If your application’s framebuffer orientation doesn’t match the display’s native orientation (portrait, for most devices), Android needs to apply an additional rotation every time a rendered frame appears on the screen. This additional rotation might incur a performance cost, depending on the device’s hardware capabilities.
In most cases, you can apply this rotation during renderingThe process of drawing graphics to the screen (or to a render texture). By default, the main camera in Unity renders its view to the screen. More info
See in Glossary with very little overhead. To do this, navigate to the Android Player SettingsSettings that let you set various player-specific options for the final game built by Unity. More info
See in Glossary (see also: PlayerSettings.vulkanEnablePreTransform) and enable Apply display rotation during rendering.
Note: The rotation only applies when Unity renders directly to the backbuffer. It has no effect when rendering to a Render TextureA special type of Texture that is created and updated at runtime. To use them, first create a new Render Texture and designate one of your Cameras to render into it. Then you can use the Render Texture in a Material just like a regular Texture. More info
See in Glossary.
To apply the rotation, Unity modifies the projection matrix (UNITY_MATRIX_MVP, UNITY_MATRIX_P). This means that the rotation itself is applied in the vertex shaderA small script that contains the mathematical calculations and algorithms for calculating the Color of each pixel rendered, based on the lighting input and the Material configuration. More info
See in Glossary.
The preTransform setting doesn’t affect the behavior of Unity’s C# API. For example, the value of Screen.width doesn’t change because of the preTransform setting. The same applies to viewportsThe user’s visible area of an app on their screen.
See in Glossary and scissor rects. Unity adjusts these as needed, and also handles readback operations from the backbuffer such as Grab Pass, ReadPixels, or Screenshot.
Unity provides utility macros to handle special cases in shaders (for more information, see the Known limitations section below).
The macro UNITY_PRETRANSFORM_TO_DISPLAY_ORIENTATION is only defined if all of the following conditions are true (otherwise, it’s undefined):
preTransform is enabled in the Player SettingsUNITY_DISPLAY_ORIENTATION_PRETRANSFORM is a constant that is set to the current preTransform rotation. Its value is one of the following:
If UNITY_PRETRANSFORM_TO_DISPLAY_ORIENTATION is undefined, or when rendering to a Render Texture, the value of UNITY_DISPLAY_ORIENTATION_PRETRANSFORM is UNITY_DISPLAY_ORIENTATION_0.
UNITY_DISPLAY_ORIENTATION_PRETRANSFORM is translated into a Vulkan specialization constant, which makes it efficient to use in if or switch statements.
In the following cases, it’s likely that enabling preTransform requires additional modifications to your Unity Project before you can use it:
SV_Position)These cases only apply when rendering directly to the backbuffer.