No more staging buffer; generic buffer doubles as staging

src/engine/Skybox.zig

@@ -10,7 +10,6 @@ const vm = @import("vecmath");
 const CommandBuffer = @import("CommandBuffer.zig");
 const Engine = @import("Engine.zig");
 const GenericBuffer = @import("GenericBuffer.zig").GenericBuffer;
-const StagingBuffer = @import("StagingBuffer.zig");
 const Swapchain = @import("Swapchain.zig");
 const Texture = @import("Texture.zig");
 
@@ -69,15 +68,21 @@ pub fn load(
 
     // --- LOAD IMAGE INTO STAGING BUFFER --------------------------------------
 
-    var staging_buffer = try StagingBuffer.init(.{
-        .capacity = @intCast(img.width * img.height * @sizeOf(vm.ColorHdr)),
+    var staging_buffer = try GenericBuffer(vm.ColorHdr).init(.{
+        .usage = .staging,
         .target_queue = .compute,
+        .mappable = true,
+        .capacity = img.width * img.height,
     });
     defer staging_buffer.deinit();
 
-    const staging_memory = try staging_buffer.map();
-    @memcpy(staging_memory, @as([*]const u8, @ptrCast(img.data)));
-    staging_buffer.unmap();
+    {
+        const staging_memory = try staging_buffer.mapSlice();
+        defer staging_buffer.unmap();
+
+        @memcpy(staging_memory, img.data);
+        try staging_buffer.flush(0, img.width * img.height);
+    }
 
     // --- CREATE EQUIRECTANGULAR IMAGE ----------------------------------------