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--- cn:orx:tutorials:viewport [2010/07/06 05:53 (15 years ago)] – created jtianling
+++ cn:orx:tutorials:viewport [2020/08/19 20:19 (5 years ago)] (current) – Old content sausage
@@ Line 1: / Line 1: @@
-本页由 落后的簔羽鹤 翻译自[[en:orx:tutorials:viewport | 官方的教程]]。
-====== 视口与摄像机 ======
-===== 综述 =====
-前面的基本教程[[cn:orx:tutorials:main|基础]],[[object | 对象创建)]],[[clock| 时钟]] , [[frame| 框架层次结构]] 和 [[anim | 动画]]。
-此教程显示了如何使用有多个摄像机的多视口技术。教程中将同时创建4个视口。
-分别为左上角的（Viewport1），右下角的（Viewport4），它们共用一个摄像机(Camera1)，实现此功能，只需要在配置文件中配置2个视口的Camera属性，为同一个(也就是Camera1)。当我们使用鼠标的左右键旋转摄像机(Camera1),left Control或left Shift键+方向键进行摄像机的缩放操作，关联的两个Viewport1和Viewport4将相应的发生变化。
-右上角视口（Viewport2）是基于另一个摄像机（Camrea2），此摄像机的视锥较第一个窄，所以显示时比例是其的两倍大。在教程的程序中，我们不能通过任何操作设置此视口。
-最后一个视口（Viewport3）是基于Camera3的，Camera3的配置与Camera1完全一样。
-NB：当两个视口重叠，较先创建的将显示在顶层。
-最后，有一个固定不动的箱子和一个世界坐标随着鼠标实时移动的小兵，也就是说无论如何设置视口的摄像机，无论鼠标在那个视口上移动，小兵在它所属的视口中，相对于鼠标在在屏幕中的位置移动。
-在配置文件中使用随机关键字符‘~’,使的视口和基本对象的颜色和大小可以随机创建。
-NB：摄像机将它的坐标/缩放尺度/旋转存放在orxFRAME structure中，在
-[[frame|frame]]教程中我们看到他们是orxFrame hierarchy的一部分。另一方面Object应该置于其Camera所关联的Viewport中。
-===== 详细说明 =====
-常我们需要首先载入配置文件，创建时钟和注册回调的 Update函数，最后创建主要的Object信息。关于实现的详情，请联系前面的教程。
-  虽然这次我们创建了4个视口，却没有什么新东西，仅仅是以下4行代码。
-<code c>pstViewport = orxViewport_CreateFromConfig("Viewport1");
-orxViewport_CreateFromConfig("Viewport2");
-orxViewport_CreateFromConfig("Viewport3");
-orxViewport_CreateFromConfig("Viewport4");</code>
-正如你所看到的，我们只使用了 Viewport1的引用，以便后面进行操作。
-让我们直接跳到Update函数的代码。
-首先我们通过捕捉鼠标的坐标，设置士兵的位置。我们已经在frame tutorial里实现过了。这里我们做了一样的事情，但在4个视口中工作的都很完美。当鼠标离开视口时，世界坐标的指针，将被orxNull值所代替，也就不会触发士兵的移动了。
-<code c>orxVECTOR vPos;
-if(orxRender_GetWorldPosition(orxMouse_GetPosition(&vPos), &vPos) != orxNULL)
-{
-  orxVECTOR vSoldierPos;
-  orxObject_GetWorldPosition(pstSoldier, &vSoldierPos);
-  vPos.fZ = vSoldierPos.fZ;
-  orxObject_SetPosition(pstSoldier, &vPos);
-}</code>
-在操作视口之前，我们先关注下视口所关联的摄像机，我们可以移动，旋转和缩放它。获取摄像机的代码如下所示：
-<code c>pstCamera = orxViewport_GetCamera(pstViewport);</code>
-非常简单。让我们实现旋转。 ((其他方向仅仅只有部分代码，但是逻辑是一样的)).
-<code c>if(orxInput_IsActive("CameraRotateLeft"))
-{
-  orxCamera_SetRotation(pstCamera, orxCamera_GetRotation(pstCamera) + orx2F(-4.0f) * _pstClockInfo->fDT);
-}</code>
-我们再次看到旋转的角度时间并不依赖于FPS而是时钟的DT。我们也可以通过设置System这个配置选项来设置旋转速度，而不是使用硬编码。
-实现缩放如下：
-<code c>if(orxInput_IsActive("CameraZoomIn"))
-{
-  orxCamera_SetZoom(pstCamera, orxCamera_GetZoom(pstCamera) * orx2F(1.02f));
-}</code>
-因为这个代码没有使用时钟信息，所以他将会被时钟频率和帧率所影响。
-最后让我们移动摄像机。
-<code c>orxCamera_GetPosition(pstCamera, &vPos);
-if(orxInput_IsActive("CameraRight"))
-{
-  vPos.fX += orx2F(500) * _pstClockInfo->fDT;
-}
-orxCamera_SetPosition(pstCamera, &vPos);</code>
-We're now done playing with the camera.\\
-As we'll see a bit later in this tutorial, this same camera is linked to two different viewports.\\
-They'll thus both be affected when we play with it.
-As for viewport direct interactions, we can alter it's size of position, for example.\\
-We can do it like this, for example.
-<code c>orxFLOAT fWidth, fHeight, fX, fY;
-orxViewport_GetRelativeSize(pstViewport, &fWidth, &fHeight);
-if(orxInput_IsActive("ViewportScaleUp"))
-{
-  fWidth *= orx2F(1.02f);
-  fHeight*= orx2F(1.02f);
-}
-orxViewport_SetRelativeSize(pstViewport, fWidth, fHeight);
-orxViewport_GetPosition(pstViewport, &fX, &fY);
-if(orxInput_IsActive("ViewportRight"))
-{
-  fX += orx2F(500) * _pstClockInfo->fDT;
-}
-orxViewport_SetPosition(pstViewport, fX, fY);</code>
-Nothing really surprising as you can see.
-Let's now have a look to the data side of our viewports.
-<code ini>[Viewport1]
-Camera            = Camera1
-RelativeSize      = (0.5, 0.5, 0.0)
-RelativePosition  = top left
-BackgroundColor   = (0, 100, 0) ~ (0, 255, 0)
-[Viewport2]
-Camera            = Camera2
-RelativeSize      = @Viewport1
-RelativePosition  = top right
-BackgroundColor   = (100, 0, 0) ~ (255, 0, 0)
-[Viewport3]
-Camera            = Camera3
-RelativeSize      = @Viewport1
-RelativePosition  = bottom left
-BackgroundColor   = (0, 0, 100) ~ (0, 0, 255)
-[Viewport4]
-Camera            = @Viewport1
-RelativeSize      = @Viewport1
-RelativePosition  = bottom right
-BackgroundColor   = (255, 255, 0)#(0, 255, 255)#(255, 0, 255)</code>
-As we can see, nothing really surprising here either.\\
-We have three cameras for 4 viewports as we're using ''Camera1'' for both ''Viewport1'' and '' Viewport4''.\\
-We can also notice that all our viewports begins with a relative size of ''(0.5, 0.5, 0.0)''.
-This means each viewport will use half the display size vertically and horizontally (the Z coordinate is ignored).\\
-In other words, each viewport covers exactly a quart of our display, whichever sizes we have chosen for it, fullscreen or not.\\
-As you may have noticed, we only gave an explicit value for the ''RelativeSize'' for our ''Viewport1''.\\
-All the other viewports inherits from the ''Viewport1'' ''RelativeSize'' as we wrote ''@Viewport1''.\\
-That means that this value will be the same than the one from ''Viewport1'' with the same key (''RelativeSize'').\\
-We did it exactly the same way for ''Viewport4'''s ''Camera'' by using ''@Viewport1''.
-We then need to place them on screen to prevent them to be all displayed on top of each other.\\
-To do so, we use the property ''RelativePosition'' that can take either a literal value ((composed of keywords ''top'', ''bottom'', ''center'', ''right'' and ''left'')) or a vector in the same way we did for its ''RelativeSize''.
-Lastly, the first three viewports use different shades for their ''BackgroundColor''.\\
-For example,
-<code ini>BackgroundColor = (200, 0, 0) ~ (255, 0, 0)</code>
-means the this viewport will use a random ((the '~' character is used as a random operator between two numeric values)) shade of red.
-If we want to color more presicely the ''BackgroundColor'' but still keep a random, we can use a list as in
-<code ini>BackgroundColor = (255, 255, 0)#(0, 255, 255)#(255, 0, 255)</code>
-This gives three possibilities for our random color: yellow, cyan and magenta.
-Finally, let's have a look to our cameras.
-<code ini>[Camera1]
-FrustumWidth  = @Display.ScreenWidth
-FrustumHeight = @Display.ScreenHeight
-FrustumFar    = 1.0
-FrustumNear   = 0.0
-Position      = (0.0, 0.0, -1.0)
-[Camera2]
-FrustumWidth  = 400.0
-FrustumHeight = 300.0
-FrustumFar    = 1.0
-FrustumNear   = 0.0
-Position      = (0.0, 0.0, -1.0)
-[Camera3@Camera1]</code>
-We basically define their [[wp>Viewing_frustum|frustum]] (ie. the part of world space that will be //seen// by the camera and rendered on the viewport).\\
-//NB: As we're using ''2D'' cameras, the frustum shape is [[wp>Cuboid#Rectangular_cuboid|rectangular cuboid]].//
-Note that the ''Camera3'' inherits from ''Camera1'' but don't override any property: they have the exact same property.\\
-//NB: When inheritance is used for a whole section, it's written this way: [MySection@ParentSection].//\\
-Why using two different cameras then? Only so as to have two physical entities: when we alter properties of ''Camera1'' in our code, the ''Camera3'' will remain unchanged.\\
-We can also notice that ''Camera1'''s ''FrustumWidth'' and ''FrustumHeight'' inherits from the ''Display'''s screen settings.\\
-//NB: When inheritance is used for a value, it's written like this ''MyKey = @ParentSection.ParentKey''.\\
-The parent's key can be omitted if it's the same as our key: ''SameKey = @ParentSection''.//
-Lastly we notice that our ''Camera2'' has a smaller frustum.\\
-This means ''Camera2'' will see a smaller portion of the world space. Therefore the corresponding viewport display will look like it's zoomed! =)
-===== Resources =====
-Source code: [[https://orx.svn.sourceforge.net/svnroot/orx/trunk/tutorial/src/05_Viewport/05_Viewport.c|05_Viewport.c]]
-Config file: [[https://orx.svn.sourceforge.net/svnroot/orx/trunk/tutorial/bin/05_Viewport.ini|05_Viewport.ini]]

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