Attention: Here be dragons
This is the
(unstable) version of this documentation, which may document features
not available in or compatible with released stable versions of Godot.
Think of a Viewport as a screen onto which the game is projected. In order to see the game, we need to have a surface on which to draw it. That surface is the Root Viewport.
SubViewports are a kind of Viewport that can be added to the scene so that there are multiple surfaces to draw on. When we are drawing to a SubViewport, we call it a render target. We can access the contents of a render target by accessing its corresponding texture. By using a SubViewport as render target, we can either render multiple scenes simultaneously or we can render to a ViewportTexture which is applied to an object in the scene, for example a dynamic skybox.
SubViewports have a variety of use cases, including:
所有这些用例的共同点是, 你被赋予了在纹理上绘制物体的能力, 就好像它是另一个屏幕一样, 然后可以选择如何处理产生的纹理.
Another kind of Viewports in Godot are Windows. They allow their content to be projected onto a window. While the Root Viewport is a Window, they are less flexible. If you want to use the texture of a Viewport, you'll be working with SubViewports most of the time.
Viewports are also responsible for delivering properly adjusted and scaled input events to their children nodes. By default SubViewports don't automatically receive input, unless they receive it from their direct SubViewportContainer parent node. In this case, input can be disabled with the Disable Input property.
For more information on how Godot handles input, please read the Input Event Tutorial.
Godot supports 3D sound (in both 2D and 3D nodes). More on this can be found in the Audio Streams Tutorial. For this type of sound to be audible, the Viewport needs to be enabled as a listener (for 2D or 3D). If you are using a SubViewport to display your World3D or World2D, don't forget to enable this!
摄像机（2D 和 3D）¶
CameraA will display on the Root Viewport and it will draw
will be captured by the SubViewport along with
MeshB. Even though
MeshB is in the scene
hierarchy, it will still not be drawn to the Root Viewport. Similarly,
MeshA will not
be visible from the SubViewport because SubViewports only
capture nodes below them in the hierarchy.
SubViewports have a size property, which represents the size of the SubViewport in pixels. For SubViewports which are children of SubViewportContainers, these values are overridden, but for all others, this sets their resolution.
It is also possible to scale the 2D content and make the SubViewport resolution different from the one specified in size, by calling:
sub_viewport.set_size_2d_override(Vector2i(width, height)) # Custom size for 2D. sub_viewport.set_size_2d_override_stretch(true) # Enable stretch for custom size.
For information on scaling and stretching with the Root Viewport visit the Multiple Resolutions Tutorial
For 3D, a Viewport will contain a World3D. This is basically the universe that links physics and rendering together. Node3D-based nodes will register using the World3D of the closest Viewport. By default, newly created Viewports do not contain a World3D but use the same as their parent Viewport. The Root Viewport always contains a World3D, which is the one objects are rendered to by default.
A World3D can be set in a Viewport using the World 3D property, that will separate all children nodes of this Viewport and will prevent them from interacting with the parent Viewport's World3D. This is especially useful in scenarios where, for example, you might want to show a separate character in 3D imposed over the game (like in StarCraft).
As a helper for situations where you want to create Viewports that display single objects and don't want to create a World3D, Viewport has the option to use its Own World3D. This is useful when you want to instance 3D characters or objects in World2D.
It is possible to query a capture of the Viewport contents. For the Root Viewport, this is effectively a screen capture. This is done with the following code:
# Retrieve the captured Image using get_image(). var img = get_viewport().get_texture().get_image() # Convert Image to ImageTexture. var tex = ImageTexture.create_from_image(img) # Set sprite texture. sprite.texture = tex
_ready() 中使用, 或者从 Viewport 的 初始化的第一帧开始使用, 你会得到一个空的纹理, 因为没有什么可以作为纹理获得. 你可以用来处理它, 例如:
# Wait until the frame has finished before getting the texture. await RenderingServer.frame_post_draw # You can get the image after this.
Due to the fact that the Viewport is an entryway into another rendering surface, it exposes a few
rendering properties that can be different from the project settings. You can
choose to use a different level of MSAA for each Viewport. The default behavior is
If you know that the Viewport is only going to be used for 2D, you can Disable 3D. Godot will then restrict how the Viewport is drawn. Disabling 3D is slightly faster and uses less memory compared to enabled 3D. It's a good idea to disable 3D if your viewport doesn't render anything in 3D.
If you need to render 3D shadows in the viewport, make sure to set the viewport's positional_shadow_atlas_size property to a value higher than
Otherwise, shadows won't be rendered. By default, the equivalent project setting is set to
4096 on desktop platforms and
2048 on mobile platforms.
Godot also provides a way of customizing how everything is drawn inside Viewports using Debug Draw.
Debug Draw allows you to specify a mode which determines how the Viewport will display things drawn
inside it. Debug Draw is
Disabled by default. Some other options are
Wireframe. For a full list, refer to the Viewport Documentation.
Debug Draw = Disabled (default): The scene is drawn normally.
Debug Draw = Unshaded: Unshaded draws the scene without using lighting information so all the objects appear flatly colored in their albedo color.
Debug Draw = Overdraw: Overdraw draws the meshes semi-transparent with an additive blend so you can see how the meshes overlap.
Debug Draw = Wireframe: Wireframe draws the scene using only the edges of triangles in the meshes.
Debug Draw modes are currently not supported when using the Compatibility rendering method. They will appear as regular draw modes.
When rendering to a SubViewport, whatever is inside will not be visible in the scene editor. To display the contents, you have to draw the SubViewport's ViewportTexture somewhere. This can be requested via code using (for example):
# This gives us the ViewportTexture. var tex = viewport.get_texture() sprite.texture = tex
Every frame, the Viewport's texture is cleared away with the default clear color (or a transparent
color if Transparent BG is set to
true). This can be changed by setting Clear Mode to
As the name implies, Never means the texture will never be cleared, while next frame will
clear the texture on the next frame and then set itself to Never.
By default, re-rendering of the SubViewport happens when
its ViewportTexture has been drawn in a frame. If visible, it will be
rendered, otherwise, it will not. This behavior can be changed by setting Update Mode to
When Parent Visible.
Never and Always will never or always re-render respectively. Once will re-render the next frame and change to Never afterwards. This can be used to manually update the Viewport.
This flexibility allows users to render an image once and then use the texture without incurring the cost of rendering every frame.
Make sure to check the Viewport demos. They are available in the viewport folder of the demos archive, or at https://github.com/godotengine/godot-demo-projects/tree/master/viewport.