texture freeing + render updates done a bit nicer

src/render/texture.rs

@@ -1,28 +1,43 @@
 use image::{DynamicImage, EncodableLayout};
 use wgpu::{util::DeviceExt, *};
 
-use crate::TextureUpdates;
+use crate::{TextureUpdate, Textures};
 
 pub struct GpuTextures {
     device: Device,
     queue: Queue,
     views: Vec<TextureView>,
     samplers: Vec<Sampler>,
+    null_view: TextureView,
     no_views: Vec<TextureView>,
 }
 
 impl GpuTextures {
-    pub fn apply(&mut self, updates: TextureUpdates) -> bool {
-        if let Some(images) = updates.images {
-            for img in images {
-                self.add_view(img);
+    pub fn update(&mut self, textures: &mut Textures) -> bool {
+        let mut changed = false;
+        for update in textures.updates() {
+            changed = true;
+            match update {
+                TextureUpdate::Push(image) => self.push(image),
+                TextureUpdate::Set(i, image) => self.set(i, image),
+                TextureUpdate::Free(i) => self.free(i),
             }
-            true
-        } else {
-            false
         }
+        changed
     }
-    fn add_view(&mut self, image: &DynamicImage) {
+    fn set(&mut self, i: u32, image: &DynamicImage) {
+        let view = self.create_view(image);
+        self.views[i as usize] = view;
+    }
+    fn free(&mut self, i: u32) {
+        self.views[i as usize] = self.null_view.clone();
+    }
+    fn push(&mut self, image: &DynamicImage) {
+        let view = self.create_view(image);
+        self.views.push(view);
+    }
+
+    fn create_view(&self, image: &DynamicImage) -> TextureView {
         let image = image.to_rgba8();
         let (width, height) = image.dimensions();
         let texture = self.device.create_texture_with_data(
@@ -44,17 +59,18 @@ impl GpuTextures {
             wgt::TextureDataOrder::MipMajor,
             image.as_bytes(),
         );
-        let view = texture.create_view(&TextureViewDescriptor::default());
-        self.views.push(view);
+        texture.create_view(&TextureViewDescriptor::default())
     }
 
     pub fn new(device: &Device, queue: &Queue) -> Self {
+        let null_view = null_texture_view(device);
         Self {
             device: device.clone(),
             queue: queue.clone(),
             views: Vec::new(),
             samplers: vec![default_sampler(device)],
-            no_views: vec![null_texture_view(device)],
+            no_views: vec![null_view.clone()],
+            null_view,
         }
     }