Simplify render_to_texture examples (#14855)

# Objective

- The examples use a more verbose than necessary way to initialize the
image
- The order of the camera doesn't need to be specified. At least I
didn't see a difference in my testing

## Solution

- Use `Image::new_fill()` to fill the image instead of abusing
`resize()`
- Remove the camera ordering

examples/3d/render_to_texture.rs

@@ -5,12 +5,11 @@ use std::f32::consts::PI;
 use bevy::{
  prelude::*,
  render::{
- render_resource::{
- Extent3d, TextureDescriptor, TextureDimension, TextureFormat, TextureUsages,
- },
+ render_resource::{Extent3d, TextureDimension, TextureFormat, TextureUsages},
  view::RenderLayers,
  },
 };
+use bevy_render::render_asset::RenderAssetUsages;
 
 fn main() {
  App::new()
@@ -41,24 +40,16 @@ fn setup(
  };
 
  // This is the texture that will be rendered to.
- let mut image = Image {
- texture_descriptor: TextureDescriptor {
- label: None,
- size,
- dimension: TextureDimension::D2,
- format: TextureFormat::Bgra8UnormSrgb,
- mip_level_count: 1,
- sample_count: 1,
- usage: TextureUsages::TEXTURE_BINDING
- | TextureUsages::COPY_DST
- | TextureUsages::RENDER_ATTACHMENT,
- view_formats: &[],
- },
- ..default()
- };
-
- // fill image.data with zeroes
- image.resize(size);
+ let mut image = Image::new_fill(
+ size,
+ TextureDimension::D2,
+ &[0, 0, 0, 0],
+ TextureFormat::Bgra8UnormSrgb,
+ RenderAssetUsages::default(),
+ );
+ // You need to set these texture usage flags in order to use the image as a render target
+ image.texture_descriptor.usage =
+ TextureUsages::TEXTURE_BINDING | TextureUsages::COPY_DST | TextureUsages::RENDER_ATTACHMENT;
 
  let image_handle = images.add(image);
 
@@ -100,8 +91,6 @@ fn setup(
  commands.spawn((
  Camera3dBundle {
  camera: Camera {
- // render before the "main pass" camera
- order: -1,
  target: image_handle.clone().into(),
  clear_color: Color::WHITE.into(),
  ..default()

examples/ui/render_ui_to_texture.rs

@@ -7,11 +7,10 @@ use bevy::{
  prelude::*,
  render::{
  camera::RenderTarget,
- render_resource::{
- Extent3d, TextureDescriptor, TextureDimension, TextureFormat, TextureUsages,
- },
+ render_resource::{Extent3d, TextureDimension, TextureFormat, TextureUsages},
  },
 };
+use bevy_render::render_asset::RenderAssetUsages;
 
 fn main() {
  App::new()
@@ -38,24 +37,16 @@ fn setup(
  };
 
  // This is the texture that will be rendered to.
- let mut image = Image {
- texture_descriptor: TextureDescriptor {
- label: None,
- size,
- dimension: TextureDimension::D2,
- format: TextureFormat::Bgra8UnormSrgb,
- mip_level_count: 1,
- sample_count: 1,
- usage: TextureUsages::TEXTURE_BINDING
- | TextureUsages::COPY_DST
- | TextureUsages::RENDER_ATTACHMENT,
- view_formats: &[],
- },
- ..default()
- };
-
- // fill image.data with zeroes
- image.resize(size);
+ let mut image = Image::new_fill(
+ size,
+ TextureDimension::D2,
+ &[0, 0, 0, 0],
+ TextureFormat::Bgra8UnormSrgb,
+ RenderAssetUsages::default(),
+ );
+ // You need to set these texture usage flags in order to use the image as a render target
+ image.texture_descriptor.usage =
+ TextureUsages::TEXTURE_BINDING | TextureUsages::COPY_DST | TextureUsages::RENDER_ATTACHMENT;
 
  let image_handle = images.add(image);
 
@@ -65,8 +56,6 @@ fn setup(
  let texture_camera = commands
  .spawn(Camera2dBundle {
  camera: Camera {
- // render before the "main pass" camera
- order: -1,
  target: RenderTarget::Image(image_handle.clone()),
  ..default()
  },