maximum number of bones influencing a vertex by default on most platforms is also four. This means that a vertex that is influenced by five or more bones will only use the four most influential bones in its skinning. This may result in cracks in sections where many bones come together like the back of the neck and the crotch. Careful modeling and weight assignment will help to minimize this problem. This does not mean that you should always use four bones per vertex. In fact, it is best to use as few weights as are visually acceptable per vertex. This will help substantially when partitioning the mesh because more vertices will be able to fit into a partition.

    What should you take away from this discussion? First off, how you skin your character will directly transfer into performance for that character. Listed below are some useful hints on how to analyze your skinning performance and tips for getting good performance in general.

    • Do not use N-Links when skinning with Physique. Stick with No Blending or 2-Links.

    • Use the SkinAnalyzer plug-in to see how exactly your skin was broken apart into partitions.

    • Use the Skin Weight Threshold export option to drop weights that are trivial. This will greatly improve performance. Be careful to make sure that odd skinning artifacts do not result when this value is raised.

    • Use a pixel/vertex shader for skinning. This can really boost your performance if you can accept the fact that the shader will not work on cards that are not compliant with the version of pixel and vertex shader used. Often you can reduce the partition count to one or two using shaders.

    Physique vs. Skin modifier

    The Gamebryo Max Plug-in supports the two major modifiers for skinning. We have found the recent  versions of Skin to be more reliable and robust then Physique, even when applied to bipeds, however both are supported.

    Gamebryo doesn't support floating bones for physique. If your model requires this capability, we suggest modeling with Skin instead of physique.  In the Physique Level-Of-Detail panel, we only support Rigid Skin Update. When using Deformable, the exporter treats it like Rigid.

    Linking your skinned object

    Do not attach a skin to a bone in the hierarchy below that to which the skin is bound. This causes the mesh to translate twice, once for the skin binding and another for the child translation. You can create a node above the Bip01or base node to which the skin is attached, or use a character node to organize a bone structure and skin together.

    The mesh that has the Skin or Physique modifier uses the bones to determine its bounding volume. The hierarchy is updated by a depth-first traversal of the scene. If the skin occurs before the bones in a depth first traversal of the scene, the skin's bounding volume will lag one frame. Move the skin so that it occurs after the bone hierarchy in a depth first traversal to avoid this problem.

    Scaling your skinned object

    Do not scale a mesh after binding. If you scale a mesh you must unbind it first and rebind it after it has been properly scaled and translated. Scale it first and reset its transforms before you bind it to the bone system for best results.

    Morph and Skin work together

    Even though we support combining skin & morph targets we do not suggest it. If you want to make a character have facial animation morph targets, detach the head from the rest of the body and have it attached to the head bone as a direct link. The head mesh can use a morph target and translate via its relation with the head bone while the body uses a skin or physique modifier. When both modifiers are combined on a mesh it is much slower as all the vertices are being transformed twice, once in software and once in hardware. Please take this into consideration when making characters that have facial expression. See the section on Morphing Faces on Skinned Characters for more information.

    Morph Targets

    The Morph Modifier and Morph compound object are both supported in Gamebryo. We have found the Morph Modifier more reliable then the compound object in Max. Morph is inherently slower than skinning due to the fact that morphing is still done in software. However, there are many things that are easier to do with morph targets than with bone movement. Suggested uses for Morph targets are things like animated flags, facial expression and non-uniform scales.

    Instancing with Skinning and Morphing

    Objects that are skinned or morphed are exported such that clones (instances) are independently controlled and animated. However, when the Mesh Instancing tool plug-in is used, CPU skinned and morphed objects that are instances or exact copies in the Max scene will be exported as hardware instances. As a result, there is only one animated object and every other instance appears exactly the same. Move CPU skinned and morphed instances to another Max scene or use export selected to prevent this behavior when using the Mesh Instancing plug-in.

    Reading Skin Analyizer Plug-in Output

    The following section is a sample output from the skin analyzer plug-in.

    image1

    The model was broken into 23 partitions out of 28 bones. This model will likely perform moderately well. The key problems come around partition 19 in the list. Here we drop below 40 triangles per partition. At this point we are paying a fair amount of overhead for 6 partitions that don't have that many triangles in them. DirectX especially pays for this overhead. Often, this is unavoidable in modeling as some sections are the nexus of many bones and will be prone to small partitions (the neck and groin in particular). In general, the thing to be wary of is when the number of partitions exceeds the number of bones. This is horrible for performance because it also means that many of the partitions are incredibly small.

    Listed below the main chunk of text is a breakdown of each partition. This lists the bones involved in that partition and what the average weights were for that bone. This text can often be useful in pinpointing problem vertices since the bones in that partition would influence them

    Cloning and Instancing with 3ds Max

    3ds Max中的克隆和实例

    Instanced objects in Max are shared in Gamebryo as well. This technique can be extremely useful on memory-starved consoles. Note: If you adjust the pivot or non-uniform scale of an instance, it will become unique. Uniform scale is supported, but non-uniform scale cannot work with instances in Gamebryo because non-uniform scale is baked into the geometry. It should also be noted that instanced objects in Gamebryo must share the same material, unlike in Max. Instanced objects that need different materials should be made unique.

    Max中实例对象可以在Gamebryo很好的共享。这项技术对于内存受限的主机非常的实用。注意:如果你调整轴心点或者不成比例缩放一个实例,它将变得唯一。均匀缩放是被支持的,然而,不能对Gamebryo中实例进行不均匀缩放,因为不均匀缩放会烘培几何体(使几何体发生不规则变形,max有烘培一个操作)。还要注意Gamebryo中的实例对象必须共享相同的材质,这点不同于Max。 需要不同材质的实例对象应该制作成唯一的,不共享的。

    Non-Uniform & Uniform Scale

    不均匀和均匀缩放

    Gamebryo does not support animating non-uniform scales (i.e. scales with different values in the x, y, and z axes). Animating non-uniform scale is not supported and will be treated like a uniform scale when animating. All static non-uniform scales are baked into the geometry data itself.

    If you need to have something non-uniformly scaled or squashed, use a morph target to achieve the action. Morph targets can be created by squashing an object in 3ds max and using Tools / Snapshot to grab a desired morph target.

    Gamebryo不支持动画不均匀的缩放(比如在x,y和z轴上有不同的缩放比例) 。动画的不均匀缩放是不支持的并且在动画中做为等比例缩放的方式来处理。所有静态的不均匀缩放会烘培到几何数据本身。

    如果你需要使某些东西非等比例的缩放或者挤压,应用变形动画修改器对象(morph target)来完成这个任务。变形对象(morph target)可以在3ds max中通过挤压来制作,并应用Tools/Snapshot来获取一个想要的变形体对象(morph target)。

    Multi/Sub-Object and Triangle/Mesh Ratios

    Multi/Sub-对象 和 Triangle/Mesh 比率

    A convenient way of texturing an object in Max is to use the Multi/Sub-Object material. However, Gamebryo only supports one material per mesh because most hardware can only handle one material per set of triangles. When the Gamebryo 3ds max Plug-in encounters a Multi/Sub-Object material it must split the Max Mesh into multiple NiMesh objects (one for each material).

    在Max中贴图一个对象便利的方法是应用Multi/Sub-Object 材质。然而,Gamebryo只支持每个网格一个材质,因为大部分硬件只能为一个三角形集合处理一个材质。当 Gamebryo 3ds max 插件遇到一个Multi/Sub-Object材质,它必须将Max网格分开成多个NiMesh 对象 (每个网格对应一个材质)。

    Over-use of Multi/Sub-Objects is the most common offender in terms of performance in most data sets support receives.
    技术支持收到的大部分性能相关的问题都是和过度使用Multi/Sub-Objects 相关的

    If used indiscriminately, Multi/Sub-Object materials can lay waste to the triangle/mesh ratio and you end up with a single object made of many little pieces. Multi/Sub-Object materials do not need to be completely avoided but they should be used cautiously and with a consideration of the triangle/mesh ratio constraints.

    如果不加选择的使用Multi/Sub-Object材质可能造成triangle/mesh 比率的浪费以及导致一个单独物体被分成很多片。也不是绝对要禁用Multi/Sub-Object材质,但是应该小心的应用并且考虑到triangle/mesh比值的限制。

    When doing characters and discreet objects, the concept of a single texture 'Skin' for the subject is recommended.
    当处理角色和离散物体时,推荐使用"皮肤",它代表一个单独纹理的概念。

    An item made of 1 or 2 objects draws faster than one made of 12 or 13.  This is not to say, "Never use Multi-Subs" as they are very convenient. However, as an example we have received a support question on performance with a single character that had a multi-sub material on it. He was created in such a way that when exported, this single character turned into 42 different objects! This laid waste to performance since each of those 42 objects became individual meshes each with non-trivial overhead.

    一个由一两项组成的对象比由12或13个项组成的画得快。这不是说即使便利也不使用Multi-Subs。对于拥有multi-sub材质的单一角色性能问题,我们收到过一个技术支持的例子。它在导出时以这样的方式进行,这个单一的角色被转换成了42个不同的对象! 这造成了性能浪费,因为这42个对象中每一个都是单独的网格以至于造成了不平凡的开销。

    如果使用了它,Gamebryo exporter就会把一个Mesh分成多个导出。而每一个Mesh都需要一个Draw call来完成渲染。这就影响效率了。
    举个例子,如果你要做一片草地,每棵小草就是一个Model的话,那么就有太多的geometry nodes。从而需要太多的Draw call来渲染。如果把一小片草地组成一个geometry node,Draw call就减少了。因为每一个Draw call都要相应地改变Render state,这就消耗了一定的时间。
    结论应该是,不是不能用(因为有的时候用起来较为方便),而是慎用。用的时侯尽量考虑到对效率的影响。

    对于directx draw call 调用次数也是有限制的。即使函数什么都不做。当然切换渲染状态相对较小。但如果不需要的渲染状态也会影响。如没有用到alpha blend ,但打开了alpha blend 渲染状态。

    更多性能问题参考文档
    http://topameng.spaces.live.com/blog/cns!F962D4854A8233D!352.entry

    Multiple UVs, Smoothing Groups and Vertices

    多重 UVs,平滑群组和顶点

    Another geometric concern is Max's Mesh representation itself. Max can have more than one normal and UV (within a single UV channel) per vertex while real-time engines cannot. To resolve this incompatibility our 3ds max Plug-in will add additional vertices so that the NiMesh created has only one normal and UV per vertex. The NiMesh will look the same as the Max Mesh but will have more vertices. This vertex bloat will push the transform-rate but it is seldom a big problem. Using a lot of smoothing groups or complicated UV Mappings will make the problem worse but some vertex bloat is unavoidable.

    Having things smooth is faster than having things flat shaded. Vertexbloat.max is also a good example of this phenomenon. A 120-triangle sphere with 1 smoothing group has 62 vertices and a flat or un-shaded version has 358 vertices.

    另一个几何上的关注点是Max网格描述本身。Max每个顶点可以拥有超过一个的法线和UV (带一个单独的UV通道) 而实时的引擎却不可以。为解决这种不兼容性的3ds max 插件加入了额外的顶点,所以创建的NiMesh每个顶点只有唯一的法线及UV。NiMesh 看上去将和Max中网格一样但它拥有更多的顶点。这种顶点膨胀将给变换速率造成负担,但是它不是一个大问题。应用很多平滑群组或者复杂的UV Mappings将会加重这个问题,但是一些顶点的膨胀是无法避免的。

    使物体原滑比使他们平坦着色更快些。 Vertexbloat.max也是这个现象的很好的例子。一个120三角面的球带一个平滑的群组拥有62个顶点而一个平坦或者无着色的版本有358个顶点。


    image002

    The test case Vertexbloat.Max demonstrates this effect.

    Box01 has the usual Max UV mapping and a texture map that visualizes the UVs. In Max the vertex at the tip of the pink corner has the three UVs (1,0), (0,0) and (0,1).

    The Gamebryo 3ds max Plug-in will generate three vertices to replace this one Max vertex —one for each UV.  While 3ds max represents Box01 as 12 triangles and 8 vertices, the Gamebryo 3ds max Plug-in will convert this model into 12 triangles and 24 vertices.

    测试例子中 Vertexbloat.Max 演示了这种效果。

    Box01拥有通常的贴图以及一个可视化UV的材质贴图。在Max中在粉色角落顶点上有3个UV(1,0), (0,0) 以及 (0,1)。

    Gamebryo 3ds max 插件产生了3个顶点来代替这个Max中的顶点,每个UV对应一个。虽然3ds max将 Box01 描述成12个三角和8个顶点,但Gamebryo 3ds max 插件将这个模型转化成12个三角和24个顶点。

     

    Mesh Profile Custom Attribute
    网格档案Profile定制属性

    Every piece of geometry has a Mesh Packing Profile associated with it. This is used by the Packer tool plug-in to create the platform-specific geometry streams used by the graphics card. Depending on the situation, it can be necessary for a specific mesh to override the scene default packing profile and use its own profile. To override the scene default packing profile one would click on the "Add/Remove Mesh Profile attribute" button to add a Mesh Profile Attribute to the selected mesh.
    几何体的全部面片拥有一个 Mesh Packing Profile和它相关联。打包插件使用它来创建平台细节几何体流。基于这个情况,使用自定义的Profile覆盖特定网格上的scene default packing profile 是必须的。为了覆盖场景默认的包装profile可以点击 "Add/Remove Mesh Profile attribute"按钮来添加一个网格profile属性到选择的网格上。

    MeshProfileSelection

    For additional information on mesh profiles see Introduction to Mesh Profiles.
    更多关于网格profiles的信息请参考Introduction to Mesh Profiles

    Precache Custom Attributes
    缓存定制属性

    PrecacheCustAttribs The precache attributes serve a similar pupose to the Mesh Profile Custom Attribute. The mesh profile system provies all of the functionality of the precache attributes and more. The precache attribtues still exist in case a user wants precache control without having to author a custom profile as well as for backwards compatibility.

    These custom attributes tell the Gamebryo renderers how to treat an object once they have created the platform-specific versions of it. Creating the platform-specific version is called "pre-caching" the object. In some cases it may be useful for applications to keep information lying around after it has been "pre-cached".

    As an important example, triangle-triangle collision detection will not work if the triangles are thrown away once the renderer has pre-cached its data.

    Typically, artists will not need to add these attributes, since any application that pre-caches geometry, can set the "Keep" flags to hold on to data that is needed, as well. The UI exists so that advanced users can have complete control over how specific art assets are used by the renderers.

    These flags can be added through the user-interface via the Gamebryo toolbar. Click on the "Add/Remove Precache flags" icon.
    缓存属性和Mesh Profile Custom Attribute章节目标相似。网格Profile系统提供了所有的预先缓存属性的功能,甚至更多。预先缓存属性存在目的是,用户想要缓存管理而不想创建一个定制的profile,同时也是为了向后兼容。

    这些定制属性告诉Gamebryo渲染器,在创建平台细节的版本时如何对待对象。创建具体平台版本称为"pre-caching"对象。在某些情况下,应用程序在"pre-cached"之后,保持闲置信息是十分有用的。
    一个重要的例子,如果渲染器在预存数据后扔掉了三角形数据,那么三角形对三角形的碰撞检测就不能工作。
    一般而言,不需要美工来添加这些属性,因为预先缓存几何体的应用程序,可以设置"keep"标志来保持它需要的数据。这个UI保留着,以便让高级用户能够完全控制特定的美术资源如何被渲染器使用。

    这些标志这些标志可以通过用户界面的 Gamebryo toolbar 加入。点击 "Add/Remove Precache flags" 图标。

    Geometry Data Consistency
    几何数据一致性

    This radio button allows you to set how the renderer treats the data at runtime. "Default" sets the consistency to whatever Gamebryo best determines the data to be. "Static" means that once the data is in the renderer it will never change. This is a good setting for set pieces like buildings. "Mutable" means that the object may change from time to time. This would be useful for an application effect like changing a car's geometry to reflect hits it has taken on the road while driving. "Volatile" means that the object changes every frame. This setting is best set for when you are changing vertex colors on the fly or manually animating the UV coordinates.
    这个单选按钮允许用户设定渲染器在实时状态下如何处理数据。"Default" 由Gamebryo 来决定数据的一致性。"static" 指一旦数据进入了渲染器将不再改变。这个选项是用于设定类似建筑物的部件的好选择。"Mutable"意味着对象可能偶尔发生变化。比如需要表现出一辆汽车在驾驶过程中因碰撞发生形状改变效果,这时这个选项对应用程序就十分有用了。"Volatile"意味着这个对象每一帧都要发生改变。当你正在改变顶点颜色或者手工动画绘制UV坐标时,这个选项就是最好的选择。

    Data To Preserve
    保留的数据

    These check boxes allow the user to set which data is kept around after the "pre-cache" has occurred.

    这些复选框允许用户设定哪些数据在 "pre-cache"后需要保留下来。

    June 06

    terrain

    对于2.3地形是通过max或者maya导出来的网格。可能只有地形。而花草树木等等地面上的东西要在场景里面加入,然后拼接在一起。2.5 说有场景编辑器开始自带地形编辑器。不知道是否好用

    gamebryo release 与 ship 区别

    The Release builds include optimizaed code, but with the NiMemory system, NiMetrics, and release mode logging enabled. The Shipping builds do not have these systems enabled.
    ship 和 release 工程设置基本相同,但没有NiMemory、NiMetrics、release mode logging.更像是非常稳定之后的版本
    release 还会产生记录内存泄漏的xml。这个文件会越来越大。
    ship 对类内变量初始化与release有些不同,印象中一个bug:一个变量在release未初始化然后乘0正常为0,但在ship中结果不为0.faint
    June 04

    Gamebryo2.2 8*00系列显卡调试错误

    Debug fails with 8600GT

    Hi, I am getting assertions in my debug builds when using Geforce 8600GT. Everything was working fine when using 6600GT...
    I can only debug using the release version now
    I'm using Gamebryo 2.2.2.0 (24th Jan 2007)
    Graphics driver: 6.14.11.102 (I tried 158.22 too)
    DX SDK: Aug2006
    The following was from Debug version of Tutorial01.
    The assert message:
    Assertion failed!
    Program: ...
    File: m:\gamebryo2.2rc_win32_src_build...\nidx9s...esc.cpp
    Line: 88
    Expression: eType == D3DMULTISAMPLE_NONMASKABLE || uiResult == 1
    The call stack:
           msvcr80d.dll!_wassert(const wchar_t * expr=0x007b14e0, const wchar_t * filename=0x007b1560, unsigned int lineno=88)  Line 384      C
    >      Tutorial01.exe!NiDX9DeviceDesc:DisplayFormatInfo:DisplayFormatInfo()  + 0x1b3 bytes      
           Tutorial01.exe!NiDX9DeviceDesc::NiDX9DeviceDesc()  + 0x22d bytes      
           Tutorial01.exe!NiDX9AdapterDesc::NiDX9AdapterDesc()  + 0x272 bytes      
           Tutorial01.exe!NiDX9SystemDesc::FillAdapterInformation()  + 0xe1 bytes      
           Tutorial01.exe!NiDX9SystemDesc::NiDX9SystemDesc()  + 0x4b bytes      
           Tutorial01.exe!NiDX9Renderer::GetSystemDesc()  + 0xcf bytes      
           Tutorial01.exe!NiDX9Renderer::Initialize()  + 0xda bytes      
           Tutorial01.exe!NiDX9Renderer::Create()  + 0x113 bytes      
           Tutorial01.exe!Renderers::CreateRenderer()  Line 35 + 0x33 bytes      C++
           Tutorial01.exe!NiApplication::Initialize()  + 0x59 bytes      
           Tutorial01.exe!_WinMain@16()  + 0x2e0 bytes      
           Tutorial01.exe!__tmainCRTStartup()  Line 578 + 0x35 bytes      C
           Tutorial01.exe!WinMainCRTStartup()  Line 403      C
           kernel32.dll!7c816fd7()      
           [Frames below may be incorrect and/or missing, no symbols loaded for kernel32.dll]      


    The GeForce 8*00 series exposes multisample capabilities in a different way than other graphics cards, which causes older versions of Gamebryo to hit this assertion. The bug was fixed in Gamebryo 2.3.

    So are we saying that any applications built on Gamebryo 2.2 can't be debugged if using an 8000 series card? I have been getting the same error and finally found this post. We probably won't be getting Gamebryo 2.3 for another 1 or 2 months so I'd be grateful if anyone knows of a workaround for this. I'd really like to be able to debug my software, but still run the new graphics card. Any possible workarounds?

    If you have a copy of Gamebryo 2.3 lying around, you could move the NiDX9SystemDesc.h, .inl, and .cpp files from 2.3 into your copy of 2.2. You'll need to change any instances of "NIASSERT" to "assert", and there may be other minor changes necessary as well, but fixing this bug was the only significant change to occur in those files between those two branches.

    May 30

    GameBryo 笔记

    很久以前就申请了Google 笔记本,还一直没有使用。现在先用它来记录 GameBryo 一些知识点。而且笔记本是可以多人一起修改的,谁想修改给我留言哈。地址:
    http://www.google.com/notebook/public/12209111529083700989/BDRCSIwoQ3dOhhNQi?hl=__MSG_locale__

    May 29

    GameBryo2.2 SceneDesigner 不能启动

    装了gb 2.2 之后又安装了 gb2.3 而启动2.3 的场景编辑器之后 2.2 就不能启动了。因为这两个程序用的配置文件放入了相同的目录,并且有相同的名字,这样2.2 加载时发现版本不对,就会启动失败。
    删除文件
    C:\Documents and Settings\你的用户名\Local Settings\Application Data\Emergent Game Technologies\Gamebryo Scene Designer\tool.settings
    C:\Documents and Settings\All users\Local Settings\Application Data\Emergent Game Technologies\Gamebryo Scene Designer\tool.settings

    开始还以为是.net 框架打补丁影响了。一通狂卸载、最后vc2005、office 2007 都卸掉了,熬到了3点。看来得补习c#了。如果能熟练应用它,调试一下就可以更早发现这个问题

    May 09

    编译 gamebryo2.3 Tutorial

    使用vc2003 编译gamebryo教程时,因为有dx 10 不能通过编译.
    在 d3d10.h 中加入:

    #pragma warning( disable: 4049 )  /* more than 64k source lines */ 
    //加入这后面的内容
    #define   __out /**/
    #define   __in  /**/
    #define  __inout

    #define   __in_opt /**/
    #define   __out_opt /**/
    #define   __inout_opt   /**/

    #define   __in_ecount(THING)   /**/
    #define   __in_ecount_opt(THING)   /**/
    #define   __out_ecount(THING)   /**/
    #define   __out_ecount_opt(THING)   /**/
    #define   __inout_ecount(THING)   /**/
    #define   __inout_ecount_opt(THING)   /**/

    #define   __in_bcount_opt(THING)   /**/
    #define   __out_bcount_opt(THING)   /**/
    #define   __inout_bcount_opt(THING)   /**/

    #define   WINAPI_INLINE   WINAPI
    或者下载 Windows Server 2003 R2 Platform SDK from March 2006,这个sdk就有点大了

    引擎好像没有renderstate 切换管理,搞得用dx debug 调试输出了很多warning,很是不爽(太多了难免影响调试,尽管这个不怎么影响效率),想dx改似乎不太现实。突然想起那句:凡人的智慧啊。还能要求什么,三流的引擎唉!
    更正:gamebryo 没有quake3那样的renderstate 切换,但系统还是有一个Renderstate 重复设置相同值的判断设置的,至于debug输出的重复设置,应该是第一次设置的renderstate值和显卡内部默认值相同了。这个应该是resetdevice时设置的。影响不大