Render to texture

AddRenderTextureCamera makes an entity's camera draw into a texture instead of the window: a rear-view mirror, a security monitor, a minimap. The texture is an ordinary texture: the emissive map of a monitor's material, the fill of a shape, a sprite.

var feed = game.AddRenderTextureCamera(cameraEntity, width: 512, height: 512);

// feed.Texture on anything that takes a texture; feed.Entity is the camera, aim it like any other

E09_3D_RenderToTexture draws five feeds, each on a monitor, and a big screen that shows the selected one. 1 to 5 select a feed and Space steps through them. The ShapeBatch gallery (E11_3D_ShapeBatch_Gallery, station "Second camera in a panel") fills a shape with a feed's texture.

What the call builds

1. A texture that is both a render target and a shader resource.
2. A camera slot of its own in the compositor, with the entity's CameraComponent bound to it. The entity gets a CameraComponent if it has none. The camera's aspect ratio is set to the texture's.
3. A renderer branch appended to the compositor's top-level collection: a SceneCameraRenderer for the slot, wrapping a RenderTextureSceneRenderer for the texture, wrapping a second ForwardRenderer over the compositor's existing opaque and transparent stages. Sharing the stages makes the feed draw the same meshes, particles and shapes as the main view.
4. The handle, RenderTextureCamera: Texture, Entity, Camera, Slot, Renderer and Forward. Dispose it to remove the feed from the compositor and release the texture.

The feed draws after the main view, so the texture holds the previous frame.

Parameter	Default	Description
width, height		The texture size in pixels
format	PixelFormat.R16G16B16A16_Float	The texture format. Keep it HDR unless the feed tone-maps itself: the scene is lit in HDR, so an 8-bit texture saturates to white. An HDR texture is tone-mapped by the main view with everything else it draws
postEffects	null	A callback that configures the feed's post effects. See Post effects on a feed

Note

The feed needs a second ForwardRenderer. The compositor's own renderer is reference-counted and throws AddReference/Release pair must match at shutdown if it is placed under the feed as well.

Post effects on a feed

Each feed has its own forward renderer, so it can have its own post-effects chain.

var thermal = game.AddRenderTextureCamera(cameraEntity, 512, 512,
    postEffects: fx => fx.ColorTransforms.Transforms.Add(new Thermal()));

The callback receives a PostProcessingEffects with every effect switched off. Enable what the feed needs, or add colour transforms. Adding a transform enables the colour-transform group.

Stride.CommunityToolkit.Effects ships two colour transforms in the Stride.CommunityToolkit.Effects.PostProcessing namespace. They also work on the main camera.

Transform	Effect	Properties
NightVision	Amplified luminance in one colour, bright sources bloom to white, moving grain, scanlines and a vignette	Gain (4), Tint (0.2, 1, 0.35), NoiseAmount (0.08), VignetteRadius (0.55)
Thermal	Luminance on a false-colour ramp from dark blue through violet, red, orange and yellow to white	Exposure (2.5): how much of the scene reads as hot

Both run on HDR colour before the tone map, so an emissive object is the brightest thing in the picture. To write a colour transform of your own, see Shaders in a toolkit package.

Limitations

• A colour transform cannot produce a wireframe or a depth view. Those need a rasterizer state or a post effect that reads the depth buffer.
• Every feed is another pass over the scene. Five 512-pixel feeds are cheap; five full-resolution feeds are five extra frames per frame.
• The texture shows the previous frame. A feed that must show the current frame has to be inserted before the main view rather than appended.